Institute for Telecommunication Sciences

1998 Technical Progress Report

U.S. Department of Commerce William M. Daley, Secretary Larry Irving, Assistant Secretary for Communications and Information

Certain commercial equipment, components, and software are identified in this report to adequately describe the design and conduct of the research and experiments at ITS. In no case does such identification imply rec­ ommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment, components, or software identified is necessarily the best available for the particu­ lar applications or uses.

111 Contents

Page

Disclaimer 111

The ITS Mission 1

Overview 2

Spectrum Planning and Assessment 5 Domestic Spectrum Analysis 6 Spectrum Compatibility Testing 8 Spectrum Occupancy Measurements 10 Spectral Assessment of Government Systems 12 Radio Frequency Interference Monitoring System 14 Modulation Bandwidth Requirements 16 ITU-R Activities 18

Telecommunication Standards Development 21 Video Quality Standards Development 22 Audio Quality Standards Development 24 Broadband Network Standards 26 Telecommunication Terminology Standards 28 Wireless Standards Support 30 Law Enforcement Telecommunication Standards 32 ITU-T Standardization Activities 34

Telecommunication System Planning 37 DOC Telecommunications Planning 38 Intelligent Transportation Systems Planning 40 Railroad Telecommunication Planning 42 Telecommunications Analysis Services 44 Augmented Global Positioning System 46 Low-Cost HF Automatic Link Establishment 48

IV Page

Telecommunication System Performance Assessment 51 Radio System Design and Performance Software 52 Satellite Studies 54 Multimedia Performance Handbook 56 Wireless Telephony Performance Measurements 58 Applied Research 61 Cooperative Research with Industry 62 Millimeter-wave Research 64 Adaptive Antenna Testbed 66 Wireless System Modeling and Simulation 68 HF Channel Modeling and Simulation 70 Wireless Propagation Research 72 Impulsive Noise and Digital Systems 74 Electromagnetic Compatibility Research 76 Advanced Radio Technologies 78 ITS Tools and Facilities 81

ITS Projects in FY 1998 91

ITS Publications in FY 1998 97

Publications Cited 106

Abbreviations/Acronyms 107

v . I

ITS antennas on the roof of the Department of Commerce Boulder Laboratories (p hotograph by FH Sanders) .

Vl The ITS Mission

The Institute for Telecommunication Sciences (ITS) Federal agencies, state and local Governments, pri­ is the chief research and engineering arm of the vate corporations and associations, and international National Telecommunications and Information organizations. Administration (NTIA). ITS supports such NTIA telecommunications objectives as promotion of Cooperative research agreements based upon the advanced telecommunications and information infra­ Federal Technology Transfer Act of 1986 are the structure development in the United States, enhance­ principal means of aiding the private sector. This ment of domestic competitiveness, improvement of Act provides the legal basis fo r and encourages foreign trade opportunities for U.S. telecommunica­ shared use of Government facilities and resources tions firms, and facilitation of more efficient and with the private sector in advanced telecommunica­ effective use of the radio spectrum. tions technologies. These partnerships aid in the commercialization of new products and services. ITS also serves as a principal Federal resource fo r solving the telecommunications concerns of other

Advanced Communications Te chnology Satellite (A CTS) antenna (ph otograph by FH. Sanders) .

1 Overview

The Institute for Te lecommunication Sciences (ITS), Telecommunication Systems Planning: located in Boulder, Colorado, is the chief research The Institute relates the needs of users with and engineering arm of the National Telecommuni­ present and futuretelecommunication tech­ cations and Information Administration (NTIA) of nologies to assist in the development of the U.S. Department of Commerce. ITS employs organizational plans for the effective use of individuals with substantial engineering and scientif­ telecommunications. ic skills and experience to support our technical pro­ grams. The majority of our employees are electron­ Telecommunication System Performance ics engineers, with a complement of mathematicians, Assessment: The Institute forecasts the perform­ physicists, computer scientists, and computer pro­ ance of individual communication elements in a grammers. ITS' support during the 1998 fiscal year system, and tests and measures systems in a lab­ consisted of $4.4 million of direct funding from the oratmy or operational environment. Depatiment of Commerce and approximately $5.2 million for work sponsored by other Federal Telecommunications Standards Development: Government agencies and U.S. industry. The Institute contributes to and develops Federal, national, and international telecom­ munications standards. History ITS began in the 1940s as the Interservice Radio Applied Research: The Institute models radio Propagation Laboratory, which later became the wave travel frompoint to point in various fre­ Central Radio Propagation Laboratory (CRPL) of quency bands and evaluates the way informa­ the National Bureau of Standards of the Department tion is carried by radio signals. of Commerce. In 1965, CRPL became part of the Environmental Science Services Administration and Benefits was renamed the Institute for Telecommunication The Institute's research significantly benefits both Sciences and Aeronomy (ITSA). In 1967, the the public and private sectors in several areas: telecommunications function of ITSA was trans­ fer red into the newly formed Officeof Telecom­ Spectrum Utilization: Optimization of Federal munications (OT). Finally, under the President's spectrum allocation methods, identification of Reorganization Act #1 of 1977, OT and the Office unused frequencies and potential interference of Telecommunications Policy merged to form through field measurements, and promotion of NTIA. Since that time, ITS has performed telecom­ technology advances to aid in efficientuse of munications research and provided technical engi­ the spectrum. neering support to NTIA and to other Federal agen­ cies on a reimbursable basis. Over the last decade, Telecommunications Negotiations: Expert tech­ ITS has pursued cooperative research with U.S. nical leadership at international conferences and industry under the provisions of the Federal development of negotiation suppmi tools such Technology Transfer Act of 1986. as interference prediction programs.

Activities International Trade: Promulgation of nomestric­ tive international telecommunications standards The Institute performs telecommunications research, to remove technical barriers to U.S. export of planning, and engineering in the fo llowing areas: telecommunications equipment and services.

Spectrum Planning and Assessment: The Domestic Competition: Development of user­ Institute analyzes spectrum use in selected oriented, technology-independent methods of fr equency bands and prepares U.S. technical measuring telecommunications performance to positions for international spectrum allocation give users a practical way of comparing com­ conferences. peting equipment and services.

2 National Defense: Improvement of network improving the performance of Federal and private operation and management, enhancement of telecommunication networks, developing domestic survivability, expansion of network interconnec­ and internationaltelecommunications standards for tions and interoperation, and improvement of networks, and evaluating new technologies for emergency communications that contribute to future needs. the strength and cost-effectiveness of the U.S. Armed Forces. The ITS Executive Officemanages administrative matters. The Executive Office also manages the Technology Transfer: Direct transfer of research Institute's budget and program-planning functions results and measurements to U.S. industry and and interacts with various administrative offices Governments to support national and interna­ within other parts of the Department of Commerce tional competitiveness, hasten the advent of new to meet its payroll, procurement, personnel, facilities technology to users, and expand the capabilities management, civil affairs, and publications needs. of national and global telecommunications infrastructures. Sponsors Activities at the Institute are undertaken thr ough a Outputs combination of programs sponsored by the Depart­ Major outputs of the Institute's research and engi­ ment of Commerce and other Government agencies, neering activities include: and through cooperative research agreements with the private sector. The Institute's policy provides Engineering Tools and Analyses: Predictions of that research sponsored by other agencies result in transmission media conditions and equipment contributions to and reinforcement ofNTIA's overall performance; test design and data analysis of program and must be directed toward supporting the computer programs; and laboratory and field goals of the Department of Commerce. Various tests of experimental and operational equip­ agencies within the Department of Defense provide ment, systems, and networks. the maj ority of the Institute's fundingfr om other agencies. Other sponsors include the Department of Standards, Guidelines, and Procedures: Contri­ Transportation, the Federal Aviation Administration, butions to and development of national and and the National Institute of Standards and international standards in such areas as network Technology. interconnection and interoperation, performance evaluation, and information protection. Cooperative research agreements with telecommuni­ cation-operating companies imd manufacturers sup­ Research Results: Mathematical models for port technology transfer and commercialization of electromagnetic wave propagation, noise, and telecommunications products and services, which interference characterization. are maj or goals of the Department of Commerce. ITS has cooperative research agreements with large Expert Services: Training courses and work­ established companies as well as small, start-up shops to communicate technology advances and companies. Partnerships such as these enhance syn­ applications to industry and Government users. ergies between entrepreneurial ventures and broad national goals. Organization ITS is organized into two program divisions: Because of its centralized Federal position, ITS is Spectrum Research and Analysis, and Systems and able to provide a cost-effective, expert resource that Networks Research and Analysis. The Spectrum supports many Federal agencies and industry organi­ Division concentrates on analyses directed toward zations. ITS provides scientific research and engi­ understanding radio wave behavior at various fr e­ neering that is critical to continued U.S. leadership quencies, determining methods to enhance spectrum in providing telecommunications and information use, and predicting and improving the performance equipment and services. This Progress Report sum­ of existing and emerging technologies. The Systems marizes technical contributions made by ITS during and Networks Division fo cuses on assessing and Fiscal Year 1998 to both the public and private sectors.

3 Ve rtical antenna array used by ITS adaptive antenna testbed (ph otograph by FH. Sanders) .

4 Spectrum Planning and Assessment

NTIA is responsible for managing the Federal ing effective EMC mitigation techniques and effi­ Government's use of the radio spectrum and is the cient long term solutions; and helping to develop President's advisor on telecommunications. NTIA's improved spectrum management tools that promote responsibilities include establishing policies on spectrum efficiency and maximize the usefulness of spectrum use - directed toward ensuring that the spectrum-based systems. ITS provides technical sup­ spectrum provides the maximum benefit to all users, port for NTIA in the development and advocacy of while continuing to accommodate new users and the United State's position at international spectrum new services. conferences. Decisions made at these bodies signifi­ cantly affect spectrum use in the United States and ITS supports these activities by performing theoret­ worldwide. Major impacts occur in U.S. export mar­ ical studies and spectrum measurements directed kets and interoperability of global communication toward assessing present spectrum use and predict­ systems. ITS develops software and hardware to ing future spectrum requirements; identifying exist­ support Federal spectrum management. Many of ing and potential electromagnetic compatibility these products are also useful to the private sector (EMC) problems among radio sy stems; recommend- and are available on a reimbursable basis.

Areas of Emphasis

Domestic Spectrum Analysis The Institute assists in the development of national radio policies by assessing current spectrum use and predicting the impact of new technologies and policies. Projects are fundedby the Department of Transportation (DOT) and NTIA.

Spectrum Compatibility Testing The Institute helps to prevent interference in new and existing spectrum applications through measurement and analysis of potential interferers and potential victim systems. Projects are fundedby AAMA and NTIA.

Spectrum Occupancy Measurements The Institute performs usage measurements across a wide range of spectrum services and environments to understand trends in spectrum crowding and opportunities to support new services. Projects are funded by FAA and NTIA.

Spectral Assessment of Government Systems The Institute performs emission measurements on radio systems as required to verify properoperation or to identify and mitigate interference in operational and plannedsystems. Projects are funded by NTIA.

Radio Frequency Interference Monitoring Systems The Institute provides expertise in the design and development of radio monitoring systems to Federal agencies that use such systems. Projects are fundedby FAA and NTIA.

Modulation Bandwidth Requirements The Institute develops improved mathematical models to examine digital modulation techniques from the perspectives of spectrum efficiency and adjacent channel interference. Projects are fundedby NTIA.

ITU-R Activities The Institute assists in the development of international regulations, tools and techniques, and policies for using the radio spectrum through participation and chairmanships in the working groups of the International Telecommunications Union-Radiocommunications Sector. Projects are fundedby NTIA.

5 Domestic Spectrum Analysis

Outputs Up-to-date information on the Fixed Services is imp01iant to government spectrum regulators like Fixed Services report progress. NTIA, because some of these Fixed Service bands are considered possible candidates for reallocation Participation in 706 Petition and broadband to new wireless services. Even when such drastic alternatives studies. reallocations are not contemplated, many bands must contend with proposed new sharing ar rangements Spectrum Use Rights report draft. with various new satellite services. The updated ITS study of 30 Fixed Service bands is expected to be Television coverage studies. published in FY 99. Study of use of higher wireless fr equencies. Based largely on research aimed at understanding developments in the Fixed Services, the Institute During FY 1998 ITS provided technical inputs to was able to supply NTIA with information on alter­ NTIA in numerous areas related to domestic spec­ native means to deliver broadband access, which trum policies and actions. In many cases, the Insti­ was an important issue in the FCC "706 petition" tute's intended role was to add a solid technical concerning regulation of local exchange carriers engineering perspective to issues that often require (LECs). The existing ITS knowledge of broadband being examined from many angles. digital wireless technologies was extended to include wireline access such as power line carriers, Work continued on a revision to a 1993 report on the various digital subscriber line (xDSL) systems from Fixed Services, which historically have consisted the telephone companies, digital cable techniques, mainly of the traditional point-to-point microwave and various optical fiber configurations. links. However, recent developments are rapidly adding new categories of services, many of which Institute staff participated with NTIA staff in operate in new frequency bands. New services like extended discussions aimed at developing improved Teligent's wireless local loop (WLL) at 24 GHz, the spectrum management techniques and policies. As a recently auctioned cellular cable (LMDS) at 28 partial outgrowth of this effort, Institute staff have GHz, and Winstar's "wireless fiber" at 38 GHz are prepared a draf t document proposing a series of among the more visible recent entries. spectrum use rights, as related to interference issues. The maj or goal of this paper is to help formulate These new services differ fr om existing services in joint FCC/NTIApolicies on interference. More several ways. First, they all operate in frequency detailed and explicit interference policies are needed bands that were until recently considered to be much to help spectrum users make full use of the extra too high for widespread consumer applications. flexibility that has been allowed in most of the Second, although these services each originally bands where licenses have been recently auctioned. started out to provide various individual traditional services (e.g., consumer TV, individual telephone ITS staff have continued to provide technical service, wideband digital telephone trunks), they all assistance to NTIA and the FCC on numerous issues appear to be morphing into a single generalized related to broadcast TV. For example, the Institute broadband digital service (the great digital conver­ provided more accurate terrestrial broadcast TV gence). Third, they are all trying to become success­ coverage maps to show regions of adequate signal ful competitors of the local telephone companies and coverage frombroadcast TV stations. These maps cable TV companies, a development with great were needed, because the present FCC regulations implications for the entire telecommunications regu­ state that direct broadcast satellite (DBS) companies latory environment. And, finally, this is all happen­ cannot provide network TV programming to any ing in the Fixed Services, which many observers viewers who can adequately receive the same net­ believed were becoming obsolete because of com­ works directly over-the-air from the local TV sta­ petition from optical fiber. tions. The TA Services facility (see pp. 44-45 and pp. 87-88) provided 200+ detailed terrain-based

6 I I Spectrum Planning and Assessment I

(Langley-Rice) coverage maps fo r selected TV sta­ ITS staff completed work on a report that described tions in all U.S. TV markets. These coverage maps why higher fr equency bands are suitable fo r many have been placed on the ITS website at types of wireless systems. This tutorial paper was written to dispel a widespread (but often fa lse) belief http :// flattop .its.bldrdoc.gov / gifs_ ntia /gi fs index.htm that modem wireless services must be located at­ providing an independent technical means for poten­ frequencies below 3 GHz. A major premise of the tial satellite customers to document whether they paper is that systems using higher fr equencies need can receive the local TV broadcasting stations. to be engineered differently from traditional systems Though the FCC has scheduled extensive future implemented at lower frequencies. The key is to rec­ hearings on these regulations, this ITS capability has ognize the differences and to design the system to provided useful information while the difficultpoli­ exploit the unique advantages available at higher cy issues are debated. frequencies.

80000

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60000 Misc. • 18 GHz 50000 11 GHz 40000 10.5 GHz

• 6 GHz 30000 D 4 GHz

• 2 GHz 20000 D 10000

0 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

Common carrier licenses, showing the migration fr om the 4 GHz band to the 6 GHz band, caused by incompatibility with 4 GHz satellite downlinks.

Recent Publication For more information, contact: J.M.Vanderau, R.J. Matheson, and E.J. Haakinson, Robert J. Matheson "A technological rationale to use higher wireless (303) 497-3293 fr equencies," NTIA Report 98-349, April l998. e-mail [email protected]

7 Spectrum Compatibility Testing

Outputs fmm and characteristics of the proposed interferer are poorly known, the second type of generator may Development of the NTIA Broadband Arbitrary be used. This device, the Broadband Noise Waveform Transmitter (BAWT) for electro­ Generator (BBNG) produces a noise-like signal at magnetic compatibility (EMC) testing at field the frequency of interest with a bandwidth deter­ sites. mined by the investigator. This signal is typically directly coupled into the target system for measure­ Development of a radar signal simulation ment purposes. capability for EMC testing at field sites, and used in tests with a fixed wireless access Using the BAWT, ITS personnel participated in a system. cooperative project with engineers of the Joint Spectrum Center in Arlington, Virginia to test the Development of the Broadband Noise Generator effects of an existing frequency agile naval radar (BBNG) for interference and EMC testing in system on a proposed commercial fixed wireless laboratory environments, and application to access network which utilized a portion of the same global positioning system (GPS) interference spectrum and was scheduled for deployment. The tests. BAWT was configured to simulate the complex waveforms produced by the naval radar including Electromagnetic compatibility (EMC) problems fre­ such characteristics as fr equency hopping, pulse quently arise when new-technology systems are width modulation and phase shiftke ying. This signal deployed in proximity to existing ones. In the past, was fed into the receivers of the system under test these problems have often been dealt with more along with the desired signal, and the degree of sig­ reactively than proactively. But large investments in nal degradation versus interference was measured. new and existing systems make it desirable to per­ The results of these tests will provide valuable fo rm preliminary tests and measurements at field guidelines to designers of similar systems in the sites with transmitters that replicate the signal emis­ future. sions of new and proposed transmitter systems. For cases involving Governmenttransmitters and The BAWT was also used in a slightly different con­ receivers, ITS has developed two types of general­ figuration to evaluate the effects of interference purpose interference transmitters that can produce between a sophisticated communications system cur­ radiated waveforms identical to those produced by rently in use by U.S Armed Forces and Personal radars and other radio transmitter systems. Use of Communications Services (PCS) telephones of sev­ these transmitters in such tests is necessary in cases eral different types. In this research the BAWT was in which a potential interferer may be unavailable used to simulate signals fr om the Joint Tactical for use (such as transmitters on ships or aircraft), or Information Distribution System (JTIDS) which may still be in the early stages of development, or were radiated into various types of cellular phones may be too expensive to install unless assurances to assess their vulnerability to interference from this can be provided in advance that such an installation source. Using the BAWT allowed the generation of will not be the cause or the victim of EMC problems signals at carrier frequencies significantly different with other systems. from those normally used by JTIDS but within the bands in current use for cellular phone transmis­ The first system is known as the Broadband sions. This project was done in support of a study by Arbitrary Waveform Transmitter (BAWT) and can the NTIA Office of Spectrum Management (OSM) be used to simulate the spectral output of a wide to determine the feasibility of allocating new spec­ variety of radar and communication systems. BAWT trum space fo r PCS usage in bands currently occu­ signals can be coupled directly into a system under pied by military users. Results from these tests, test, or can be transmitted into the target system's which were accomplished within less than a four antenna to more accurately gauge its response to a week period from the project's conception, led to a real interference situation. In cases where the exact reevaluation in the spectrum allocation scheme.

8 Spectrum Planning and Assessment

Another quick reaction measurement was accom­ characteristics to band-limited noise, it was deter­ plished by ITS engineers in concert with NTIA mined that testing with a band-limited noise-like Spectrum Engineering and Analysis Division interference source at fr equencies offset from the (SEAD) personnel using the BBNG to test Global GPS L1 frequency of 1575.42 MHz would most Positioning System (GPS) receivers. The spectrum closely simulate worst case interference conditions band from 1559 MHz to 1610 MHz has been allo­ fr om these spectrally collocated systems. These cated by international agreement for satellite to tests were performed in Portsmouth, Virginia using earth radionavigation transmissions. In the past the a GPS simulator located at the United States Coast GPS was the only user of this spectrum. However, Guard Command and Control Engineering Center new satellite radionavigation systems which would (C2CEN). The BBNG provided Gaussian distrib­ share this band have recently been proposed. uted white noise at diffe rent bandwidths and at car­ Because the parameters of these systems are largely rier frequencies near 1575.42 MHz. The results of unspecified at this time, and because the GPS uses a these tests are currently under evaluation, and more spread-spectrum signal which has similar spectral such tests are expected.

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No ise power required to cause loss of acquisition in GPS receivers versus offset fr om center fr equency fo r diferentf noise bandwidths.

For more information, contact: Frank Sanders (303) 497-5727 e-mail fs [email protected]

9 Spectrum Occupancy Measurements

Outputs Reports. Spectrum surveys and emission measure­ ments on individual devices can be performed for Measurements of spectrum occupancy generated Other Agency sponsors and private industry on a by new-technology ultrawideband (UWB) radar reimbursable basis. and communication systems. In fiscal year 1998, ITS, OSM, and the Federal Measurements of digital television (DTV) Communications Commission (FCC) embarked on a spectrum occupancy, and comparison to analog joint technical effort to quantify spectrum emissions television spectrum occupancy. from new-technology ultrawideband (UWB) trans­ mitters. Designed to be used as both short-range Broadband spectrum surveys at the Department radars and as communication devices, these systems of Commerce Table Mountain Radio Quiet produce intentional emissions which are typically Zone and at the National Institute for Standards several gigahertz wide. They represent a new chal­ and Technology (NIST) outdoor antenna range lenge to U.S. spectrum managers because their facilities at Boulder, CO. emissions cannot be confined within a single band allocation. These devices are being developed com­ To accomplish the NTIA Federal spectrum manage­ mercially, but may eventually be procured by both ment mission, including assessment of current and the private sector and by Government agencies. The future trends in spectrum use, ITS performs broad­ joint measurements were performed by NTIA and band spectrum measurements at selected locations FCC personnel at the FCC Columbia, MD laborato­ and on selected wideband devices. Measurements ries, and utilized an ITS suitcase measurement sys­ are performed on both Government and non­ tem. Results of these measurements on a UWB Government devices, as either category may poten­ transmitter are shown in Figure 1. The measure­ tially cause interference to Government systems. ments quantified the spectrum occupancy impact of The results of these measurements are provided to these devices. The results are being used to deter­ the NTIA Office of Spectrum Management (OSM), mine the conditions under which these devices may to spectrum management offices in other Federal be able to share spectrum with other systems and agencies, and to the public in the form of NTIA services.

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10 Spectrum Planning and Assessment

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Figure 2. Sp ectra of analog TV (180-186 MHz) and DTV (1 86-192 MHz) transmissions side-by-side.

Digital television (DTV) represents another newly Finally, the ambient radio noise environment at the developed technology whose deployment is present­ Dept. of Commerce Radio Quiet Zone near Boulder, ing new challenges for spectrum management. To CO was quantified by an RSMS standard broadband determine the relative impact of DTV transmissions spechum survey between 30 MHz to 19.7 GHz. A and existing analog television transmissions (which similar survey was performed at the NIST outdoor are gradually being phased out as DTV is intro­ antenna range at the Boulder laboratories. The duced), the ITS Radio Spectrum Measurement results of these surveys are being used to plan fo r System (RSMS, see p. 86) was deployed to Dallas, future development and use of these facilities. TX to measure simultaneous emissions from a DTV transmitter and an adjacent-channel analog trans­ mitter to determine relative impact of the two types of signal in the spectrum. The two signals were being transmitted from the same tower and were covering the same broadcast area. Therefore, all emission fa ctors were controlled except the signal modulation. Figure 2 shows the measurement results. This measurement demonstrates that for nar­ row receiver bandwidths, DTV signals may produce less impact than analog television signals, but that for wider receiver bandwidths, it is possible fo r I. For more information, contact: DTV signals to couple more energy into receivers Frank H. Sanders than do conventional analog television signals. The (303) 497-5727 RSMS measurements quantified this effect as a e-mail [email protected] function of bandwidth.

11 Spectral Assessment of Government Systems Outputs promptly and efficiently. ITS provides extensive EMC measurement and analysis capabilities for the Spectrum emission measurements on prototype solution of EMC problems. dedicated short-range communication systems for the Federal Highway Administration. In 1998, ITS resolved existing and potential EMC problems with the following organizations: NTIA Performance measurements on maritime mobile Office of Spectrum Management (OSM), Federal radio receivers. Highway Administration (FHWA), U.S. Coast Measurements of Coast Guard maritime radio Guard (USCG), and the Radio Technical channel availability along the lower Mississippi Commission for Maritime Services (RTCM). River. As part of a study for FHWA to determine technical requirements for Intelligent Transportation Systems Growing numbers of spectrum users and new com­ (see Intelligent Transportation Systems Planning, pp. munication technologies are placing increasing 40-41 ), ITS measured spectrum emissions fr om demands upon the national spectrum. New spectrum prototype dedicated short-range communication demands often generate electromagnetic compatibil­ (DSRC) systems such as may be used for automated ity (EMC) problems that threaten Governmentradio toll collection stations. The emissions from one such operations, and it is necessary to proactively analyze device are shown in Figure 1. This measurement and resolve such EMC problems fo r new systems. determined the feasibility of spectrum sharing Further in the event that new or existing Govern­ between this type of system and other systems in the ment s stems do experience EMC problems at field same band. locations,; it is necessary to resolve these problems 5 -1

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Frequency (MHz)

Figure I. Sp ectrum of a DSRC device emission fo r FHWA study. Note separate emissions fr om the base station and the vehicular beacon.

12 Spectrum Planning and Assessment

Another concern of spectrum managers is the per­ clear channels is critical to the success of VTS. To formance of mobile radio receivers in crowded measure channel availability, ITS personnel trans­ spectrum when strong signals occur on frequencies ported a suitcase measurement system (see Radio other than the desired frequency. This problem has Spectrum Measurement Systems, p. 86) to the lower become acute in many areas for maritime mobile Mississippi River and operated it aboard a boat, in a radios. ITS, along with OSM, USCG, and RTCM, land vehicle, and at a series ofVTS base stations. therefore performed a series of measurements of a As the system moved along the river (and while parameter called the intermodulation rejection ratio installed at each base station), the quality of VTS for several maritime radio types. In these tests, radio channels was continuously assessed and desired and off- frequency (potentially interfering) recorded. For each measurement, a desired signal signals were combined and fe d into the test radios. was fed into a marine radio receiver in combination The test results were used to determine the suscepti­ with ambient signals from an outdoor antenna. bility of the radios to this type of interference, and Outputs from a computerized signal to interference also to determine the signal levels that would be noise and distortion (SINAD) meter were recorded needed for USCG Ve ssel Traffic Service (VTS) along with time and position data from a global transmitters in metropolitan environments. An inter­ positioning system (GPS) receiver. SINAD values ference problem in Savannah, GA was solved by indicated the quality of the channel for use by VTS this work. as a fu nction of both time and position along the river. A resulting graph is shown in Figure 2. This A related problem is the limited availability of clear task has been critical to the successful deployment channels for VTS communications. Availability of of this portion ofVTS.

Figure 2. Mississipp i river coverage map fo r Coast Guard VTS study.

Yellow= 04 - 07.9 dB For more information, contact: Green= 08 - 11.9 dB Frank H. Sanders Blue= 12 - 15.9 dB (303) 497-5727 Violet= 16 - dB > e-mail [email protected]

13 Radio Frequency Interference Monitoring System

Outputs equipment, but includes two pieces of equipment developed and assembled at ITS. These are a unique Initial (prototype) Radio Frequency Interference mast-top signal preamplifierand preselector system, Monitoring System (RFIMS) unit designed, and an automated antenna controller. The MCS developed, tested, and delivered to Federal (written in LabView©) controls the measurement Aviation Administration (FAA). system, and records and documents every measure­ ment. Information automatically recorded in every Two production RFIMS units delivered to FAA. scan includes data, correction factors fo r antennas, measurement system gains and losses, and equip­ Patent obtained fo r automated measurement of ment parameter settings. air traffic control radar beacon system (ATCRBS) antenna patterns. The MCS incorporates a suite of custom measure­ ment routines specified by the FAA. These auto­ ITS offe rs expertise in custom measurement system mated capabilities allow the FAA to perform stan­ design to other Federal agencies and industry. One dardized computer-controlled measurements that such design effo rt is the Federal Aviation Admin­ would be impractical to perform manually. This istration (FAA) Radio Interference Monitoring includes measurements that require highly repetitive System (RFIMS), with units to be provided nation­ tasks during measurements and extensive post pro­ wide to every FAA region. Under the RFIMS pro­ cessing. Such measurements would theoretically gram, ITS personnel analyzed FAA requirements require weeks to perform by hand, and would and developed an automated, custom-designed radio spectrum measurement system; integrated and tested a prototype mobile system; and have now integrated and tested two (of eleven total) production systems. ITS also plans and manages associated support requirements including documentation, training, and operation of the RFIMS Development Lab located in Boulder.

The RFIMS managerial effort was divided into three tasks. Task I included assessment of requirements, option evaluations, and development of a measure­ ment system specification. Task II included system acquisition and testing of a prototype RFIMS, deliv­ ered in February 1998 to We stern Pacific Head­ quarters (Figure 1). In Task III, ITS is continuing integration, testing, delivery, and training required fo r the remaining eight of the total eleven systems. Software management, development, and documen­ tation have played and continue to play a critical role in all three RFIMS Program Tasks.

The RFIMS technical program was organized by ITS into three major sub-systems: the vehicle, the Integrated Electronic Package (IEP) hardware, and the measurement control system (MCS) software. The vehicular platfotm is a Ford Econoline outfitted with three six-foot equipment racks. The IEP is Figure 1. Prototype RFIMS at Los Angeles primarily commercial off-the-shelf measurement In ternationalAi rp ort (photograph by P Raush).

14 Spectrum Planning and Assessment

produce unreliable results. An example of an MCS expensive pulse sorting hardware or required an automated measurement is the Air Traffic Control interruption of the AT CRBS to make the measure­ Radar Beacon System (ATCRBS) antenna pattern ment. Since ATCRBS is a primary air control tool, assessment. This measurement utilizes a unique such operational intenuptions are a safety concern, algorithm that resulted in a patent fo r novel use of and development of this algorithm for the FAA was software and hardware to determine directional and a breakthrough in this type of measurement. omni-directional antenna patterns without intetTupt­ ing beacon operations. Figure 2 shows the ATCRBS The RFIMS Program is an excellent example of how measurement panel. ITS can assist other Federal agencies with their spectrum measurement needs. The combination of The algorithm collects multiple fr ames of radar hardware and software engineering expertise and pulse data. Each data fr ame is sorted into directional knowledge of spectrum monitoring and measure­ and omni-directional pulse sets, normalized, and ment techniques allows ITS engineers to assist other then plotted on a polar graph. Previous techniques agencies with their automated spectrum measure­ for creating ATCRBS antenna patterns used either ment design and development needs.

SWeep Allenuauon RBW (sec) (dB) 3111HZ 0.00 t 20 Antenna System RF Path Hom 1·19 GHz •I 95685 PrtmlMHz 30 • 2 GHz '!j tO Trtg Level tlt0° Trig Level Ref. Lev(dB) Holdolr(Sec 5.200E·t 9.t20E-t -tO t.3t9E·2

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Figure 2. Th e ATCRBS measurement panel.

Recent Publication

P. Raush, J. Kub, B. Bedford, T. Sparkman, S. Davidson, and E. Gray, "The radio frequency inter­ For more information, contact: fe rence monitoring system (RFIMS)," in Proc. IEEE Patricia J. Raush I 1998 In ternationalSy mposium on Electromagnetic (303) 497-3568 Compatibility, Denver, CO, Aug. 1998 e-mail [email protected]

15 Modulation Bandwidth Requirements

Outputs polynomial describing the spectral envelope. With these results, the NBWF can be specified in terms Power spectral density for signal parameters and of: (1) meeting the 99% power BW and (2) an effi­ percent power within a bandwidth. cient spectrum requirement of keeping a proposed modulation rollof f within the spectral envelope (or a Spectral peak locations with spline interpolation specified deviation). This analysis was applied to between peaks for envelope. orthogonal frequency division multiplexing (OFDM), also referred to as multicarrier modulation Nth degree polynomial fit to envelope using (MCM), and minimum-shift-keying (MSK) that pro­ mean-square-error (MSE) criterion. vides an analytically tractable baseline for compari­ son with other modulations. Additional modulations Spectral envelope rollof f as a function of under investigation include: (1) Gaussian minimum­ bandwidth (BW). shift-keying (GMSK), (2) Feher quadrature phase shift keying (FQPSK), and (3) Multi-h continuous The Office of Spectrum Management (OSM) in phase modulation. NTIA is responsible for managing the radio spec­ trum used by the Federal Govemment. This research Analysis results for OFDM are shown in Figures 2- supports the OSM by establishing a methodology for 5. Figure 2 describes the major blocks of the trans­ specifying spectrum requirements of various modu­ mitter where T, the data block length, is used in nor­ lations employed by the Govemment. Figure 1 malizing the analysis results. The spacing of the shows the steps used in analysis of the spectrum and multi-carriers is liT in Figure 3 and frequency axes establishing necessary bandwidth fo rmulas (NBWF). are notmalized to T. The one-sided power spectrum This includes: (1) calculating a modulation spectra is shown in Figure 3 along with spectral peaks (tri­ from an analytic equation or simulating the transmit­ angles) and the resulting envelope fitted with a 15th ter and calculating the spectra from the waveform, degree polynomial. Lower order polynomials can be (2) calculating the total power contained in a BW used to specify the envelope with a resulting and specifying the 99% power BW parametrically, increase in the MSE. The spectral envelope rolloff (3) spline interpolating between spectral peaks to BW is specified by another 15th degree polynomial establish the spectral envelope, (4) fitting an nth in Figure 4 and the percentage of total power con­ degree polynomial to the envelope, and (5) specify­ tained in a BW is given in Figure 5. ing NBWF in terms of the 99% power BW and the

Compute Plot Compute Plot Simulate/Calc Modulated & & Power Spectral Density Total Power vs BW Signal Select Modulation of for & - Modulated Signal Compute BW Selected Parameters 99%

Fit Nth Degree Polynomial Spline Interpolate Validated Equation Between Peaks Detect Specify Peaks Necessary BW Equations to & for of and Envelope Total Power & Envelope Power Spectral Density Analysis Software Curves �

Figure 1. Sp ectral analysis of modulations flowchart.

