CSR Volume 1 #2, March 1990

COMMUNICATIONS STANDARDS REVIEW

Volume 1, Number 2 March, 1990

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-29, Facsimile, February 6-8, 1990 Costa Mesa, California...... 2 Liaison Reports...... 2 TR-29 Roster, February 6 - 8, 1990, Costa Mesa, CA...... 5

TR-30, Data Transmissionn, February 13-16, 1990 Fort Lauderdale, Florida...... 5 TR-30.1 Modems...... 5 TR-30.2 Digital Interfaces...... 6 TR-30.3 Data Communications Network Interfaces...... 7 TR-30.4 DTE-DCE Protocols...... 8 TR-30 Roster, February 13 - 16, 1990, Fort Lauderdale, FL...... 9

Semi-Annual Report Technical Committee TR-30, March 1990 ...... 9

SG XVII Special Rapporteurs Groups on V.32 Enhancements (Q3) and V.42 Enhancements (Q5), February 26 - March 2, 1990, Atlanta, Georgia...... 10 V.32 Enhancements...... 10 SG XVII Special Rapporteurs Groups on V.32 Enhancements (Q3) and V.42 Enhancements (Q5) Roster...... 12

Update on National Electical Code Requirements For Modems...... 13

Meeting Schedules As Of March 8, 1990...... 14

LIAISON REPORTS

JPEG (Joint Photographic Experts Group) Color Grey Scale Continuous Tone Compression Draft technical spec. (Rev 5) has been published and distributed for review and comment to CCITT SGVIII as a White Paper and circulated in the US via ANSI. It is anticipated that the DIS (Draft International Specification) of this work will be completed by Spring 1990.

Neil Starkey of Data Beam reported on JBIG (Joint Binary Image Group). There is a base line specification under development. The lossless coder is still to be finalized. JBIG development continues to lag behind JPEG.

Herman Silbiger, AT&T (now retired), reported on other work in Caen of SGVIII. On high resolution: the Japanese have proposed millimeter based resolution while the US has proposed inch based resolution. A proposal to support both needs to be developed. G3 over ISDN was discussed, but no conclusions were reached. It is desired to have the Binary File Transfer contribution as a separate T. series recommendation so that it can support all telematic services. TR-29 sent a contribution soliciting support for BFT to the Telex meeting (Q9 SGI) also occurring in Caen. Q9 SGI responded with support of the basic principal.

Herman Silbiger distributed TR-29/90-09 which discusses the work in SGVII on message handling. It describes useful clarification to X.420 (MHS recommendation) for intercommunications with G3 facsimile.

BINARY FILE TRANSFER

Philip Bogosian, Chairman of TR-29.1, discussed the status of rewriting the BFT submission based on recommendations from Caen. There is a desire to reduce the receive buffer requirement below 64kbits. However, supporting this capability requires supporting less than the full capabilities that are offered by ECM. The contribution to the Caen meeting on the use of BFT for additional functions will be forwarded on to SGVIII.

TR-29/90-29 (modifications to T.30 to support BFT) and TR-29/90-30 (draft T.BFT) were distributed. These papers are the output of editing work to accommodate BFT over various telematic services; they do not make technical changes to the previous BFT work. More editing and corrections will be made before distribution to SGVIII.

FACSIMILE EXTENSIONS TO THE AT COMMAND SET

Joe Decuir, Chairman of TR-29.2, reviewed the work in progress. The ballot comments on Class 1 were resolved; TR-29.2/89-38R5 includes all the changes. Ballot comments (from committee only) on Class 2 were also resolved. Class 2 will now be distributed for full EIA ballot. It was unanimously agreed that SP-2188 Class 1 will become an interim standard (IS). An interim standard has a life of one year. It is anticipated that the work of Class 2 will supersede (and include as an option) the work of Class 1 before the end of one year.

Note: CSR Vol 1 #1 incorrectly termed SP-2188 as SP-2120. SP-2188, Class 1 interface for a facsimile DCE, is available as a document. We apologize for any inconveniences.

TR-29.2/90-11 describes the comments to the PN-2188 Class 2.These changes will be included in the next draft of Class 2 and distributed for letter ballot.

TR-29/90-6 proposes an extension to any Class of PN-2188 with the use of a single command +FLOCAL. This powerful concept allows a local digital interface to interact with the facsimile function. It was agreed to begin this project in TR-29.2. Jim Wilcox of STF Technologies agreed to be editor and to generate a user requirements document.

