DOCSLIB.ORG

Wireless WAN: WLL & Wimax Module W.Wan.5 WLL: Wireless Local Loop

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Wireless WAN: WLL & Wimax Module W.Wan.5 WLL: Wireless Local Loop W.wan.5-2 WLL: Wireless Local Loop Access network Æ Local loop (subscriber loop) Wired systems Wireless WAN: WLL & WiMax ¾ Twisted pair Æ coaxial cable Æ optical fiber Wireless systems Module W.wan.5 ¾ WLL (Wireless Local Loop) Dr.M.Y.Wu@CSE Dr.W.Shu@ECE Shanghai Jiaotong University University of New Mexico Shanghai, China Albuquerque, NM, USA WLL architecture: Last-mile solution Source: Stalling2nd © by Dr.Wu@SJTU & Dr.Shu@UNM 1 W.wan.5-3 W.wan.5-4 WLL: Wireless Local Loop WLL: Why better? Scope of wireless coverage Lower cost ¾ PAN, 10m, 1Mbps are less expensive due to cost of cable installation that’s ¾ LAN, 100m, 10Mbps avoided ¾ MAN, 25km, 1-75Mbps Easy to install WLL = Wireless + MAN can be installed in a small fraction of the time required for a new wired system Narrowband – offers a replacement for existing telephony services Selective installation Broadband – provides high-speed two-way voice and data radio units installed for subscribers who want service at a service given time Stationary or mobile? ¾ while with a wired system, cable is laid out in anticipation of serving every subscriber in a given area Fixed Æ Portable Æ Mobil © by Dr.Wu@SJTU & Dr.Shu@UNM © by Dr.Wu@SJTU & Dr.Shu@UNM W.wan.5-5 W.wan.5-6 WLL: physical characteristics Channel requirements: LOS & NLOS WLL mainly uses millimeter wave frequencies (2 GHz LOS: Line-of-sight to about 30 GHz) Higher Frequencies range: up to 66 GHz Good things Fixed dish antenna points straight at WiMax tower from a rooftop or pole. ¾ There are wide unused frequency bands available above 25 GHz Service is stronger and more stable, capable to send a lot of data ¾ At these high frequencies, wide channel bandwidths can be used, with fewer errors. providing high data rates At higher frequencies, less interference and more bandwidth ¾ Small size transceivers and adaptive antenna arrays can be used NLOS: Non-line-of-sight Not so good things (propagation): Lower Frequency range: 2-11 GHz ¾ Free space loss increases with the square of the frequency; losses A small antenna on computer connects to a tower. are much higher in millimeter wave range Lower wavelength transmissions are not as easily disrupted by ¾ Attenuation effects due to rainfall and atmospheric or gaseous physical obstructions. absorption are large They are better able to diffract, or bend around obstacles. ¾ Multipath losses can be quite high In general, >10GHz can be LOS, <10GHz can be LOS or NLOS © by Dr.Wu@SJTU & Dr.Shu@UNM © by Dr.Wu@SJTU & Dr.Shu@UNM W.wan.5-7 W.wan.5-8 MDS: Multipoint Distribution Service MDS: Multipoint Distribution Service PMP: Point to Multipoint Distribution Two commonly used WLL: LMDS & MMDS: A single antenna transceiver is used to link to many users LMDS: Local multipoint distribution service Appeals to larger companies with greater bandwidth Contrast to cellular system demands ¾ Broadband instead of telecommunication oriented, data oriented MMDS: Multichannel multipoint distribution ¾ Mostly stationary (fixed) instead of mobile users, so no handoff service Also referred to as wireless cable ¾ Cells do