16 Spectrum Planning and Assessment

... Encode toN IFFTN Complex (l,q) L Bit Symbols Symbol Values Modulate Multi-Carrier Block ofNxl Data Bits Symbols/sec R bits/sec RIL RJ(NL)Symbols/ Subchannels on Final RF (Usually M-QAM, (Obtain N per carrier RF Carrier (T sec Block) OUTPUT M=2'L) Multi-Carriers Separated by 11T )

Figure 2. OFDM transmitter.

OFDM Normalized Log Power Spectrum, Peaks & Envelope (N=32 Subcarriers with tiTSpacing)

Spectrum Spectrum Points -5 15th Degree Polynomial Envelope

-10

"'-15 "0 .s

- 0..� 20

-25 -30 I -35L------�----LLIULI�LU��LLIUU�LL I 0 10 20 30 40 50 60 Normalized Frequency (If-felT) Figure 3. OFDM power spectrum and envelope.

OFOM Spectral Polynomial (Degree 15) E nvelope Aolloff Bandwidth (N=32 Subealriers wUh liTSpacing) OFDM Percent Total Power within Band 65 r---�-.--�--,-�---.--�--,------,------TA----o 100

60 90

3dB BW/2 " 15.6043/T 55 IOdB 8Wf2"' 16.9193/T 80

20dB BW/2 • 24.0653/T 30d8 BW/2 • 59.1428/T 70

99% BW/2 • 16.9/T 60 (I{F&.paia:lon)

]! 50 �1 * 40

30

25 20

20 10

0 10 15 20 25 30 35 0 10 15 20 25 Aolloff In dB Normalized Frequency (If-felT)

Figure 4. OFDM sp ectral envelope rolloffBW Figure 5. OFDM percent power within a bandwidth.

For more information, contact: Edmund A. Quincy (303) 497-5472 e-mail [email protected]

17 ITU-R Activities

Outputs tion issues and the latter study groups manage ser­ vice-oriented issues (see the Table). Preparation of technical standards and recom­ mendations supporting U.S. positions at radio ITU Study Groups & Associated Areas of Concern

conferences. Study Group Area of Concentration

____Sp ectru111 �anagement Leadership of U.S. participation in key ITU-R .____

3 Radiowave P Opagatl· on___ _ study groups. ! '-"-""'-"-'=-=c::: 4 Fixed-satellite service Coordination of U.S. positions on issues related to ITU-R recommendations. 7 Science services 8 Mobile, radiodetermination, amateur, The International Telecommunication Union - and related satellite services ------Radiocommunication Sector (ITU-R) is the ITU 9 Fixed service ______body responsible fo r developing international stan­ _ 10 Broadcasting service - sound dards (ITU-R Recommendations) for radio systems. The United States supports the efforts ofthe ITU-R 11 Broadcasting service - television to ensure compatibility between radio systems oper­ ating in this country and those operating in neigh­ Just as international study groupsof the ITU-R boring countries and to promote commerce by pro­ address specific radio system technologies, the viding telecommunication system standards that United States has a corresponding set of national U.S. companies can use to develop products for committees that prepare U.S. documents for consid­ international markets. The Institute provides leader­ eration by the international committees. The particu­ ship and expertise in the development of the recom­ lar topics treated by each study group vary to meet mendations, both to support U.S. interests and to current needs and to reflectthe topics that will be ensure high-quality, worthwhile international radio discussed at forthcoming radio conferences. The rec­ system standards. ommendations of the ITU-R are used to establish technical criteria that are the basis fo r spectrum allo­ The international growth in telecommunications cation decisions and spectrum use, both globally and technology and the demand fo r communication ser­ regionally. In addition, the agreements reached at the vices has compelled the ITU to provide more timely World Administrative Radio Conferences become information and standards. In the past, the introduc­ international treaties for the United States. There­ tion of new telecommunication services would take fore, it is important to the United States that ITU-R years of research and development; now faster documents accurately reflect the U.S. position on development and implementation is required. Com­ important spectrum policy matters. munication service providers are anxious to develop new services, provide alternative forms of competi­ While the ITU-R Recommendations describe the tion, and let the marketplace determine the fate of radiocommunication propagation methods and mod­ new services. els, the Recommendations do not give guidance on how to use the Recommendations nor which Recom­ To meet the demand fo r international standards, the mendations should be used in various situations. The ITU-R has divided its work program into study ITU has started the process of providing handbooks groups that develop recommendations. As study that give advice on use of the Recommendations. groups meet infrequently (with some only meeting During the past study session, the U.S. has proposed every 2 to 4 years), each study group is subdivided a draft new Handbook, intended to guide the user into working parties and task groups that provide a with practical advice on the application and interpre­ continuous forum for the development of recom­ tation of propagation calculations in the Land mendations on particular issues fo r the study group. Mobile Radio Service. The proposed Handbook will The ITU-R is comprised of eight study groups; the cover the fo llowing areas: first two consider spectrum utilization and propaga-

18 Spectrum Planning and Assessment

General Path, Propagation Loss Models L =A (1 - k-d) (1) Propagation Loss Models for Terrain Obstructed where

Paths d = distance in meters Propagation Effects due to Ground Clutter k = exp (RIA) (2) and Propagation Loss Models for Within Building and Underground Paths R = initial specific attenuation rate in dB/m

A = maximum vegetative excess loss for Characteristics of Environmental Noise one terminal within vegetation. Characteristics of Signal Variation Characteristics of Delay Spread The initial specific attenuation rate R is due to absorption or scattering from the direct ray from T The Handbook will provide the user with the appro­ to R. It is a fu nction of the type, density and condi­ priate Recommendations that should be used for a tion of the vegetative cover. The maximum excess particular situation, and provide references to other loss A is the value to which L becomes asymptotic material in the literature that the user can access. with a sufficient increase in d. It is a function of vegetation type, density, condition and geometry An example of how the U.S. contributes to the (e.g. canopy height), as well as antenna height in development of models, consider the problem of relation to canopy height, and probably of antenna characterizing propagation loss into a forested beamwidth. The physical basis fo r A is that above a region. The Figure below shows a transmitter T out­ certain attenuation of the direct T-R ray, energy will side an area of woodland or vegetation and a receiv­ reach R primarily via other paths, such as over the er R inside the vegetation at a distance d from the top of the vegetative cover, reaching R by surface­ point P where the direct ray from T to R enters the wave mechanisms at the air-vegetation interface in a vegetation. The vegetation excess loss L is defined manner analogous to ground-wave losses over as the basic transmission loss between T and R imperfectly-conducting terrain. The objective by the minus the smaller transmission loss which would U.S. and other Administrations of the ITU-R is to exist were the vegetation absent but with all other facilitate experimental work leading to a table of conditions the same. The Figure also shows the vari­ parameters on vegetation losses, which would be ation of L with d according to the expression: useful in radio system planning.

T p R

1 Excess loss L A

Distance d ----

A transmitter T outside an area of vegetation, and a receiver R inside the vegetation.

For more information, contact: Eldon J. Haakinson (303) 497-5304 e-mail [email protected]

19 I

. I

.j

ITS engineers ro utinely assess emissions fr om high-power radars. Pictured is a radar measured at Camp Pendleton, California. Th e ITS engineer is standing on the antenna during a lull in the measurements, when the radar was not radiating (photograph by FH. Sanders).

20 Telecommunication Standards Development

The Institute contributes significantly to the devel­ National Standards Institute-accredited Committee opment and application of national and international T 1, the Telecommunications Industry Association telecommunications standards. These standards pro­ (TIA), the Federal Telecommunications Standards vide a technological fr amework for evolving U.S. Committee (FTSC), the International Telecommu­ and global information infrastructures, promote nication Union's Telecommunication Standardiza­ innovation and competition in telecommunications tion and Radiocommunication Sectors (ITU-T and products and services, and enhance international ITU-R), and others. The technical standards and rec­ trade opportunities for U.S. telecommunications ommendations developed in these fo rums are blue­ firms. Institute staff members provide leadership and prints for technology evolution and can influence technical contributions to key national and interna­ billions of dollars in telecommunications research tional standards committees, including the American and development investments worldwide.

Areas of Emphasis

Video Quality Standards Development The Institute develops and implements perception-based, technology-independent video quality measures and promotes their adoption in national and international standards. Projects are funded by NTIA and by the National Communications System (NCS).

Audio Quality Standards Development The Institute conducts research and development leading to standardization and industry implementation of perception-based, technology-independent quality measures for voice and other audio communication systems. Projects are fundedby NTIA and NCS.

Broadband Networks The Institute contributes to the development and effective use of Asynchronous Transfer Mode (ATM) and advanced Internet technologies through laboratory measurements and technical contributions to national and internationalperformance standards committees. Proj ects are funded by NTIA and NCS.

Telecommunication Te rminology Standards The Institute leads the development of telecommunication terminology standards in Federal, national, and international fora and contributes to their dissemination in Internet-accessible hypertext and other innovative publication media. Projects are funded by NCS.

Wireless Standards Support The Institute contributes to the development of industry standards for personal communications services and provides objective testing and evaluation of the associated technologies. Projects are funded by NTIA, the Federal Highway Administration, the Federal Railroad Administration, and NCS.

Law Enforcement Telecommunication Standards The Institute provides engineering support, scientific analysis, technical liaison, and testing to assist NIST's Officeof Law Enforcement Standards (OLES) in the development and validation of criminal justice communi­ cations standards and other communication system products supporting law enforcement and corrections needs. Projects are fundedby OLES.

ITU-T Standardization Activities The Institute leads U.S. ITU-T preparatory committees and related internationalwork groups, provides techni­ cal contributions to ITU-T standardization activities, and drafts proposed ITU-T recommendations and com­ patible national standards. Projects are fundedby NTIA.

21 Video Quality Standards Development

Outputs The ITS-developed video quality assessment meth­ odology was adopted as a national standard by the Contributions to national and international video American National Standards Institute (ANSI) in quality measurement standards. 1996 (ANSI Tl.801.03). During FY 97 and FY 98, ITS engineers made significant enhancements to the Automated video quality measurement flexibility and accuracy of the original measurement techniques and prototype instrumentation. techniques. These enhancements were submitted in FY 98 to the International Telecommunications Technical input to development of U.S. policies Union (ITU) Video Quality Experts Group (VQEG) on advanced video technologies. to be considered for international standardization.

Digital video compression and transmission tech­ The enhanced methodology adds fine spatial impair­ niques offer an economical means of implementing ment measurements to the techniques described in video communication services in emerging national ANSI T1.801.03, while maintaining flexible provi­ and global information infrastructures. However, sions for in-service measurement. Quality parame­ these techniques cause received video quality to ters are computed fr om fe atures that are extracted change dynamically depending upon scene complex­ from spatial-temporal (S-T) regions of input and ity (e.g., spatial detail, motion) and transmission output video scenes, as shown in Figure 1. This fig­ channel operating characteristics (e.g., bit rate, ure illustrates two S-T region sizes, 8 pixels x 8 dropped packets). Hence, to accurately measure the lines x 1 fr ame and 2 pixels x 2 lines x 6 frames. received quality experienced by the end-user, per­ Since the fe atures extracted fr om these S-T regions formance measurements must be made in service require only a small transmission bandwidth in com­ (i.e., using the same program material the end user parison with the bandwidth required to send the 270 sees). ITS engineers have addressed this problem Mbit/s ITU-R Recommendation BT.601 digital through the development and standardization of a video streams, they can be readily transmitted and/or fundamentally new methodology for video quality stored as ancillary information. The S-T region size assessment. The patented, ITS-developed methodol­ determines the ancillmy information bandwidth ogy can efficiently make in-service measurements required. In-service methods based on this approach that are highly correlated with the subjective assess­ are anticipated to have the widest possible appli­ ments of human viewer panels. cation, since the measurement resolution can be

- . - . - . - - . . . - . - . - . - . - . - . - . - . :vertical-Width (L'lv) : Horizontal­ Width (L'lh)

••• •••

Vertical­ (M) ...Wid th

:Horizontal-Width (L'lh):

Video Stream Figure 1. Illustration of sp atial-temporal (S- T) regions fo r a video scene.

22 Telecommunication Standards Development

__lnp � Video Transmission System

Calibration Calibration Inpu1 t Quality Parameters Output1 Information Information Calibration & Composite Score Calibration Processor Processor Spatial � � Spatial Spatial Spatial Features Features Activity Activity - r- Filter Filter

Temporal Temporal Temporal Temporal Features :Anc: Data.iila�: Features Video Video Cali brated Cal ibrated - Activity : Channel .: Activity - Filter Quality . . Quality Filter Outp ut I nput , ...... Processor . Processor SxT .. . SxT SxT SxT Features Features - Activity Activity - Filter Filter Chroma Chroma Chroma Chroma Features Features Activity Activity - - Filter Filter

Figure 2. Measurement system overview. adapted to accommodate the available ancillary The system can measme the video delay, spatial information bandwidth. In some applications, such shift, gain, and level offs et of the video transmission as network control and fault monitoring, the avail­ system, as well as parameters that indicate perceptu­ able ancillary information ban<;iwidth might be quite al distortions in fom aspects of video quality: spa­ low, while in other applications, such as laboratory tial, temporal, chrominance (i.e., color), and spatial testing of a video codec, the available ancillary x temporal (spatial-temporal cross product). Spatial information bandwidth might be quite large. In the fe atures characterize the activity of image edges. A latter application, smaller S-T region sizes can be digital video system can add edges (e.g., edge noise) used to achieve greater measurement accuracy. or reduce edges (e.g., blurring). Temporal fe atures characterize the activity of temporal differences Figure 2 illustrates a non-intrusive in-service video (motion) between successive frames. A digital video quality monitoring system based on this approach. system can add motion (e.g., error blocks) or reduce motion (e.g., frame repeats). Chrominance fe atures characterize the activity of color information. A dig­ ital video system can add color infonnation (e.g., Recent Publications cross color - black edges on white backgrounds that produce color attifacts) or reduce color informa­ G.W. Cetmak, S. Wolf, E.P. Tweedy, M.H. Pinson, tion (e.g., color sub-sampling). A cross product of and A.A. Webster, "Validating objective measures of spatial fe atures and temporal fe atures allows one to MPEG video quality," SMP TE Jo urnal, vol. 107, no. account for relative impairment masking (i.e., 4, pp. 226-235, Apr. 1998. reduced visibility of impairments) in areas of high C. Fenimore, J. Libert, and S. Wo lf, "Perceptual spatial-temporal activity. The measurement system effects of noise in digital video compression," in also produces a composite score that is representa­ Proc. I40th SMP TE Te chnical Conference, Pasadena, tive of the overall subjective video quality. For more CA, Oct. 1998. information, see http://its.bldrdoc.gov/n3/video/

S. Wolf and M. Pinson, "In-service performance met­ rics for MPEG-2 video systems," in Proc. Made to Measure 98 - Measurement Te chniques of the For more information, contact: Digital Age Te chnical Seminar, International Acad­ Stephen Wolf emy of Broadcasting, ITU, and Technical University (303) 497-3771 of Braunschweig, Montreux, Switzerland, Nov. 1998. e-mail [email protected]

23 Audio Quality Standards Development

Outputs responses of users. These responses can be obtained by conducting subjective listening experiments, but Objective audio quality assessment and the time and cost of such experiments is often diffi­ optimization algorithms. cult to justify.

Reports on relationships between signal proc­ In its Audio Quality Standards Development pro­ essing parameters and perceived audio quality. gram, the Institute is developing practical alterna­ tives to controlled subjective listening experiments: Related telecommunications standards and digital signal-processing algorithms that objectively recommendations. estimate perceived audio quality as determined in subjective listening experiments. Quality estimates Technology advances have greatly expanded the generated by these algorithms are compared with available options for encoding and transmitting listening experiment results to ensure that the select­ audio signals � and created an urgent need for tech­ ed algorithms accurately reflecthuman perception nology-independent audio quality assessment tech­ over a wide range of encoding techniques and chan­ niques. Toll-quality speech can now be transmitted nel conditions. or stored at bit rates as low as 8 kbit/s. Fully intelli­ gible, lower quality speech can be transmitted or The ITS approach to the development of objective stored at bit rates down to about 1.6 kbit/s. These audio quality assessment algorithms is perception advances have enhanced the capacity and efficiency based. Recent ITS work has produced a family of of both wired and wireless telecommunications sys­ fundamentally new algorithms called the Measuring tems. High-quality audio signals, such as music and Normalizing Block (MNB) algorithms. These entertainment soundtracks, can now be encoded at algorithms work because they model both human rates as low as 32 or 64 kbit/s per channel, enabling hearing and human judgement. A psychoacoustic the efficient storage and dissemination of those fr equency scale and a model fo r nonlinear loudness signals. growth are included in the hearing model. The judgement model involves measuring and normaliz­ The transmission of audio signals is also being ing spectral deviations at multiple time and frequen­ changed fundamentally as new technologies are cy scales. In order to best emulate listeners' patterns introduced. Encoded audio signals can be carried as of adaptation and reaction to spectral deviations, the data packets through networks, sharing capacity with measuring normalizing blocks are combined so that other data streams in teleconferencing, distance analysis proceeds from larger scales to smaller learning, and multimedia services. scales, as illustrated in the Figure. ITS has applied for a patent on these innovative audio quality esti­ These technology advances and the associated mation algorithms. economic trade-offs have created important new measurement issues. Equipment manufacturers, ser­ During FY 98, project staff members worked vice providers, and users all need audio quality through American National Standards Institute assessment methods that work no matter how a sig­ (ANSI)-accredited standards Working Group nal has been encoded and transmitted. Increasingly TlA1.7 (Signal Processing and Network Perform­ complex, time-varying interactions among audio sig­ ance for Vo iceband Services) to develop and gain nal content, source coding, channel coding, and approval for the ANSI telecommunications standard channel conditions have made it impossible to deter­ Tl.518-1998. This standard defines an MNB algo­ mine end-to-end quality from individual component rithm and describes how it can be used to objective­ specifications. Not surprisingly, traditional wave­ ly estimate perceived speech quality of 4-kHz band­ fo rm reproduction measures developed fo r wired 4- width telecommunication systems. The Institute is kHz analog telephony are ineffective in assessing the also contributing to the work of the International listener-perceived quality of today's digital speech Telecommunication Union-Telecommunication and audio systems. The most fundamental and cor­ Standardization Sector (ITU-T) Study Group 12. A rect measures of audio quality are the subjective project staff member serves as Associate Rapporteur

24 Telecommunication Standards Development

Time Example time-frequency analysis regions fo r MNB algorithms. for Question 13/12, which addresses methods of and voice-over-Internet systems were all evaluated modeling and measuring nonlinear distortion by the MNB algorithms. Obj ective estimates of per­ processes in voice transmission. In FY 98, approval ceived speech quality were generally fo und to be in was gained for ITU-T Recommendation P. 861, good agreement with subjective listening test results. Appendix II, providing an MNB algorithm to the These objective-subj ective comparisons provide international telecommunications community. valuable information for the future refinement and extension of the MNB algorithms. Project staff applied the MNB algorithms to many diffe rent telecommunications devices in FY 98. Project staff also designed, conducted and analyzed Digital and analog radios, software speech codecs, a subj ective conversation test fo r an industry partner under a cooperative research and development agreement. Other subjective listening tests were per­ Recent Publications fotmed to gather more information to extend the MNB algorithms to address conditions outside their S. Vo ran, "Perception-based bit-allocation algo­ present scope. Analysis of other, less effective rithms for audio coding," in Proc. 1997 IEEE objective estimators was completed, and an MNB Wo rkshop on Applications of Signal Processing to algorithm was used to optimize a speech coder. Audio and Acoustics, New Paltz, NY, Oct. 1997. Project staff members disseminated objective audio S. Vo ran, "Objective estimation of perceived speech quality assessment results to industry, Government, quality using measuring normalizing blocks," NTIA and academia through numerous technical publica­ Report 98-347, Washington, D.C., Apr. 1998. tions and presentations and laboratory demonstra­ S. Vo ran, "A simplified version of the ITU algo­ tions during FY 98. Laboratory demonstrations rithm for objective measurement of speech codec fo cused on prototype audio quality test instruments quality," in Proc. 1998 IEEE In ternational that implement MNB algorithms in near real time. Conference on Acoustics, Sp eech and Signal Processing, Seattle, WA, May 1998.

S. Vo ran, "Observations on frequency domain com­ For more information, contact: panding for audio coding," in Proc. 8th IEEE Stephen D. Vo ran Digital Signal Processing Wo rkshop, Bryce Canyon, (303) 497-3839 e-mail [email protected] UT, Aug. 1998.

25 Broadband Network Standards

Outputs - Lower layers (LL), implemented in links that provide connection-oriented or connectionless Network emulation and performance measure­ data transport between IP layer entities. Links ment tools. can be implemented using a variety of technol­ ogies -for example, Asynchronous Transfer Contributions to national and international Mode (ATM), Frame Relay, Synchronous Digital performance standards committees. Hierarchy (SDH), Plesiochronous Digital Hierarchy (PDH), Integrated Services Digital Draft national and international standards. Network (ISDN), and leased lines. Several lay­ ers of transmission protocols and services can be The explosive growth of Internetusage and the evo­ embedded in a link. lution of "streaming" and other real-time Internet - The IP layer, implemented in source (SRC), applications have created an urgent need for uni­ destination (DST), and intermediate routers that form, user-oriented performance parameters to perform Internet addressing, packet fragmenta­ characterize Internet Protocol (IP) -based data com­ tion/reassembly, and packet fo rwarding func­ munication services. During FY 98, the Institute tions. The IP layer has end-to-end significance motivated and contributed strongly to the successful for a given pair of source and destination lP development of a new international standard, ITU-T addresses. Recommendation !.380, that defines such parame­ ters. The Recommendation !.380 parameters charac­ - Higher layers, implemented in source and terize IP-based services with respect to fo ur general destination hosts that provide additional commu­ performance attributes: speed, accuracy, dependabil­ nication functions supporting patiicular Internet ity, and availability. They are intended to be used by applications. The higher layer protocols may service providers in the planning, development, and include, for exmnple, Transmission Control assessment of IP services that meet user perform­ Protocol (TCP), User Datagram Protocol (UDP), ance needs; by IP network and terminal equipment File Transfer Protocol (FTP), Real Time Proto­ manufacturers as performance information that will col (RTP), and Hyper Text Transfer Protocol affe ct equipment design; and by users in evaluating (HTTP). These protocols modifY (and may end-to-end IP service performance. enhance) the end-to-end performance provided by the IP layer. An ITS staff member presented a baseline text for Recommendation !.380 at the September, 1997 In developing Recommendation !.380, the Question meeting of the ITU-T Study Group 13 Rapporteurs 13 Rapporteurs group was able to make use of the Group on Question 13. During FY 98, ITS staff performance description fratnework and principles members made strong technical and editorial contri­ evolved (under ITS leadership) in earlier network butions to the completion of that new Recommen­ performance standardization efforts. The characteri­ dation. The completed document was "determined" zation of IP network performance neve1iheless at the June, 1998 ITU-T Study Group 13 meeting required that the group address several new techni­ and is expected to be approved at the February, 1999 cal problems. meeting of that group. The connectionless nature of IP packet transfer The Figure, fr om Recommendation !.380, illustrates complicates IP network performance description the layered nature of IP service performance. The by obscuring the population (e.g., set of trans­ end-to-end performance provided to IP service users mitted packets) to which the defined parameters depends on the performance of several nested proto­ apply. The group addressed this problem by col layers: defining a population of interest in terms of specifiedsource and destination hosts and asso­ ciated complete IP addresses.

26 Telecommunication Standards Development

User Information User Information (e.g. data) (e.g. data) PerformanceHigher Layer

LayerIP Service Packet Performance____l�§UE' ______Lower Layer Performance(3 instances) ------::�------���------��-u�:�-- ---��-:-- --�:���------���:------��;------�::�;���k r r i r r n r r l r r

Layered model of pe1jormancefo r IP service - example.

The diverse routing of IP packets complicates Six IP packet transfer performance parameters are IP network performance description by requir­ standardized in Recommendation 1.380: IP packet ing consideration of packet transfer reference transfer delay, IP packet error ratio, IP packet loss events at multiple ingress and egress points, in ratio, spurious IP packets rate, and two measures of multiple transit networks, in determining packet IP service availability. The Recommendation also transfer outcomes. The group addressed this provides provisional definitions for throughput and problem by defining concepts of permissible packet delay variation. In ongoing work, ITS is ingress and egress points and corresponding assisting Study Group 13 in considering the specifi­ packets for a population of interest. The permis­ cation of IP network service classes and associated sible ingress and egress points are defined with numerical performance objectives. This work is reference to the restrictions established by glob­ being coordinated with the specification of "Differ­ al routing information. entiated Services" in the Internet Engineering Task Force (IETF). Packet fragmentation complicates IP network performance description by multiplying the During FY 98, ITS also spearheaded the develop­ number of reference events that must be ment of a national counterpart to 1.380, proposed observed in determining the outcome of an American National Standard T1.5IP, in American individual packet transfer attempt. The group National Standards Institute (ANSI) accredited addressed this problem by defining separate Wo rking Group T1A1.3. This national standard is reference events for each packet fragment and expected to be published as a "delta document" to associating them through the definition of cor­ 1.380 in 1999. responding ingress and egress events.

For more information, contact: William R. Hughes (303) 497-3728 e-mail [email protected]

27 Telecommunication Terminology Standards

Outputs Earlier versions of Federal Standard 1037 were available in hard copy only, with revisions issued at Search engine for Federal Standard 1037C 5-year intervals. Translation of the document to an online. on-line, searchable fonn has made it much more usable - and greatly expanded its use. The WWW Technical reports and joumal publications version of FED-STD-1037C received over 120,000 describing the standard's development and accesses ("hits") in the first 18 months of its on-line electronic implementation. availability. Over 75% of current on-line users employ its search engine fe ature. The document's Common understanding of teclrnical terminology is on-line availability has also made possible a more essential in a wide range of telecommunications efficient, and more timely, approach to its revision. planning functions, including the development of ITS has developed an electronic template for solicit­ product and procurement specifications. The ing proposed new terms and definitions to be used in Institute has spearheaded the development of tele­ future revisions of the glossary. The template will be communications terminology standards fo r many made accessible on the 1037C Web page to allow years through its leadership and technical contribu­ e-mail submissions of new or revised definitions. An tions in the Federal Telecommunications Standards e-mail exploder could be used to circulate, discuss, Committee (FTSC) Telecommunications Glossary and conduct ballots of reviewer comments enabling Subcommittee. the draft of a proposed revision to FED-STD-1 03 7C to be developed more quickly and more economical­ The Subcommittee's most recent product is Federal ly on-line. Standard 1 037C, Glossary of Te lecommunications Terms. This 5800-entry glossary was published in The conversion of the glossary to HTML, its posting hard copy form in 1996, and was made available in on the Web, the addition of the search engine, and HTML form on CD-ROM and the World Wide Web the facility fo r submitting e-mail proposals for (at in 1997. updates have significantly increased the availability, usability, and value of FED-STD-1 03 7C. These During FY 98, ITS staff members enhanced the CD­ enhancements should enable the standard to con­ ROM and WWW versions of the glossary by equip­ tribute strongly to the clear understanding and effec­ ping each version with a custom-designed search tive use of telecommunications terminology for engine. In response to user requests, input as charac­ many years to come. They may also motivate ter strings, each search engine examines the com­ improvements in the processes used to develop and plete 5800-entry text for related definitions and dis­ maintain other telecommunication standards. plays a relevance-ordered list of results. The search process takes 7 to 40 seconds, depending on the Hard copy and a CD-ROM of the glossary may be length of the input character string. The Figure illus­ obtained at no cost fr om trates a typical on-screen result, produced by search­ ing the online HTML glossary fo r terms and defini­ National Communications System tions relevant to the phrase "D region." A major Attn: Ms. J. Omdorff advantage of the search engine is its ability to speed 701 South Court House Road a user's access to particular entries in the glossary. Arlington, VA 22204-2198 The search engine also promotes more organized Phone: (703) 607-6204 and systematic use of the glossary by giving users access to groups of related terms.

28 Telecommunication Standards Development

ONLINE HTML

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Drt'glon

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ITS has developed a customized search engine that searches the HTML files of FED-STD-1037C, either online or on the CD-ROM. Glossary of Telecommunication Terms -

Recent Publications

W. Ingram and E. Gray, "A fe deral standard on elec­ tronic media," NTIA Report 98-350, Aug. 1998. For more information, contact: E. Gray, W. Ingram, and D. Bodson, "The ABCs of Evelyn M. Gray writing a technical glossary," Te chnical Communica­ (303) 497-3307 tion, vol. 45, no. 1, pp. 23-32, First Quarter 1998. e-mail [email protected]

29 Wireless Standards Support

Outputs managing spectrum sharing. ITS provides support to several TIA committees dealing with wireless com­ Interference prediction techniques fo r Personal munications issues: Communication Systems. TR-8 Mobile and Personal Private Radio Standards Attenuation prediction techniques fo r land mobile radio service. TR-45 Mobile and Personal Communications Systems Contributions to Telecommunications Industry Association wireless standards. TR-46 Mobile and Personal Communications

IMT 2000 International Mobile Telecommunications As wireless services continue their explosive growth, Standards spectrum is becoming a scarce commodity. Increas­ ingly, the availability and cost of spectrum will deter­ The standards progress in TR-8 is of particular inter­ mine the economic viability of proposed new wire­ est to fe deral, state and local public safety agencies. less services. More intensive use and re-use of the This committee has the responsibility of developing available spectrum improves efficiency but results in the industry standard for the APCO Proj ect 25 radio an increase in interference and a corresponding system. After the new narrowband, digital radio decrease in performance. System optimization standard (TSB-1 02) is adopted and implemented, becomes a challenge since systems that share the these agencies will need to pay particular attention to spectrum employ different technologies and are the coordination process used to ensure compatible administered by independent, sometimes competing, operations of the radio systems. While some agencies service providers. ITS contributes to the resolution of will continue to use existing wideband analog sys­ problems in commercial applications and to NTIA's tems, others will migrate to the new narrowband sys­ role as manager of government spectrum through tems. Since the systems have different thresholds of studies of interference phenomena and their effects interference, coordination on a one-on-one basis is on wireless system performance. Dming FY 98, needed to ensure non-interfering operations. TR-8 projects centered in two areas: has developed a reference standard, Wireless Com­ munications Systems, Performance in No ise- and Determining the excess attenuation due to local In terfe rence-Limited Situations, Recommended clutter (buildings, vegetation, etc.) in fr equency Methods fo r Te chnology-Independent Modeling, coordination of digital land mobile radio (LMR) Simulation, and Verification (TSB-88) which defines systems conforming to Association of Public the coordination process. Safety Communications Officials (APCO) Project 25 standards. The standard propagation model used in many LMR situations is an empirical model developed by Hata Determining the performance effects of intra­ based on measurements by Okumura et al., com­ system and inter-system interference in personal monly called the Okumura-Hata model. The user communication services (PCS). selects from a variety of environments: urban, sub­ urban, quasi-open, and open, and chooses the base The results of iTS's work have been submitted to the station antenna height (which is usually above local Telecommunications Industry Association (TIA) and clutter heights) and the mobile antenna height (which American National Standards Institute (ANSI) in is usually below). These parameters define the support of standards for wireless communications. amount of clutter attenuation that will be added to TIA is accredited by ANSI to develop voluntary the propagation loss. industry standards fo r a variety of telecommunica­ tions products. The various TIA committees produce In the coordination process, the user selects the open Technical Service Bulletins (TSBs) used by industry environment when using theOkumura-Hata model. and frequency administrators as guidelines for A clutter factor, which is a function of the particular

30 Telecommunication Standards Development

25 band used by the LMR system and the mobile · - station's environment, is added. ITS and industry have developed values of excess loss 20 due to clutter based upon measurements from Ill 'C DWater a number of sources. Figure 1 shows how the c Snow Ice 0 15 1 & "' clutter attenuation varies for the LMR bands .. e Wetland " Open land of interest and a variety of environments. "c I :a:: 1 Rangeland .. � 10 I Agricultural " The FCC recently suggested that clutter losses " .ll Residential could be added to broadcast service predic­ 1 Commercial/industrial I tions and encouraged the development of such • Mixed urban/buildings models. ITS is working to establish good excess loss values for various bands and envi­ 30-50 136-174 220-222 380-512 746-941 ronments. One important component of the Land mobile radio bands, MHz process is the land use or land cover classifi­ cation that surrounds the mobile station, but Figure I. Excess attenuation due to local clutter as a fu nction the infmmation provided by digital data bases of land mobile radio band and land use classification. available from agencies such as the U.S. Geo- logical Survey is coarse and needs to be updated con­ natural disaster or emergency situation, when dam­ stantly. ITS is researching improved land use/ land aged cell sites are repaired or replaced, and traffic cover data bases appropriate fo r these models. loads rise due to increased dependency on wireless communication. To understand the interaction Another limitation to wireless system performance is between co-located PCS systems and the nature of due to the co-location of base station transmitters, inter-PCS interference, ITS developed an interfer­ receivers, and antennas. Figure 2 shows that third­ ence model based on two PCS technologies: the order intermodulation (IM) products between two Global System fo r Mobile (GSM) based PCS1900, systems operating in different bands can affe ct them­ and the IS-95 based code division multiple access selves, systems operating in other PCS bands, as well (CDMA) system. As discussed in an NTIA report as systems operating outside of the PCS bands, such (Fenanto, 1997; see Publications Cited, p. 106), the as the military band located from 1755 to 1850 model can be expanded to cover the remaining PCS megahertz. Service providers should cooperate to technologies and can be used to predict the effect alleviate these problems, but cooperation may not be that co-located systems can have on each other, in possible during the chaotic situation fo llowing a terms of performance, capacity, and reliability. The model produces a waveform that is an aggregate of the transmitted waveforms from all base stations and mobile stations of a particular system, and can be used with mathematical models to predict system response to less than ideal conditions, or can be implemented in hardware to test existing equipment.