FACSIMILE/AUTOANSWERING EQUIPMENT INTERWORKING

TR-29/90-11, distributed by Dick Kellerman of MCI, is a set of 6 papers from a CCITT SGVIII WP1 Q.3 and Q.18 meeting in Rome, January 11-12, 1990. These papers discuss issues associated with the integration of facsimile and auto-answering equipment.

TR-29/90-23 was distributed by Harry Otto of Brother. His paper discussed the capabilities necessary to differentiate fax and telephone answering machines. He noted the need for an hoc committee to work on a US position on this issue. With committee approval, Harry agreed to chair this ad hoc group. A sign up sheet for committee members was distributed.

Lloyd McIntyre of Xerox presented TR-29/90-27. This document is a proposed flow chart of voice /fax handshaking.

HIGH SPEED OPTION FOR G3 FACSIMILE

Bruce DeGrasse, Rapporteur on Q5 SG VIII, discussed TR-29/90-12 and TR-29/90-13. TR-29/90-13 is the report of the work on Q5 (modem modulation for Telematic Services) that occurred in Caen. TR-29/90-12 is the current version of the HS Annex to T.4 and the related changes to T.30.

John Bingham of Telebit distributed three papers: TR-29/90-17, TR-29/90-18 and TR-29/90-19. These papers form a proposal by Telebit to support a modem standard temporarily termed V.fax. TR-29 agreed to support and use any resulting recommendation. (TR-30.1 was not so enthusiastic. See the TR-30 reports in this issue.)

Because the schedule of meetings for 1990 has facsimile meetings preceding modem related meetings, it is difficult to integrate V.fax into evolving facsimile standards. Therefore, TR-29 will continue to support the HS annex to T.4 which is technically equivalent to the version approved at the SGVIII WP 3 meeting in Caen.

Bruce DeGrasse presented TR-29/90-28 as a potential US contribution supporting the current efforts to standardize high speed option for G3 facsimile. It notes the desire to promote further cooperation between SGVIII and SGXVII. The technical issues were supported and extensive editorial changes were incorporated. The document was approved as a US contribution.

A liaison statement to TR-30.1 was approved and will be delivered by Ken Krechmer of ACTION Consulting with the revised version of TR-29/90-28 attached for information.

MIL-STD 188-161 E DITING

Bob Robinson of Ilex chaired the MIL STD 188-161B Ad Hoc Committee meeting. The report of this ad hoc committee is TR-29/90-022

HIGH RESOLUTION TEST CHARTS

TR-29/90-15 and TR-29/90-16 describe the work in progress on G4 Monochrome and Color Test Charts. Herman Silbiger pointed out that these charts would be better titled High Resolution. This was supported. Steve Urban will be responsible for final editing. This document was approved by voice vote for passage to SG D as a US contribution to SGVIII.

The committee planned to produce a digitized version of the test charts. Since this is about 80 mbit at a 400 pel /inch an appropriate medium for distribution needs to be selected.

AUTOGRAPHIC CONFERENCING

Granger Kelley of DoD (DCA) discussed the previously distributed Audiographic conference standard TR-29/89- 62R1. TR-29 supported this contribution for information to SG VIII. Neil Starkey presented TR-29/90-20, which is an editorial correction to TR-29/89-62R1. It will be distributed for industry ballot.

Granger Kelley also distributed TR-29/89-47R1, the current version of the Audiographics service definition. This paper will be distributed to Study Group I and should be approved for accelerated procedures.

Herman Silbiger proposed that TR-29/89-62R1 be transmitted to X3V1 (text and office systems) and X3T5 (OSI data communications). Charlie Touchton of IBM agreed to help determine the appropriate people for a distribution list for the proposed autographic standard. He will also look into a ANSI notification procedure to notify interested parties of standards development.

HIGH RESOLUTION G3

Bruce DeGrasse distributed TR-29/90-21. It was distributed to provoke discussion on a means of interworking between different resolution devices. There is some support for utilizing a specific bit that defines whether the transmitting and receiving machines are willing to transfer images when a mismatch in resolution is detected. An editing group was suggested to develop this approach further.

MULTIUSER SYSTEM /FACSIMILE ROUTING

Lloyd McIntyre of Xerox presented TR-29/90-25 which supports DTMF routing capability. Matt Shuchman agreed to create a project statement to instigate a formal project on facsimile routing operation for the next TR-29 meeting.