not overlap, frequency can be reused Used mainly by residential subscribers and small ¾ Classified as MAN instead of WAN in scope businesses © by Dr.Wu@SJTU & Dr.Shu@UNM © by Dr.Wu@SJTU & Dr.Shu@UNM W.wan.5-9 W.wan.5-10 LMDS MMDS 28GHz in USA, 40GHz in Europe, millimeter-wave spectrum 2.5GHz licensed, and 5.8GHz unlicensed, centemeter-wave High frequency, smaller cell spectrum Lower frequency, larger cell size (50 km), equipment less expensive size (2 km), LOS Relatively lower data Relatively high data rates (27-36Mbps) rates (155Mbps) MMDS signals with larger Capable of providing wavelengths can travel video, telephony, farther without losing and data significant power Relatively low cost in MMDS signals don't get comparison with blocked as easily by objects cable alternatives and are less susceptible to rain absorption OFDM can improve data rate © by Dr.Wu@SJTU & Dr.Shu@UNM © by Dr.Wu@SJTU & Dr.Shu@UNM W.wan.5-11 W.wan.5-12 LMDS & MMDS IEEE802 suite Spectrum allocations in USA IEEE 802 --- PAN/LAN/MAN Standards Wired Frequency, GHz Allocations ¾ 802.3 (Ethernet) 2.1500—2.1620 MMDS, licensed, 2 bands of 6 MHz each Wireless 2.4000—2.4835 ISM, unlicensed ¾ 802.11: Wireless LAN WiFi 2.5960—2.6440 MMDS, licensed, 8 bands of 6 MHz each ¾ 802.15: Wireless PAN 2.6500—2.6800 MMDS, licensed Bluetooth 5.7250—5.875 ISM-UNII, unlicensed, used for MMDS too ¾ 802.16: Wireless MAN 24.000—24.250 ISM, unlicensed WiMAX 27.500—31.300 LMDS, licensed, ¾ 802.20: Vehicular Mobility ? MobilFi ISM = Industrial, Scientific, and Medical Downloads (free 6 months after publication) UNII = Unlicensed National Information Infrastructure http://standards.ieee.org/getieee802 © by Dr.Wu@SJTU & Dr.Shu@UNM © by Dr.Wu@SJTU & Dr.Shu@UNM W.wan.5-13 W.wan.5-14 WiMAX & 802.16 WiMAX & 802.16 WiMAX = WLL + Standardization Technology considerations Use point-to-multipoint architecture with stationary rooftop Licensed vs unlicensed or tower-mounted antennas LOS vs NLOS Æ Worldwide interoperability for Microwave Access WiMAX Half-duplex vs full-duplex Standard: IEEE 802.16 P2P, P2MP, Mesh Frequency spectrum Fixed, portable, mobile ¾ 10-66 GHz, LMDS, Cost performance LOS, licensed ¾ ¾ 2-11 GHz, MMDS, throughput = channel bandwidth (Hz) X bits/Hz NLOS, licensed & unlicensed Last-mile tech? Last-mile technology: metropolitan area in scale ¾ WiFi backhaul Can serve as backhaul for wireless LANs (802.11) ¾ T1 replacement ¾ 3G/4G replacement? © by Dr.Wu@SJTU & Dr.Shu@UNM © by Dr.Wu@SJTU & Dr.Shu@UNM W.wan.5-15 W.wan.5-16 WiMAX/802.16 vs WiFi/802.11 WiMAX/802.16 vs 3G WiMAX/802.16 Technology WiFi/802.11b/g 2-11 GHz Spectrum 2.4 GHz WiMAX/802.16 Technology 3G Licensed, unlicensed unlicensed Wireless broadband Broadband Mobile broadband < 50 km (typical 5km) Range < 200m Laptop centric Client Phones & laptops Outdoor LOS & NLOS Coverage Indoor short range Fixed to portable mobility Roaming / mobility 5bps/Hz peak Data rate 2.7bps/Hz peak LOS or NLOS Channels NLOS < 100Mbps in 20 MHz < 54Mbps in 20MHz Optimized for data Services Optimized for voice Hundreds CPE Scalability Tens CPE WiMAX Æ potential 4G??? On demand: A/V,data QoS No Connection oriented Connection type Connectionless TDD/FDD Full duplex No TDMA Multiple access CSMA/CA © by Dr.Wu@SJTU & Dr.Shu@UNM © by Dr.Wu@SJTU & Dr.Shu@UNM.
