COMMUNICATIONS STANDARDS REVIEW Volume 11, Number 2 March-A, 2000 In This Issue The following reports of recent standards meetings represent the view of the reporter and are not official, authorized minutes of the meetings. TR-30.3, Data Comm. Equipment Evaluation and Network Interfaces, Jan. 12 – 14, 2000, Boca Raton, FL..... 2 TR-30.3 Meeting Roster, January 12 – 14, 2000, Boca Raton, FL .......................................................... 7 Q4/15, xDSL Network Access Transceivers, January 31 – February 4, 2000, Fiji .......................................... 8 G.gen................................................................................................................................................ 8 G.shdsl (Single-Pair High Speed Digital Subscriber Line Transceivers) ................................................. 10 G.vdsl............................................................................................................................................... 15 G.pnt ................................................................................................................................................ 18 G.lite-bis........................................................................................................................................... 19 G.dmt-bis .......................................................................................................................................... 20 G.hs-bis............................................................................................................................................. 21 G.ploam-bis ....................................................................................................................................... 22 G.test-bis........................................................................................................................................... 23 G.ref-bis............................................................................................................................................ 23 ITU-T STUDY GROUP 8, Terminal Equipment for Telematic Services, February 2 - 10, 2000, Geneva........... 25 Recommendations Decided by SG8 ..................................................................................................... 25 SG8 Approvals................................................................................................................................... 25 Recommendations Determined by SG8 ................................................................................................ 25 Recommendations Deleted by SG8 ...................................................................................................... 25 Question 1/8, Facsimile Terminals...................................................................................................... 26 Question 2/8, Facsimile Test Charts and Test Images ........................................................................... 32 Question 3/8, Cooperative Document Handling.................................................................................... 32 Question 4/8, Document Communication Services ............................................................................... 33 Question 5/8, Color for Telematic Applications..................................................................................... 39 Question 6/8, Common Components for Image Communication ............................................................ 42 DSL Forum Technical Committee Meeting ................................................................................................ 46 Architecture and Transport ................................................................................................................ 46 Voice over DSL (VoDSL).................................................................................................................... 48 Operations & Network Management.................................................................................................... 49 Testing & Interoperability .................................................................................................................. 50 Symmetric DSL ................................................................................................................................. 52 Emerging DSLs Study Group (EDSLSG).............................................................................................. 53 ADSL Forum Meeting Roster, February 8 – 11, Paris, France.............................................................. 54 Acronym Definitions ................................................................................................................................ 61 Year 2000 Standards Committee Meeting Schedules as of March 9, 2000...................................................... 64 Terms of Distribution for Electronic Copies................................................................................................ 65 March-A 2000 Vol. 11.2 Copyright © CSR 2000 1 COMMUNICATIONS STANDARDS REVIEW REPORT OF TR-30.3, DATA COMMUNICATIONS EQUIPMENT EVALUATION AND NETWORK INTERFACES JANUARY 12 – 14, 2000, BOCA RATON, FL The TR-30.1, TR-30.1 ad hoc, and TR-30.2 reports were published in the previous issue of CSR. J. Douglass (Conexant) is the TR-30.3 Chair. TR-30.3/00-01-001 is the report of the Clearwater, FL, Meeting December 1999. The meeting on January 12 was held jointly with SG16/Q8 (DCE - DCE protocols) for the purpose of agreeing on a set of test files that can be used for both analyzing the characteristics of candidate compression algorithms and for performance evaluation. The meetings on January 13 and 14 were held jointly with the T1E1.4 ad hoc group for xDSL Modem Performance Evaluation. TR-30.3/00-01-002 is the Assignment List from the December TR-30.3 meeting. TR-30.3/00-01-016 is the Document Register for this meeting. TR-30.3/00-01-015 (J. Douglass, Conexant) reports that TIA/EIA-3700, Telephone Network Transmission Model for Evaluating Analog Modem Performance, is now published and is available on the ITU Q10/16 ftp site for consideration to be included in Rec. V.56bis. TR-30.3 is presently not working on an international version of this document, since there is limited application of modem peer- to-peer connections. However, TR-30.3 is working on an international version of PN-3857, International Telephone Network Transmission Model for Evaluating Analog Client and Digitally Connected Server. It is believed that this work is more representative of today’s Internet-connected modem applications. LIAISON REPORTS TR-30.3/00-01-003 (J. Douglass, Conexant) describes problems with the operation of V.90 modems over cable telephony circuits that use GR303 Integrated Digital Loop Carrier signaling. GR303 specifies a Robbed Bit Signaling (RBS) pattern of 0101 for the Line Current Feed (LCF) ABCD code. Most V.90 modems currently deployed are not optimized to operate over lines that have an RBS pattern of 0101. This contribution recommends the following possible solutions: • Specify using 0000 or 1111 RBS pattern for Line Current Feed instead of 0101. (This will be difficult to change because the T1 standard [ANSI T1-403.2-1999] is based on the GR303 specification.) • Partition the CO Switch and IDLC as required to use 0000 or 1111 for Line Current Feed instead of 0101 • Add an option for bit-stuffing on DS1 interfaces with the IDLC system • Issue a field warning about the problem TR-30.3/00-01-012 (F. Lucas, 3Com, TR-30 Chair) is a liaison to the Cable Telephone Committee, T1E1.1, T1E1.2, T1E1.4 and the GR303 committee (Telcordia). It describes the operational problems of V.90 modems over cable telephony/HFC (hybrid fiber coax) circuits that use GR303 signaling. Cable companies are experiencing 50 reported problems per 2500 lines that are installed - a very high number. Field testing has shown: • Most V.90 client modems don’t operate well over circuits with 0101 RBS patterns. • Many of the Cable Telephony circuits don’t synchronize robbed bits which results in up to 5 robbed bits being seen by the modem. All V.90 modems connect at lower speeds and have lower throughput when more bits are robbed. • Some of the installed Cable Telephony circuits don’t follow the fixed loss plan which results in a high receive signal level. Typically modems are not optimized to operate over circuits with high receive levels, since standard telephone lines have local loops, which attenuate the signal. It has been found that the V.90 modems operate better over the Cable Telephony circuits, if there is a fixed loss of 6 dB in the downstream direction. 2 Vol. 11.2 Copyright © CSR 2000 March-A 2000 COMMUNICATIONS STANDARDS REVIEW The liaison also discusses in detail operational and technical solutions to the problems. TR-30.3 responded via a liaison to the DSL Forum’s question regarding recommendations concerning references to specification or other documents that would describe dial mode impairments (i.e., ringing, offhook, state changes). In addition a tutorial on the subject was provided. (See the DSL Forum report in this issue of CSR.) Also, TR-30.3 responded that they have no issues or suggestions concerning the Forum’s proposed alternative method for measuring error ratios using ATM Cell errors, as contained in Annex B of DSL Forum’s WT-29. PN-3509, REVISION OF TSB-38 (TEST PROCEDURES FOR EVALUATING MODEM PERFORMANCE) TR-30.3/00-01-006 (W. Henderson Jr., Henderson Labs) contains comparative test results