TR-29/90-26, presented by Matt Shuchman, discusses possible routing schemes and their desirability. It was agreed that it is unnecessary to define network supplied addressing capabilities at this time. However, input to this project is desired.

G3 OVER ISDN

Herman Silbiger presented TR-29/90-07 on the subject of G3 facsimile on the ISDN. This subject will be discussed at the Budapest meeting. There was some discussion on how to negotiate facilities between analog and digital services. It was proposed and seconded to forwarded this paper to Study Group D as a proposed US contribution to the SGVIII meeting in Budapest.

AD HOC COMMITTEE MEETING ON FUTURE HIGHER SPEED G3 FACSIMILE

John Bingham presented TR-29/90-32 as the background to developing a future high speed G3 fax recommendation. He reviewed changes that would provide the highest possible page throughput over the broadest range of analog telephone facilities. With the technical support of other members, he will refine the areas where potential improvements can be made.

MISCELLANEOUS

Yoshikazu Yokomizo of Canon presented TR-29/90-24 which proposes expanding the paper handling capabilities of Group 4 facsimile, particularly needed when cut sheet paper is used. There is support in TR-29 for adding these additional paper sizes to T.563. This position will be supported at the Budapest meeting.

TR-29 supported the intent of TR-29/90-08 which describes how manufacturer codes are assigned in a manner compatible with individual country procedures.

Ken Krechmer, ACTION Consulting

TR-29 ROSTER, FEBRUARY 6 - 8, 1990, COSTA MESA, CA.

ACTION Consulting Ken Krechmer IBM Charles Touchton Applied Resources Robert W. Ayers Ilex Systems, Inc. Bob Robinson AT&T Herman Silbiger Intel Steve Packer BDM Int'l William Walden Magnavox Joanne Dow Brother Int'l Harry Otto Magnavox Martin Hardy Canon Y. Yokomizo Magnavox David Prihar Castelle Peter Knott MCI Dick Kellerman Compfax Matt Shuchman Nat'l Semiconductor Israel Greiss Connext Bill Wegryn NCS Dennis Bodson Cryptek Steven Rogers Ricoh Gene Gavenman Data Beam Corp. James Galvin Rockwell Bruce DeGrasse Data Beam Corp. Neil Starkey Rockwell Glen Griffith Data Race Les Staples Silicon Systems Tom Glad Delta Info. Systems Stephen Urban Solutions, Inc. Tom Evslin DoD (DCA) K. G. Kelley STF Technologies James R. Wilcox DoD (JTC3A) Otto Schultz Telebit John Bingham DoD (JTC3A) Major E.R. Sive Thought Comm. Philip Bogosian Everex Joe Decuir Thought Works Bob Kulakowski General Electric Barbara Thompson Time & Space Proc. Neil Wiseman Hayes Toby Nixon Unifax Comm. Stuart Lynne Hayes Dan Pierce Xerox Corp. Lloyd McIntyre Hycom Gus Kinoshita Yamaha LSI Simon McGrath IBM Craig Lamprecht --- Don Weber

REPORT OF TR-30, FORT LAUDERDALE, FLORIDA FEBRUARY 13-16, 1990

TR-30.1 MODEMS

LIAISON

Dick Brandt gave a liaison report from ISO /JTC3 /SC6 /WG3. Owing to a paperwork delay, no significant work on Network Management occurred. Dick Slezak resigned his editorship position. Work on ISO 2110 (EIA 530) to support balanced operation continued. The ISDN primary rate connector also progressed, however ETSI has raised an issue of shielding requirements which could delay the project. The US is concerned that requiring shielding of the PRI would require rewiring when migrating from BRI to PRI.

V.42bis was approved unanimously by CCITT members.

TR-30.1/90-02013 is a report from Study Group VII (Q24) on network management. Alan Clark of Dowty proposed and SG VII accepted an architectural model. One of the managed objects proposed is a model of a V series modem that includes several separate managed objects. Reports at the next SG XVII will cover this topic.

Ken Krechmer of ACTION Consulting presented TR-30.1/90-02009 and TR-30.1/90-02008 as liaison from TR-29. These documents support the Telebit proposal (TR-30.1/90-02005). TR-29 will continue work on the HS Annex to T.4 in the event that a V.fax proposal is not forthcoming from TR-30 and SGXVII.