ITS' expertise in interference modeling has been of value in the development of the TIA handbook Licensed PCS to PCS In terference (TSB-84A) which �DID �BID is intended to help equipment manufacturers, service i! ElF providers, and fieldpersonnel minimize interference CIC EIE through the design and implementation phases of FIF CIF PCS systems. CIE em ��----�--� MlLITARY For more information, contact: �� s � � � � � � � FREQUENCY; � � � (MHz) I I � � � I � I � I I Timothy J. Riley (303) 497-5735 Figure 2. Coverage of third-order intermodulation e-mail [email protected] Eldon Haakinson (303) 497-5304 products produced by co-located PCS systems. e-mail [email protected]

31 Law Enforcement Telecommunication Standards Outputs system and the benefits of its standardization. To facilitate the development of ALERT NIJ standards, National Institute of Justice standards. ITS established liaison with developers of data bus standards at the Society of Automotive Engineers. National Institute of Justice technology guides. More information about the New Te chnology Batteries Guide and Video Surveillance Equipment Analysis of criminal justice community Guide is provided below. telecommunications needs.

New Te chnology Batteries Guide (NIJ Guide 200-98) The Institute provides engineering support, scientific This guide reviews the fundamentals of battery tech­ analysis, technical liaison, and testing to assist nology and describes several diffe rent battery types NIST's Office of Law Enforcement Standards (e.g., Zinc-Carbon (Zn-C), Nickel-Cadmium (Ni­ (OLES) in the development and validation of crimi­ Cad), Nickel-Metal Hydride (Ni-MH), Lithium, nal justice communications standards and other Lithium Ion, rechargeable alkaline) used in law communication system products supporting law enforcement applications. Battery performance, bat­ enforcement and corrections needs. As an integral tery economics, and the trade-offs between them, are component of the National Institute of Justice's discussed. For example, voltage profiles and memo­ (NIJ's) National Law Enforcement and Corrections ry effects are explained, as well as self-discharge Te chnology Center System, OLES is tasked to apply rates and cycle life. Data tables and curves illustrate science and technology to the needs of the criminal the differences among batteries. The buyer/user is justice community. ITS supports the OLES Commu­ assisted in selecting the proper battery for particular nications Program by determining customer needs, applications and operating environments and is recommending program initiatives to address those advised on how to handle and maintain batteries. needs, and developing NIJ standards, guides, hand­ Battery chargers and adapters are addressed both in books, and other fo rms of documentation that are general and in the context of certain battery types used by thousands of agencies across the country. (e.g., Ni-Cad). The guide provides a glossary ofbat­ tery terms, a bibliography to facilitate further study, The Institute conducted a number of projects sup­ and a list of typical products and suppliers. porting OLES and NIJ during FY 98. ITS staff members updated NIJ Standards for Fixed/Base The accompanying Table, from the guide, recom­ Station and Mobile Antennas, and delivered the mends battery types for various usage conditions. In updated standards to OLES fo r publication. A New the Table, the term "primary" indicates that the bat­ Te chnology Batteries Guide was developed and pub­ tery produces electric current through an electro­ lished. ITS progressed with work on an Antenna chemical reaction that is not efficiently reversible. Guide fo r Land Mobile Radio, and began updating a Hence, it is not normally recharged. "Secondary" Video Surveillance Equipment Guide developed ear­ battery types may be economically recharged. lier. ITS also developed an NIJ tactical plan fo r the standardization of the Advanced Law Enforcement An on-line version of the entire battery guide may Response Technology (ALERT) system, and pre­ be found on the Internet at pared a magazine article describing the ALERT http ://www.nlectc.org/oles/batteryguide/ba-m.htm.

BATTERY TYPE DEVICE DRAIN RATE DEVICE USE FREQUENCY Primary Alkaline High Moderate

Secondary Alkaline Moderate Moderate

Primary Lithium High Frequent

Secondary Ni-Cd High Frequent

Primary Zn-C ("Heavy Duty") Moderate Regular

Primary Zn-C ("Standard") Low Occasional

32 Telecommunication Standards Development

Video Surveillance Equipment Guide The guide defines the technical parameters that most This guide assists law enforcement and corrections strongly influence operational performance in a sec­ agencies in selecting video surveillance systems for tion called, "Quality Parameters and the User ­ use in collecting evidence, promoting officersafety, Interpreting Manufacturers' Specifications." These and other applications. The guide addresses both parameters include image resolution, signal-to-noise general-use video equipment (e.g., separate video ratio, minimum illumination, and color accuracy. The cameras, self-contained camcorders, video recorders/ ergonomic aspects of equipment are discussed in players, monitors) and special-purpose video equip­ detail. The document provides guidelines fo r apply­ ment (e.g., surveillance systems for police cars, ing video equipment to meet specific functional retractable and portable units). The guide begins with requirements. For example, an appendix addresses a description of typical video surveillance assign­ surveillance work in low-light situations - a particu­ ments - the basic user requirements for police video lar need of the law enforcement and corrections com­ applications. These requirements serve as a context munity. The guide presents results of laboratory and reference fo r all subsequent evaluations. The experiments conducted at ITS to compare camera guide provides an extensive description of video sur­ performance. It describes PC-based image enhance­ veillance components and systems, including a ment techniques that can dramatically improve the review of the available video technology for each clarity of fa ces and other images recorded in near equipment category (cameras, camcorders, etc.), as darkness. The Figures shown here represent an image well as common and special features and accessories. before and after such image enhancement processing.

An example of image enhancement fr om a low-light scene.

For more information, contact: Val Pietrasiewicz (303) 497-5 132 e-mail [email protected]

33 ITU-T Standardization Activities

Outputs Infrastructure (Gil) envisioned by government lead­ ers and network planners worldwide. U.S. and international ITU-T standards leadership. The Institute also provides direct leadership in the ITU-T, and in American National Standards Institute Technical standards contributions. (ANSI) accredited standards committees whose work supports ITU-T goals. During FY 98, Institute Proposed ITU-T Recommendations. representatives continued technical leadership of ITU-T Working Party 4/13, and the ITU-T Rappor­ The International Telecommunication Union - teur groups for Questions 11, 13, and 22/12; and Telecommunications Standardization Sector (ITU-T) assumed a new (elected) position as Chair of ANSI­ plays a vital role in the cooperative planning of pub­ accredited Technical Subcommittee TlAl. Working lic telecommunication systems and services world­ Party 4/13 develops performance specifications and wide. The technical standards (Recommendations) measurement methods for B-ISDN/ATM and IP­ developed in the ITU-T impact both the evolution of based network services and the Gil. The three Study the U.S. telecommunications infrastructure and the Group 12 Rapporteur groups headed by ITS staff competitiveness of U.S. telecommunications prod­ members develop international standards that define ucts and services in internationaltrade. The Institute subjective and perception-based objective quality-of­ supports ITU-T activities by leading U.S. prepara­ service measures fo r speech transmission, audio/ tory committees and international work groups, pre­ visual, and multimedia communication systems. paring technical contributions to ITU-T standardiza­ Technical Subcommittee TlAl develops national tion activities, and drafting proposed new ITU-T standards (and U.S. contributions to ITU-T) in the Recommendations in technology areas important to areas of network performance and signal processing. U.S. Government and industry organizations. During FY 98, an ITS staff member was presented the Committee T1 Outstanding Contributor Award The Institute provides strong support to the U.S. for his contributions to the work of TlAl. Department of State in leading the U.S. Organiza­ tion for the ITU-T. During FY 98, Institute person­ The Institute's FY 98 activities in Study Group 13 nel served on the U.S. International Telecommuni­ contributed strongly to the completion of a proposed cations Advisory Committee (ITAC), provided tech­ new ITU-T Recommendation 1.380, that defines nical leadership and administration for U.S. ITU-T parameters for specifyingand assessing the speed, Study Group B, and headed the U.S. Delegation to accuracy, dependability, and availability of IP-based an international meeting of iTU-T Study Group 13. networks. ITS participants also developed the text The U.S. ITAC guides overall U.S. participation in for a corresponding American National Standard, ITU-T activities. U.S. Study Group B approves and Tl.SIP, and spearheaded national and international presents U.S. contributions to ITU-T Study Groups efforts to coordinate the IP performance standards 4 (Telecommunications Management Networks and work with related activities in the Internet Engineer­ Network Maintenance), 6 (Outside Plant), 10 (Lan­ ing Task Force (IETF), the Cross-Industry Working guages and General Software Aspects for Telecom­ Team (XIWT), and other Internet-relatedorga niza­ munications Systems), 11 (Signaling Requirements tions. In related ITU-T work, ITS staff members and Protocols), 13 (General Network Aspects), and contributed to the advancement of proposed new 15 (Transpmi Networks, Systems, and Equipment). Recommendation Y.Perf, which will establish gen­ Study Group 13 develops Recommendations for eral principles and a fr amework for Gil performance advanced telecommunication networks using high­ description. This new Recommendation is expected speed synchronous digital hierarchy (SDH), broad­ to be important in providing a common understand­ band integrated services digital network (B-ISDN), ing of performance concepts among the several asynchronous transfer mode (ATM), and Internet industries (e.g., telephone, computer, cable televi­ Protocol (IP)-based technologies, and is leading sion, wireless, satellite, and broadcasting) whose ITU-T efforts to define the Global Information technologies will comprise the Gil.

34 Telecommunication Standards Development

MPI MPT (1,2) MPI MPT (1) MPI (2, 1) (2) (1,3)

MPT = Measurement Point Terminal - Q.2971 (DSS-2) Signalling

MPI = Measurement Point International - Q.2761 (B-ISUP) Signalling

CSUD = Call Setup Delay

Reference configuration fo r B-ISDN call processing performance.

ITS also directed and contributed technically to the in cases where an MPI supports a multipoint con­ development of a new ITU-T Recommendation, nection segment that branches to several diffe rent !.358, that specifies call processing performance for parties. A third index can be added to permit charac­ B-ISDNs. This work required the specification of a terization of multi-connection cells. reference configuration, reference events, and a set of performance parameters capable of characterizing The !.358 parameters can be applied between any a number of new call processing fu nctions more pair of measurement points. This generality facili­ powerful (and more complex) than those implement­ tates the allocation of end-to-end performance obj ec­ ed in traditional telephony networks. The planned tives to the branches of a multipoint connection and functions include the establishment of multipoint their component national and international portions. connections and multiconnection calls and modifica­ For example, the connection setup delay attributable tion of the topologies, capacities, and performance to the connection portion between any specified pair of established connections. The Figure illustrates the of MPs (Mpi, MPj) is defined as the delay (Di) defined reference configuration in a simplified fo rm. between connection request and response events A hypothetical multipoint B-ISDN connection is (e.g., setup, connect) at the first MP minus the corre­ divided into national and international portions sponding delay (Dj ) at the second MP. This defini­ delimited by measurement points (MPs) at which tion makes the delays of concatenated portions call processing reference events, defined on the basis directly additive, and ensures that delays attributable of ITU-T standardized signalling messages, can be to called users (and "downstream" connection por­ observed. Measurement Point T (MPT) occurs at tions) are excluded from the network performance user (terminal) interfaces; Measurement Point I values specified fo r a particular connection portion. (MPI) occurs at interfaces that terminate an ATM In addition to call setup delay, Recommendation transmission system at an international switching !.358 defines call setup accuracy and dependability center. The indexed notation illustrated in the Figure parameters and a corresponding set of speed, accura­ is useful in identifying related events and parameters cy, and dependability parameters for the connection release, add party, and drop party functions.

Recent Publication For more information, contact: N. B. Seitz and K. C. Glossbrenner, "Performance Neal B. Seitz Standards for the Gil," IEEE Communications (303) 497-3106 Magazine, Vo l. 36, No. 8, Aug. 1998, pp. 116-121. e-mail [email protected]

35 Ubiquitous facility with anywhere, anytime access

Organizational

. I

Schematic view of the telecommunications infr astructure.

36 Telecommunication System Planning

The ultimate goal of the telecommunication plan­ technologies, develop alternative architectures and ning process is to ensure that systems or networks modes of operation, and select the best approaches satisfyuser requirements at an appropriate cost. The based on a derived set of evaluation criteria. process involves a set of related, but independent, Classical analysis, computer models and simula­ steps that consider all aspects of the telecommuni­ tions, laboratory experiments, and prototype testing cations environment. For example, these steps iden­ are oftenused to validate system designs and net­ tify current and projected user requirements, evalu­ work architectures at various stages of development. ate existing infrastructure and associated assets, The Institute has the resources to assist with any or identify regulatory or policy restraints, investigate all facets of telecommunications system planning. relevant standards, assess existing and emerging

Areas of Emphasis

Department of Commerce Telecommunications Planning The Institute performs Department-wide telecommunications assessment by characterizing the efficiencyand effectiveness of existing resources within a strategic planning context. Projects are funded by the Office of Systems and Telecommunications Management, U.S. Department of Commerce.

Intelligent Transportation Systems Planning The Institute characterizes the electromagnetic spectrum environment, develops propagation models, analyzes electromagnetic compatibility, and examines new telecommunication technologies to support the development of intelligent transportation systems. Projects are funded by the Federal Highway Administration (FHWA).

Railroad Telecommunication Planning The Institute performs engineering analyses, including objective voice quality assessments, of radio system designs being considered for use in the railroad industty. Projects are funded by the Federal Railroad Administration.

Telecommunications Analysis Services The Institute provides network-based public access to the latest ITS research results, engineering models, and databases supporting broad applications in wireless telecommunications system design and the evaluation of broadcast, mobile, and radar systems. The telecommunication system planning tools are funded by fee-for-use charges paid by the users of the services and by fe e-for-development charges for new software/model tools. Both funding methods are available through Cooperative Research and Development Agreements (CRADAs) between the users of the services and the Institute.

Augmented Global Positioning System The Institute supports the design and optimization of a nationwide navigation and positioning service by assessing the needs of system users, and determining the most desirable locations and operating parameters for differential global positioning system reference stations. Projects are funded by the FHWA.

Low-Cost HF Automatic Link Establishment (ALE) The Institute implements ALE functionality in personal computer (PC) software to enable users of inexpensive commercial HF radios (e.g., amateur radio operators) to participate in ALE networks supporting emergency communication needs. The project is funded by the National Communications System (NCS).

37 DOC Telecommunications Planning

Outputs These data and the associated telecommunications assessment results were valuable from several per­ Assessment of U.S. Department of Commerce spectives. First, they provided, perhaps for the first telecommunications infrastructure. time, a relatively complete (and understandable) pic­ Recommendations for infrastructure ture of the Department's overall telecommunications optimization and cost savings. assets. Second, they enabled cost analyses that re­ vealed several instances where billing errors existed or savings could be achieved immediately without During Fiscal Year 1998, ITS assisted the Depart­ any change in service levels or performance. Finally, ment of Commerce's Office of Systems and Tele­ and most importantly, they provided a basis and in­ communications Management (OSTM) in long­ centive for information sharing and cooperative range planning for a Department-wide enterprise planning among agencies. Following are a few gen­ network by conducting a detailed assessment of the eral observations derived from the Assessment Department's existing telecommunications assets. In results: this study, ITS and OSTM determined what telecom­ munications equipment and services are presently The Department's 33,000 employees are widely available within the various Commerce agencies and dispersed geographically across the United examined how well these existing resources satisfy States and beyond. The Department receives current and projected needs. The study results communications services at over 5,100 Service achieved economies in specific service-dedicated Delivery Points in over 1,600 different geo­ networks and provided a framework for cooperative graphical locations. planning of future infrastructure capabilities. Commerce Department agencies use a substan­ The study team firstcollected facility and traffic tial number of independently-procured commer­ data from the various Commerce agencies using a cial communication services in addition to FTS structured survey. The survey results were volumi­ services in meeting their mission needs. Figure nous and useful, but nevertheless incomplete. Indi­ 1 illustrates the non-FTS dedicated circuits used vidual agency responses varied greatly in level of by one Commerce agency, the National Weather detail and were not easy to integrate. Information Service. needed to assess agency use of existing assets was not always available. Accord­ ingly, ITS identified and ob­ tained supplementary infor­ mation from other sources, such as the Federal Te lecom­ munications System (FTS) billing databases, local ex­ change carrier records, human resource databases, Internet Web sites, and direct contacts with agency representatives. The survey results and this supplementary information were integrated with software analysis and graphical presen­ tation tools that enabled the proj ect team to view the Commerce infrastructure from various perspectives and Figure 1. National We ather Service non-FTS dedicated circuits. levels of detail.

38 Telecommunication System Planning

0.45

0.4

0.35

0.3

Origination Area Code

1• <202) • <206) o(208) o(301) •<304) 1:1 (305) •<408) o(410) • <503) • <650) o(703) o (704) • <801) • <805) • <808) • <907) 1

Figure 2. Average cost per minute fo r area code pairs where monthly bills exceed $1 000/mo.

Even within FTS switched voice service, the in a similar way in situations where an agency's average cost per minute of a telephone call work is concentrated in a limited geographic varies widely for different area code pairs. See area. Figure 2. ITS is currently working with OSTM to develop the There are numerous opportunities to optimize Department's Strategic Te lecommunications Plan ­ telecommunication arrangements at Commerce a structured methodology for evolving Commerce's locations to achieve economies of scale. The telecommunications infrastructure into the 21st cen­ study's identification of the collective assets at tury. The detailed information obtained in the tele­ some locations has already prompted consolida­ communications assessment proj ect will enable the tion actions, supported by the user agencies, that Department to make maximum use of current assets have netted substantial cost savings. in this evolution, thereby reducing costs. The Stra­ tegic Plan will provide a framework from which No comprehensive plan for a Department-wide Department officials can make decisions regarding enterprise network exists today. A number of both normal and emergency telecommunication the Department's largest networks operate inde­ operations. It will also facilitate the establishment of pendently with little interaction or coordinated regulations and guidelines pertaining to the procure­ network management. ment, implementations, ownership, management, maintenance, and upgrading of telecommunication Network plans being developed in several system elements across all agencies. Major tenets Commerce agencies could serve as valuable guiding the plan are mission effectiveness, flexibility templates for similar planning in other agencies to accommodate evolving needs, reliability, and - or for cooperative planning of more integrat­ minimum life cycle cost. The plan will enable the ed, multi-agency solutions. As examples, the various agencies to implement mission-specific National Weather Service's Advanced We ather capabilities in the context of a broader commerce Interactive Processing system (AWIPS) tele­ enterprise network. communication network architecture could pro­ vide a useful planning model for other Com­ For more information, contact: merce services involving significant geographic Val J. Pietrasiewicz dispersion. The Patent and Trademark Office's (303) 497-5 132 I campus network evolution plan could be applied e-mail [email protected]

39 Intelligent Transportation Systems Planning

Outputs industry with resultant loss of productivity and profit, wasted energy, increased emissions, and Electromagnetic compatibility analysis of the possible spoilage of perishable cargo. Automated intelligent transportation system & subsystems. weigh-in is accomplished as the tluck drives at high­ way speed along the highways which have been out­ Low and medium fr equency propagation model fitted with a special scale and electronic identifica­ development for differential global positioning tion and tolling system. This procedure has none of system and advanced traffic information the disadvantages of the conventional weigh-in sys­ systems analysis. tem. Toll collection is one function for which dedi­ cated short-range communication (DSRC) systems Electromagnetic compatibility analysis and are used. testing of dedicated short-range communication systems for intelligent transportation systems. The Institute has been working to ensure electro­ magnetic compatiblity (EMC) between ITS electron­ Vehicle traffic congestion is on the increase in the ic systems and the electrical/electronic environment. United States. Unless it can be checked, the contin­ EMC is the ability of electronic equipment to ued increase will result in productivity loss, acci­ achieve a specified level of operability when operat­ dents, \vasted energy, and increased vehicle emis­ ing in an uncontrolled environment. EMC involves sions. The conventional approach to this problem is the orchestration and integration of system compo­ to build more roads or expand the number of lanes nents to control interference coupling. It is a primary on existing highways. But financial and environmen­ factor in the performance, safe ty, and effective oper­ tal constraints are making these techniques less and ation of ITS systems, and thus a primary considera­ less fe asible. The approach of intelligent transporta­ tion in ITS system design. The electronic devices tion systems (ITS) is to utilize computer and tele­ and equipment used for ITS, and the coupling of communications technology to provide information external signals and interference from external to travelers about road and transit travel conditions sources represent a complex interactive electromag­ and to monitor, guide, and control the operation of netic environmentwith emitters and receptors. Inter­ vehicles. ITS can improve safety, reduce congestion, ference problems may arise when radio communica­ enhance mobility, minimize environmental impact, tions equipment and other electronic devices are save energy, and promote economic productivity on operated around ITS-equipped vehicles. This could the Nation's transportation system. ITS will allow cause interference among ITS equipment, the resi­ travelers to plan their mode of transportation ahead dent automotive electronic systems and the electron­ of time, and to make more informed choices about ic equipment in the rest of the environment. EMC routes, time, and modes of travel. In addition, must be achieved to prevent interference problems. authorities will be able to manage transportation systems and control traffic more efficiently in a Recent activities and accomplishments by the dynamically changing traffic environment. Institute to address the EMC of ITS include:

Another area of development for ITS is electronic 1. Analysis and testing of two DSRC Systems that toll collection to reduce traffic delays and congestion determine the potential EMC problems with radars at toll booths on bridges and highways. Related to in the 5850 to 5925 MHz band. One system con­ this area is automated in-transit commercial vehicle fo rms to the European Standard and the other to the weigh-in fo r trailer truck traffic. Truckers traveling Japanese Standard. Both systems are in the develop­ across the United States must weigh in frequently as ment phase and have been proposed fo r use in elec­ they pass through different states so that interstate tronic toll collection. trucking fe es and taxes can be properly assessed. Conventional weigh-in procedures require the truck 2. Measurements of radar characteristics in the 5850 to pull up onto a large off-road scale to determine to 5925 MHz band to assist in characterizing emis­ the vehicle and cargo weight. This causes significant sions in that fr equency band in order to assess inter­ delays in delivery and scheduling for the trucking ference potential to the DSRC Systems.

40 Telecommunication System Planning

-72W -lOW -68W -66W

Radio coverage fo r an AM broadcast subcarrier system generated by the low and medium fr equency prop agation model developed by the Institute (illustration by A. Romero) .

3. Measurement of satellite uplink interference lev­ Future activities of the Institute include but are not els in the 5850 to 5925 MHz band to characterize limited to: characterization and measurement of the the emission spectmm specifically for interference electromagnetic environment, spectrum planning, analysis to the DSRC systems. propagation model development, determination of suitable new and emerging communications technol­ 4. Development of a low and medium fr equency ogy for ITS, prediction of radio coverage for com­ propagation model to be used for analysis of the munication systems, and selection/establishment of Diffe rential Global Positioning System (DGPS) sig­ an EMC requirement standard fo r ITS. nal for refinement of position accuracy and the AM subcarrier advanced traveler information system The Figure is an actual output of the low and medi­ (ATIS). This AT IS system would be used to dissemi­ um frequency propagation model developed by the nate information to travelers in the mral roadway Institute. It shows the coverage fo r an AM radio sta­ environment. This analysis will support the design tion that would be used to disseminate traffic and and field operational testing of the AM subcarrier weather information for an AM subcarrier traveler evaluation effort fo r ATIS. information system of the ITS.

Recent Publications

N. DeMinco and C.L. Holloway, "Propagation mod­ eling for ITS applications in the roadway environ­ ment," In telligent Transporation Sys tems Jo urnal, For more information, contact: Vo l. 3, No. 4, Aug. 1997. Nicholas DeMinco (303) 497-3660 R.A. Dalke, F.H. Sanders, and B.L. Bedford, e-mail [email protected] "Electromagnetic compatibility testing of a dedicat­ Roger A. Dalke ed short-range communication system," NTIA (303) 497-3 109 Report 98-352, Jul. 1998. e-mail [email protected]

41 Railroad Telecommunication Planning

Outputs kHz channel spacing environment of the NARRN channel plan. The second is the improvement in Proj ect 25 land-mobile radio speech quality speech intelligibility and geographic coverage under different channel spacing and interference afforded by the P25 radio. conditions. ITS performed a series of measurements to relate the Example radio coverage contour predictions delivered audio quality of speech signals transmitted comparing geographical coverages of digital through P25-compliant radios to radio sensitivity, and analog modulation formats. adjacent channel rejection and cochannel rejection parameters. The measurements were performed with As a result of the Federal Communications Com­ the radios operated in both P25-digital and conven­ mission's (FCC) radio spectrum realignment initia­ tional analog FM modes. For a given degree of tive, the FCC has directed that all newly designed speech intelligibility, it was fo und that the RF sensi­ land-mobile radio (LMR) equipment will incorpo­ tivity of the P25 digital mode was better than for rate narrowband technology solutions. Since future conventional analog FM. From this data, a represen­ radio systems and equipment will, by necessity, be tative case study illustrating the improvement in narrowband, users should begin planning now to radio coverage afforded by the P25 platform was deal with migration and compatibility issues when perfonned. The Figure shows two radio-coverage they introduce new equipment and systems into their contours, one for P25 digital mode and one for con­ existing LMR infrastructures. ventional analog FM mode.

The railroad industry has responded to this initiative The contours delineate the regions where it is pre­ by fo rming an ad-hoc industry committee, the North dicted that the delivered audio quality of speech will American Railroad Radio Network (NARRN). This be greater than some perceived level of intelligibili­ committee is chartered to investigate how to best ty. The purple-shaded area corresponds to the region migrate the railroad industry's existing 160-MHz where a 5-watt portable analog FM radio will deliv­ analog land mobile radio equipment to more mod­ er good speech intelligibility to a base station site. A em, spectrally-efficientsystems, and to develop a 5-watt portable P25 digital-mode radio will deliver strategy to accomplish this migration. The Federal comparable or superior speech intelligibility to the Railroad Administration (FRA) wishes to ensure that same base station over an even larger territory. This adopting NARRN's recommendations will not additional territory is denoted by the green-shaded adversely affe ct public safety. ITS was tasked by the area in the Figure. FRA to evaluate NARRN's proposed rechanneliza­ tion plan and provide input to NARRN and the FRA Since the transmission bandwidth of the P25 radio is regarding the efficacy of the recommended radio 12.5 kHz, and the channel spacing in the railroad platform. VHF band is 7.5 kHz, considerable spectrum over­ lap between adjacent-channel signals can occur. One ofNARRN's recommendations is to adopt the Ongoing work is categorizing the delivered audio digital radio platform adopted by the Telecommuni­ quality of a wanted speech signal, received in the cations Industry Association. This radio platform is presence of adjacent-channel interference. Four known as Project 25, or simply P25. P25 provides interference modes are of interest: (1) an unwanted an open design standard, which any vendor can digital signal interfering with a desired digital chan­ build to and ensure interoperability with other ven­ nel, (2) an unwanted analog signal interfering with a dors' P25-compliant equipment and older, analog desired digital channel, (3) an unwanted analog sig­ FM equipment. nal interfering with a desired analog channel, and (4) an unwanted digital signal interfering with a desired Using a P25 radio in the NARRN channel plan envi­ analog channel. The results of this activity will ronment has brought to light several important directly affect "cellular" system design layouts in issues. First and fo remost is the effe ct of the P25 congested rail centers by influencing the choice of radio's 12.5-kHz bandwidth when used in the 7.5- frequencies in neighboring cells.

42 Telecommunication System Planning

Situallonvarlal>fity: 50.00% Relablity. 90.00% Frequency: 161.000MHz P-: VOftical .005 5/m Conductivity: OieWJctricconstant: 15.0 Climatezone: Continentaltempefate Basestn callaJgn: KEX417 Base stnlocatlon: 41.1869N103.0497W Base stn sitetrievation : 1313.0 m Base stn ant ht AGL; 78.00 m Base stn line k>sses: 4.0 dB Basestn antenna gain: 9.00 dBd Base stn ant horz pattern: Omridiredlonal PO

• AnalogPM Area: 6290 sqkm

8 P25DigitalC4PM Area: 8100 sq Jaa

• Area: 48010 sqkm

Ty pical analog and digital mode terrain coverage contours, fo r equal speech intelligibility.

For more information, contact: John Vanderau (303) 497-3506 e-mail j vanderau@its. b ldrdoc. gov

43 Telecommunications Analysis Services

Outputs digital television). This model allows the user to cre­ ate scenarios of desired and undesired station mixes. Network access for U.S. industry and The model maintains a catalog of television stations Government agencies to the latest ITS and advanced television stations from which these engineering models and databases. scenarios are made. Results of analyses show those Broad applications in telecommunication system areas of new interference and the population and design and evaluation of broadcast, mobile, and households within those areas. Figure 1 shows the radar systems. result of a study done for a proposed digital station in Connecticut. In addition to determining the contri­ Standardized models and methods of system bution to interference fr om other stations to a select­ analysis for comparing competing designs for ed station, the model can tell the user the amount of proposed telecommunication services. interference a selected station gives to other stations. This allows the engineer to make modifications to his/her station and determine the effect these modifi­ Telecommunications Analysis Services (TA cations have on the interference the station gives Services) gives industry and Government agencies other surrounding stations. In addition to creating a access to the latest ITS research and engineering on plot similar to that shown in Figure 1, the program a cost reimbursable basis. It uses a series of comput­ creates a table which shows the distance and bearing er programs designed for users with minimal com­ from the selected station to each potential interferer puter expertise or in-depth knowledge of radio prop­ as well as a breakdown of the amount of interfer­ agation. The services are updated as new data and ence each station generates. This model can now be methodologies are developed by the Institute's engi­ accessed via a network browser. neering and

research pro­ TA Services TA services grams. For Dlgl tal liTIC, Ct 10-Mar->ae 16:16:12 information on RSOOCN:>V0996A.ques available pro­ grams, see pp. 87-88 ofthis report or call the contact list­ ed below.

TA Services is currently assist- ing broadcast television pro- viders with B1J;r'IB1. to [nterferenoe rat1o CJ No ln�or"""" their transition N"oa: 1&T�O. oa ko Pop..ll.At.10t\ 321.5000, to digital tele- Hou!H!holM: 107QOOO. HJ'tV lr"'t.�rf@�r"'(l· vision (DTV) NUtllt 40. ttt1 knl �t!""' 17000 I by providing a HouocholdCI eooo. NTSC Int.fll'f.I"OI"t!• model fo r use At·emt 1aa7o- � kfl �Mon: 2W3000. in advanced 1-bJQahQlc;JC: e17'()C(l0, - 81Qnul tJDlow minlmlll television anal- Aroa: 111410. aq ko Poc>.Jllltlort 24eTIIOOO. ysis (high-defi- Houl4ilt,Oldlll! 61!541000, nition televi- " sion, advanced television, and Figure 1. Interference analysis fo r a proposed digital station in Connecticut.

44 Telecommunication System Planning

TA Services continues to develop models in the GIS environment for personal communica­ tions services (PCS) and Local Multipoint Distribution Systems (LMDS). A GIS effi­ "' 15 Azimuth fro�n TruG Nor1h 09 Osm Lint�r ciently captures, stores, updates, manipulates, >O _ OS analyzes, and displays all fo rms of geographi­ 315 cally referenced information. The use of GIS 300 has grown substantially over the past several years in business, Government, and academia. .Js As a result, databases necessary fo r telecom­ munication system analysis are now becoming available in fo rms easily imported into the GIS 255 . lOS environment. These databases, including ter­ rain, roads, communications infrastructure, building locations and fo otprints, land type and use, and others, can be maintained in relational database management systems (RDBMS) that '" 165 can be connected to the GIS or placed into the GIS RDBMS. This reduces the amount of data­ base development necessary in PCS/LMDS Figure 2. Antenna patternfro m the user catalog modeling. in the TA Services PCSIL MDS model.