Load more

Recommended publications
  • Broadband Glossary
    Broadband Glossary This a non-exhaustive list of relevant terms relevant to broadband. © iStock by Getty Images -1077605220 Daniel Chetroni Page Contents # A B C D E F G H I K L M N O P R S T U V W X # 5G Fifth generation wireless technology for digital cellular networks A Access (to equipment, facilities, services etc.) The making available of facilities and/or services to another undertaking, under defined conditions, on either an exclusive or non-exclusive basis, for the purpose of providing electronic communications services, including when they are used for the delivery of information society services or broadcast content services. It covers inter alia: access to network elements and associated facilities, which may involve the connection of equipment, by fixed or non-fixed means (in particular this includes access to the local loop and to facilities and services necessary to provide services over the local loop); access to physical infrastructure including buildings, ducts and masts; access to relevant software systems including operational support systems; access to information systems or databases for pre-ordering, provisioning, ordering, maintaining and repair requests, and billing; access to number translation or systems offering equivalent functionality; access to fixed and mobile networks, in particular for roaming; access to conditional access systems for digital television services and access to virtual network services. ADC - Access Deficit Cost Cover the gap between tariff and costs - Access deficit arises when the tariff specified
    [Show full text]
  • Telecommunication/ICT Indicators from Administrative Data Sources
    Committed to Connecting the World ITU Regional Forum and Training Workshop on Telecommunication/ICT Indicators: Measuring the Information Society and ITU-ASEAN Meeting on Establishing National ICT Statistics Portals and Measuring ASEAN ICT targets Bangkok, 13-16 October 2014 Telecommunication/ICT indicators from administrative data sources Esperanza Magpantay/Susan Teltscher ICT Data and Statistics Division BDT/ ITU International Telecommunication Union © ITU 2014 Committed to Connecting the World Agenda . ITU Handbook . ITU indicators from administrative sources 2 © ITU 2014 Committed to Connecting the World ITU Handbook .Covers 81 indicators on telecommunication/ICT services .Covers data collected from administrative sources (e.g. telecom operators) .Reflects the outcome by ITU Expert Group on Telecom/ICT Indicators (EGTI) .Available in six ITU languages at: http://www.itu.int/pub/D-IND-ITC_IND_HBK- 2011 . Will be revised in 2015 3 © ITU 2014 Committed to Connecting the World ITU Handbook (cont.) Groupings: .Definition . Fixed-telephone networks . Mobile-cellular networks .Clarifications and . Internet scope . Traffic . Tariffs .Method of collection . Quality of service .Relationship with . Persons employed other indicators . Revenue . Investment .Methodological issues . Public access . Broadcasting and other .Examples indicators 4 © ITU 2014 Committed to Connecting the World ITU Handbook – updates . Revision of revenue and investment indicators . New indicators added . Fixed broadband and mobile QoS . Broadband Internet traffic . Pay-TV subscriptions . Mobile-broadband prices 5 © ITU 2014 Committed to Connecting the World Context: indicators from administrative sources 81 Indicators ITU Handbook . Data per operator Indicators collected in 65 ITU administrative Administrative . Sub-national questionnaires indicators data collected by countries . Data for market Core indicators on analysis ICT infrastructure 10 and access .
    [Show full text]
  • Introduction to Digital Subscriber's Line (DSL) Chapter 2 Telephone
    Introduction to Digital Subscriber’s Line (DSL) Professor Fu Li, Ph.D., P.E. © Chapter 2 Telephone Infrastructure · Telephone line dates back to Bell in 1875 · Digital Transmission technology using complex algorithm based on DSP and VLSI to compensate impairments common to phone lines. · Phone line carries the single voice signal with 3.4 KHz bandwidth, DSL conveys 100 Compressed voice signals or a video signals. 1 · 15% phones require upgrade activities. · Phone company spent approximately 1 trillion US dollars to construct lines; · 700 millions are in service in 1997, 900 millions by 2001. · Most lines will support 1 Mb/s for DSL and many will support well above 1Mb/s data rate. Typical Voice Network 2 THE ACCESS NETWORK • DSL is really an access technology, and the associated DSL equipment is deployed in the local access network. • The access network consists of the local loops and associated equipment that connects the service user location to the central office. • This network typically consists of cable bundles carrying thousands of twisted-wire pairs to feeder distribution interfaces (FDIs). Two primary ways traditionally to deal with long loops: • 1.Use loading coils to modify the electrical characteristics of the local loop, allowing better quality voice-frequency transmission over extended distances (typically greater than 18,000 feet). • Loading coils are not compatible with the higher frequency attributes of DSL transmissions and they must be removed before DSL-based services can be provisioned. 3 Two primary ways traditionally to deal with long loops • 2. Set up remote terminals where the signals could be terminated at an intermediate point, aggregated and backhauled to the central office.