Joe Decuir discussed the voice/data /fax question raised by the TR-30.4 paper from Everex (TR-30.4/90-02004). Jack Moran of Codex noted that MCI is interested in the use of calling tone in the data modem. Of particular interest is a capability to impress V.21 modulated information on the calling tone to define the modem type originating the call (V.25bis uses V.23). It is not clear which standards group would be appropriate to undertake voice/data/fax differentiation work. There is little interest in TR-30 in undertaking this work. However, the use of a V.25-specified calling tone could represent a desirable feature of a future data modem as it could provide a user benefit.

V.ASYM (V.FAX)

John Bingham of Telebit presented TR-30.1/90-02005. This paper represents an interesting compromise that was discussed the preceding week with TR-29. Telebit is willing to delete the multi-carrier Annex if the main body (QAM V.33 like modulation) does not include a backward channel. When the V.asym recommendation is cut back by deleting the multicarrier annex and backward channel, it is colloquially termed V.fax. V.fax is still desirable for facsimile but noncompetitive with the Telebit or other asymmetrical products. Two other issues mentioned in this paper are the use of a fast retrain and talker echo protection. It is likely that both these issues will need some work. US Robotics presented TR-30.1/90-02011 and AT&T Paradyne presented TR-30.1/90-02012. Both of these papers are in opposition to the Telebit proposal. Their position deadlocks the V.asym issue and makes a US position, which is necessary to move the work forward, very unlikely.

MODEM INTERWORKING

TR-30.1/90-02001 is a draft EIA/TIA standard on US type modem interworking from Ken Jones of Octocom. The timer T103 could be 800 milsec. (propagation delay assumed) + 270 +/-40 milsec. = 1070 +/-50 milsec. This needs to be reviewed. It was noted that some 212 modems hang-up upon the receipt of 2100Hz answer tone. TR-30.1/90-02007 from AT&T is an excerpt from AT&T PUB 41214 that describes 212 and 103 handshaking. CELLULAR MODEMS

John Bingham of Telebit presented TR-30.1/90-02004. This suggests a US position on the review of modulation mechanisms for cellular operation. This will be edited and presented as a US contribution.

19.2KBIT/S DATA RATES

Glen Griffith of Rockwell presented TR-30.1/90-02003, a proposal to study high speed modem data rates. This proposal will be edited and presented as a potential contribution to SG XVII in April. V.32 EXTENDED RATE SEQUENCES

Jack Moran of Codex presented TR-30.1/90-02006 which is the final form USA contribution proposing rate sequences for 14,400 bit/s operations. See additional information in V.32/V.42 Rapporteurs meeting report in this issue of Communications Standards Review. Ken Krechmer, ACTION Consulting

TR-30.2 DIGITAL INTERFACES

ISO JTC1/SC6/WG3 LIAISON REPORT

Richard Brandt (dB Consulting, for AT&T) presented a verbal liaison report of the January 1990 ISO JTC1/SC6/WG3 meeting. He reported that the proposed addendum to ISO 2110, which will add the balanced interface of EIA-530 to the international standard, was moved forward to international ballot as a full draft addendum (DAD to ISO 2110). Assuming that no unresolvable negative ballots are received, it can be expected that it will be a formal addendum at the October meeting of ISO JTC1/SC6/WG3. This is the first step in adopting EIA-530 as an international standard. Next will be a requirement for CCITT SGXVII to include V.10 and V.11 references in the V series of recommendations.

JTC1/SC6/WG3 is in the process of revising ISO 7480, Start-Stop Transmission Signal Quality (TR30.2/90- 02007).

STUDY GROUP XVII L IAISON

TR30.2/90-02007 addresses the difficulty with operation of V.28 above 20 kbit/s. It discusses the Appendix to V.28. This paper was approved at the December TR-30.2 meeting for submission to U.S. Study Group D and has now been approved for submission to CCITT Study Group XVII.

TR-30.2.1 REPORT

Jack Moran, charmain of the ad hoc TR-30.2.1 committee, reported on his committee's work on Tuesday, February 13. The committee is starting to make good progress on the cable considerations for the revision to EIA-422-A. The goal of TR-30.2.1 is to complete a final draft of EIA-422-B in early 1991.

Because of major shortcomings in the Appendix to V.28, the committee recommended that a contribution of a draft V.28bis recommendation to Study Group XVII be delayed. TR-30.2 agreed with this recommendation. This recommendation was also carried into the work which TR-30.2 is doing on EIA-232-E. It had been the intent of the committee to include an appendix to EIA-232-E which would provide guidance for those who might wish to use EIA-232 at data rates above 20 kbit/s. EIA-232-E will continue to maintain an upper limit of 20 kbit/s with the committee again recommending use of EIA-530 at the higher data rates.