As the fr equency of an application increases, the A user can create a database of transmitters and level of detail required to adequately describe the antenna patterns from which analysis scenarios can path also increases. At PCS and LMDS frequencies, be created. Transmitters can be described easily and it is increasingly important to know the location of placed either by defining the latitude and longitude trees and buildings, as well as other terrain obstruc­ or zooming in or out on the map and selecting the tions. At these higher frequencies, it also becomes location of the transmitter. The GIS software reads important to know what kind of vegetation a signal the location fr om the map and stores it in the trans­ is penetrating. As ray tracing becomes practical in mitter definition table. Antenna patterns can be GIS models, it will become important to know the imported, entered in table form, or drawn on the shape and materials used in buildings. Information screen by a user as shown in Figure 2. The user can on building heights and vegetation is not commonly then give the pattern a name and store it in a person­ available. However, some city and county Govern­ al catalog for future use. Analysis scenarios created ments are beginning to enhance their GIS databases by a user consist of a set of transmitters, antennas, to include this data, and this trend is expected to and models chosen to produce propagation results continue. Software is available and under develop­ for a region of interest. Models include a line of ment that allows a user to import digital stereo pho­ sight (LOS) model, a road-guided path loss model, tographs or other remote sensing data taken from and a diffraction model. The program allows the aircraft at relatively low altitudes or even spacecraft. user to vary receiver heights as well as turn on and If this data is taken with sufficient quality it can be off the contribution of any transmitter to the overall used to create three-dimensional surfaces for the coverage. GIS with accuracies on the order of a meter or less. This will greatly reduce the cost of developing data­ bases with the accuracies necessary to ensure reli­ able analysis results.

The PCS/LMDS model currently under development at ITS allows a user to select a city or region of interest that has a database developed and imported into the model. Once on board, these environment For more information, contact: and analysis results can be displayed in two or three Robert 0. DeBolt dimensions. (303) 497-5324 e-mail [email protected]

45 Augmented Global Positioning System

Outputs Guard's (USCG) local area DGPS, to provide nationwide coverage of DGPS for surface applica­ Verification of the performance of the first tions (DeBolt et al., 1994; see Publications Cited, p. GWEN differential GPS reference station. 1 06). The Institute has completed a study, sponsored by the Federal Highway Administration, to deter­ Planning ofthe number and location of GWEN mine the optimum location and operating parameters differential GPS reference stations required to of the DGPS reference stations required to provide provide nationwide signal coverage. this civil navigation and positioning service to all surface users across the nation. The use of this Recommended frequency assignments for service will have an enormous impact on a diverse differential GPS reference stations. set of uses including ocean and land transpotiation, surveying and mapping, farming, waterway dredg­ ing, recreation, emergency location and rescue The NAVSTAR global positioning system (GPS) is a operations, and many others that have not yet been space-based radionavigation system which consists identified. of a constellation of 24 satellites in 6 orbital planes; it provides accurate three-dimensional position, This new service will be known as the nationwide velocity, and precise time to users worldwide, 24 differential global positioning system (nDGPS). The hours per day. GPS was originally developed as a foundation of this system is the DGPS reference sta­ military force enhancement system. Although still tions cmTently operating or planned by the USCG used in this capacity, GPS also provides significant and the U.S. Army Corps of Engineers; this system benefits to the civilian community. To make GPS provides coverage of the radiobeacon DGPS signal service available to the greatest number of users for coastal areas, harbors, and inland waterways. while ensuring that the national security interests are protected, two GPS services are provided. The pre­ ITS added additional DGPS reference stations to this cise positioning service (PPS) provides full system foundation to provide nationwide coverage of the accuracy to military users. The standard positioning DGPS signal. To achieve this additional signal cov­ service (SPS) is available for civilian use but has erage, ITS used the Ground Wave Emergency less accurate positioning capability than PPS. Network (GWEN) sites, owned by the Air Force Air Combat Command. The GWEN system is an exist­ SPS accuracy of 100 m does not meet most civilian ing Federal Government asset that provides a cost­ navigation and positioning requirements. Various effective method of implementing nationwide cover­ augmentations to GPS are used to provide increased age of the DGPS signal. The GWEN sites were used accuracy and integrity of the SPS signal. One form at existing locations or moved to new locations as of augmentation, differential GPS (DGPS), can pro­ required to complete the nationwide DGPS signal vide 1- to 10-m accuracy fo r dynamic applications coverage. The GWEN sites provided the infrastruc­ and better than 1-m fo r static users. In the 1994 ture required for a DGPS reference station (Figure NTIA special publication, "A technical report to the 1 ). Installation of these GWEN DGPS reference sta­ Secretary of Transportation on a national approach tions has already begun, with six stations scheduled to augmented GPS services," ITS recommended for operation in FY 99. The projected signal cover­ implementation of a radio beacon system, operating age of a typical GWEN DGPS reference station is in the 300-kHz band, modeled after the U.S. Coast shown in Figure 2.

46 Telecommunication System Planning

Figure I. Typical Ground Wa ve Emergency Network (G WEN) transmitter site.

$ VV h itney

BN

188""' 186W 1C212W ...... sew ssw

Figure 2. Predicted DGPS signal coverage fr om a GWEN site at Wh itney, NE .

Recent Publication For more information, contact: J. R. Hoffman, J. J. Lemmon, and R. L. Ketchum, Ronald L. Ketchum "DGPS field strength measurements at a GWEN (303) 497-7600 site," NTIA Report 98-346, Apr. 1998. e-mail [email protected]

47 Low-Cost HF Automatic Link Establishment Outputs National Communications System (NCS) and its member agencies in achieving this goal by develop­ Software ALE capability fo r personal ing and demonstrating a low cost HF ALE capability computers. for the personal computer (PC).

Prototype HF ALE demonstration system. Under the ITS approach, FED-STD-1 045A commu­ nication functions such as sounding and channel The High Frequency (HF) band, 3-30 MHz, is one evaluation will be implemented in PC software. of the oldest wireless communications media. During the first half of FY 98, ITS engineers devel­ Although it is commonly regarded as the province of oped a prototype "Phase I" ALE system that hobbyists and amateur radio enthusiasts (hams), this demonstrates the feasibility of using real-time soft­ band has great potential value as a backup to other, ware embedded in PCs to control inexpensive HF more vulnerable elements of the U.S. communica­ radios and modems - and to establish operational tions infrastructure in times of national emergency. HF links. Figure I shows the commercial equipment Unfortunately, achieving this potential has required that was used in developing the Phase I system. highly trained operators as a result of the extreme During the latter half of FY 98, ITS began develop­ variability, and complexity, of the HF medium. ing a Phase 2 ALE software system that will imple­ FED-STD-1 045A, HF Radio Automatic Link ment the extremely robust FED-STD-1045A modem Establishment (ALE), was developed to simplify and waveforms and the standard's automatic channel facilitate HF radio operation by automating the evaluation capabilities. ALE protocol waveforms for selection of transmission fr equencies. The standard channel selection and negotiation will be generated specifies channel sounding algorithms, transmission and decoded in software, using ITS-developed data­ waveforms, and a protocol fo r automatically estab­ bases of precision audio tones and ITS-developed lishing and maintaining an HF radio link. ALE demodulation techniques. The ALE software will removes the difficultyof choosing an HF communi­ also include modules for configuration management, cations channel by polling and scoring a number of radio control, protocol management, message encod­ potential channels for link quality. Using this infor­ ing and decoding, signal modulation and demodula­ mation, the receiving radio negotiates with the trans­ tion, and the maintenance of a database of detected mitting radio fo r a suitable link frequency. ALE dra­ signals. The resulting software-based ALE radios matically reduces the time necessary to set up an HF will interwork directly with commercial, hardware­ communications link - and increases the likelihood based FED-STD-1045A radios costing up to 10 of satisfactory communications over the selected fr e­ times as much. quency - by eliminating the need for users to understand ionospheric radio propagation. Linkreli­ The key technical challenge in the Low-Cost ALE ability is improved by using ALE's sounding and project is to develop a demodulation technique that channel evaluation capabilities. ALE radios are easy is robust enough to detect the transmitted ALE tones and efficientto operate, even in the hands of the in the presence of severe HF channel noise and most inexperienced users. interference, yet simple enough to be implemented in real-time software on a Windows® based PC. Despite its advantages, HF ALE has not been imple­ Figures 2 and 3 indicate the quality of the fr equency mented widely by non-government users because of discrimination that has been easily achievable in the its relatively high equipment cost. There would be ITS HF radio laboratory. In future work, ITS will substantial benefits to the National Security and select the demodulator algorithm, implement that Emergency Preparedness (NS/EP) missions of the algorithm and the other key ALE functions in soft­ National Communications System (NCS) and other ware, and demonstrate the system's performance Federal Agencies if ALE technology could be made under realistic HF channel conditions. The ITS HF more widely available. Coordination with hams in ALE software will bring software radio equipment times of emergency has greatly enhanced previous to any desktop, greatly increasing the effectiveness disaster relief efforts. Broadening HF connectivity of Federal NS/EP efforts. would speed future relief efforts. ITS is assisting the

48 Telecommunication System Planning

RS-232 RS-232

Data

IIIII Control RS-232 R5-232

Figure 1. Phase One QuasiALE.

120 9 r===-======-======� ,------�---,

7 7 5 5 5 5 4 44 555 8 8 7 5 8 8 22 100 8 2

2 20 1o�==�10��2�0��3�0==�40��5�o==�6�0==�70 Time in milliseconds �����10-�2-0-�3�0�---40-�5�0 ���60��70 Tlme in milliseconds Figure 2. ALE wavefo rm demodulation Figure 3. ALE wavefo rm demodulation using the energy op erator. using Goertzel method.

For more information, contact: Christopher Behm (303) 497-3640 e-mail [email protected]

49 · I

ITS 4-GHz earth station under construction. Th is station is being used to determine susceptibility of satellite downlinks to interference fr om radar signals (photograph by FH. Sanders) .

50 Telecommunication System Perfo rmance Assessment

The Institute develops tools, facilities, guidelines, ments evaluated span the range from individual and procedures fo r telecommunication system per­ equipment components (e.g,. signal encoders and formance assessment and applies these resources in decoders) to end-to-end communication links and predicting and measuring the performance of partic­ networks comprised of many independent transmis­ ular systems and their components on behalf of sion and switching elements. Institute engineers telecommunications users, equipment manufacturers, have assessed terrestrial wireless, wireline, and and service providers. The performance assessment satellite transmission media and a variety of services resources developed and used at ITS include stan­ and technologies including cellular radio, land dard performance metrics and measurement meth­ mobile radio, personal communication services ods; software and hardware simulation and testbed (PCS), synchronous optical network/synchronous facilities capable of emulating equipment perfor­ digital hierarchy (SONET/SDH), asynchronous mance under repeatable laboratory conditions; envi­ transfer mode (ATM), and both X.25-based and ronment generators that accurately reproduce desired Internet Protocol (IP)-based packet switching. The traffic, climate, terrain, propagation, and noise/inter­ Institute's system performance assessment results ference effects; standard source materials represent­ are used in advanced technology development, ing specific types of voice, video, data, and multi­ equipment design and prototype testing, and the media communications signals; and computer-based evaluation and optimization of communication ser­ test equipment fo r collecting, reducing, analyzing, vices from both provider and end user perspectives. and presenting system performance data. The ele-

Areas of Emphasis

Radio System Design and Performance Software The Institute applies its enhanced Jammer Effectiveness Model, a Windows-based computer program, in assessing the impacts of jamming and interference on communications and radar system performance in elec­ tronic warfare scenarios. Projects are funded by the U.S. Army National Ground Intelligence Center.

Satellite Studies The Institute applies ITS-developed standard performance metrics in assessing satellite-based data, voice, video, and multimedia communication services and presents results in national and international standards organizations. Proj ects are funded by NTIA.

Multimedia Performance Handbook The Institute develops technical information and specific examples to assist users in specifying, evaluating, acquiring, and operating video teleconferencing and other multimedia communication systems, and documents the results in successively more comprehensive releases of a CD-ROM based interactive multimedia docu­ ment. Projects are funded by NCS.

Wireless Telephony Performance Measurements The Institute measures the transmission performance and delivered audio quality of advanced digital land­ mobile radio systems to assist users in LMR network design and operation. Projects are fundedby Federal Railroad Administration.

51 Radio System Design and Performance Software Outputs Databases are created as a result of this data entry and saved as scenario descriptions. Current version of Jammer Effectiveness Model for communications analysis in use by the U.S. The communications analysis version of JEM is Army. primarily used to model communication systems in electronic warfare scenarios where these systems are Additional version of Jammer Effectiveness being jammed or interfered with. The Figure illus­ Model for radar analysis in use by the U.S. trates a jammer attempting to jam a point-to-point Army. microwave communication link. This version of JEM is organized into six scenarios, each of which Multiple jammer and interferer analysis represents either a communication path geometry capability on a wireless network. description or a jamming geometry description. The four scenario types in the communication geometry In FY 98, ITS continued to make improvements to description are: ground-to-ground, ground-to-satel­ the Jammer Effectiveness Model (JEM). JEM, lite, ground-to-aircraft, and aircraft-to-satellite. The which was developed by ITS fo r the U.S. Army in two scenario types in the jamming geometry order to evaluate electronic warfare scenarios, runs description are jamming and jammer versus net­ as a Windows application on a personal computer. work. The jamming scenario analyzes: received jam­ This model is a very flexible analysis tool and can mer power versus distance, received transmitter be used to perform many different types of analysis, power versus distance, jammer fo otprint, and because it is highly structured and modular in isopower contours. Recently added in FY 98 is an design. ITS has developed two versions of JEM: one area of isopower contours computation. The jammer for communications analysis and the other for radar versus network scenario analyzes and evaluates the analysis. effects of up to three jammers on up to five commu­ nications nodes. For the jamming geometry descrip­ Each version of JEM includes a user-created catalog tion, the receiver, transmitter, and jammer platforms of equipment, ground stations, aircraft and satellite can be on the ground or airborne. platforms; the software fo r creating and maintaining this catalog; a climatological database for much of The jamming and jammer versus network scenarios the world; a library of propagation subroutines; and are the major fe atures of JEM for electronic warfare the analysis software. The JEM propagation library and interference analysis. The other four scenario includes subroutines for use in calculating clear-air types are used to help evaluate and design attenuation, rain attenuation, multipath attenuation, microwave communication systems. They allow the diffraction losses, and troposcatter losses. In FY 98, user to simulate a wide variety of propagation ITS developed printer setup capability fo r both JEM effects on the system that occur in the higher fre­ versions. The valid frequency range of the commu­ quency ranges by including clear-air absorption loss­ nication version of JEM is currently 2 MHz to 300 es and losses due to rain attenuation. In FY 98, the GHz, while that of the radar version is currently 30 ability to perform the received signal power versus MHz to 20 GHz. range computation independent of a scenario has been added. Also new in FY 98 is three dimensional JEM uses scenarios to completely characterize a antenna patterncapabilit y. communication linkor radar configuration with or without a jamming situation. The scenario descrip­ The radar version of JEM allows radar analysis for tion includes ground or airborne station location and different combinations of radars and jammers that physical factors such as climate and terrain. Each of are on the ground or carried by airborne stations. the analysis programs within a scenario analyzes the The radar analyses consist of either evaluating the case represented by the scenario description data. performance of a radar trying to detect and track a Data entry in JEM to create a scenario is simplified target or evaluating the ability of a synthetic aperture by the use of user-friendly menus and options. radar to map a location. The analysis can be

52 Telecommunication System Performance Assessment performed both with and without the presence of a There are three analysis modes available in the radar jammer. One scenario includes the jamming of an jamming scenario: a radar jammer fo otprint, a radar airborneradar by a ground-based or airborneja m­ isopower contour, and a radar burn-through range. mer to protect potential targets that can either be For the radar jammer footprint analysis a jammer is collocated with the jammer or separated from the able to jam a radar that is on or within a contour of jammer. A second scenario involves the jamming of distance to jammer versus azimuth angle, and pre­ a synthetic aperture radar on an airborne platform vent it fr om detecting a target. The isopower contour fr om either an airborne or ground-based jammer analysis is a plot of signal power density about the platform. The three dimensional geometry of these radar or jammer versus distance and azimuth angle radar scenarios requires three dimensional antenna about the radar or jammer. The radar burn-through patterns which are also included in the analysis range analysis is the minimum range to the target models. versus azimuth angle at which the target is obscured by jamming. It is also the maximum range versus azimuth angle at which the radar detects the target.

A jammer attempting to jam a point-to-point microwave communication link (i llustration by A. Romero) .

For more information, contact: Nicholas DeMinco (303) 497-3660 e-mail [email protected]

53 Satellite Studies

Outputs Emerging low Eatih orbit (LEO), medium Eatih orbit (MEO), and highly elliptical orbit satellite con­ Transportable video quality measurement stellations will suppmi direct communications with system. mobile and hand-held terminals, giving users access to telephone and Internet services from any point on Report on national security and emergency the Earth's surface. preparedness experiments using the Advanced Communications Technology Satellite (ACTS). These advanced satellite capabilities can only be fullyeff ective if the satellite systems are seamlessly integrated with the terrestrial networks. The Insti­ Recent technology advances are giving communica­ tute's Satellite Studies Project contributes to satellite tion satellite systems new capabilities that should technology enhancement and interoperability enable them to play a strong role in future global through system and link perfmmance measurements communications. The early satellites were simple and technical contributions to national and interna­ analog repeaters placed at a very high altitude, usu­ tional standards committees. The project's current ally in geostationary Earth orbit(G EO). Today's fo cus is on digital satellite systems that use asyn­ advanced GEO satellites are digital, use on-board chronous transfer mode (ATM) technology for data, switching, and have multiple steerable spot beams. voice, video, and multimedia applications.

� I Video 1 Source I

"41 • �_/ Outp��Q M;- !Actual Satellite ·I I Channel

1

Figure 1. Te st configurations fo r planned video quality measurements. Path 1 willdeterm ine the effects of MPEG-2 encoding and decoding. Path 2 transports the MPEG-2 over ATM Path 3 passes the ATM cells through a bit-level channel simulator, and path 4 uses an actual satellite channel.

54 Telecommunication System Performance Assessment

The transmission of ATM over satellite is currently being studied in several standards committees. The Wireless ATM group of the ATM Forum is working to promote satellite/terrestrial ATM interoperability to ensure that satellite links can be used in any part of an ATM network. To achieve this, they need a common air interface (CAl) specification. This spec­ ification is being developed by a working group in the Satellite Communications Division (TR-34) of the Telecommunications Industry Association (TIA). The Institute contributed strongly to the reference architectures developed by the ATM Forum and used in the draft CAl specification.

U.S. Working Party 4B of the International Tele­ communication Union, Radiocommunication Sector (ITU-R) is developing two new Recommendations that will specify Quality of Service (QoS) obj ectives for ATM satellite links. These new Recommenda­ Figure 2. ACTS Earth station antenna, part of the tions will complement ITU-T Recommendation ACTS fa cility at ITS in the satellite laboratory 1.356 (developed under ITS leadership), which (photograph by FH Sanders) . defines minimum, end-to-end quality objectives fo r ATM networks. The need, and challenge, at this time is to determine the minimum satellite link quality TVQMS will be used. The planned experiments will required to support the ATM performance levels be conducted during FY 99. already agreed upon for terrestrial (fiber optic) trans­ Project staff members also published the results of a mission. During FY 98, the Institute developed test set of experiments performed over NASA's capabilities and experiment plans that will enable it Advanced Communications Technology Satellite to collect quantitative measurement data addressing (ACTS) during FY 98. These experiments used the that need. This experimental work will apply the ACTS Earth station at ITS (see photograph of the Institute's unique ability to make repeatable, accu­ antenna in Figure 2) and two others to fo rm a small rate, objective measurements of end-to-end video network. These experiments provided information quality. on the ability of an advanced satellite to support Many believe that MPEG-2 digital video is one of National Security and Emergency Preparedness the most demanding applications fo r ATM network (NS/EP) functions using off-the-shelf applications. transport. During FY 98, the Satellite Communica­ Desktop conferencing, local area network (LAN) tions Project staff completed a test facility that bridging, and voice communications were all effec­ includes a transportable video quality measurement tively supported. An important findingof these system (TVQMS) that can make quality measure­ experiments was that satellite networks will require ments of MPEG-2 video over either simulated or special protocol provisions (e.g. larger retransmis­ real satellite channels employing ATM. The block sion window sizes) to provide TCP/IP (transmission diagram in Figure 1 illustrates several test config­ control protocol I Internet protocol) support compa­ urations, of increasing complexity, on which the rable to that provided by terrestrial facilities.

Recent Publication

W.A. Kissick, et al., "National security and emer­ For more information, contact: gency preparedness communications experiments William A. Kissick using the advanced communications technology (303) 497-7410 satellite," NTIA Report 98-354, Aug. 1998. e-mail [email protected]

55 Multimedia Performance Handbook

Outputs information base. In FY 98, ITS provided a product that is easier to use and more versatile. The revised Interactive CD-ROM application fo r video­ Handbook is well-suited to the needs of current (or teleconferencing system performance future) Federal users of multimedia communications. specification. In particular, it addresses videoconferencing (VTC) requirements that are important to the National Tutorial and reference material on multimedia Security and Emergency Preparedness (NS/EP) performance assessment. telecommunications mission ofNCS. The Handbook provides a wealth of technical information and many Several years ago, ITS engineers recognized the specific examples to assist users in making effective need for a convenient source of practical informa­ decisions in the specification, procurement, and use tion to assist users in assessing the performance of of multimedia communication systems. The Hand­ multimedia communication systems. They fo resaw book's extensive use of audio, video, and graphical that such information would find application in the presentations greatly enhances the impact and value procurement of multimedia products, in product of its technical content. The hyperlinking of key text acceptance testing, and in the operation and mainte­ allows users to skim familiar material and delve nance of products after installation. Much of the more deeply into other topics. necessary information had been or was being pro­ duced in related ITS programs on telecommunica­ Version 2.0 of the Handbook implemented a new tion performance standardization, but additional specification "applet" (a small application program) product-specific information and more systematic that assists users in establishing multimedia perfor­ selection criteria were needed. For example, ITS had mance requirements. The applet enables users to been involved for several years in developing tech­ experience interactively the likely performance of niques for obj ective, technology-independent mea­ particular VTC configurations. For example, after surement of video image quality. While the resulting entering the specification applet and choosing the information was extremely valuable, consumers also videoconferencing application, the user can choose wanted information concerning the image quality of either desktop videoconferencing or conference specific types of video monitors and other video room videoconferencing as the multimedia context. equipment. ITS sought and received support from Assuming the former choice is made, the user is the National Communications System (NCS) to next shown the classes of video content for which develop a more comprehensive quality assessment performance examples will be given. On the next guide. This product, known as the Multimedia page, the user can choose the quality level of the Performance Handbook, originally was envisioned videoconferencing system�low, medium, medium as a printed report that would undergo frequent (and high, high, or source quality. The user can then see sometimes extensive) revisions to reflect technology and hear examples of the performance to be expect­ changes. However, ITS engineers soon discovered ed for the selected combination of content and sys­ that a more flexible and effective means of present­ tem quality level. The media options provided ing this information would be an interactive multi­ include motion video (with and without audio), media application implemented on a CD-ROM. audio only, and a still image frame (at half and full resolution). Numerical quality ratings (derived from A firstprototype of the Handbook was produced in ITS-developed industry performance standards) are FY 95. This product integrated audio, video, graphi­ provided to enable the user to relate the media cal information, and hyperlinked text in the context examples to subj ective and obj ective performance of an interactive graphical user interface to present assessment scores. At each step along this interac­ required technical information in a user-friendly tive process, information is provided in several ways computer application. During FY 97, ITS completed to help the user make these choices. "Tell Me More" a substantial enhancement to the Handbook (Version buttons are available on each page and hyperlinks 2.0), combining increased functionality with a larger are abundant.

56 Telecommunication System Performance Assessment

� Multimedia Pe1lormance Handbook

11 00% El lllllllll1 Welcome to the Multimedia will be. Complexity can result from high-pitched sounds in an audio clip. Or Performance Demonstration complexity can be a lot of motion or detail in a video scena.

The two video examples below show twodiWerent scenes that have been In this demo, you can explore combinations of compressed by the same method. Both scenes have been compressed to run at �I media content, performance levels, and 128 kb/s. The scene on the top is a relatively uncomplicated scene. There is very system costs. little motion and not a lot of detail. This scene is typical of a desktop video conferenciog scene. The scene on the bottom is much more complicated. There is a lot of detail in the man's shirt and in the bookshelf in the background. There is also a lot of motion. The motion comes from the man moving, and because he is such a large portion of the video scene. Begin by pressing the'What's Good Enough' button below.

that the scene on the top is of quality than the scene on Because the top scene is <"'"'�"""""· it was much easier to and results in better quality e scene on the bottom.

that the content of the input or audio clip aWects the Use scenes or clips that your application when testing Example screen fr om the NCS Mu ltimedia Performance Handbook.

This and other version 3.0 applets make extensive computer operating system. During the recording use of real audio and video clips, derived from com­ process, each source clip was processed through a monly available multimedia communications sys­ number of different real or emulated coding systems tems and equipment. These clips illustrate perform­ to allow the effe cts of such coders on user percep­ ance impairments and demonstrate their effects on tion to be illustrated. Upon the release of version 3.0 particular source materiaL This fe ature gives users a of the Handbook, the development team had pro­ realistic view of product performance before any duced over 600 mb of digitized audio, video, and product is procured. The Figure shows a page from image data. Over 500 mb of this data was digitized the Multimedia Performance Demonstration Applet. video! The applet explores several aspects of multimedia quality. Development of the Handbook was an excit­ In sum, the Multimedia Performance Handbook ing, though demanding, task. The development team combines innovative use of multimedia program­ used several commercially available programming ming techniques, unique ITS-developed performance tools to produce the large quantity of custom audio, measurement technologies, and a broad view of video, and image data included in the document. A telecommunications to produce a tool that can sub­ standard hyperlinked text browser was used to pro­ stantially improve the specification and assessment vide access to the thousands of lines of tutorial and of multimedia systems in Government and private reference information. Applets and the overall user sector user organizations. The Handbook also pro­ interface were created using Microsoft Visual Basic vides a model for presenting technical information 5.0 supplemented by special-purpose library pack­ in the future. ages. Creation of the audio and video data was the most time-intensive task. Each audio or video clip For more information, contact: was recorded by the development team and then Arthur A. Webster (303) 497-3567 digitized in formats that could be played by the set e-mail [email protected] of standard multimedia players included with the

57 Wireless Telephony Performance Measurements

Outputs these conditions. The TIA defines the numeric val­ ues of DAQ and their corresponding quality of RF sensitivity, adjacent channel rej ection ratio, speech intelligibility as fo llows: and cochannel rejection ratio of a P25 radio. DAQ 1 Unusable. Speech present but not Delivered audio quality (DAQ) of speech understandable. signals transmitted through a P25 radio system. DAQ 2 Speech understandable with considerable effo rt. Requires fr equent The Telecommunications Industry Association's repetition due to noise/distortion. (TIA) open-standard design specification for the next generation of land mobile radios is known as DAQ 3 Speech understandable with slight Project 25, or simply P25. Organizations that plan to effort. Requires occasional repetition infuse new P25-compliant radio equipment into their due to noise/distortion. radio fleets must determine the minimum level of acceptable speech intelligibility that is required. The DAQ 3.4 Speech understandable without level of speech intelligibility is directly related to the repetition. Some noise/distortion minimum acceptable levels of received signal present. strength and interference rejection ratio, which in tum influences the design specification for the radio DAQ 4 Speech easily understood. Occasional network infrastructure (range of coverage, distance noise/distortion present. between adj acent channel and cochannel transmit­ ters, etc.). Figure 1 shows the DAQ of analog and digital radios as functions of the analog radio's signal-plus­ ITS measured the RF sensitivity, adjacent channel noise-plus-distortion-to-noise-plus-distortion rejection ratio, and cochannel rej ection ratio of a (SINAD) ratio and the digital radio's bit error ratio P25-compliant radio. ITS also determined the corre­ (BER). Also shown in Figure 1 are the TIA's report­ sponding delivered audio quality (DAQ) values of ed values relating DAQ to SINAD and BER. speech signals transmitted through the radio under

Delivered Audio Quality 100 10 0.1 BER (%) 5 ��TrT-r-� DAQ (dimen- sionless) 4

3

2

- �- • TIA reference SINAD (dBS) --+-- BER (%)

- -x - • TIA reference BER (%) o������======r----� ·10 0 10 20 30 40 SINAD (dBS)

Figure 1. A comparison of Delivered Audio Quality versus analog SINA D and digital BER.

58 Telecommunication Standards Development

Receiver Sensitivity

0.1 40 SINAD BER (dBS) (%) 30 1.0 20

10 10.0 --- siNAD (dBS) 0 -+-BER (%)

·10 100.0 ·140 ·120 ·100 ·80 Power (dBm)

Figure 2. Typical receiver reference sensitivity levels vs. SINA D or BER.

To facilitate a direct comparison between the DAQ than does analog modulation. For example, Figure 1 performance of the analog and digital operating shows that a 22 dBS analog signal and a 6.5% BER modes, the SINAD and BER axes in Figure 1 were digital signal both yield a DAQ of about 2.8. From scaled and aligned to point-match the analog and Figure 2, the RF sensitivities of a 22 dBS analog digital DAQ values that had been reported previous­ signal and a 6.5% BER digital signal are about

ly by the TIA, at both the DAQ = 2 and the DAQ = -115 dBm and -123 dBm, respectively. Therefore, a 4 operating points. Using these horizontal-axis weaker digital signal will deliver the same speech scales, TIA's analog and digital mode DAQ operat­ quality as will a stronger analog signal. ing points are observed to essentially coincide at A thorough discussion of all these measurements both DAQ = 3 and DAQ = 3.4. (RF sensitivity, adj acent channel and cochannel Figure 2 shows some sample RF sensitivity data for rejection, and DAQ) and the consequent results can analog and digital radios. Comparing ITS' measured be fo und in NTIA Report 99-358, referenced below. DAQ data presented in Figure 1 to the receiver sen­ Additional information, including speech files at sitivity data plotted in Figure 2, one can generalize various DAQ levels, is available at ITS' web site: that at comparable received signal strengths, digital http://flattop.its.bldrdoc.gov/spectrum/P25/index.htm modulation yields better received audio performance

I I Recent Publication For more information, contact: J. Vanderau, "Delivered audio quality measurements John M. Vanderau on Project 25 land mobile radios," NTIA Report 99- (303) 497-3506 358, Nov. 1998. e-mail [email protected]

59 . I

ITS engineers (R andy Hoffman and Ye h Lo) with a wideband impulse measurement system designed and built at the Laboratory (photograph by F.H. Sanders) .

60 Applied Research

The rapid growth of telecommunications in the last increasing our understanding of the propagation of 40 years has caused crowding in the radio spectrum. millimeter-wave frequencies, thus providing a huge New technology requires a new understanding of the band for future expansion of radio communication behavior of radio waves in all parts of the radio services. The Institute's historical involvement in spectrum. The Institute studies all frequencies in radio-wave research and propagation prediction use, extending our understanding of how radio sig­ development provides a substantial knowledge base nal propagation is affected by the earth's surface, the for the development of state-of-the-art telecommuni­ atmosphere, and the ionosphere. This work is result­ cation systems. ITS transfers this technology to both ing in new propagation models for the broadband public and private users, where knowledge is trans­ signals used in new radio systems. Other efforts are fo rmed into new products and new opportunities.

Areas of Emphasis

Cooperative Research with Industry The Institute engages in technology transfer through cooperative research with industry. Proj ects are funded by US WEST Advanced Technologies, Inc., Netrix Corporation, the American Automobile Manufacturers Association, and Hewlett-Packard Co.

Millimeter-wave Research The Institute conducts research on the millimeter-wave radio propagation channel. The results of the research enable industry to develop and deploy LMDS systems. Projects are funded by NTIA, and Hewlett-Packard Co.

Adaptive Antenna Testbed The Institute is developing an advanced antenna testbed to be used in the investigation of "smart" antennas, which will greatly increase the capacity of wireless communications systems. The project is fundedby NTIA.

Wireless System Modeling and Simulation The Institute conducts software simulation of wireless systems to predict performance for new radio systems. Proj ects are fundedby NTIA and the U.S. Air Force.

HF Channel Modeling and Simulation The Institute contributes to HF channelmodeling and simulation that enables network users and administrators to optimize network utilization. Projects are fundedby NTIA and the National Communications System.

Wireless Propagation Research The Institute conducts research involving the radio propagation channels that will be employed in new wire­ less communication technologies such as personal communications services. This knowledge will aid both Govermnent and industry. Projects are fundedby NTIA, the U.S. Air Force, and Hewlett-Packard Co.