    [Show full text]
  • Wireless LAN Technology: Current State and Future Trends
    Wireless LAN Technology: Current State and Future Trends Zahed Iqbal Helsinki University of Technology Telecommunications Software and Multimedia Laboratory [email protected] Abstract In this paper, a comprehensive overview of the current state and future trends of Wireless Local Area Network (WLAN) has been presented. This document stud- ies and compares two most competing commercialy potential WLAN technologies, namely IEEE 802.11 and ETSI HiperLAN. This study also addresses the challenges of their coexistance and convengences towards a global standards. KEYWORDS: Wireless Local Area Network (WLAN), IEEE 802.11, ETSI, HiperLAN 1 Introduction Wireless Local Area Network (WLAN) is a flexible data communication system that can either replace or extend a wired LAN to provide added functionality. Using Radio Fre- quency (RF) technology, or Infrared (IR) WLANs transmit and receive data over the air, through wall, ceilings, and even cement structures, without wired cabling. A WLAN pro- vides all the features and benefits of traditional LAN technologies like Ethernet and Token Ring, but without the limitations of being connected by a cable. This provides greatly increased freedom and flexibility. [8] Wireless Local Area Networks have been used increasingly in many critical applications over the past few years, particularly since 1997 when the first IEEE802.11 WLAN standard was issued followed by its European competitor standard High Performance LAN (Hiper- LAN). In certain locations, the use of WLANs could save millions of dollars in cost and deployment time when compared to permanent wired networks. In other locations, WLAN services are complimentary to existing wired LANs adding the advantage of user mobility.
    [Show full text]
  • QUESTION 20-1/2 Examination of Access Technologies for Broadband Communications
    International Telecommunication Union QUESTION 20-1/2 Examination of access technologies for broadband communications ITU-D STUDY GROUP 2 3rd STUDY PERIOD (2002-2006) Report on broadband access technologies eport on broadband access technologies QUESTION 20-1/2 R International Telecommunication Union ITU-D THE STUDY GROUPS OF ITU-D The ITU-D Study Groups were set up in accordance with Resolutions 2 of the World Tele- communication Development Conference (WTDC) held in Buenos Aires, Argentina, in 1994. For the period 2002-2006, Study Group 1 is entrusted with the study of seven Questions in the field of telecommunication development strategies and policies. Study Group 2 is entrusted with the study of eleven Questions in the field of development and management of telecommunication services and networks. For this period, in order to respond as quickly as possible to the concerns of developing countries, instead of being approved during the WTDC, the output of each Question is published as and when it is ready. For further information: Please contact Ms Alessandra PILERI Telecommunication Development Bureau (BDT) ITU Place des Nations CH-1211 GENEVA 20 Switzerland Telephone: +41 22 730 6698 Fax: +41 22 730 5484 E-mail: [email protected] Free download: www.itu.int/ITU-D/study_groups/index.html Electronic Bookshop of ITU: www.itu.int/publications © ITU 2006 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. International Telecommunication Union QUESTION 20-1/2 Examination of access technologies for broadband communications ITU-D STUDY GROUP 2 3rd STUDY PERIOD (2002-2006) Report on broadband access technologies DISCLAIMER This report has been prepared by many volunteers from different Administrations and companies.
    [Show full text]
  • Local-Loop and DSL REFERENCE GUIDE Table of Contents
    Local-Loop and DSL REFERENCE GUIDE Table of Contents Prologue ............................................................................ 2 2.3.9.3 REIN ....................................................................32 2.3.9.4 SHINE..................................................................32 1. Introduction ................................................................. 5 2.3.9.5 PEIN ....................................................................32 2. What is DSL? ................................................................ 6 2.3.10 Bonding...............................................................33 2.3.11 Vectoring ............................................................35 2.1 Pre-DSL Delivery of Data ........................................................... 6 2.3.12 G.Fast ..................................................................36 2.1.1 Dial-Up ................................................................................ 6 2.1.2 ISDN .................................................................................... 7 3. DSL Deployment Issues ...........................................38 2.2 xDSL Overview ............................................................................. 8 3.1 Determining the Nature of the Problem ...............................39 2.3 DSL In-Depth .............................................................................12 3.2 Performing a Visual Inspection ..............................................44 2.3.1 ISDN ..................................................................................13
    [Show full text]
  • Controlpoint™
    White Paper on MDF Management ControlPoint™ MDF/IDF Line Management in an ILEC Central Office or Remote Environment February 2001 Introduction The deregulation of telecommunications services and recent FCC rulings has changed the dynamics of the local loop. Collocation is an everyday reality in most central offices and potentially in many remotes. Connection management, as customers migrate between providers, is challenging and presents a "service strain" to the service provider. "Line sharing" rulings are expected to accelerate demand and pose new line-qualification challenges to the ILEC. The dramatic increase in competition for the local loop increased the level of activity centering on connection, maintenance, and management of copper wire and wireline services. Given these high levels of activity in the loop, the traditional labor- intensive manual approach to cross-connect management is no longer viable via manual labor and processes. “Truck rolls” are too slow and expensive to be effective in today's competitive industry. The obvious answer: automate the provisioning process and provide intelligent wireline management at the physical layer. NHC's innovative ControlPoint Cross-Connect System replaces labor intensive wiring, reducing operating costs and maintenance, improving service delivery cycles. ControlPoint dramatically reduces labor, space, and time of service versus conven- tional MDF/IDF and OSP distribution frames that require on-site wiring by experi- enced technicians. The NHC solution provides the ILEC with complete control over the entire service deployment cycle, and ensures quality of service (QoS) via fallback switching. ControlPoint works with all copper based services including POTS, ISDN, T1, xDSL and other voice and data protocols.
    [Show full text]
  • Understanding Mmwave for 5G Networks 1
    5G Americas | Understanding mmWave for 5G Networks 1 Contents 1 Introduction ..................................................................................................................................................... 6 2 Status of Millimeter Wave Spectrum ............................................................................................................. 9 2.1 Regional Status ........................................................................................................................................... 9 2.2 Global Millimeter Wave Auctions .............................................................................................................12 3 Millimeter Wave Technical Rules in the United States ...............................................................................15 3.1 Licensed Spectrum ..................................................................................................................................15 3.2 Lightly Licensed .......................................................................................................................................16 3.3 Unlicensed Spectrum ..............................................................................................................................17 4 Millimeter Wave Challenges and Opportunities ..........................................................................................19 4.1 Losses in Millimeter Wave .......................................................................................................................19
    [Show full text]
  • WIRELESS LOCAL LOOP in DEVELOPING COUNTRIES: IS IT TOO SOON for DATA? the Case of Kenya
    WIRELESS LOCAL LOOP IN DEVELOPING COUNTRIES: IS IT TOO SOON FOR DATA? The case of Kenya by MUGO KIBATI MBA, International Business MA, International Economics George Washington University, 1997 B.S., Electrical Engineering Moi University, 1991 Submitted to the Technology and Policy Program in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN TECHNOLOGY AND POLICY at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY May, 1999 1999 Mugo Kibati. All rights reserved The author hereby grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis for the purpose of publishing other works. Signature of Author Technology Policy Program May 14, 1999 Certified by Sharon Eisner Gillett Research Associate, Internet and Telecoms Convergence Consortium Thesis Supervisor Certified by Professor Richard de Neufville Chairman, Technology and Policy Program WIRELESS LOCAL LOOP IN DEVELOPING COUNTRIES: IS IT TOO SOON FOR DATA? The case of Kenya by Mugo Kibati Submitted the Technology and Policy Program in Partial Fulfillment of the Requirements for the Degree of Master of Science in Technology and Policy May 1999 ABSTRACT The demand for data communications in Kenya is growing at a steady rate. Information technologies have become ubiquitous all over the world, including in developing countries like Kenya. Already, educational, health and trade networks connecting remote regions to the rest of the world are taking advantage of the Internet phenomenon. Banks, insurance and financial services firms, and other corporations need data communications for real time information gathering, automated remote services, intra-corporate voice and data communications, etc. However, like in many developing countries, communications infrastructure in Kenya is woefully underdeveloped and ill prepared to satisfy the increasing demand for data communications.