Impulsive Noise and Digital Systems

The Institute performs measurements to define the RF noise environment that is experienced by communica­ tion systems and develops models to predict the effect on digital communications. Projects are funded by NTIA and the National Oceanic and Atmospheric Administration.

Electromagnetic Compatibility Research The Institute conducts research involving the electromagnetic compatibility of a variety of communications systems. Projects are fundedby NTIA and the Federal Highway Administration.

Advanced Radio Te chnologies The Institute conducted the 1998 International Symposium on Advanced Radio Technologies. The Institute is also involved in research of advanced radio systems including software radios and smart antennas. Projects are funded by NTIA and the Department of Defense.

61 Cooperative Research with Industry

Outputs in commercially important areas that it would not othetwise be able to do. A report detailing the field trials of six proposed PCS air-interface standards in the Boulder Much of the Institute's work in personal communi­ Industry Testbed. cations services (PCS) has been accomplished through CRADAs. As part of a CRADA with US Algorithms that estimate the perceived quality WEST, ITS served as a neutral independent observer of speech that has been transmitted through a as the Joint Technical Committee on Wireless Access telecommunications system. (JTC) conducted fieldtrials of six proposed PCS air­ interface standards in the Boulder Industry Te stbed. Measurements defining the electromagnetic The results of these six separate field trials have been environment near military and air-traffic control compiled and published as an NTIA report. radar facilities that may have an effe ct on vehicular electronics. ITS is conducting a CRADA with AAMA to collect field data that will define the electromagnetic envi­ The Technology Transfer Act of 1986 (FTTA), as ronment at specific locations in the United States. As amended, allows Federal laboratories to enter into electronic devices proliferate, it becomes important cooperative research agreements with private indus­ fo r the motor vehicle industry to have knowledge of try, universities, and other interested parties. The law the electromagnetic environment in which vehicular was passed in order to provide laboratories with clear electronics will operate. Of specific interest are elec­ legal authority to enter into these arrangements and tromagnetic environments near military and air-traf­ thus encourage technology transfer fr om Federal lab­ fic control facilities using radars. This knowledge is oratories to the private sector. Under this Act, a essential to the development of future automotive cooperative research and development agreement electronics. (CRADA) can be implemented that protects propri­ etary information, grants patent rights, and provides A CRADA with Netrix Corporation ofHemdon, fo r user licenses to corporations, while allowing Virginia draws on ITS expertise in objective and sub­ Govemment expertise and facilities to be applied to jective audio quality testing. In FY 98, ITS designed, interests in the private sector. conducted and analyzed a subjective conversation test to compare a Netrix Vo ice-over-Intemet Protocol ITS pmiicipates in technology transfer and commer­ (VoiP) product with the conventional telephone net­ cialization efforts by fo stering cooperative telecom­ work. In the double-blind test, randomly selected munications research with industry where benefits pairs of subj ects performed picture sorting tasks in can directly facilitate U.S. competitiveness and mar­ sound-isolated rooms. Subjects used standard tele­ ket opportunities. ITS has participated for a number phones to communicate with each other in order to of years in CRADAs with private sector organiza­ accomplish the tasks. These phones were randomly tions to design, develop, test, and evaluate advanced switched between the two systems under test, and telecommunication concepts. Research has been con­ 128 opinions were collected fo r each system. This ducted under agreements with Bell South Enter­ work continues with the application of ITS objective prises; Telesis Technology Laboratories; US WEST audio quality assessment tools. These tools provide Advanced Technologies (US WEST); Bell Atlantic real-time estimates of transmission delay and per­ Mobile Systems; GTE Laboratories Inc.; US WEST ceived speech quality for vm·ious telecommunications New Vector Group; General Electric Company; systems. Motorola Inc.; Hewlett-Packard Company (HP); Integrator Corporation; AudioLogic, Inc.; Industrial ITS has recently developed a family of algorithms Technology, Inc.; Netrix Corporation; and the that estimate the perceived quality of speech that has American Automobile Manufacturers Association been transmitted through a telecommunications (AAMA). Not only does the private industry partner system. These novel algorithms emulate human benefit, but the Institute is able to undertake research hearing and judgment and explicitly model listeners' pattems of adaptation and reaction to spectral

62 Applied Research

Participant in a subjective conversation test, in the ITS Audio Lab (photograph by F.H. Sanders) . deviations. ITS has applied for a patent on these radio channel impulse response, and is ideally suited innovative audio quality estimation algorithms and for making outdoor impulse response measurements. the algorithms have attracted significant industry attention. One company has licensed the algorithms Cooperative research with private industry has for use in cellular telephone test equipment. This helped ITS accomplish its mission to support indus­ equipment sends digitally recorded speech signals try's productivity and competitiveness by providing through a cellular network, and uses the ITS algo­ insight into industry needs. This has led to adjust­ rithm to compare the transmitted and received sig­ ments in the focus and direction of other Institute nals, resulting in an estimate of the customer-per­ programs to improve their effectiveness and value. ceived speech quality at that location. It is expected that this new equipment will provide cellular opera­ ITS is interested in assisting private industry in all tors with important information that can be used to areas of telecommunications. The pages of this tech­ optimize the coverage and services they provide. nical progress report reveal many technological capa­ bilities that may be of value to various private sector ITS has been a premier laboratory in millimeter­ organizations. Such organizations are encouraged to wave research for two decades. Now ITS is applying contact ITS if they believe that ITS may have tech­ this unique expertise while conducting research into nology that would be useful to them. radio propagation considerations fo r LMDS. ITS has a CRADA with HP for LMDS research. Under the Because of the great commercial importance of many current agreements, ITS has developed propagation new emerging telecommunication technologies, models fo r the LMDS channel, conducted field mea­ including PCS, wireless local area networks, digital surements to characterize radio frequency propaga­ broadcasting, LMDS, the National Information Infra­ tion of an LMDS system, and developed a three­ structure, and intelligent transportation systems, ITS dimensional signal coverage map of the area of inter­ plans to vigorously pursue technology transfer to the est fo r LMDS transmission. The field measurements private sector through CRADAs and thereby con­ use an innovative impulse response measurement tribute to the rapid commercialization of these new system called a digital sampling channel probe. This technologies. In addition, ITS plans to commit sub­ system allows measurement of the complex-valued stantial resources of its own to the development of these new technologies and standards.

Recent Publication For more information, contact: J. Wepman, "Personal communications services Ronald L. Ketchum technology field trials," NTIA Report 98-356, Sep. (303) 497-7600 1998. e-mail [email protected] Millimeter-wave Research

Outputs For over three decades, ITS has been a leader in the study of propagation effects fo r millimeter waves. LMDS 30 GHz time variability study. This work includes: the development of measure­ ment techniques; a database of measured propaga­ Measurement of 30 GHz signal attenuation by tion effects in urban and rural environments; and the vegetation. development of analytical methods for prediction of atmospheric effects (e.g., attenuation and dispersion In the past few years, consideration has been given by molecular absorption lines). Through cooperative to spectrum allocation in the extremely high fr e­ research agreements, ITS is making its technical quency (EHF) band so that wireless video, voice, expertise in millimeter waves available to the com­ and data services could be made commercially avail­ mercial sector for the planning and development of able to consumers. Spectrum has been allocated fo r LMDS. one of these "wireless" services, known as Local Multi-point Distribution Services (LMDS), a type of In recent years, ITS has completed a number of broadband wireless access. Of particular interest is propagation experiments and studies relating to the development of broadband wireless connectivity propagation in urban and suburban environments for for businesses and the home that will provide for several private sector organizations interested in competition to the local exchange carrier local loop LMDS. These studies resulted in a detailed analysis for telephone and internet access services and to of area coverage fo r 30 GHz LMDS, including cable television services. LMDS has resulted in an depolarization caused by vegetation (Papazian et al., increased interest in propagation effects fo r millime­ 1997; and Papazian and Hufford, 1997; see Publi­ ter waves. A clear understanding of the millimeter­ cations Cited, p. 106). In Fiscal Year 1998, ITS wave propagation effects for proposed deployment completed a study of seasonal variations in signal architectures is essential to the development and attenuation by vegetation (trees). A nanowband link implementation of LMDS. at 28.8 GHz was set up on a 1000 meter path. The

Figure 1. Measurement of 28.8 GHz signal propagation through vegetation (photo by FH. Sanders) .

64 Applied Research transmitting antenna beamwidth was 1.2 10/30/97 degrees and the receiving antenna beam­ width was 6 degrees. There was a single tree about 15 meters fr om the receiver.

Figure 1 shows the experimental setup. h -50 (kmp ) - - - W me --- P dBm) The dual polarized receiver was mounted I med� I 80 on a cart. The arrow points to the trans­ tm300607 to tm300630 mitter location 1 km away on the mesa. 60 minute median \ Propagation measurements were made 60 :c \ with the tree on path and near path for -"E \ :0 several weeks with leaves both on the E' /'-.... Q) £!) -60 \ Q) "0 I "- tree and off. Figure 2 and Figure 3 give a a::- '//'�/"'- (f) """ -./"' "0 \ I "' c few preliminary results. In Figure 2 we \ I 40 � have plotted the hourly median received \ I \I signal strength over a 24-hour period. We 1�\ I \ I \ see a 5 dB drop in power at hour 3 and a I -' I, I 10 dB drop at hour 13 when median I, I I 20 I I wind-speeds reached 25 and 35 km/hr -70 I I I I respectively. The CDF for this period I I ' I I '/ (Figure 3) shows a 10 dB fade margin is I \ / I required for 99.9% service during this 'I 0 period. 0 5 10 15 20 25

hours

Figure 2. Th e hourly median wind-speed and the hourly median received power fo r a 24-hour period.

Rayleigh Plot

tm300607 to tm300630

15 60 Minute Median I 10 tm300607 to tm300630

5

0

E' £!) -5 "0 a::-

-10

-15

-20

-25

10 30 50 7080 90 97 99 99.9 99.99 For more information, contact: Percent robability abscissa is exceeded p Peter Papazian Figure 3. Cumulative distribution fu nction fo r received power (303) 497-5369 during the same 24-hour period shown in Figure 2. e-mail [email protected]

65 Adaptive Antenna Testbed

Outputs The ATB expands this concept to eight receiving channels. Thus, the radio channel seen by up to Wideband radio channel measurement system. eight antennas can be simultaneously monitored. Digitization of the received data allows for post 8 simultaneous measurement channels. processing to examine various combining algorithms and digital beam forming. Data can be streamed Smart antenna fading and diversity gain continuously or in bursts depending on the channel statistics. investigation required. System and combining algorithm evaluation. An example of an ATB application is the four-ele­ ment PCS antenna receiving array shown in Figure The use of wireless, mobile, personal communica­ 1. The antenna elements are spaced 2, 5, and 10 tions services (PCS) is expanding rapidly. Multiple­ wavelengths with respect to the left end element. A access schemes based on frequencydivision, time 511 bit PN code on a 1.92-GHz carrier frequency division, and orthogonal codes are presently used to was used. The transmitting antenna was a van­ increase channel capacity and optimize channel effi­ mounted monopole. The 10 Mb/s transmitted code ciency. Adaptive or "smart" antenna arrays can fur­ was sampled at a rate of 40 MHz at the receiver ther increase channel capacity through spatial divi­ (oversampling is used to reduce noise). A total of sion. Antenna arrays can produce multiple beams as 2044 samples per impulse were taken, yielding an opposed to a simple omni-directional antenna. These impulse duration of 51 !lS. Data were collected in numerous narrow beams can be used to divide space the burst mode with a 3 s delay between bursts. A allowing the re-use of multiple-access schemes, burst consisted of 128 impulses with a 3 ms delay thereby increasing channel capacity. Adaptive anten­ between impulses, yielding a burst duration of nas can also track mobile users, improving both sig­ approximately 400 ms. At normal suburban driving nal range and quality. For these reasons, next gener­ speeds (30-60 kph) a burst covered a 20-40 wave­ ation smart antenna systems for PCS systems have length path length. attracted widespread interest in the telecommunica­ tions industry. Examples of single channel power delay profile and power spectral density curves are shown in Figure 2. ITS has developed an advanced antenna testbed The channel location was a suburban neighborhood. (ATB) to serve as a common reference for testing Multipath effects appear as echoes in the impulse smart PCS antenna arrays, signal combining algo­ signal and frequencyselective fading in the power rithms, and complete systems. The ATB is based on spectral density. These channel data can be used to previously developed ITS wideband channel mea­ determine fa ding and delay statistics, diversity gain, surement systems. These systems use a maximal angle of arrival, and correlation bandwidth. These length pseudo-random (PN) code generator to BPSK results can then be used to examine expected chan­ modulate a radio channel carrier fr equency at the nel performance. transmitter. The received signal is autocorrelated at the receiver with the known PN code producing an The ATB system is portable: both transmit and impulse response. The impulse response character­ receive systems may be van mounted. ATB mea­ izes the channel over a wide bandwidth about the sured data can be applied to the design of smart carrier fr equency. antenna PCS systems, evaluating system perfor­ mance, channel model development and verification, and large communications system simulations. (See p. 81 for more information about the ATB.)

66 Applied Research

Figure I. A fo ur element antenna array. Th e elements are sp aced 2, 5, and I 0 A, with respect to the left end element (photograph by FH Sanders) .

-10 40

-20 30

-30 20

-40 10 E E [l) -50 [l) 0 " "

-60 -10

-70 -20

-80 -30

-90 -40 0 5 10 -10 -5 0 10 Time (us) Frequency (MHz)

Figure 2. Impulse signal power and power spectral densityfo r a channel with fa ding.

Recent Publication

P. Papazian, M. Cotton, and p_ Wilson, "A test bed For more information, contact: for the evaluation of adaptive antennas," in Proc. Perry F. Wilson I998 In ti. Sy mp. on Advanced Radio Te chnologies, (303) 497-3406 Boulder, CO, Sep. 1998. e-mail [email protected]

67 Wireless System Modeling and Simulation

Outputs or communication system. Typical parameters fo r the system simulated are: a PRF of 10 MHz, a pulse Ultra-wideband radar (UWBR) simulation and width (before Gaussian derivative shaping) of 0.5 ns, receiver analysis software modules. a duty cycle of 0.5%, a shaping filter center fre­ quency of 2 GHz, and a 3 dB bandwidth of 2 GHz. Ty pical transmitter and receiver spectra and waveforms. The spectrum and time waveform are shown for the transmitter output in Figure 2 and fo r the receiver Predicted receiver interference peak power filteroutput in Figure 3. The receiving filterwas dependence on bandwidth (BW). centered in the middle of the radio navigation receiver band at 1.575 GHz and employed a 3 dB Effect of pulse repetition frequency (PRF) on bandwidth half of the PRF (5 MHz) for the example spectrum management issues. in Figure 3. If the PRF is greater than the receiver BW, then the transmitted pulses are smeared over Interest by the Government andprivate sector in the time, reducing the peak power. Received peak power potential application of ultra-wideband devices has was calculated fr om the time domain pulse trains, stimulated a measurement and analysis program to assuming an ideal propagation channel, and is determine the interference effe ct of these devices on shown as a function of receiver BW in Figure 4. generic victim receivers. Our parametric results show the effect of receiver bandwidth and filter Peak power was shown to fo llow different logarith­ shape on peak power. mic trends above (20 log[BW]) and below (1 0 log[BW]) the PRF. These results are of specific The simulated ultra wideband device shown in interest to the Government and manufacturers since Figure 1 transmits a psuedo-periodic, very low duty they show that systems with high PRFs compared to cycle pulse train where nanow pulses were shaped receiver bandwidths significantly reduce peak inter­ with a Gaussian derivative filter and dithered ference. Results are provided fo r a Gaussian shaped according to a psuedo-noise code. These operations filter and an ideal rectangular filter to determine the produce a noise-like, spread spectrum that enables effe ct of filter shape on these trends. the system to operate as a low-power radar imaging

Dithered "Periodic" Monocycle Dither Xtrans Pulse Train Gaussian Derivative Pseudo Noise Generator Filter Generator Control Pulsetrain PRF=10MHz, PW=O.Sns Tau=0.5ns, BW=2GHz

Xtrans Receiver IF Compute Spectrum Plot Peak Power Filter Calculate and vs Peak Power Time Waveform Bandwidth Output fc=1 .575GHz

Figure 1. Ultra-wideband radar simulation and victim receiver analysis flowchart.

68 Applied Research

UWBR Transmitter Output Victim Receiver Gaussian IF Response to UW8R (BW3db=S MHz, PRF.ctOMHz)

50 - -100 �·· 150 - � Av Rec Power (Watts)= . ,,,J, Average Xtr Power(Watts)=5.5039e-007, PAF=10 MHZ lt�l 00 I -2 ""----,-L'::ss .,L':csss=-- -:-L':::s7= -- -,-LS:':7o -s -----,1-':1.97458-01.s=--a 4-:- 1.c'ss:c:-s ----:1-':.s•=--' 10 12 14 16 ------�'\ Frequency in GHz Frequency in GHz

0.01 0.005 � 0 0.005 � - -1 Peak lnst. Xtr Power (MaxPkSQ)={t00018694, PAF=10 MHz 0.01 1 -- I 2 - - 100 150 200 250 Time in nSec Time in nSec

Figure 2. UWBR output sp ectrum (top) Figure 3. Victim receiver UWBR response and wavefo rm (bottom). sp ectrum (top) and wavefo rm (bottom) .

40

10 Log(BW) & 20 Log(BW) -3 dB Trends 35 + Reel Fill Peak Power Norm to Peak Power in 1 MHz BW - -€>-

30

25 : . -�-

(o' : co � 20 Q; ;;: 0 0... -"" 15 Cll (!) 0... E 10 0 z

5 ./ I

-0- -d 0

-5 :.....

-10 10-1 3dB IF Bandwidth (MHz) Figure 4. Vi ctim receiver peak power analysis fo r UWBR transmission.

Recent Publication For more information, contact: E.A. Quincy, "Ship compartment channel effects on Edmund A. Quincy wireless FM speech performance," in Proc. Wireless (303) 497-5472 98 Conf Vo l. 2, Calgary, Alberta, Canada, Jul. 1998, e-mail [email protected] pp. 483-502.

69 HF Channel Modeling and Simulation

Outputs single skywave path; negligible delay dispersion; and stationary behavior in delay and fr equency. The Hardware-based wideband HF channel ITS-developed wideband model can represent HF simulator. channels with up to a 1 MHz bandwidth. The model can emulate several time-varying aspects of an HF Software implementation of the HF channel channel: Doppler shift, Doppler spread, delay model transfer function. spread, and delay offset. The model can represent multiple propagation paths and can introduce a vari­ Application of wideband model in narrowband ety of noise and interference effects (Lemmon and HF modem testing. Behm, 1991a and b; Mastrangelo et al., 1997; and Vo gler and Hoffm eyer, 1988, 1990, 1992, 1993; see Contributions to international standards Publications Cited, p.l06). committees.

High-frequency (HF) radio propagation conditions The Institute has also developed a software imple­ vary widely as a result of long-term (sunspot cycle) mentation of the wideband HF channel model trans­ and diurnal ionospheric changes and a number of fer function. The program is designed to run on a short-term ionospheric phenomena (e.g., multipath, personal computer. Its output is the input to the fa ding, and delay dispersion). Received HF signals wideband simulator. The program enhances opera­ can be conupted by noise from man-made and nat­ tion of the wideband simulator by making changes ural sources (e.g., vehicle ignition, lightning), and by in transfer function easy to accomplish during test­ interference due to spectrum congestion. The vari­ ing. The program also computes spectrally averaged ability and complexity of these effects make it desir­ scattering functions. Spectral averaging makes it able to test HF radio technologies and systems in the possible to verify the transfer function with the laboratory, under controlled and repeatable condi­ model input. These scattering functions are averages tions, rather than in the field, where desired test con­ of many "runs" of the program. They make it possi­ ditions can be difficult to achieve. Laboratory testing ble to examine the statistics of a simulated channel enables the experimenter to establish the exact chan­ to ensure that the program's primary output fa irly nel conditions under which a particular HF system represents the expectations of the model in terms of feature should be tested; to quickly create variations the input parameters that characterize the channel. in channel conditions that might take years to The stochastic nature of the simulation makes it observe in the field; and to subj ect different HF virtually impossible to analyze a single scattering systems to the same test conditions to facilitate function. comparison and optimization. The Institute has developed a widel5and HF channel model and a hardware-based, computer-controlled wideband 1879 HF channel simulator that provide an efficient, •u :: 1,874).ls accurate means of representing complex HF 1873 channels in such laboratory testing. Iu 1867 ITS engineers applied the simulator in several � tc = 1,863�s l 1861 HF modem tests during FY 98. Results were pre- � Power (dB) sented to ITU-R Working Party 9C, which is ;g 1855 D-3 - -2.5 considering adoption of the wideband HF chan- - -2 1849 - - 1.5 J; � -0.1 Hz nel model in a new Recommendation. The wide­ ,------D-I fsL "" 0.0 Hz band model overcomes several limitations of the 1844 '--"-�-'-�..__--'-�--'-�-'-----'�-'-�--'-__j D-o.s -0.25 0.0 0.25 - above existing ITU-R HF channel model (Watterson et Doppler Frequency (Heitz) a!., 1970; see Publications Cited, p. 1 06), includ- ing a restriction of bandwidth to less than 12- Figure I. Sp ectral average scattering fu nction contours kHz; a restriction of the propagation model to a above -3.1 dB. Average of 80 scattering fu nctions.

70 Applied Research

The software implementation of the wideband HF design. More careful modeling of specificpaths channel transfer function is documented in an NTIA would mitigate the discrepancies at the expense of Report (Sutherland, 1998). Figure 1, fr om that time and complexity. report, presents the contour plot of a spectrally aver­ aged scattering function. This function is the average The Institute has also developed a simulator that of 80 scattering functions or 80 runs of the program. applies the wideband model in a narrowband setting. The input data is from 1-hop P-layer returns ofthe This simulator runs on a personal computer extraordinary mode over a 126-km path near the enhanced with a commercially available digital sig­ Pacific Coast during the winter. The spread of ener­ nal processing (DSP) card. This narrowband system gy in both delay and in frequency is apparent. The simulates the effects of delay dispersion. During FY contour plot is used to verify and validate the propa­ 98, this system was used to test HF modems in the gation model. The outer contour represents the 3-dB laboratory. Results of tests conducted on several level, the level at which the input parameters are implementations of the MIL-STD-188-11 OA single specified. For example, the graph indicates that the tone waveform were reported in Behm, 1997 (see delay spread is approximately 17 J.lS. The input para­ Publications Cited, p. 106). The test results were meters are the upper and lower ends of the delay used as the basis for a contribution to Working Party spread, ' and ' respectively. The difference of 9C ofiTU-R. This contribution helped to motivate U L' 20 J.lSis the input delay spread. The Doppler fre­ adoption of the wideband channel model as an ITU­ quency, f , at the mean delay, ' is in the center of R Recommendation by demonstrating the ability of s c' the 3-dB contour as expected. The expected Doppler the narrowband application to simulate a harsh HF frequency, f ' at ' is approximately verified; the channel environment. Figure 2 shows that modem sL L' lower end of the 3-dB contour does not quite extend performance is vulnerable to delay spread above approximately 0.5 ms. The graph indicates the abili­ to the 'L level. Discrepancies are associated with digital filtering effects. The model is a general ty of the modem test system to measure bit error rate down to 0.1 over the MIL-STD-11OA modems.

--- ______-1 ·- • ]

-2 -- -�� ' ��- ' � - - �-� --t-- - - -3 • ;--- �

- �

• - --- ��------� I - - - �-r-. -• --: 3� -5 -4 --- r- ___ • -6 -- , -�---- �� ___ ---�- � _ --· --- ! ' · __ - ,__ .1I __ -- 1, • -7 ------tI ------L------r------�------�� E�grs ---•-.-••" • } •-•- •• 1-- •� - 1 - - 1 --- ' 0 200 400 600 800 1000 1200 Delay Spread (microseconds)

Figure 2. Scatterplot of delay spread vs. bit-error-ratio. Results of MS- 11OA modem tests. Modem op erating at 1200 bps. No interleaving.

Recent Publication For more iriformation, contact: D. A. Sutherland Jr., "Software implementation of a Dave Sutherland wideband HF channel transfer function," NTIA (303) 497-5161 Report 98-348, Jan. 1998. e-mail [email protected]

71 Wireless Propagation Research

Outputs accuracy. This method has been used to calculate reflection and transmission coefficients for rein­ Indoor and outdoor channel modeling and fo rced concrete walls fo r a fr equency range of 00 measurements. I MHz to 6 GHz for various material prope1ties and

·. Impulse response measurements and rebar configurations. Figure I shows results for the predictions. reflection and transmission coefficient of a rein­ forced concrete wall 20.32cm thick with a rebar Smart antenna analysis. spacing of I5.24cm and diameter of 1.9Icm.

Delay spread prediction. The Institute is developing a geometric optics (or ray-tracing) model for calculating the power delay profile fo r an indoor radio propagation channel. A The Institute is involved in several research and recursive-imaging algorithm is used to find all possi­ development efforts related to wireless communica­ ble rays with up to a specifiednumber of wall, ceil­ tions. In the past year our efforts concentrated on ing, and/or floorref lections. Figure 2 shows an building penetration through reinforced concrete example of a power delay profile fo r a room deter­ walls, developing measurement systems for charac­ mined from the ray-trace model. With this ray-trace terizing multipath environments, and developing model, we have investigated the effect of frequency­ models to predict power delay profile characteristics dependent reflection coefficients of walls on the fo r an indoor and outdoor channel. power delay profile. Figure 2 also shows a compari­ son of the power delay profile obtained by assuming In designing wireless telecommunications systems, it different frequency-dependent reflection coeffi­ is crucial to control or detennine the intersymbol cients. One curve corresponds to a reflection coeffi­ interference (lSI), the bit error rate (BER), and the cient independent of frequency (a frequency flat fading of the communications signal. Thus, there is reflection) and the other curve conesponds to a a growing need for accurate propagation models that highly frequency-dependent reflection coefficient. can predict signal levels fo r indoor and outdoor These two results differ in both their second-central- communication channels, as well as building penetration models. Business campuses utilizing wireless private branch exchanges (PBXs) and wireless local area networks (LANs) to provide -10.00

mobile voice and data communications, " " " vehicular communications through urban " " canyons to nearby relays, and micro­ " ill ·20.00 cellular personal communications ser­ :s. Cl) vices (PCS) deployment in malls and air­ -o :e ports are just a fe w examples. For short a. propagation paths like these, the accurate � -30.00 behavior of waves reflecting off walls Transmission coefficient can be very important. Reflection coefficient -40.00 Crucial to these modeling efforts is the accurate characterization of the reflection and transmission properties of various -50.00 f I I �------r-1- r- commonly used building materials. 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Finite-difference time-domain (FDTD) Frequency (MHz) methods can be used to determine reflec­ Figure 1. Reflection and transmission coefficient fo r a tion and transmission coefficients of rein­ reinforced concrete wall. fo rced concrete walls with a high level of

72 Applied Research

moment and in their maximum delay, 0.00 --.------, illustrating the impmiance of using accu­ rate reflection coefficients in field predic­ tion models.

-20.00 The Institute has developed a model fo r

quickly determining both the power delay ill profile and the rms delay spread of an � Q; indoor radio propagation channel. The :,: 0 -40.00 a.. advantage of this model over ray-trace Q) and FDTD models is that it is based upon > � Qi simple assumptions, such that the propa­ 0:: gation characteristics of indoor propaga­ tion channels can be dete1mined in a mat­ -60.00 ter of seconds on a personal computer. Frequency flat

Figure 3 shows a comparison of the sim­ Frequency dependent plified model to measured data obtained by averaging several locations throughout

a large laboratory. This model is present­ 0.00 10.00 20.00 30.00 40.00 ly being extended to analyze metal ware­ house and shipboard communications Figure 2. Power delay profile with different reflection systems. coefficients. The Institute is also developing mea­ 0.00 -ti1------surement systems for sampling various indoor and outdoor radio environments for use in capacity and diversity studies. For example, an indoor direction diversi­ ty at 5.8 GHz study has recently been completed (Achatz et al. 1998). -20.00 ill � a.. 0 a..

8-- PDP model -40.00 Measured data Recent Publications

C.L. Holloway, M.G. Cotton, and P. McKenna, "A simplified model for 0 10 20 30 40 50 60 70 80 90 100 110 predicting the power delay profile , (ns) characteristics of an indoor radio propagation channel," NTIA Report Figure 3. Comparison of the power delay profile model 98-353, Aug. 1998. to measurements.

R.J. Achatz, Y. Lo, and E.E. Pol, "Indoor direction diversity at 5.8 GHz," NTIA Report 98-351, Jul. 1998.

P. Perini and C.L. Holloway, "Angle and space For more iriformation, contact: diversity comparisons in different mobile radio Christopher L. Holloway environments," IEEE Trans. on Antennas and (303) 497-6184 Propagation, vol. 46, no. 6, pp. 764-775, Jun. 1998. e-mail [email protected]

73 Impulsive Noise and Digital Systems

Outputs Man-made noise below 1 GHz is non-Gaussian in business environments at most locations and times. Non-Gaussian noise measurements and models. This noise is produced by sources such as electrical power distribution and transmission lines, electronic Performance prediction of radio links operating devices, electric motors, arc welders, and internal in non-Gaussian noise environments. combustion engine ignition systems. Above 1 GHz, non-Gaussian man-made noise is localized to areas near a single source (Spaulding, 1996; see Digital radio link performance, for many appli­ Publications Cited, p. 1 06). cations, is dependent upon statistics of the noise that is added to the signal prior to demodulation The Institute has developed measurement, modeling, (Spaulding, 1982; see Publications Cited, p. 1 06). and simulation techniques to more fully characterize Narrowband, radio-frequency noise is divided into non-Gaussian radio noise statistics so that the per­ two classes: white-Gaussian noise and non-Gaussian fo rmance of digital radio links operating in non­ noise. White-Gaussian noise is continuous, broad­ Gaussian noise environments can be predicted. In band, and has Rayleigh-distributed amplitudes. The FY 96 ITS measured the amplitude statistics of man­ perfmmance of digital radio links operating in made noise at 137 MHz in business, residential, and white-Gaussian noise environments can be predicted rural enviromnents. These measurements were con­ fr om the ratio of mean signal-power to mean noise­ ducted to support the National Oceanic and Atmo­ power (SNR). spheric Administration in converting their meteoro­ logical satellite radio links from analog to digital. In Impulsive non-Gaussian noise is composed of dis­ FY 97 ITS modeled the amplitude and pulse arrival crete noise "pulses" whose amplitudes are some­ rate of this noise and developed algorithms that times modeled with the power-Rayleigh distribution. could replicate it in a digital radio simulation (Dalke The discrete pulses can occur randomly or periodi­ et al., 1998; Achatz et al., 1998). cally in time and are not necessarily broadband. Ricean non-Gaussian noise adds a continuous wave In FY 98 ITS used the algorithms to predict the per­ component to white-Gaussian noise. The SNR is formance of a digital radio link with software simu­ insufficientto predict the performance of digital lation (Achatz and Dalke, 1998). Figures 1 and 2 radio links operating in non-Gaussian noise show the results of some of these predictions. Figure environments. 1 a shows the amplitude probability distribution

0.1

0.01

00ffi

0.001

0.0001

-10

SNR (dB) (b)

.001 1 1 5 10 20 35 50 70 80 90 95 99 Figure 1. APD (a) and BER (b) of man-made noise at a Percent exceeding ordinate Lakewood, CO, residence on November 10, 1996, from 3:30 (a) p.m. to 4:00p.m. Average noise power is 5. 6 dB above kT0b.

74 Applied Research

1 ':;:;:: : =� =::� =:;::;:::::::::::::: :::::� = ::� =:::-: ::-:::::::�: :::::::::::-:::::::t ::: : ; ;; ;;: ;

0·1 1 .....:; :::�����-����l:�:��:::�t����::;;;:;;:;;:!.,: .. ,;.: ======�======�======��======�======�======;======�

� 0 w � SNR(dB)

(b)

Figure 2. APD (a) and BER (b) of man-made noise measured in .001 .1 1 5 10 20 35 50 70 80 90 95 99 an offi ce park in Golden, CO, on November 2 7, 1996, fr om Percent exceeding ordinate 11:15 to 11:45 a.m. Average noise power is 14.5 dB above kT0b. (a)

(APD) fo r measured and modeled man-made noise Figure 2a shows an APD of noise measured in an in a residential environment. The kT 0b units on the officepark. The abrupt change in slope at 0.01 %, abscissa represent the noise available fr om a black­ once again, is indicative of impulsive non-Gaussian body at temperature T 0 in bandwidth b. The abrupt noise. The difference in slope between measured change in slope at 1% is indicative of impulsive noise and Rayleigh-distributed noise at the high non-Gaussian noise. exceedence probabilities is indicative of a continu­ ous wave noise component produced, perhaps, by a Figure 1 b shows the bit error-ratio (BER) of a spectral line of a pulsed source. Figure 2b shows differentially-coherent binary phase-shift keyed that a DCBPSK digital radio link needs 8 dB more (DCBPSK) digital radio link operating in this noise SNR to achieve a BER of 1 o-3 in this noise environ­ environment. The circles represent performance in ment than it would in white-Gaussian noise. white-Gaussian noise whereas the squares represent performance in the non-Gaussian noise. A digital The contrast between the residential and business radio link operating in this noise needs 5 dB less APDs and the SNR required to achieve a 1 o-3 BER SNR to achieve a 10·3 BER than it would in white­ highlight the difficulty in predicting digital radio Gaussian noise. performance in non-Gaussian noise environments. In future, ITS plans to characterize the noise over a broader fr equency range and over more locations Recent Publications and times. The information derived from this work will assist industry and government in efficiently R.A. Dalke, R. Achatz, Y. Lo, P. Papazian, and G. utilizing our valuable spectral resources. Hufford, "Statistics of man-made noise at 137 MHz," in Proc. 1998 International Sy mposium on Electromagnetic Compatibility, Denver, Co., Aug. 1998, pp. 427-43 1.

R.J. Achatz, Y. Lo, P.B. Papazian, R. A. Dalke, and G. Hufford, "Man-made noise in the 136 to 138- MHz meteorological satellite band," NTIA Report 98-356, Sep. 1998.

R.J. Achatz and R. Dalke, "VHF space-to-earth For more information, contact: radio link performance in various man-made noise Robert Achatz environments," in Proc. 1998 IEEE Radio and (303) 497-3498 Wi reless Conference, Colorado Springs, Co., Aug. e-mail [email protected] 1998, pp. 257-260.

75 Electromagnetic Compatibility Research

Outputs frequency (30-1000 MHz) electromagnetic absorbers. This has spawned an emergence of new System performance. absorber designs. One such design is hollow pyra­ mids. Using a technique known as homogenization, Immunity and emission compliance. we have developed a model that efficiently calcu­ lates the performance (the reflection coefficient) of System interference and susceptibility. this type of absorbing structure. The reflection coef­ ficients calculated using this model have been com­ Material properties modeling. pared to and closely agree with measured data. Such a comparison is shown in Figure 2. The Institute is involved in several research effmts related to electromagnetic compatibility (EMC) and Dedicated short-range communication systems have electromagnetic interference (EMI). In the past year been proposed for automatic toll collection on high­ our efforts concentrated on electromagnetic charac­ ways operations at locations across the United States terization of composite materials, absorbing materi­ in the 5850- to 5925-MHz band. Various search and als, anechoic chambers, radiated emissions fr om tracking high-power radars operate at or near this printed circuits boards, rf interference for wireless fr equency band and are a source of potential inter­ communication systems, and standards activities. fe rence. The performance of such digital communi­ cation systems is dependent upon compatible opera­ Advanced fiber composite materials are commonly tion and coexistence with these radars. The Institute used in aircraft and EMC/EMI shielding materials. has recently completed an electromagnetic compati­ These composite materials have made tremendous bility analysis of these systems. This analysis inroads into industry due to their light weight, involved both theoretical considerations and mea­ shielding properties, and affordability. Plastics are surements utilizing a commercial system subjected inherently nonconductive and cannot shield sensitive to simulated radar interference. The results of this electronic apparatuses and systems fr om electromag­ netic interference (EMI) in order p/A. to comply with regulations. Con­ 0.00 0.20 0.40 0.60 0.80 1.00 ductive fibers, such as carbon 1.60 I I I I I fibers, nickel coated graphite Effective layer model fibers, copper fibers, brass fibers, 1.40 - o o o and stainless steel fibers, have 0 FE results 0 been used to overcome these defi­ :s.(0 1.20 - (f) ! ciencies and make the plastics (f) 0 Q) - c 1.00 0 conductive. The Institute has Q) developed mathematical expres­ > t5 0.80 - 0 0 sions for the effective electromag­ & w 0 netic material properties of fiber Cl 0.60 - c 0 composites, which can be used to '6 0 0 ]1 - 0 calculate efficiently the reflection .s::: 0.40 0 0 0 and transmission coefficients and (/) 0 - () the shielding effectiveness of 0.20 0 0 these fiber composites. Figure 1 0ooo 0 0 o0o 0.00 o""o shows a comparison of the shield­ lB I I I I ing effectiveness obtained using 0 2000 4000 6000 8000 10000 this effective material property Frequency (MHz) model to numerical values. Figure 1. Comparison of shielding effectiveness fo r a fiber composite layer obtained fr om the effective layer model to numerical values In recent years there has been an based on finite element (FE) results. increase in the demand for low

76 Applied Research

p/A. effort are of significant importance 0.00 0.20 0.40 0.60 0.80 1.00 to the successful deployment of these systems and the transportation and spectrum utilization goals of the

Federal Government. 0.80 -

The use of power efficient nonlinear X Numerical results amplifiers with variable envelope ti Homogenization results Q) 0 modulations fo r portable microwave () c communication devices can result in 0 interference with communications u Q) 0.40 systems in adjacent bands. To better 0:::� understand possible electromagnetic compatibility issues involving the use of such devices, ITS has com­ pleted a study which analyzes the relationship between nonlinear oper­ ation of a typical PCS portable trans­ 0.00 200.00 400.00 600.00 800.00 1000.00 ceiver power amplifier and battery Frequency (MHz) current, adjacent band interference, and range. A mathematical model of the power Figure 2. Comparison of the reflection coefficient amplifierbased on these measurements was of a hollow pyramidal absorber. used to simulate the communications link for purposes of determining the power spectral density and symbol-error ratio fo r a digitally modulated sig­ analyzed. This study provides important information nal using n:/4DQPSK with 35% root raised cosine regarding the spectral efficiency of a typical portable filtering. The adjacent band interference characteris­ microwave communications device as a function of tics and corresponding system performance were amplifier current.

Recent Publications

C.L. Holloway, M. Johansson, and M.S. Sarto, "An R. Dalke, "EMC analysis of C-band radar interfer­ effective layer model for analyzing fiber compos­ ence for dedicated short-range communications sys­ ites," in Proc. EMC '98 ROMA In ternational tems," in Proc. 1998 IEEE In ternational Sy mposium Sy mposium on Electromagnetic Compatibility, on Electromagnetic Compatibility, Denver, CO, Rome, Italy, Sep. 1998. Aug. 1998, pp. 46-50.

R.T. Johnk, A.R. Ondrejka, and C.L. Holloway, R. Achatz, R. Dalke, and Y. Lo, "Power amplifier "Time-domain free-space evaluations of urethane model fo r optimizing battery current, interference, slabs with finite-difference time-domain computer and link margin," in Proc. 1998 IEEE International simulations," in Proc. 1998 EMC International Sy mposium on Electromagnetic Compatibility, Sy mp osium on Electromagnetic Compatibility, Denver, CO, Aug. 1998, pp. 434-438. Denver, CO, Aug. 1998, pp. 290-295.

C.L. Holloway and E.F. Kuester, "Net and partial inductance of a microstrip ground plane," IEEE Tr ans. on Electromagnetic Compatibility, vol. 40, no. 1, pp. 33-46, Feb. 1998.

R.A. Dalke, F. H. Sanders, and B. L. Bedford, For more information, contact: "Electromagnetic compatibility testing of a dedi­ Christopher L. Holloway cated short-range communications system," NTIA (303) 497-6184 e-mail [email protected] Report 98-352, Jul. 1998.

77 Advanced Radio Technologies

Outputs transmission. Digitization in the receiver and digital­ to-analog conversion in the transmitter may occur at Development and EMC testing of an example the RF, IF, or even at baseband. Inherent in the soft­ cellular base station software radio receiver. ware radio definition is some level of programmabil­ ity to change the way the transmitted and received Recommendations fo r changes needed in infor­ signals are processed. Software radios present an mation requested by NTIA to accommodate opportunity for many advantages over traditional system review of software radios for spectrum radios. One key advantage is in the software radio's management. reprogrammability or reconfigmability permitting the use of different modulation types, fr equency Organization and chairmanship of, and bands, filtering, and other processing via software. presentations at, the 1998 International Symposium on Advanced Radio Technologies. Smart antennas are antennas whose radiation pat­ terns can be altered based upon the nature and loca­ Rapid advances have occmTed in analog-to-digital tion of the desired and undesired signals present in converter, digital-to-analog converter, and especially the environment. Potential advantages in using smart digital signal processing technology. These advances antennas include an increased carrier-to-interference have spawned a proliferation of research and devel­ ratio, increased geographic coverage area, and opment efforts in advanced radio technologies such increased user capacity. as software radios and smart antennas. Work at the Institute in the area of advanced radio While there are differing opinions as to what the technologies continued in the investigation to help definition of a software radio is, one (very broad) assess the impact of software radios on the manage­ definition is best given by describing the receiver ment of Federal Government use of the radio spec­ and transmitter separately. In a software radio trum. In support of this effort, an example software receiver, the received signal is digitized and then radio receiver was configured by ITS that allowed processed using digital signal processing techniques. observation of signals at various stages of process­ In a software radio transmitter, the modulated signal ing. Electromagnetic compatibility (EMC) testing on to be transmitted is generated as a digital signal this receiver was performed in the presence of noise using digital signal processing techniques. The digi­ and various interfering signals. The example soft­ tal signal is then converted to an analog signal for ware radio receiver emulated an Advanced Mobile

•

Monitor

Cellular Cellular ECL to Digital TIL Audio Downconverter Converter Downconverter RF Processor Input Audio Output \ Pre-processed Digitized IF Output Personal Computer Analog Audio Output

Figure 1. Block diagram of the cellular base station software radio receiver.

78 Applied Research

Phone System (AMPS) cellular base station 20

receiver with digitization of the entire cellular 0 B band (a 14 MHz bandwidth). The receiver -20 was configured using a commercially avail- Dither noise Aliased signal able digital downconvetter board that oper­ -40 u. / ates in a personal computer, a separate fr ont "''1l -60 ...... _ end that includes an analog downconverter -80 and digitizer, and an interface board designed 1 ..l by ITS. A simplifiedblock diagram of the -100 -...... �· " receiver is shown in Figure 1. The architec- -120 ture of the receiver allowed testing to be per­ 0 2 4 6 8 10 12 14 16 Frequency (MHz) formed at the digitized IF output, the digitally downconverted and filtered baseband, the dig- Figure 2. Effe cts of aliasing in the cellular base station ital FM demodulator output, and the analog software radio receiver. audio output. The testing of the receiver at all of these outputs was exploited to help gain insight Drawing upon the knowledge and experience gained into the operation of software radio receivers and in previous work with software radios at the how they may behave differently than traditional Institute, ITS analyzed the information requested on radios. A sponsor report discussing the testing pro­ the equipment characteristics fo rms and its applica­ cedures and the details of the receiver design was bility to software radios. Recommendations for written. The results of the EMC testing were pro­ changes needed in these fo rms to accommodate soft­ vided in a presentation to the sponsor. ware radios were made. A sponsor report providing a discussion of the similarities and differences One difference between software radios and tradi­ between software radios and traditional radios and tional radios is the potential for a type of distortion discussing the analyses of and recommendations fo r in the received signal called aliasing. Aliasing can the equipment characteristics fo rms was generated. occur because of the digitization process in a soft­ / ware radio receiver and does not occur in traditional ITS hosted the 1998 International Symposium on radios. An example result fr om the software radio Advanced Radio Technologies which fo cused on EMC testing, showing the effects of aliasing, is state-of-the art and future trends in software radio given in Figure 2. The aliased signal appearing at and smart antenna technologies and applications. 14.65 MHz is caused by a 16.07 MHz signal present Sessions included presentations by leading experts at the IF before digitization at a sampling rate of in software radio and smart-antenna fields fr om gov­ 30.72 Msamples/second. ernment, industry, and academia fo llowed by fo r­ ward-looking open roundtable discussions on emerg­ To compliment previous work in software radio ing radio technologies and future applications. Of receivers, ITS conducted a brief study of the theory, particular interest were sessions describing new and concepts, and practical limitations of software radio innovative architectures for both software radio sys­ transmitters. The key aspects of software radio trans­ tems and smart antennas. The Symposium consisted mitters were identified and studied, including digital of 29 presentations by leading experts involved in signal processing, digital-to-analog conversion with advanced radio technology research, development, the associated filtering, and power amplification. and applications. Presentations given by ITS staff Before new, major telecommunication systems or included a software radio overview, an overview of subsystems can be implemented and used by spectrum management issues, and a presentation on Govermnent agencies, they must be certified by the ITS Advanced Antenna Testbed. Approximately NTIA that the required spectrum is available. This 240 individuals representing 12 countries attended spectrum certification can be obtained through the the Symposium. Spectrum Planning Subcommittee (a subcommittee of the Interdepartment Radio Advisory Committee (IRAC)) system review process. The NTIA transmit­ For more information, contact: ter and receiver equipment characteristics forms Jeffe ry A. Wepman (NTIA-33 and NTIA-34) are used to obtain informa­ (4 10) 415-5541 tion needed for the system review process. e-mail jwepman@its. bldrdoc.gov

79 Radio Frequency In terference Monitoring System (R FIMS) vans awaiting delivery to the FA A. A fleet of these vans has been designed, developed, and built by ITS fo r the FA A (photograph by FH. Sanders) .

80 ITS Tools and Facilities

Adaptive Antenna Te stbed During the past year, NASA decided to allow the ACTS orbit to become inclined. Although the orbit The adaptive antenna testbed (ATB) is a multi-chan­ is still geosynchronous, it is not geostationary. nel test facility based on ITS digital sampling chan­ Satellite station-keeping in the east-west direction nel probe technology (see pp. 66-67). The VMEbus will be maintained, but station-keeping north-south based system can simultaneously characterize eight has been disabled to conserve on-board fuel. This wideband radio channels. The received signals are will extend the usefullif e of the satellite for a num­ digitized for flexible post processing. Data from ber of years. The antenna and control systems in the multiple channels can be used to test the diversity ES at ITS were upgraded during FY 98 to support gain resulting from various signal combining algo­ the required tracking. The ITS ACTS test fa cility is rithms. Digital beam forming techniques may also available for use by other Government agencies, be examined. The present AT B configuration has a industry, and academia fo llowing application to (and nominal bandwidth of 20 MHz about carrier fr e­ approval by) the NASA ACTS Experiment Office. quencies in the range 0.5-3.0 GHz.

The advanced antenna testbed provides a common Audio Quality Laboratory reference fo r evaluating next-generation personal The Audio Quality Laboratory supports the communication services (PCS) antenna systems. A Institute's audio quality research and standards well-characterized cell site in Boulder, CO serves as development. The laboratory equipment allows high­ a known platform for evaluating existing and new quality recording, processing, analysis, and repro­ PCS components and systems. Alternately, the AT B duction of audio signals. Audio Quality Laboratory transmitting and receiving systems may be van­ equipment includes digital audio tape recorders, mounted for site mapping studies at any required compact disk players, digital audio encoders and location. decoders, a spectrum analyzer, signal generators, level meters, mixers, amplifiers, processors, speak­ Advanced Communications Technology ers, and microphones. Workstations equipped with Satellite Test Facility 16-bit digital-to-analog and analog-to-digital con­ The central element of this test facility is a complete verters provide for additional signal conversion and Earth station (ES) specifically designed for use with processing flexibilities. NASA's Advanced Communications Technology The Audio Quality Laboratory is interconnected Satellite (ACTS). This ES was provided to ITS by with the Multimedia Subj ective Testing Laboratory. NASA under a Memorandum of Understanding Together, these two laboratories support subj ective between the two agencies. The ACTS was launched analyses of audio signals through listening and con­ by NASA to support satellite technology advance­ versation tests. Additional connections to the Video ment through communications experiments. It oper­ Quality Laboratory and the Integrated Networks ates at Ka-band and is capable of on-board switch­ Testbed enable integrated testing of multimedia ing to provide highly flexible connectivity between communication systems that transport audio, video, any two, or within any group, of ACTS ES's. The and data communications. ES at ITS is capable of supporting a raw T1 rate (1.544 Mb/s) or 1.8 Mb/s integrated services digital network (ISDN) communications. Digital Sampling Channel Probe ITS has developed and patented an innovative digi­ Other major equipment and capabilities in this test tal sampling channel probe (DSCP) which has fa cility include: an ISDN switch, terminal adapters, recently been reconfigured as a VME based system. and narrowband ISDN interfaces; an ATM switch The probe, consisting of both a transmitter and a and ATM interfaces; data communications test sets receiver, is used to make complex impulse response implemented on UNIX workstations, a voice quality measurements of outdoor communication channels measurement system; and the most recent addition, and in tum determine the wideband propagation an ITS-developed, standards-based objective video characteristics. Such measurements are used for quality measurement system.

81 modeling and simulation. Employed extensively for A wide bandwidth (0.2 - 1.0 GHz null-to-null), high channel characterization of cellular and personal frequency (1.5 - 30.0 GHz) digital sampling probe is communications services, ITS has included addition­ also under development and is particularly suited for al fe atures for the study of adaptive antenna arrays indoor measurements where high resolution is used in mobile communications. Unlike the analog required. For further information on this system as sliding conelator equivalent, the DSCP is capable of well as existing channel probes, look fo r a full impulse responses acquisitions within the period of description at the fo llowing web site address: one PN code word length (typically 51 s ). The probe has typically been configmed for a null-to-null http://www.its.bldrdoc.gov/pub/chprobe/dsp.htm bandwidth of 20 MHz, providing a delay resolution of 100 ns and a maximum measurable delay of 51 s. FED-STD-1037C Search Engine Bandwidths as large as 50 MHz have also been The search engine developed fo r Federal Standard used. The most recent developments add a quad 1037C, Glossary of Te lecommunication Terms (see channel capability, making it possible to perform pp. 28-29) was tailored specifically to search for any spatial and polarization diversity experiments. By character string in the entire text file of the 5800- using synchronized timing, the probe can measure entry glossary and to display on screen the ordered absolute time-of-flight from transmitter to receiver. results of the search. The search engine is installed In addition, it has the capability for a rapid succes­ online at sion of acquisitions over extended periods of time and thus the ability to determine Doppler spread at http:// glossary. its.bldrdoc.gov/fs -1 03 7 high vehicle speeds. The present system uses an and is available for anyone to use, with easy-to-fol­ AGC and is, therefore, capable of measuring signals low, menu-driven instructions. within a range of power seen in cellular sites charac­ terized by severe multipath and shadow fading. The illustration shows the on-screen results after Concunent acquisition of GPS has given the system using the search engine to find the occurrence of the the capability of marking the data with speed and word "telephone" in all entries in the glossary. In 9 location. seconds, the search engine found 226 definitions using the word "telephone." All occUITences are dis- played in the right­ hand frame (with a browser using frames). Scrolling to the bot­ tom of the list in the right-hand frame, the Federal Standard 1037C with Search Results user is invited to per­ form another search Search Engine • �860 definitions searched in9 seconds (actual time to transmit resu!U to your for a different charac­ browser may have takenlonger) ter string. • 226 definitions fo und thatcontain the item 'tel phone'. The central advantage of the search engine is that it significantly Runthe NEWsearch engine from theW'mdow on the right,or aoto the speeds a user's access non·aeweh·enaine version of�. to any particular entry in the 400-page glos­ . J sary. Thus, the search engine promotes a more organized and more thorough review of the entire glossary.

Results of using the FED-STD-1037C search engine to findthe word "telephone " in the glossary.

82 ITS Tools and Facilities

HF Communications System Te st and The real-time hardware channel simulation capabili­ Evaluation Facility ty consists of a conventional narrowband (Watterson Model) channel simulator, a narrowband simulator The ITS HF Communications System Test and based on the ITS wideband HF model, and a wide­ Evaluation Facility supports ITS and its clients in band channel simulator. All of these simulators were the development, optimization, and testing of developed at ITS. Each simulator has a unique capa­ advanced HF technologies and systems. Its primary bility for representing the channel conditions components are (1) audio compact disk (CD) equip­ encountered on HF communication links to evaluate ment and software for testing HF radio automatic the performance of HF radios under a variety of link establishment (ALE) interoperability; (2) HF repeatable, controllable conditions. The wideband radios, modems, and modem software; and (3) nar­ channel simulator employs state-of-the-art digital rowband and wideband real-time HF channel simu­ signal-processing technology to implement new lators. This facility is used particularly in testing the mathematical models of the propagation, noise, and performance and interoperability of HF communica­ interference environments. Unlike past HF channel tions systems supporting National Security and simulators that are only valid over narrowband (sev­ Emergency Preparedness. The facility also is used in eral kHz bandwidth) channels, the new simulator is conducting proof-of-concept testing that is critical to based on a fundamentally new approach that enables Federal standards development. The audio CD the simulation of wideband (on the order of 1-MHz equipment and associated software have been used bandwidth) as well as narrowband channels, both to test ALE protocols and techniques for adaptive disturbed and nondisturbed. The HF channel simula­ HF radios as defined in Federal Standard 1045A tor is used to test the operation of complex state-of­ (FED-STD-1045A). All ALE radios procured by the the-art HF systems over simulated HF transmission U.S. Government must perform the functions paths. This includes testing systems that use robust defined in this Standard. This ensures that all ALE transmission algorithms such as code-combining, radios will intemperate successfully regardless of Golay, and other forward-error correction codes with vendor. Since each radio system must be tested fe a­ either broadcast or automatic repeat request modes. ture-by-feature to verify its interoperability, ITS has developed a digital audio CD for ALE interoper­ The test facility has been used for interoperability ability testing to ensure uniform, standardized con­ and performance testing of advanced HF modems ditions and repeatable results. This reference inter­ and ALE systems. For example, the facility has been pretation and implementation of FED-STD-1 045A is used to conduct proof-of-concept testing of robust, available to all Government agencies, industry, and high-speed systems such as the proposed Federal other ALE users. With a standard audio CD player, Standard 1052, Data Link Protocol. The facility also anyone can use the ALE CD to test a radio against has been used in tests needed by the National Com­ FED-STD-1045A. The test is performed by connect­ munications System, the National Reconnaissance ing the headphone jack output of the player to the Office, and the Federal Emergency Management voice-activated input of an HF transceiver. By play­ Agency. In one recent test, ITS staff members com­ ing a selected portion of the CD, the transceiver pared modems that employ simple, cost-effective transmits a call to an ALE radio under test. The HF protocols such as PACTOR, AMTOR, ARTOR, channel and modem software simulator consists of SITOR, CLOVER II, ALE, and G-TOR to deter­ software modules for ALE protocol testing, error mine their suitability in emergency situations. correction, and linking protection techniques used in ALE radios. Through simulation studies using these Integrated Networks Simulation products, throughput and delay effects of advanced Environment networking fe atures such as sounding, polling, direct and indirect message routing, automatic message Computer-based simulation is used widely in perfor­ exchange, and store-and-forward message exchange mance prediction and design optimization in the can be determined. System users and administrators field of telecommunications engineering. ITS is can use these results to choose the proper mix of expanding its telecommunications modeling and network features and functions to achieve maximum simulation capabilities through the development of a channel efficiency. These results also are useful to comprehensive laboratory environment for network­ HF ALE radio users, standards developers, network level simulation. The modeling and simulation tools designers, and radio manufacturers and vendors. available in the Institute's network-level simulation environment include the obj ect-oriented Optimized

83 Network Engineering Tools (OPNET) program; the support ANSI Tl standards committees. Some high­ Block Oriented Network Simulation (BONeS) pro­ lights of ITS Internet Services include: gram for developing, executing, debugging, and ana­ lyzing simulation models; and several ITS-devel­ The on-line version of FED-STD 1037C, oped network-monitoring and analysis tools. These Glossary of Te lecommunication Te rms, featuring programs are hosted on Silicon Graphics, SUN, and over 5800 technical definitions linked together NT workstations in a networked environment to in hypertext. Available at allow sharing of resources. The OPNET, BONeS, http ://glossary.its.bldrdoc.gov/fs - l 037I and ITS-developed network simulation tools have fl exible capabilities for modeling and testing com­ Recent ITS publications including NTIA plex telecommunications networks including Reports and journal articles. Available at Ethernet and FDDI local area networks, packet- and http ://www. its.bldrdoc.gov/pub/pubs.html circuit-switched networks, asynchronous transfer Telecommunications Analysis Services. mode networks, satellite links, and other systems. Available at http://www.its.bldrdoc.gov/tas/ ITS has also developed a computer model to simu­ late the effe ct of different TCP/IP parameters when An overview of the ITS mission and programs. sending e-mail over HF radio links under different Available at ionospheric conditions. This will aide in determining http://www.its.bldrdoc.gov/bluebookl optimum settings for emergency HF usage. A complete listing of ITS staff with contact Integrated Networks Test Bed information. Available at http://www. ils.bldnloc.gov/home/peopie/ This fa cility provides integrated services digital net­ staff.html work-switching and emulation capabilities, and a wide range of facilities to support broadband net­ Anonymous FTP distribution of some ITS work testing including a real-time asynchronous developed software programs. Av ailable at transfer mode (ATM) switching capability. In con­ flp .its.bldrdoc.gov junction with a broadband network emulator that implements synchronous optical network and syn­ For more detailed information regarding ITS infor­ chronous digital hierarchy (SONET/SDH) transmis­ mation services please e-mail [email protected]­ sion protocols, this capability enables researchers to doc.gov or contact Darren L. Smith (303) 497-3960. study the effects of transmission errors and traffic loading on AT M network performance. The ATM ITS Local Area Network switches can route live streams of digitized audio, video, or other digital information through ITS maintains a highly flexible local area network SONET/SDH equipment operating at transmission (LAN) to support intranetworking services and labo­ speeds up to 155 Mbit/s. The laboratory is intercon­ ratory interconnection. A structured cabling system nected and interoperable with the Audio Quality, interconnects all offices and laboratories with both Video Quality, and Multimedia Subjective Testing optical fiber and Category 5 twisted-pair cabling to Laboratories (described separately in this section). support high-bandwidth communications on The set of applications of this group of integrated demand. Over 200 devices are supported on laboratories includes support for the development of 1 OBase-T and 1 OOBase-TX ethernet segments. performance standards pertaining to multimedia Connections can also be made to laboratory testbeds communications. fe aturing synchronous optical network/asynchronous h·ansfer mode (SONET/ATM). This provides ITS with great flexibility and rapid reconfiguration capa­ ITS Internet Services bility for new programmatic needs. ITS provides public Internetaccess to NTIA/ITS publications, program information and on-line For more detailed information regarding ITS Te lecommunications Analysis Services used by information services or network technology, please other Federal agencies, research partners and private e-mail [email protected] or contact Darren L. industry. Restricted-access services including elec­ Smith (303) 497-3960. tronic mail lists are used to facilitate communica­ tions with project sponsors and partners, and to

84 ITS Tools and Facilities

Mobile Radio Communication DeliveredAudio Quar with 15-kHz Ad'acen :-Channel fntelfelence Performance Facility The Telecommunications Industry Association has s ------f�. ��� ·��i.s� lfrAQ r- -<�t-a&lilhtS endorsed an open-standard design specification fo r �i!fi tnelllt­ --a5'AS/i�S the next generation of land-mobile radios. This spec­ sioalass) 4 --d!ASIJ tS ification is known as Project 25, or simply P25. As public safety agencies plan their migration strategies to infuse newP25- compliant radio equipment into their radio fleets, a determination of acceptable speech intelligibility is required. The level of speech 2t L---�--�--�------�--�1 intelligibility is directly related to the minimum � � m oo acceptable levels of received signal strength and ll:ttefe�em��:e IReie.diiilmIRlltiO. ..(;;(11 'aS) interference rejection ratio, which in tum influences the design specification for the radio network infra­ Figure 2. Ty pical delivered audio quality vs. inter­ structure (range of coverage, distance between adja­ fe rence rejection ratio performance measurement. cent channel and cochannel transmitters, etc.). ITS Conditions shown: unwanted digital signal, 15 kHz has the capability to measure P25 performance para­ offi et, interfe ring with desired digital channel meters, such as RF sensitivity and adjacent channel (d/D/1 5) , unwanted 5-kHz deviation analog signal, rejection ratio. ITS also possesses the ability to 15 kHz offi et, interfe ring with desired digital chan­ determine the delivered audio quality of speech sig­ nel (a 5/D/1 5), unwanted 5-kHz deviation analog sig­ nals transmitted through P25-compliant radios. nal, 15 kHz offi et, interfe ring with desired 5-kHz Figure 1 shows a block diagram of a test configura­ deviation analog channel (a 5/A5/15), and unwanted tion to determine the delivered audio quality of digital signal, 15 kHz offi et, interfe ring with desired transmitted speech in the presence of adjacent chan­ 5-kHz deviation analog channel (a 5/A5/1 5) . nel or cochannel interference. Figure 2 shows an example set of performance curves relating the Mobile Radio Propagation Measurement delivered audio quality of transmitted speech to Facilities adjacent channel interference rejection. These types ITS maintains a measurement vehicle capable of of measurements can be performed fo r a variety of radio channel characterization over a wide frequency radio channel and interference environments, and range. The vehicle is equipped with on-board power, mission-oriented audio samples of these speech a telescoping mast, azimuth elevation controllers, transmissions can be provided to clients, with the and a global positioning system with dead-reckoning delivered audio quality scores and radio channel backup. A suite of measurement equipment also is environment conditions. Several transmitted speech available for use in this vehicle. This includes wide­ samples may be heard at ITS' internetsite, band systems for measuring radio channel impulse http:/!flattop. its. bldrdoc.gov/ spectrum/P25/index.htm response at 450MHz ,1350MHz, 1920 MHz and 30.3 GHz. In addition there is narrow-band measure­ ment capability up to 96 GHz. Impulse response measurement capability at 30 GHz with 2ns resolu­ tion has been enhanced with the addition of a fully digital wideband recording system.

During the past year ITS increased its mobile chan­ nel measurement capability with the addition of a VME computer-based system. This system has real­ time processing capability using onboard digital sig­ nal processing as well as increased data throughput for multi-channel data. This increased capability allows continuous recordings of the mobile radio channel. Multi-channel acquisition can be used for Figure 1. Block diagram of the test configuration antenna arrays measurements or multi-frequency to obtain transmitted speech samples broadband measurements. This data can then be fo r delivered audio qualityscoring. used to simulate and model radio systems.