    [Show full text]
  • 5G: Issues & Challenges
    RÉPUBLIQUE FRANÇAISE 5G: ISSUES & CHALLENGES March 2017 The issues and challenges surrounding 5G The telecoms industry is currently in the process of designing the technologies that are due to take over from 4G, which is still being deployed today. A great deal of work is thus underway to prepare these “5G” technologies. To prepare for the arrival of this new generation of technologies, Arcep wanted to take a detailed look at the industry to better understand what is in the works. This report is the fruit of the interviews and research that Arcep conducted over the course of 2016, and which the Authority wanted to publish as a way to contribute to the public debate over 5G. Its aim it to provide as objective and exhaustive an overview as possible, and deliver a concise, informative snapshot of the work that is currently underway on the future generation of mobile networks. This report reflects the views of the stakeholders who were interviewed, but in no way represents Arcep’s positions on or roadmap for 5G. Arcep awarded in 2015 the 700 MHz band and is currently working towards licensing the 3.5 GHz band, both of which have been identified as 5G bands. Arcep is also working with the Direction générale des entreprises and the Agence nationale des fréquences towards enabling spectrum for 5G. Arcep would like to thank all of the entities (listed on the last page) who agreed to take part in this process, and who were willing to contribute to the regulator’s investigation into the development of 4G’s successor.
    [Show full text]
  • Structure of IEEE 802.11 Packets at Various Physical Layers
    Appendix A: Structure of IEEE 802.11 Packets at Various Physical Layers This appendix gives a detailed description of the structure of packets in IEEE 802.11 for the different physical layers. 1. Packet Format of Frequency Hopping Spread-spectrum Physical Layer (FHSS PHY) The packet is made up of the following elements (Figure A.1): 1.1 Preamble It depends on the physical layer and includes: – Synch: a sequence of 80 bits alterning 0 and 1, used by the physical circuits to select the correct antenna (if more than one are in use), and correct offsets of frequency and synchronization. – SFD: start frame delimiter consists of a pattern of 16 bits: 0000 1100 1011 1101, used to define the beginning of the frame. 1.2 Physical Layer Convergence Protocol Header The Physical Layer Convergence Protocol (PLCP) header is always transmitted at 1 Mbps and carries some logical information used by the physical layer to decode the frame: – Length of word of PLCP PDU (PLW): representing the number of bytes in the packet, useful to the physical layer to detect correctly the end of the packet. – Flag of signalization PLCP (PSF): indicating the supported rate going from 1 to 4.5 Mbps with steps of 0.5 Mbps. Even though the standard gives the combinations of bits for PSF (see Table A.1) to support eight different rates, only the modulations for 1 and 2 Mbps have been defined. – Control error field (HEC): CRC field for error detection of 16 bits (or 32 bits). The polynomial generator used is G(x)=x16 + x12 + x5 +1.
    [Show full text]
  • Connecting Australia! Wireless Broadband
    The Parliament of the Commonwealth of Australia CONNECTING AUSTRALIA! WIRELESS BROADBAND HOUSE OF REPRESENTATIVES STANDING COMMITTEE ON COMMUNICATIONS, INFORMATION TECHNOLOGY AND THE ARTS NOVEMBER 2002 © Commonwealth of Australia 2002 Printed by CanPrint Communications Pty Ltd ii Foreword Wireless broadband has an important role to play in extending the reach of broadband services to all Australians. There is no one particular wireless broadband technology that can solve all telecommunications problems. The future will see a mix of various technologies and the market should be permitted to determine, over time, which ones best suit particular applications. The government should maintain a general regulatory policy of ‘technology-neutrality’ (not favouring any particular technology, whether it be wireless or wire-line). Specific measures should be put in place to extend the understanding and takeup of wireless broadband. The recommendations contained in this report reflect the broad observations and statements of principle set out above. If they are adopted by the government, they would greatly facilitate the expansion of wireless broadband services in metropolitan, regional and rural areas. The Committee also has made recommendations to assist the hearing-impaired gain access to wireless broadband services, to improve the regulatory framework and to preserve the power of police and intelligence services to protect the community against illegal activities. Many people contributed to this inquiry and, in particular, the Committee benefited from the 60 submissions and many witnesses who addressed us at our eight public hearings. Also, the Committee acknowledges the invaluable assistance of Professor Harris and Dr Borg (of the Plasma Research Laboratory of the ANU) who were contracted to produce a draft report.
    [Show full text]