85 Multimedia Subjective Testing and medical devices, broadcast signals, and special­ Laboratory purpose transmitter systems can be measured. For a complete description of the RSMS, go to ITS on-line The Multimedia Subjective Testing Laboratory pro­ publications and down- vides controlled acoustic and visual environments load applicable appendices fr om any RSMS mea­ for the subjective testing of audio and video signals. surement report (e.g., Appendix A ofNTIA Report These environments are specified in ITU-T Recom­ 97-334; see Publications Cited, p. 106). mendation P. SOO and ITU-R Recommendation BT.SOO respectively. These specifications address background noise levels, reverberation times, wall RFIMS Development Lab colors, light levels, room dimensions, and other Under the FAA Radio Interference Monitoring properties. The Multimedia Subjective Te sting System (RFIMS) Program, ITS engineers have cre­ Laboratory consists of two separate rooms that con­ ated the RFIMS Development Lab. The lab houses form to these specifications. and maintains complete RFIMS hardware and soft­ ware configurations. The lab is available to all nine Because two separate rooms are available, the labo­ FAA regions as well as FAA Headquarters and ratory can support conversation, teleconferencing, Technical Center to support their use of RFIMS. and video teleconferencing tests as well as listening RFIMS is a custom radio spectrum measurement and viewing tests. Electronic screens and pens are system integrated into a mobile field platform. In the used in some tests to automate the collection of RFIMS Development Lab, ITS engineers can quick­ responses from test subjects. Other supporting audio ly and accurately re-create field measurements and and video equipment in the laboratory includes cam­ simulate FAA data acquisition. The RFIMS eras, monitors, microphones, loudspeakers, head­ Development Lab allows ITS engineers to assist the phones, and handsets. Professional quality analog FAA in troubleshooting any problems, identifying and digital audio and video recording and playback anomalies, and verifying field results fr om deployed equipment are available as well. units. The RFIMS program currently has three mobile units deployed in three FAA regions. Eight Radio Spectrum Measurement Systems more RFIMS will be deployed in 1999. ITS has designed, constructed, and currently oper­ ates a number of automated spectrum measurement Spectrum Compatibility Test and systems. The Radio Spectrum Measurement System Measurement Sets (RSMS), ITS's primary system, is a vehicularly The introduction of new systems in close frequency mounted, self-contained facility for measurements proximity to older ones often causes electromagnetic between 1 MHz and 24 GHz. ITS also has available compatibility (EMC) problems. Although models a number of suitcase-deployable systems called and simulations provide much useful information in Compact Radio Spectrum Measurement Systems guiding design decisions, the complexity of modern (CRSMS). RSMS and CRSMS facilities incorporate systems and the existing spectral environment often a combination of commercial off-the-shelf hardware, requires real world measurements of a proposed sys­ hardware custom-designed by ITS, and control soft­ tem's effects within its proposed operating environ­ ware written by ITS. The RSMS is RF-shielded, and ment to determine its impact on other users of the includes two 30-ft masts, an on-board 10-kW gener­ radio spectrum. Another problem is the production ator, air conditioners, four full-height equipment of a controlled interfering signal with known charac­ racks, and storage space. CRSMS capabilities utilize teristics in environments where the suspected inter­ the same software but typically include only as ferer may be unavailable fo r use. This includes situ­ much hardware as is required for any given mea­ ations such as laboratory tests using interference surement task. Local arrangements must be made for from ship or aircraft mounted radars or communica­ CRSMS shelter and power. tions systems. In both situations a system which could simulate the spectral emissions of other Both RSMS and CRSMS rely extensively upon devices with a wide range of latitude is needed. computer control of measurements. These systems can be operated in fully automatic, semi-automatic, To meet these needs, ITS engineers have developed and fully manual modes. Mobile radios, fixed com­ two different types of interference generators. The munication links, radars, personal communication first system is the Broadband Arbitrary Waveform systems, earth station uplinks, industrial, scientific,

86 ITS Tools and Facilities

Transmitter (BAWT) that is used to simulate the census data; Federal Communications Commission spectral output of a wide variety of radar and com­ (FCC) databases; and geographic information sys­ munication systems. These signals can be coupled tems (GIS) databases (arcinfo). Other Government directly into the system under test or they can be databases and reports are available through a bul­ transmitted into the target system's antenna to more letin board service available to all users of TA accurately gauge its response to a real interference Services as they are developed. TA Services has situation. In cases where the exact form and charac­ developed models that predict communication sys­ teristics of the proposed interferer are poorly known, tem coverage, and interference for many broadcast a second type of generator may be used. This applications. New models in the GIS environment device, the Broadband Noise Generator (BBNG) for personal communications services (PCS) and produces a noise-like signal at the frequency of local multipoint distribution services (LMDS) have interest with a bandwidth determined by the investi­ been developed (see Telecommunications Analysis gator. This signal is typically directly coupled into Services, pp. 44-45). The following is a brief the target system for measurement purposes. The description of some programs available through TA BBNG is especially useful for assessment of system Services. performance in the presence of noise-like spurious emissions fr om adjacent-band systems. PATH PARAMTRS - Calculates Great Circle dis­ tances and bearings between user-specified loca­ tions, and also provides delta-H and average terrain Table Mountain Radio Quiet Zone heights for those locations. This unique facility (one of only two in the nation) is controlled by public law to keep the lowest pos­ PCS/LMDS - Allows the user to create or import sible levels of unwanted radio frequency energy surfaces that may include terrain, buildings, vegeta­ within the test area. This allows research concerned tion and other obstructions in order to perform line­ with low signal levels, such as fr om deep space, of-sight and diffraction studies. extraterrestrial low-signal satellites, or very sensitive receiver techniques, to be conducted without the FCCFIND, FMFIND, TVFIND, AMFIND, and interference found in most areas of the nation. As TOWERFIND - Allow a user to search the FCC the use of electronic systems (e.g., garage door database for particular stations or by search radius openers, computers, citizen band radios, cellular around a point of interest. telephones, arc welders, and microwave ovens), the number of radio and television stations, and new INMOD - Calculates and lists intermodulation prod­ uses for the radio fr equency spectrum increase, the ucts in a user-specified receiverbandpass fr om up to average level of electromagnetic energy across the 40 transmitters, 40 receivers (up to seventh order), spectrum will also increase. This is important to and with up to 5 concurrently operating transmitters. companies that develop sensitive radio receivers and PROFILE - Extracts path profiles according to user­ signal-processing equipment, since the equipment is specifiedinput parameters, such as location and often saturated by the background signal level. This bearing. After the data is extracted, either the indi­ facility is available fo r use by private parties on a vidual elevations or an average elevation along the reimbursable basis. profile can be obtained. A user also can receive plots of the profiles adjusted for various K factors Telecommunications Analysis Services depending upon the intended use of the path. For Telecommunications Analysis Services (TA Ser­ microwave links, Fresnel zone clearance can be vices) provide the latest engineering models and determined easily fr om the plots so that poor paths research data developed by ITS to industry and other can be eliminated fr om a planned circuit or network. Government agencies. TA Services is interactive and is becoming Web-based. It is designed to be both HORIZON - Plots the radio horizon around a speci­ user-friendly and efficient. It offers a broad range of fied location in the U.S.-digitized topographic data. programs that allow the user to design or analyze the It is generally used for sighting satellite terminals performance of telecommunications systems. Cur­ and radars so that terrain-shielding effects and limits rently available are: on-line terrain data with 3-arc­ on the visible elevations can be determined. seconds (90 m) resolution for much of the world and 5-min resolution data for the entire world; the 1990 SHADOW - Plots the radio line-of-sight (LOS) regions around a specified location in the United

87 States using digitized topographic data. It shows the user or plotted in brilliant colors on clear plastic areas that are LOS to the base of the antenna, areas to a specified scale fo r overlaying on geopolitical that are LOS to the top of the antenna, and areas that maps. This is the most detailed of the signal calcula­ are beyond LOS to the antenna. tion programs available and uses ITS's Inegular Terrain Model in a point-to-point mode. The FCC COVERAGE - Calculates the receive signal levels rules, as well as other widely available models, also along radials that are spaced at user-definedinter­ can be chosen. New models are placed on-line with­ vals of bearing around the transmitter. The program in CSPM as they become available. CSPM is capa­ lists the contours of signal coverage of the transmit­ ble of combining coverage fr om several transmitters ter along each radial and lists distances to user-spec­ to show the coverage from a network of stations. ified contours fo r each radial. Either the FCC broad­ Interference regions also can be plotted to determine cast rules or the ITS Irregular Terrain Model can be potential interference from a user-specifiedtran smit­ chosen for calculations. ter within the area of interest. The plots show the population, households, and areas covered within CSPM - Determines the system performance of each of the signal ranges. The most ambitious use of mobile and broadcast systems in detailed output CSPM to date involves determining the population plots of signal intensity, as shown in the Figure covered by education television stations. below. Plotted outputs can either be faxed directly to

TR Services SarT'flle CSPH Covera§l" LR 50/50 9--Nov-98 10:3€1:09 CSI1011Novi1,991JRLca1C

Fieldrt;y(dBJVr Irrtens rll

D Greater than 70.00 Area: q240. sq km Populatlono 5467ee0. Hous1:tlo 'ld:s;�19&12121il.

68.0el'l0 t

- 4a.eee0 t

- L=« than qa,eeeo Area• 45390. oq km Popula�IOn: 3025el00. Households' 1011aeo.

Example of a transmitter coverage using CSPM.

88 ITS Tools and Facilities

Video Quality Laboratory Wireless Link Simulation Laboratory The ITS Video Quality Laboratory contains objec­ This ITS laboratory provides an environment to tive and subjective measurement fa cilities that are simulate wireless systems and channels fo r per­ used to develop and test automated techniques for formance prediction of data, compressed or uncom­ assessing the quality of video and image data. The pressed speech and images, and fax source trans­ video quality studies conducted in this laboratory mission. ITS specializes in end-to-end results by support national and international standardization perfom1ing channel characterization measurements, and associated Government and industry technology modeling the measurements, imbedding the models assessment needs. The objective measurement facili­ in simulation software, and predicting the system ties include (1) several high performance worksta­ performance and spectrum requirements via simula­ tions that are used for prototyping and testing the tion. Typically, predicted speech and image quality video and image parameters; (2) an ensemble of are determined as a function of signal-to-noise ratio, switcher-connected broadcast quality cameras, video carrier-to-interference ratio, and bit error ratio for a recorders (including an ITU-R Recommendation selected radio system and channel parameters. Real­ BT.601, 360 Mbits/sec digital video recorder), video time link bit error generator models are available for monitors, video capture and display equipment, each simulation used to study the effects of the link video signal generators, and video coders/decoders conditions on various sources and may also be (codecs); and (3) an 80-GB read/write optical juke­ employed as a link model in wireless network simu­ box, a 12-GB 4mm tape drive, and an 8-GB 8mm lation. These capabilities are useful in determining tape drive, all for storing digitized images. The predicted performance of proposed wireless systems objective quality measurement software, written in and standards and may be used to determine design C++, can perform pixel-accurate and field-accurate and deployment specifications for these systems. processing of sampled input and output video streams in accordance with ANSI T1.801.03-l996 PC/DOS-based, Windows 95, and UNIX-based link (Digital Transport of One-Way Video Signals - software simulation packages and a generic channel Parameters for Objective Performance Assessment). simulator software package are available to perform The Multimedia Subjective Testing Laboratory pro­ wireless simulations, predict performance, predict vides a means for validating objective video and spectrum requirements, and perform signal process­ image parameters implemented in computer-based ing. Laboratory hardware consists ofRISC and measurement systems. The video quality laboratory Pentium workstations to run simulation and signal hardware and software have been designed specifi­ processing software. An audio cassette, S-VHS cally to address the difficultproblem of assessing recorder and players, and S-VHS TV monitor are the end-to-end quality of digital video systems. For available fo r storing and demonstrating speech, example, video codecs are used in conjunction with images, and video. Programmable digital signal­ the Integrated Networks Testbed to generate processing boards and card cage are available to impaired digital video for objective and subjective download wireless link simulations for real-time quality testing. testing of transmitters, receivers, and channel models. A programmable 6-MHz bandwidth hard­ ware channel simulator is also available for testing transmitters and receivers.

89 ITS suitcase measurement system deployed on a rooftop in Wa shington, D. C. in 1990-91. Th is photograph was taken during an Other Agency-funded microwave receivabilitypro ject that was classified at that time, but has subsequently been declassified (photograph by FH. Sanders).

90 ITS Proj ects in FY 1998

Department of Commerce interference. Add map boundary modifications to existing propagation model for low and medium Telecommunications Assessment and Strategic fr equencies. Plan - Determine what telecommunications Robert J. Matheson (303) 497-3293, resources and capabilities are presently available Project Leaders: Roger Dalke (303) 497-3 109, Nicholas DeMinco (303) within the various organizations of the Department. 497-3660, and Frank H. Sanders (303) 497-5727 Develop a structured, effective, and efficientmeth­ e-mail [email protected], [email protected], odology for moving the Department's telecommuni­ [email protected], and fs [email protected] cations infrastructure into the 21st century.

Project Leader: Val J. Pietrasiewicz (303) 497-5 132 Technical Support for Implementation of a e-mail [email protected] Nationwide Global Positioning System Service ­ Provide continuing support for the implementation Department of Defense of a nationwide DGPS Service. Utilize results

Adaptive Radio and Adaptive Antenna obtained in field testing to develop a network of fewer total DGPS reference stations, in order to Symposium - Plan, organize, host, and chair a symposium on adaptive radio and adaptive antenna reduce the number of potential interference prob­ technologies, in order to gather information on new lems and the number of stations that must be developments in these technologies. operated and maintained. John J. Lemmon (303) 497-3414 Project Leader: Christopher L. Holloway (303) 497-6184 Project Leader: e-mail [email protected] e-mail [email protected]

Federal Aviation Administration Federal Railroad Administration

Telecomm nications Study - FAA Radio Frequency Interference Monitoring 11 Review the railroad's next generation telecommunications system design Systems - Integrate and test prototype mobile RFIMS measurement systems. Procure and test addi­ and demonstration projects to be used on positive tional mobile systems, install subsystems and soft­ control systems and advise the Federal Railroad ware into each new vehicle, perform final integra­ Administration on telecommunication issues. tion testing, and deliver the vehicles to the FAA. Project Leader: John M. Vanderau (303) 497-3036 e-mail [email protected] Project Leader: Patricia J. Raush (303) 497-3568 e-mail [email protected] Hewlett-Packard Company

Federal Highway Administration Local Multipoint Distribution Service Model

Development - Electromagnetic Compatibility of the Intelligent Develop computer models to predict excess path loss for the local multipoint distribution Tr ansportation System - Develop communication systems to provide information to travelers, their system signal. vehicles, and the infrastructure. Support develop­ Project Leader: Robert 0. DeBolt (303) 497-5324 ment of standards and identify spectrum issues e-mail [email protected] related to electromagnetic compatibility (EMC) of the intelligent transportation systems. Perform Industrial Technology, Inc. measurements for an EMC analysis to determine the Calibration and Verification Listening Te st - levels of radio fr equency radiation coupled from an Conduct a subjective test that will result in data that Earth station operating in the 5875- to 5925-MHz will be used to calibrate and verify the operation of band to a highway environment location. Perform an a cellular telephone test instrument currently under EMC analysis for dedicated short-range communica­ development. tions systems in this band. Determine potential worst Project Leader: Stephen D. Voran (303) 497-3839 case interference distances, conduct testing, and e-mail [email protected] perform analysis to identify techniques to mitigate

91 Miscellaneous Federal and Non-Federal HF Modem Performance and Interoperability Agencies Testing - Upgrade the ITS HF testbed to aid in the performance of extensive, unattended testing of HF Telecommunications Analysis Services - Make equipment under simulated, degraded atmospheric available to other Government agencies and to the conditions. Conduct performance tests on new low­ public, through user-friendly computer programs, a cost modems, and assess software-based and hard­ large menu of engineering models, scientific and ware-based modem interoperability. informative databases, and other useful communi­ cation tools. Project Leader: Timothy J. Riley (303) 497-3307 e-mail [email protected] Project Leader: Robert 0. DeBolt (303) 497-5324 e-mail [email protected] International HF Radio Standards Development - Gain international acceptance in the ITU-R of the National Communications System NCS-sponsored HF channel and noise/interference

Advanced Audio Quality Testing - Test and verify models and the HF channel and noise/interference advanced audio quality measurement algorithms. simulators. Incorporate Federal Standard HF ALE Develop techniques to integrate existing video qual­ technology in the ITU-R Adaptive HF Handbook. ity measurement algorithms with newly developed Project Leader: Christopher Redding (303) 497-3 104 algorithms. Prepare results fo r the Mu ltimedia e-mail [email protected] Performance Handbook. Land Mobile Radio Interoperability Standards - Stephen D. Voran (303) 497-3839 Project Leader: Assist in developing interoperability standards for e-mail [email protected] digital land mobile radio. Lead the Encryption Task Group, develop security standards, provide systems Broadband Digital Telecommunications - Te st and verify broadband multimedia quality measurements. engineering support to other Task Groups, and par­ Contribute results to national and international stan­ ticipate in various committees. dards organizations. Project Leader: William J. Pomper (303) 497-3730 e-mail [email protected] Project Leader: Arthur A. Webster (303) 497-3567 e-mail [email protected] Low-Cost ALE Controller: Develop Low-Cost

Digital Vo ice over HF Radio Transmissions - DSP Card - Develop the hardware portion of the Select and test vocoders and modulation methods for low-cost ALE controller/modem, based on DSP use in the low baud rate HF environment, in order to technology, for volunteer radio operators to use in provide increased clarity and reliability for HF conjunction with HF SSB radios. emergency radio operations. Project Leader: Christopher Behm (303) 497-3640 e-mail [email protected] Project Leader: Christopher Behm (303) 497-3640 e-mail cbehm@its. bldrdoc.gov Low-Cost ALE Controller: Develop DSP

FTSC Standards Coordination - Develop and test Software - Develop the software portion of low-cost a search engine to work on all hyperlinkedFederal ALE controller/modem, based on DSP technology. Standards. Develop and maintain a "Federal Stand­ Project Leader: Robert A. McLean (303) 497-5947 ards Online" web page, integrated with the search e-mail [email protected] engine. Analyze technological and economic impact assessments of prospective Federal Telecommunica­ Multiband, Multimode Wireless Communications Standards - Participate in U.S. Technical Group 811 tion Recommendations and Standards. and ITU-R Technical Group 8/1, which are in the Evelyn M. Gray (303) 497-3307 Project Leader: process of developing recommendations for the next e-mail [email protected] generation of wireless systems. Project Leader: Christopher Redding (303) 497-3 104 e-mail [email protected]

92 ITS Projects

Multimedia Performance Ha ndbook - Design and Real-Time Channel Simulation to Support ITU-R implement Version 3.0 of the Multimedia Perform­ Contributions - Demonstrate the limitations of the ance Handbook, conduct preliminary testing, and ITU-R Narrowband HF (NBHF) model. Compare perform standards work in TlAl and the FTSC. the difference between a current NATO standardized Project Leader: Arthur A. Webster (303) 497-3567 NBHF simulator and the ITS NBHF simulator, e-mail [email protected] based on the more generalized ITS Wideband HF channel model, in order to assess the effect of delay Mu ltimedia Performance Ha ndbook: Desktop spread on NBHF modem performance. Video Teleconferencing Testing - Produce prelimi­ Project Leader: Christopher Behm (303) 497-3640 nary performance information concerning a typical e-mail [email protected] desktop video teleconferencing system. Produce content for the Multimedia Performance Handbook Standards Publication Support - Provide the fo l­ and contribute to national and international stand­ lowing expert standards publication support to NCS: ards bodies. enhancement of the Federal Standard 1037C search Project Leader: Arthur A. Webster (303) 497-3567 engine, electronic distribution of FED-STD-1 037C e-mail [email protected] and other Federal Standards, and maintenance plan­ ning fo r FED-STD-1037C. Mu ltimedia Performance Handbook: Handbook Project Leader: Evelyn M. Gray (303) 497-3307 Revision, Subjective Te sting, and Standards e-mail [email protected] Development - Convert the Handbook to web com­ patible software technology. Perform a subjective Wideband HF Simulator Te sting to support quality measurement experiment involving the trans­ Standards Development - Validate both narrow­ mission of low-rate video teleconferencing signals. band and wideband channel simulators using proce­ Help develop international standards for the mea­ dures specified by the NATO HF Communications surement of the quality of MPEG coded video. System Group. Project Leader: Arthur A. Webster (303) 497-3567 Project Leader: Christopher Behm (303) 497-3640 e-mail [email protected] e-mail [email protected]

National HF Radio Standards Development - National Institute of Standards and Provide effective leadership and administrative sup­ Technology port for the Federal Telecommunications Standards Committee's HF Radio Subcommittee. Develop Communication Standards for Office of Law technical contributions and complete texts for pro­ Enforcement Standards - Provide engineering sup­ posed new or revised Federal HF radio standards. port, scientific analysis, technical liaison, and test Complete and publish an HF ALE handbook to design and implementation in the development and assist communication managers, administrators, and validation of criminal justice communications operators in planning, implementing, and controlling standards. HF ALE networks. Project Leader: Val J. Pietrasiewicz (303) 497-5 132 e-mail [email protected] Project Leader: Christopher Redding (303) 497-3 104 e-mail [email protected] National Oceanic and Atmospheric Performance Assessment of HF E-mail Protocols Administration - Quantifythe performance of Internet e-mail utiliz­ NOAA Weather Satellite System Analysis - ing a DSP-based HF channel simulator over various Provide consulting services for the in-band man­ channel conditions. Conduct over-the-air tests to made noise model developed by ITS. demonstrate system performance and assess an HF­ Robert J. Achatz (303) 497-3498 optimized protocol stack for sending Internet e-mail Project Leader: e-mail [email protected] messages over HF channels. Project Leader: Christopher Redding (303) 497-3 104 e-mail [email protected]

93 National Security Agency Broadband Wireless Standards - Provide leader­ ship and technical contributions to national and Secure Telecommunications Analysis Services - international wireless standards development that Develop a secure TA Services with new NSA-sup­ enhance domestic competitiveness, improve foreign plied algorithms which NSA can utilize remotely. trade oppmtunities, and facilitate more efficientuse Robert DeBolt (303) 497-5324 Project Leader: 0. of the radio spectmm. Actively support the Interna­ e-mail [email protected] tional Telecommunication Union-Radiocommuni­ cation Sector, the Joint Technical Committee for Standards Development fo r Personal Personal Communications Services Air-Interface Communications Services - Present standards requirements fr om anticipated Federal users of wire­ Standards, and the IEEE 802.11 Wireless Local Area less products and services, stressing incorporation of Networks Standards Committee. synchronous dat services with STU-111 applications Project Leader: Eldon J. Haakinson (303) 497-5304 in the proposed TR41.6 unlicensed personal commu­ e-mail [email protected] nications services standards. Broadband Wireless Systems Research - Support Steven M. Davidson (303) 497-3411 Project Leader: the development of broadband radio technologies e-mail [email protected] and applications, especially high-data-rate, digital communications. Measure and model millimeter­ National Telecommunications and wave propagation. Measure and model broadband Information Administration indoor propagation and support the development of Audio Quality Standards - Develop perception­ wireless local area network standards. based objective audio quality assessment techniques Project Leader: Peter B. Papazian (303) 497-5369 and standards contributions in support of advan�ed e-mail [email protected] audio-coding and integrated services digital network standards within T1 and the International Telecom­ Digital Networks Performance fo r the Global munication Union-Telecommunication Standardiza­ Information Infrastructure - Develop and promote tion Sector. the adoption of a new ANSI standards project in TIA1 that will provide a fo cus for U.S. contribu­ Project Leader: Stephen D. Voran (303) 497-3839 e-mail [email protected] tions on GII!Internetperf ormance in the ITU-T. Project Leader: William R. Hughes (303) 497-3728

Broadcasting and Related Propagation Studies - e-mail [email protected] Provide engineering support to the Executive Branch to select the best alternatives for efficient use of the International Standards - Provide leadership to T1 broadcasting spectmm. Develop tools to evaluate the and U.S. International Telecommunication Union­ FCC's planned allocation fo r high-definition televi­ Telecommunication Standardization Sector (ITU-T) sion assignments, and develop techniques for high­ committees and internationalwork groups. Prepare definition television station owners to evaluate their technical contributions to advance ITU-T standards station's performance. development and draft recommendations on integrat­ ed services digital networks and associated voice, Project Leader: Eldon J. Haakinson (303) 497-5304 e-mail [email protected] data, and video communication services. Project Leader: Neal B. Seitz (303) 497-3 106 Broadband Networks - Build the infrastmcture e-mail [email protected] necessary for ITS to lead in the development of a broadband research community by expanding and Personal Communications Services Interference enhancing the Institute's capabilities for broadband Modeling - Extend the ITS-developed personal networks performance measurement. communications services (PCS) interference model to cover additional PCS technologies. Participate in Project Leader: William R. Hughes (303) 497-3728 e-mail [email protected] technical working groups to produce a handbook assisting equipment manufacturers and field person­ nel in avoiding and eliminating PCS to PCS interference. Project Leader: Timothy J. Riley (303) 497-5735 e-mail [email protected]

94 ITS Projects

Personal Communications Services Radio System Video Quality Standards - Develop video quality To ols - Provide support for the development of per­ assessment techniques and standards contributions in sonal communications services radio technology support of digital transmissions systems relevant to through measurements, modeling, and simulation of the National Information Infrastructure within T1 the radio channel; analyze spectrum issues including and the International Telecommunication Union­ spectrum sharing, interference, and access methods; Telecommunication Standardization Sector. Develop and provide technical support for national and inter­ the required technology for assessing performance national standards development. of digital video transmission systems and transfer Project Leader: Robert J. Achatz (303) 497-3498 this technology to other Government agencies and e-mail [email protected] end-users, national and international standards bod­ ies, and the U.S. telecommunications industry. Radio Spectrum Measurement System - Support Project Leader: Stephen Wolf (303) 497-3771 Federal Government spectrum management needs e-mail [email protected] through development of new capabilities for the radio spectrum measurement system (RSMS). N etrix, Inc. Develop new techniques, algorithms, and hardware for the RSMS. Netrix Conversation Te st - Conduct subj ective and obj ective measurements of speech quality, using a Project Leader: Bradley J. Ramsey (303) 497-3165 e-mail [email protected] conversation test and prototype speech quality test instruments. Measurements will be made on existing Radio Spectrum Measurement System and emerging speech compression and transmission Operations - Support Federal Government spectrum technologies. management needs through spectrum measurements. Project Leader: Stephen D. Voran (303) 497-3839 Spectrum measurements quantify Government and e-mail [email protected] non-Government spectrum occupancy, the emission characteristics of individual emitters, and the U.S. Air Force electromagnetic compatibility of systems that use Investigation of CW Waves Through Reinforced radio spectrum. Concrete and Circular Waveguides - Obtain an Project Leader: Frank H. Sanders (303) 497-5727 analytical solution of electromagnetic waves propa­ e-mail fs [email protected] gating through reinforced concrete walls, in order to study the propagation and attenuation characteristics Satellite/ATM Interoperability - Examine and pro­ mote the interoperability of satellite and terrestrial of the walls. Investigate the propagation of a signal systems and services, with an emphasis on ATM and through a 15-inch circular hole in the ground to related protocols. Measure and provide information determine the optimum frequency for on the performance and interoperability of commu­ communications. nications links that include satellites. Project Leader: Christopher L. Holloway (303) 497-6184 e-mail [email protected] Project Leader: William A. Kissick (303) 497-7410 e-mail [email protected] Radar Target Identification Development - Assist in the development of optimal fe ature sets and clas­ Spectrum Engineering Models - Provide engi­ neering and analysis in support of the Office of sifiers for automatic target recognition using radar Spectrum Management of NTIA regarding studies of sensor data. spectrum utilization and electromagnetic Project Leader: Edmund A. Quincy (303) 497-5472 compatibility. e-mail [email protected] Project Leader: Robert J. Matheson (303) 497-3293 e-mail [email protected] U.S. Army

Jammer Effectiveness Model - Develop a Jammer Spectrum Technical Studies - Use state-of-the-art Effectiveness Model using the AMOS interface shell spectrum measurement techniques, algorithms, and and ITM, GWAPA, and IONCAP propagation hardware to perform spectrum management research models. for the Office of Spectrum Management of NTIA. Project Leader: Nicholas DeMinco (303) 497-3660 Frank H. Sanders (303) 497-5727 Project Leader: e-mail [email protected] e-mail fs [email protected]

95 ' I

I

. I

Th e Radio Sp ectrum Measurement Sys tem (R SMS) above Los Angeles during a broadbandNT IA spectrum survey (photograph by FH. Sanders) .

96 ITS Publications in FY 1998

NTIA Publications Dedicated short-range communication systems have been proposed for operation at locations R.J. Achatz, Lo, P.B. Papazian, R.A. Dalke, and Y. across the United States in the 5850- to 5925- G.A. Hufford, "Man-made noise in the 136 to 138- MHz band. Various search and tracking high­ MHz VHF meteorological satellite band," NTIA power radars operate at or near this frequency Report 98-355, Sep. 1998. band and are a source of potential interference. Satellite radio system performance in the 136 to The successful operationof such digital com­ 138-MHz VHF meteorological satellite band is munication systems is dependent upon compati­ compromised by man-made noise external to ble operation and coexistence with these radars. the receiver. Methods used for predicting man­ The Institute for Telecommunication Sciences made noise power in this band are based on has performed a series of interference tests to measurements conducted in the 1970's. These determine the electromagnetic compatibility of methods may be inaccurate due to technological DSRC systems used for automatic toll collec­ advances such as quieter automotive ignition tion and high-power 5-GHz radars. The meth­ systems and the proliferation of consumer elec­ ods used to perform the tests and results are pre­ tronic devices such as the personal computer. sented in this report. This report describes noise power measurements J.R. Hoffman, J.J. Lemmon, and R.L. Ketchum, the Institute for Telecommunication Sciences "DGPS field strength measurements at a GWEN performed in the 136 to 138-MHz VHF meteo­ site," NTIA Report 98-346, Apr. 1998. rological satellite band. Statistics of average noise power were compared to those of mea­ Field strength measurements of a 300-kHz dif­ surements conducted in the 1970's. The noise ferential global positioning system signal trans­ power measurements were also used to model mitted at a Ground Wave Emergency Network instantaneous noise power for simulation of site at Appleton, Washington were conducted. radio links. Data were acquired continually along five dif­ ferent routes and tagged with geographical posi­ R.J. Achatz, Lo, and E.E. Pol, "Indoor direction Y. tion. Field strength along each individual route diversity at 5.8 GHz," NTIA Report 98-351, Jul. was plotted against distance fr om the transmitter 1998. and related to geological landmarks. Results Complex impulse response measurements of a were used as model inputs and to compare mea­ warehouse building were made at 5.8 GHz with sured signal strengths with model predictions. a sliding correlator channel probe. These mea­ C.L. Holloway, M.G. Cotton, and P. McKenna, "A surements were made with vertically and hori­ simplified model for predicting the power delay pro­ zontally polarized directional antennas so per­ filecharacteristics of an indoor radio propagation formance improvement due to polarization- and channel," NTIA Report 98-353, Aug. 1998. direction-diversity could be evaluated. Improve­ ment in perfmmance was determined by Multipath channels in indoor wireless commu­ changes in the radio channel's delay spread. nication systems exhibit a characteristic power Performance improved with direction diversity; delay profile, which can be a detriment to sys­ however, adding polarization diversity yielded tem performance. In this paper, we present a little improvement over direction diversity simplifiedmodel fo r calculating the decay rate alone. of the power delay profile for propagation within rooms. This simplified model provides a R.A. Dalke, F.H. Sanders, and B.L. Bedford, time-efficientmeans of predicting system per­ "Electromagnetic compatibility testing of a dedi­ formance. Predictions of this indoor power cated short-range communication system," NTIA delay profile (IPDP) model are compared to Report 98-352, Jul. 1998. results obtained from a finite-difference time-

97 domain (FDTD) model. Additionally, compar­ HTML. In several ways, a large telecommuni­ isons of the IPDP model to measured data are cations glossary was ideally suited for presenta­ presented. The rms delay spread is the second tion in hypertext format. The most significant central moment of the power delay profile of a advantage to the hypertext format is the rapidity propagation channel and is a measure of the with which users can jump from definition to communication link degradation due to multi­ definitionwithout having to tum a precise (and path. We also show results of the estimated rms often large) number of pages to arrive at the delay spread from this model and show compar­ next desired definition. Yet, the very great size isons to the measured data. This IPDP model of the Glossary introduced one of the biggest can be used to investigate the effects of variable hurdles in its hypertext development. The ITS room size and properties of the surfaces (or editors of the Glossary surmounted that hurdle walls) on the decay characteristics of the power by using Perl scripts to generate automatically delay profile. the many thousands of required hyperlinks in the large glossary. This paper describes those C.L. Holloway and E.F. Kuester, "Analysis and automated techniques. In addition, the paper calculations of the ground plane inductance addresses special considerations (of equipment, associated with a printed circuit board," NTIA software, and image display) for presenting a Report 98-344, Nov. 1997. user-friendly HTML product.

A knowledge of the net inductance of the In the months since the electronic version of ground plane can aid in the analysis and investi­ Federal Standard 1037C first became available, gation of printed circuit board emissions. In this more than 450 copies of the CD ROM version report, we present a method, based on the con­ have been distributed and the Web version has cept of partial inductance, to determine the net been accessed more than 75,000 times. This inductance of the ground plane associated with shows that there is a wide and ready audience a microstrip line. This method is based on a for electronic access to the Glossary, and, very previously derived expression for the current likely, other Federal standards. density on the ground plane. We show calcula­ tions fo r the net, self-partial, and mutual-partial W. Kissick, D. Sutherland, M. Weibel, W. McCoy, inductance of the ground plane for various trace M. Ruhl, R. Toense, U. Borkar, and M. Hariharan, geometries of practical interest. We also illus­ "National security and emergency preparedness trate how the classical transmission line induc­ communications experiments using the advanced tance of a microstrip line can be obtained from communications technology satellite," NTIA Repmi the concept of partial inductance. Comparisons 98-354, Aug. 1998. to different experimental results are also given. Many govemment telecommunications needs, W. Ingram and E. Gray, "A federal standard on especially those that suppmi National Security electronic media," NTIA Report 98-350, Aug. 1998. and Emergency Preparedness (NS/EP) missions, are becoming increasingly dependent on com­ Federal telecommunications standards have mercially available equipment and services. traditionally been distributed in hard copy, i.e., This is consistent with the goals and concepts of in book form, with mandated 5-year revisions the National Information Infrastructure. This requiring a new book or new change pages for report examines the use of an advanced satellite every updated edition. Distributing Federal - in this case, NASA's Advanced Communi­ telecommunications standards on the World cations Technology Satellite (ACTS) - with Wide Web (Web) or on CD ROM in electronic ISDN and frame relay protocols to support form presents possibilities fo r speeding and NS/EP communications requirements. A net­ enhancing user access to specific subsections of work using three ACTS Earth stations was the document, providing wider distribution to established as a research facility. With this small the intended audience, and promoting conser­ network, several experiments were performed. vation of paper resources at the same time. Using new objective methods, voice quality was Federal Standard 1037C on the Web and on CD measured over the satellite and compared to ROM represents successful applications of other connections such as commercial, terres­ trial lines. The performance of applications -

98 ITS Publications

desktop conferencing, file transfer, and LAN performs well and should find use as both an bridging - that are likely to be useful in NS/EP engineering tool and as the basis for a new situations, was determined. The performance of standard propagation model. TCP/IP running over fr ame relay was examined. The results indicate that advanced satellites can M. Terada, "Analysis of spectrum utilization and be very useful for emergency communications message length statistics for the railroad land mobile due to the rapidity that Earth stations can be radio service," NTIA Report 98-345, Nov. 1997. deployed, the ease of reconfiguring the satellite, and the practicality of using commonly avail­ In support of the Federal Railroad Administra­ able applications running over commonly used tion of the United States Department of Trans­ protocols. However, there are some limitations portation, the Institute fo r Telecommunication to the performance of some applications or parts Sciences (ITS) has completed a field spectrum of applications due to the propagation delay of a utilization survey designed to examine individ­ satellite channel. Telecommunications protocols ual channel utilization and message length such as TCP/IP must be significantly modified distributions. The measurement system was to performwell over a satellite channel and to developed by ITS staff members to measure take full advantage ofbandwidth-on-demand signal strength in each of the 91 channels used capabilities of an advanced satellite. by the railroad industry in the fr equency band fr om 160.215-161.565 MHz. The measurement F.H. Sanders, G.R. Hand, and V.S. Lawrence, "Land system surveyed three different sites selected mobile radio channel usage measurements at the for varying conditions such as the different 1996 Summer Olympic Games," NTIA Report 98- types of traffic over the channels, propagation 357, Sep. 1998. environments, line-of-sight conditions, and electromagnetic interference. The National Telecommunications and Infor­ mation Administration (NTIA) is responsible J.M. Vanderau, R.J. Matheson, and E.J. Haakinson, for managing the Federal Government's use of "A technological rationale to use higher wireless the radio spectrum. In discharging this responsi­ frequencies," NTIA Report 98-349, Apr. 1998. bility, NTIA uses the ITS radio spectrum mea­ surement system and portable measurement sys­ Trends within the wireless and mobile commu­ tems to collect data for spectrum utilization nications industry are examined and extrapo­ assessments. This report details an NTIA proj ­ lated into the near future. The paper examines ect to measure and analyze land mobile radio the relationships between propagation loss and channel usage statistics in the metropolitan area antenna gain at higher fr equencies, shows how of Atlanta, Georgia, before, during, and after the dense intelligent infrastructure affects cell size 1996 Summer Olympic Games. and system capacity, and describes the improv­ ing high fr equency capabilities of rf electronics D.A. Sutherland, Jr., "Software implementation of a technology. The authors conclude that fr equen­ wideband HF channel transfer function,"NTIA cies above 3 GHz may be uniquely suited to Report 98-348, Apr. 1998. many wireless applications, but that non-tradi­ tional system architectures and technologies will This report presents an analytic model imple­ need to be used. mented as the computer program of the transfer function of a wideband HF channel model fo r S.D. Vo ran, "Objective estimation of perceived use in a hardware simulator. The transfer func­ speech quality using measuring normalizing blocks," tion is the basic input to the hardware simulator. NTIA Report 98-347, Apr. 1998. The mathematical basis of the program and the propagation model is presented. Parameters that Perceived speech quality is most directly mea­ characterize the skywave paths of a particular sured by subjective listening tests. These tests HF ionospheric condition are inputs to the pro­ are often slow and expensive, and numerous gram. The program code is listed and docu­ attempts have been made to supplement them mentation is provided. Graphical verification with objective estimators of perceived speech using spectrally averaged scattering functions quality. These attempts have found limited indicates that the transfer functionprogram success, primarily in analog and higher-rate,

99 error-free digital environments where speech Outside Publications waveforms are preserved or nearly preserved. R.J. Achatz and R. Dalke, "VHF space-to-earth How to objectively measure the perceived radio link performance in various man-made noise quality of highly compressed digital speech, environments," in Pro c. IEEE 1998 Radio and possibly with bit enors or fr ame erasures, has Wireless Conference, Colorado Springs, CO, Aug. remained an open question. We describe a new 1998, pp. 257-260. approach to this problem, using a simple but effective perceptual transfom1ation, and a hier­ The performance of a differentially-coherent archy of measuring normalizing blocks to com­ binary-phase-shift-keyed radio link operating at pare perceptually transfonned speech signals. a fr equency of 137 MHz in various man-made The resulting estimates of perceived speech noise environments was detetmined by Monte­ quality were conelated with the results of nine Carlo simulation. The man-made noise was subj ective listening tests. To gether, these tests generated by a model built fr om noise mea­ include 219 4-kHz bandwidth speech encoders/ surement data. The results show that the per­ decoders, transmission systems, and reference fmmance can be severely degraded in links that conditions, with bit rates ranging fr om 2.4-64 operate in residential and business environments kb/s. When compared with six other estimators, or near power lines. Further measurements and significant improvements were seen in many analysis is needed to determine the extent of cases, particularly at lower bit rates, and when this degradation. bit errors or frame erasures were present. These hierarchical structures of measuring normalizing R.J. Achatz, R.A. Dalke, and Y. Lo, "Power blocks, or other structures of measuring normal­ amplifier model fo r optimizing battety cunent, izing blocks, may also address open issues in interference, and link margin, " in Proc. IEEE 1998 perceived audio quality estimation, layered International Sy mposium on Electromagnetic speech or audio coding, automatic speech or Compatibility, Denver, CO, Aug. 1998, pp. 434-438. speaker recognition, audio signal enhancement, and other areas. The power amplifier consumes a large fraction of the total battery current used by a portable J.A. Wepman (ed.), "Personal communications transceiver. The power amplifier's bias and services technology field trials," NTIA Report 98- input power can be adjusted to decrease battery 356, Sep. 1998. current demands. These adjustments may intro­ duce nonlinearities in the power amplifier gain Te chnology field trials for six personal commu­ that will increase out-of-channel power and nications services (PCS) common air-interface decrease the link margin when variable enve­ technologies (whose standards were developed lope digital modulations are used. In this paper by the Joint Te chnical Committee on Wireless we describe a portable transceiver power ampli­ Access) were performed at the US West fier model, derived from measurements, that Boulder Industry Test Bed (BITB). The BITB allows engineers to optimize battery cunent, provided a common environment fo r the field out-of-channel interference, and link margin. testing of all of the technologies. The same con­ The models and approach presented in this figuration (cell site layout, antenna type, and paper are useful for assessing the electromag­ antenna orientation) was used for all of the sys­ netic compatibility of portable transceivers and tems tested as high-tier systems. Similarly, receivers operating in adjacent bands. another configuration was used for all systems tested as low-tier systems. Field testing of the D. Bodson, E.M. Gray, and W.J. Ingram, "Federal technologies typically consisted of four general Standard 1037C now available three ways," NSIEP types: area coverage testing, han doff testing, Te lecom News, Issue 1, pp. 21-24, 1998. interference testing, and voice quality testing. Results from these fieldtrials, and descriptions No abstract used. of the measurement and data analysis proce­ dures, are presented in this report. G.W. Cennak, S. Wolf, E.P. Tw eedy, M.H. Pinson, and A.A. Webster, "Validating obj ective measures of MPEG video quality," SMP TE Jo urnal, vol. 107, no. 4, pp. 226-235, Apr. 1998.

100 ITS Publications

In 1996, the American National Standards digital satellite weather images at 137 MHz. Institute (ANSI) adopted ANSI T1.801 .03, The measured noise statistics were used to which presents a number of new objective video develop analytical representations of the first­ quality metrics for quantifying the effects of order probability distributions for man-made digital compression and transmission impair­ noise in various environments (business, resi­ ments. The measurements in ANSI T1.801 .03 dential, and rural). Such noise models are useful were selected based on an extensive multilabo­ for simulating the perfmmance of communica­ ratory quality assessment study that included tions systems in environments where non­ video systems fr om bit rates of 64 kbits/sec to Gaussian man-made noise may degrade system 45 Mbits/sec and video test scenes that spanned performance. The statistical models as well as a wide range of spatial and temporal coding dif­ first-order probability distributions for several ficulties. The set of obj ective video quality mea­ environments are presented in this paper. surements effectively accounted for subjective judgments by human viewers. While 25 video S.M. Davidson, "Standardized and comparable systems were tested, this multilaboratory study measurements using Lab VIEW ," in Pro c. did not include MPEG video systems and did NI Week98 Conf, Austin, TX, Aug. 1998. not cover any bit rates between 1.6 and 10 Mbits/sec. This paper presents the results from In most measurement systems there is a need to two MPEG studies designed to fill in the bit­ have standardized and comparable measure­ rate gap in the previous multilaboratory study. ments. This is especially important fo r any system that must deal with safety issues and R.A. Dalke, "EMC analysis of C-band radar inter­ measurements at varied locations. This paper ference for dedicated short-range communications describes the design and development of a systems, " in Proc. IEEE 1998 International measurement system that automatically records Sy mposium on Electromagnetic Compatibility, and recalls parameters required for a complex Denver, CO, Aug. 1998, pp. 46-50. measurement through the use of Lab VIEW control defaults, log files, and a custom file Dedicated short-range communication systems system. This process provides a high degree of have been proposed for operation at locations confidence that measurements taken by diffe rent across the United States in the 5850- to 5925- users at different locations are standardized and MHz band. Various search and tracking high­ immediately comparable. power radars operate at or near this fr equency band and are a source of potential interference. E. Gray, W. Ingram, and D. Bodson, "The ABCs of The perfmmance of such digital communication writing a technical glossary, " Te chnical systems is dependent upon compatible operation Communication, pp. 23-32, First Quarter 1998. and coexistence with these radars. In this paper we derive analytical expressions that can be This paper identifies and explains fo rmat rules, used to estimate the performance of dedicated style rules, and lexicographic conventions that short-range communication systems that are have been shown to improve the clarity and subject to pulsed RF interference. precision in a technical glossary. Rationale for the rules of language, presentation, and style are

R. Dalke, R. Achatz, and Y. Lo, "Statistics of man­ examined. made noise at 137 MHz, " in Proc. IEEE 1998 International Sy mposium on Electromagnetic This paper also describes the computer-display Compatibility, Denver, CO, Aug. 1998, pp. 427-431. techniques and file-management system used in committee to develop Federal Standard 1037C, Statistical noise models that simulate man-made Glossary of Te lecommunications Te rms, and to noise are essential for the design of radio sys­ display the results both in the meeting room and tems. Recently, the Institute fo r Telecommuni­ on the Internet between meetings. In addition, cation Sciences measured man-made VHF radio this paper describes the interactive mode of noise in the 136 to 138 MHz meteorological developing the glossary in committee; this mode satellite band. These measurements were made allowed the participants to address actively, as part of a link analysis for the broadcast of thousands of proposed definitions, revisions,

101 and drawings, and to display the results of their International Sy mposium on Electromagnetic deliberations on computer monitors in meetings Compatibility, Denver, CO, pp. 290-295, Aug. 1998. and on the World Wide Web . This paper describes the extraction of electrical C.L. Holloway, M. Jonansson, and M.S. Satio, "An material properties of lossy, carbon-doped ure­ effective layer model for analyzing fiber compos­ thane slabs using a free-space time-domain ites," in Proc. EMC '98 ROMA : In ternational reflectivity measurement system developed by Sy mposium on Electromagnetic Compatibility, the National Institute of Standards and Tech­ Rome, Italy, Sep. 1998. nology (NIST). In order to validate the mea­ surement results, the measurement system was In this paper, we present expressions for the simulated using finite-diffe rence time-domain effective material properties of fiber composites (FDTD) techniques. Reflectivity measurement that are commonly used in aircraft and EMC/ results and theoretical predictions as a function EMI shielding materials. These expressions can of carbon-doping, fr equency, and angle of inci­ be used to calculate efficiently the reflection dence are presented. Complex permittivity and transmission coefficients and the shielding results are also presented for two urethane slabs effectiveness of these fiber composites. We with different carbon-doping levels. compare results of the reflection coefficient obtained from these effective propetiies to C. Jones and D.J. Atkinson, "Development of results obtained from a finite-element (FE) opinion-based audiovisual quality models for solution of the actual periodic fiber composite. desktop video-teleconferencing," in Proc. Sixth This comparison indicates that the model pre­ In ternational Wo rkshop on Quality of Service sented here is accurate fo r representing the (I WQoS '98), Napa Va lley, CA, May 1998. properties of fiber composites. This paper discusses the analysis of an audio­ C.L. Holloway and E.F. Kuester, "Net and partial visual desktop video-teleconferencing subjective inductance of a microstrip ground plane," IEEE experiment conducted at the Institnte for Tele­ Tr ans. on Electromagnetic Compatibility, vol. 40, communication Sciences. Objective models of no. 1, pp. 33-46, Feb. 1998. the individual audio and video quality are pre­ sented. Also discussed is an objective model of A knowledge of the net inductance of the the audiovisual quality based upon the results of ground plane can aid in the analysis and inves­ the individual objective audio and video quality tigation of printed circuit board emissions. In models. Finally, a subjective model of audio­ this paper, we present a method, based on the visual quality based upon users' ratings of the concept of partial inductance, to determine the audio and video quality is discussed. net inductance of the ground plane associated with a microstrip line. This method is based on P.B. Papazian, K.C. Allen, and M.G. Cotton, "A test a previously derived expression for the current bed fo r the evaluation of adaptive antennas used for density on the ground plane. We show calcula­ mobile communications," in Proc. IEEE 1998 tions for the net, self-partial, and mutnal-partial Aerospace Conference, Snowmass at Aspen, CO, inductance of the ground plane fo r various trace Mar. 1998. geometries of practical interest. We also illus­ trate various trace geometries of practical inter­ This paper describes an advanced antenna test est. We also illustrate how the classical trans­ bed which will be used for mobile communica­ mission line inductance of a microstrip line can tions research. The test bed provides a common be obtained from the concept of partial induc­ environment for testing advanced antennas and tance. Comparisons to different experimental measurement data gathered in a realistic envi­ results are also given. ronment for evaluation of advanced antenna algorithms. The test bed was previously used to R.T. Johnk, A. R. Ondrejka, and C.L. Holloway, fieldtest the five current personal communica­ "Time-domain free-space measurements of carbon­ tions services (PCS) technology standards in the doped urethane slabs with FDTD simulations and United States. The test bed cells are described system verification," in Proc. IEEE 1998 and a typical PCS field trial measurement is presented. A wideband measurement system

102 ITS Publications

developed for advanced antenna measurements provided little or no ( <2 dB) fading reduction. is described. The system uses multiple mobile A description of the experiment, data reduction transmitters using maximal length pseudo ran­ and analyses, and calculation of diversity gain dom noise generators to modulate a radio fre­ are presented. The motivation for this experi­ quency (RF) carrier. This provides a wideband ment is the application of fixed multiple beam signal for characterization of the radio channel. antennas (FMBA) in cellular radio and digital Central to the measurement methodology is the personal communication systems. capability to characterize radio wave propaga­ tion simultaneously on each antenna element of E.A. Quincy, "Ship compartment channel effects on an antenna array. A multichannel receiver wireless FM speech performance," in Proc. IEEE employs IF digitization and raw data storage to 1Oth In ternational Conference on Wireless Comm., maximize post-processing capabilities. Its fea­ vol. 2, Jul. 1998, pp. 483-502. tures allow a random sampling of the radio ­ channel suitable for mobile communications In this research we modeled and simulated an research. The receiver also has the capability to existing UHF analog wireless trunked FM radio continuously stream data that is suitable for system operating in steel ship compartments and modeling and simulation studies of specific predicted speech quality performance. A fading communication systems. Ricean channel with equal power in the domi­ nant path and multipath and a 10 Hz Doppler P.L. Perini and C.L. Holloway, "Angle and space fading rate was used in the simulations. Band­ diversity comparisons in different mobile radio limited noise resulted in speech quality that environments," IEEE Trans. on Antennas and ranged from barely intelligible with a carrier-to­ Propagation (special issue), vol. 46, no. 6, pp. 764- noise ratio (CNR) of 0 dB to slightly noisy at a 775, Jun. 1998. CNR of 40 dB. These results can be calibrated with the existing FM system field performance The angle diversity performances of two types and used as a benchmark for comparing and

of high-gain multibeam antennas - 24 verti­ predicting improvements by simulation of the cally polarized 15° beams, and 12 vertically proposed digital PCS modems. polarized 30° beams - were tested and com­ pared to the space-diversity performances of E.A. Quincy, R.A. Stafford, C.L. Holloway, M.G. traditional sector antenna configurations. The Cotton, and A.S. Ali, "Wavelet compression distor­ antennas were tested at 850 MHz in dense urban tion measures for SAR images in ATR," in Proc. and rural cellular mobile radio environments. A Sixth ATR Conference, vol I, Oct. 1997, p. 15. vehicle equipped with a mobile transmitter was driven in the coverage area, while the received This research investigates and develops distor­ signal strength (RSS) was recorded on multiple tion measures for assessment of wavelet com­ receiver channels attached to multibeam and pression effects on synthetic aperture radar sector antennas at the base site. The RSS data images. The end obj ective is to select those recorded included fast (Rayleigh) fading and measures that relate most directly to aided/ was averaged into local means based on the automatic target recognition (ATR) perform­ mobile's position/speed. The fast fading was ance. Windowed measures were developed that extracted from the recorded RSS, and the fading relate to ATR feature size. These were the most distributions of the two multibeam antennas sensitive to distortion, and they provide an tested were studied in two distinctly different effective method for assessing tradeoff between mobile environments. Fading cumulative distri­ compression and distortion. We compare mean­ butions for the angular diverse antennas were square-error (MSE), maximum MSE, peak compared to those of spatially diverse antennas. signal-to-noise ratio, entropy, edge energy and Diversity gain was calculated and compared to functions of these in our paper. traditional space diversity in these mobile P. Raush, J. Kub, B. Bedford, T. Sparkman, S. environments. Results in urban environments Davidson, and E. Gray, "The radio frequency inter­ indicated that angular diversity performance ference monitoring system (RFIMS)," in Proc. IEEE was comparable to space diversity ( �-8 dB 1998 In ternational Sy mposium on Electromagnetic improvement). Rural tests typically suggested Compatibility, Denver, CO, Aug. 1998. that both space diversity and angular diversity

103 The mobile Radio Frequency and Interference N.B. Seitz and K.C. Glossbrenner, "Performance Monitoring System (RFIMS), developed for the standards for the Gil, "IEEE Communications Federal Aviation Administration (FAA), is Magazine, pp. 116-121, Aug. 1998. designed to monitor radio fr equency emissions from 100 kHz to 18 GHz, using both custom­ This article summarizes the traditional process designed and commercial off-the-shelf hardware for developing international telecommunication and software, combining to fo rm a computer­ performance standards and describes enhance­ controlled integrated electronics package. The ments that will be needed to adapt the process system allows a variety of spectrum-monitoring for use in the emerging global information methods which are used to characterize the RF infrastructure (Gil). The necessary enhance­ emissions of various FAA and commercial ments are being developed under the auspices of transmitters. These include radars, navigational ITU-T Study Group 13. aids, HF communication systems, and commer­ cial broadcast systems. This paper describes the T.G. Sparkman, "Characterizing U.S. airport RFIMS design obj ectives and discusses the emitters using the radio fr equency interference power ofRFIMS as a spectrum monitoring tool monitoring system and LabVIEW®," in Proc. and as an interference-resolution mechanism. NI Week98 Corif., Austin, TX, Aug. 1998.

C. Redding and D. We ddle, "Value assessment of As a part of the Federal Aviation Administra­ automatic link maintenance in modem HF data tion's (FAA's) ongoing radio fr equency (RF) networks," in Proc. Nordic HF Conf, Faro, Sweden, monitoring in and around airports, the radio Aug. 1998. frequency interference monitoring system (RFIMS) analyzes the power output of aero­ Applications of high fr equency (HF) radio com­ nautical emitters nationwide. The RFIMS munications are increasingly evolving toward spectrum signature module verifies the emitters' digital data applications such as automatic trans­ operative parameters as an indication of emitter fer of facsimile, e-mail, and computer files, as health. The Lab VIEW® software which con­ well as message traffic and other HF data. This trols the RFIMS instruments via GPIB makes more sophisticated use of the medium is a shift RFIMS both a unique and very powerful tool away from the use of voice as the primary for fr equency spectrum management. means of HF communications. The change is consistent with new HF technology made possi­ S.D. Vo ran, "Perception-based bit-allocation algo­ ble by continued improvements in computer rithms for audio coding," in Proc. IEEE ASSP 1997 technology at affordable costs. The new tech­ Wo rkshop on Applications of Signal Processing to nologies include automatic link establishment, Audio and Acoustics, New Paltz, NY, Oct. 1997. forward error correcting HF modems, digital We describe six algorithms for bit allocation in signal processing, and other computer-based audio coding. Each algorithm stems from the improvements such as automatic repeat request minimization of a different perceptually­ protocols that produce higher data rates and motivated obj ective function. Three of these lower error rates. The Institute for Te lecommu­ objective functions are extensions of existing nication Sciences, under the sponsorship of the ones, and three are new. Closed-form bit-allo­ National Communications System, initiated an cation equations result in five cases, and an effo rt to assess advanced HF technology that iterative approach is required in the sixth. could provide the basis for the next generation of adaptive HF standards. One such adaptive S.D. Vo ran, "A simplified version of the ITU HF radio system was employed on an HF link algorithm for objective measurement of speech between the United States (US) and Australia. codec quality," in Proc. IEEE 1998 International This paper reports preliminary results of the Conference on Acoustics, Sp eech, and Signal trials conducted over this link, fo cusing on the Processing, Seattle, WA , May 1998. automatic link maintenance characteristic. It further relates these and other findings to the ITU-T Recommendation P. 861 describes an emerging third-generation adaptive HF stand­ objective speech quality assessment algorithm ard, which is being developed in the US for for speech codecs. This algorithm transforms data-intensive HF networks. codec input and output speech signals into a

104 ITS Publications

perceptual domain, compares them, and gener­ S. Wo lf, M.H. Pinson, A.A. Webster, G.W. Cermak, ates a noise disturbance value, which can be and E.P. Tweedy, "Objective and subj ective used to estimate perceived speech quality. The measures of MPEG video quality," in Proc. I 39th performance of this algorithm can be judged by SMP TE Te chnical Conference, New York, NY, Nov. the correlation between those estimates and 1997. actual listener opinions from formal subjective listening tests. We show that significant simpli­ In 1996, the American National Standards fications can be made to the P. 861 algorithm Institute (ANSI) adopted ANSI Tl.801.03, with very minimal effect on its performance. which presents a number of new objective video Specifically, for the portions of the algorithm quality metrics for quantifying the effects of under study here, 64% of the floating point digital compression and transmission impair­ operations can be eliminated with only a 3.5% ments. The measurements in ANSI Tl.801.03 decrease in average correlation to listener opin­ were selected based on an extensive multilabo­ ions. The resulting simplified algorithm may ratory quality assessment study that included offer a practical new objective function to drive video systems fr om bit rates of 64 kbits/sec to parameter selections, excitation searches, and 45 Mbits/sec and video test scenes that spanned bit-allocations in speech and audio coders. a wide range of spatial and temporal coding difficulties. The set of objective video quality S.D. Vo ran, "Observations on frequency-domain measurements effectively accounted for subjec­ companding for audio coding," in Proc. Eighth tive judgments by human viewers. While 25 IEEE DSP Wo rkshop, Bryce Canyon National Park, video systems were tested, this multilaboratory UT, Aug. 1998. study did not include MPEG video systems and did not cover any bit rates between 1.6 and 10 Frequency-domain companding can be used in Mbits/sec. This paper presents the results from conjunction with audio coders that produce two MPEG studies designed to fill in the bit­ white coding noise. Previous work has demon­ rate gap in the previous multilaboratory study. strated empirically that this technique colors In these studies, we concentrated on bit rates white coding noise so that it is better masked by from 1.5 - 8.3 Mbit/sec and examined the per­ audio signals, resulting in higher perceived formance of MPEG 1 and MPEG 2 codecs audio quality. This paper offers additional (coder -decoders) specifically. The effectiveness theoretical background and empirical results on of the ANSI standard objective video quality this companding technique. A simplifying metrics was examined for these bit rates and assumption of previous work is analyzed, the coding technologies. Our analysis revealed that effect of the companding exponent a on the the objective video quality metrics primarily spectral flatness measure is investigated, and measure four principal components of video optimal values of a are identified for PCM and quality: added edges, lost edges, added motion, ADPCM speech coding. and lost motion; we found that parameters selected fr om these principal components can be used as effective predictors of subjective quality ratings fo r entertainment video systems.

105 Publications Cited*

American National Standards Institute (ANSI), service radio channel," IEEE Transactions on ANSI Tl.801.03-1996, "American National Broadcasting, vol. 43, no. 2, Jun. 1997. Standard for Telecommunications - Digital Transport of One-Way Video Signals - Parameters P. Papazian and G.A. Hufford, "Time variability and fo r Obj ective Performance Assessment," New York, depolarization of the LMDS radio channel," in Proc. NY, 1996. 199 7 Wi reless Communications Conference, Boulder, CO, Aug. 1997. American National Standards Institute (ANSI), ANSI Tl.518-1998, "Telecommunications - F.H. Sanders, B.J. Ramsey, and V. S. Lawrence, Obj ective Measurement of Te lephone Band Speech "Broadband spectrum survey at San Diego, Quality Using Measuring Normalizing Blocks California,"NTIA Report 97-334, Dec. 1996. (MNBs)," New York, NY, 1998. A.D. Spaulding, "Digital system performance soft­ C. J. Behm, "A narrowband HF channel simulator ware utilizing noise measurement data," NTIA with delay spread," in Proc. HF Radio Systems and Report 82-95, Feb. 1982. Te chniques Conference, IEEE Conference Publica­ tion Number 441, Jul. 7-10, 1997, pp. 388-391. A.D. Spaulding, "The natural and man-made noise environment in personal communications services R.O. DeBolt et al., "A technical report to the bands," NTIA Report 96-330, May 1996. Secretary of Transportation on a national approach to augmented GPS services," NTIA Special Telecommunications Industry Association, TIA/EIA Publication 94-30, Dec. 1994. Telecommunications Systems Bulletin TSB-84, "Licensed PCS to PCS Interference," Dec. 1997. J.G. Ferranto, "Interference simulation for personal communications services testing, evaluation, and Telecommunications Industry Association, TIA/EIA modeling," NTIA Report 97-338, Jul. 1997. Telecommunications Systems Bulletin TSB-88, "Wireless Communications Systems - Performance J.J. Lemon and C.J. Behm, "Wideband HF in Noise and Interference-Limited Situations ­ noise/interference modeling - Part I: First order Recommended Methods for Technology ­ statistics," NTIA Report 91-277, May 1991. "Part II: Independent Modeling, Simulation and Higher-order statistics," NTIA Report 93-293, Jan. Verification," Jan. 1998. 1993. L.E. Vo gler and J.A. Hoffm eyer, "A model for wide­ J.F. Mastrangelo, J.J. Lemon, L.E. Vo gler, J.A. band HF propagation channels," Radio Science, vol. Hoffm eyer, L.E. Pratt, and C.J. Behm, "A new wide­ 28, no. 6, pp. 1131-1142, 1993. band high fr equency channel simulation system," IEEE Tr ansactions on Communications, vol.. 45, no. L.E. Vo gler and J.A. Hoffmeyer, "A new approach 1, pp. 26-34, 1997. to HF channel modeling and simulation - Part I: Deterministic model." NTIA Report 88-240, Dec. National Communications System, Federal Standard 1988. "Part II: Stochastic model." NTIA Report 90- 1 037C, "Glossary of Telecommunication Terms," 255, Feb. 1990. "Part III: Transfer function." NTIA Arlington, VA , 1996. Report 92-284, Mar. 1992.

National Communications System, Federal Standard C.C. Watterson, J.R. Juroshek, and W.D. Bensema, 1 045A, "Telecommunications: HF Radio Automatic "Experimental confitmation of an HF channel Link Establishment," Arlington, VA , Oct. 18, 1993. model," IEEE Transactions on Communication Te chnology, COM-18, pp. 792-803, 1970. P. Papazian, G.A. Hufford, R. Achatz, and R. Hoffman, "Study of the local multipoint distribution

*Publications cited in the report that are not Fiscal Year 1998 reports.

106 Abbreviations/Acr onyms

AAMA American Automobile Manufacturers BW bandwidth Association C2CEN Command and Control Engineering ACTS Advanced Communications Center (U.S. Coast Guard) Technology Satellite CAl common air interface ADPCM adaptive differential pulse-code modulation CD compact disk

ALE automatic link establishment CDMA code division multiple access

ALERT Advanced Law Enforcement Response CD-ROM compact disk read-only memory Technology CNR carrier-to-noise ratio AM amplitude modulation CRADA cooperative research and development AMPS advanced mobile phone system agreement

ANSI American National Standards Institute CRPL Central Radio Propagation Laboratory

APCO Association of Public Safety CRSMS compact radio spectrum measurement Communications Officials system

APD amplitude probability distribution CSUD call setup delay

ATB antenna testbed DAQ delivered audio quality

ATCRBS air traffic control radar beacon system DBS direct broadcast satellite

ATIS Advanced Traveler Information System DCBPSK differentially-coherent binary phase- shift keying ATM asynchronous transfer mode DGPS differential global positioning system ATR automatic target recognition DOC Department of Commerce AWIPS Advanced Weather Interactive Processing System DOD Department of Defense

BAWT broadband arbitrary waveform DOS disk operating system transmitter DOT Department of Transportation BBNG broadband noise generator DQPSK differential quadrature phase-shift BER bit error ratio keying

B-ISDN broadband integrated services digital DSCP digital sampling channel probe network DSP digital signal processing BITB Boulder Industry Test Bed DSRC dedicated short-range communication BONeS block oriented network simulation DTV digital television BPSK binary phase-shift keying

107 EMC electromagnetic compatibility lAB InternationalAcademy of Broadcasting

EMI electromagnetic interference IEEE Institute of Electrical and Electronics Engineers ES Earth station IEP integrated electronic package FAA Federal Aviation Administration IETF Internet Engineering Task Force FCC Federal Communications Commission IM intermodulation FDDI fiber distributed data interface IP Internetprotocol FDTD finite-difference time domain IPDP indoor power delay profile FED-STD Federal Standard IRAC Interdepartment Radio Advisory FHWA Federal Highway Administration Committee

FM fr equency modulation ISDN integrated services digital network

FMBA fixed multiple beam antenna lSI intersymbol interference

FQPSK Feher quadrature phase-shift keying ITAC International Telecommunications Advisory Committee FRA Federal Railroad Administration ITS Institute for Telecommunication FTP file transfer protocol Sciences

FTS Federal Telecommunications System Intelligent Transportation System

FTSC Federal Telecommunications Standards ITSA Institute for Telecommunication Committee Sciences and Aeronomy

FTTA Federal Technology Transfer Act ITU-R International Telecommunication Union-Radiocommunication Sector GEO geostationary earth orbit ITU-T International Telecommunication GHz gigahertz Union-Telecommunication Gil Global Information Infrastructure Standardization Sector

GIS geographic information systems JTC Joint Technical Committee on Wireless Access GMSK Gaussian minimum-shift keying JTIDS Joint Tactical Information Distribution GPS global positioning system System

GSM Global System fo r Mobile JEM Jammer Effectiveness Model

GWEN Ground Wave Emergency Network kHz kilohertz

HF high frequency LAN local area network

HP Hewlett-Packard LEC local exchange carrier

HTML hypertext markup language LEO low earth orbit

HTTP hypertext transfer protocol LL lower layer

108 Abbreviations/Acronyms

LMDS local multipoint distribution service OLES Office of Law Enforcement Standards

LMR land mobile radio OPNET optimized network engineering tools

LOS line-of-sight OSM Office of Spectrum Management

MCM multicarrier modulation OSTM Office of Systems and Telecommunications Management MCS measurement control system OT Officeof Telecommunications MEO medium earth orbit P25 Proj ect 25 MHz megahertz PBX private branch exchange MNB measuring normalizing block PC personal computer MP measurement point PCM pulse-code modulation MPEG Motion Picture Experts Group PCS personal communications services MSE mean-square error PDH plesiochronous digital hierarchy MSK minimum-shift keying PN pseudo-random NARRN North American Railroad Radio Network PPS precise positioning service

NASA National Aeronautics and Space PRF pulse-repetition fr equency Administration QoS quality of service NAVSTAR Navigation Satellite Timing and Ranging RDBMS relational database management system

NBHF narrowband HF RF radio frequency

NBWF necessary bandwidth formulas RFIMS radio frequency interference monitoring system NCS National Communications System RISC Reduced Instruction Set Computer nDGPS nationwide differential global positioning system RSMS radio spectrum measurement system

NIJ National Institute of Justice RSS received signal strength

NIST National Institute of Standards and RTCM Radio Technical Commission for Technology Maritime Services

NSA National Security Agency RTP real time protocol

NS/EP National Security and Emergency SDH synchronous digital hierarchy Preparedness SEAD Spectrum Engineering and Analysis NTIA National Telecommunications and Division Information Administration SINAD signal to interference noise and OFDM orthogonal frequency-division distortion multiplexing SNR signal-to-noise ratio

109 SONET synchronous optical network

SPS standard positioning service

SRC source

SSB single sideband

S-T spatial-temporal

S-VHS super VHS (Video Home System)

TA Services Telecommunications Analysis Services

TCP transmission control protocol

TIA Telecommunications Industry Association

TSB Technical Service Bulletin

TVQMS transportable video quality measurement system

UDP user datagram protocol

USCG U.S. Coast Guard

US WEST US West Advanced Technologies, Inc.

UWB ultra wideband

UWBR ultra-wideband radar

VHF vety high fr equency

Vo iP Vo ice-over-Internet Protocol

VQEG Video Quality Experts Group

VTC video-teleconferencing

• VTS Ve ssel Traffic Service

WLL wireless local loop

www worldwide web

xDSL various digital subscriber line

XIWT Cross-Industry Working Team

110