REVISION OF EIA-232-D TO EIA-232-E

The major task of the February meeting of TR-30.2 was completion of the draft of EIA-232-E. The major revisions to the most popular of all data communications standards, are the inclusion of the Alternate A connector and inclusion of hardware flow control. Both had previously been described in EIA Technical Systems Bulletins TSB-25 and TSB-26. Various other editorial and minor definition changes have been made to align with the work done internationally. The committee completed its work and the draft standard was approved for letter ballot. It is expected that it will be at least six months before the new standard has been printed and available for purchase.

EIA-530 R EVISION

With the completion of the editing work on EIA-232-E, the committee will now undertake a revision of EIA-530 to EIA-530-A. This work will include similar revisions as were made on EIA-232-E, to include the Alternate A connector and hardware flow control. In addition, to bring this standard into alignment with the DAD to ISO 2110, the pin-out will require revision. This will change the interchange circuits, DTE Ready and DCE Ready to Category II circuits (unbalanced), and include an additional circuit ground and Ring indicator. This work will begin at the April meeting of the committee.

Fred Lucas, Chairman, TR-30.2

TR-30.3 DATA COMMUNICATIONS NETWORK INTERFACES

LIAISON

Jack Moran presented TR-30.3/90-02007. This paper indicates T1E1's interest in specifying "Analog Non- Switched Special Access Lines" (leased lines). The T1Q1.1 ad hoc group will meet March 20, 1990 in Mansfield, MA to begin specifying the network performance.

Jack also reported on the T1Q1 meeting (TR-30.3/90-02011). This paper describes the interest of T1Q1 in specifying leased line performance as well as PSTN performance. EIA/TIA 496-B

TR-30.3/90-02012 is a report from TR-30.3 to T1Q1. It provides an overview of the current work of TR-30.3. T1Q1 did not feel that loop #6 was realistic, as there are very few such loops in existence. T1Q1 preferred a variation of loop #7. TR-30.3/90-02013 represents Jack Moran's calculations of the model identified in TR- 30.3/90-02014 as BellSouth Loop #19. TR-30.3/90-02013 discusses the difficulty of simulating a loop with

March 1990 Vol. 1.2 Copyright © CSR 1990 7 COMMUNICATIONS STANDARDS REVIEW multiple loading coils. According to the 1983 Bell survey, 23% of all loops have loading coils. Although this percentage is dropping, no new survey data is available.

The committee agreed that the first five loops should be standardized and suggested that test equipment manufacturers review these loops to determine if they can be properly simulated. The committee also agreed that loop #6 should be deleted and that loop #7 become loop #6. The new #7 will have an extra loading coil.

Jack Moran suggests that the power source be a current source capable of 25 to 65 milliamps.

Jack Douglas requested that the test equipment suppliers consider how to model the hybrid line interface and power source. PTT and TAS agreed to help if they could.

With the local loop impairments defined and hybrid and power source impairments being developed, the remaining issue is to specify the IEC portion of the total impairments. Considerable discussion of the potential impairments of the IEC occurred during the meeting. It was agreed that additional information from the carriers is needed.

Jack Moran noted that the carriers have a problem installing RJ45 jacks that are behind the network interface and therefore not the responsibility of the Local Exchange Carrier. TR-30.3 will attempt to support the carriers by trying to resolve this problem. This could evolve into a way to access a data-specified local loop. Such access would be highly desirable to support modems that operate at over 9600bit/s.

Ken Krechmer, ACTION Consulting

TR-30.4 DTE-DCE PROTOCOLS

TR-30.4/90-02001 is a comment from Radionics (an alarm system manufacturer) on a specific requirement to include a C0 function. The C0 command turns off modulated carrier. Carrier turn off (without hang-up) is not supported as full-duplex modem recommendations do not allow it. Designers can do what they wish with the C0 command as it is not specified for any other function. Radionics can use it as they choose without causing command incompatibility.

TR-30.4/89-10023R1 from Universal Data Systems proposes the command to control V.42 configuration and operation.

TR-30.4/90-02002 and TR-30.4/90-02003 from Everex discuss the semantics and syntax of DTE commands. TR-30.4/90-003 deals with control of DCE modulation.

TR-30.4/90-02004 from Everex discusses the use of a 1300Hz calling tone to identify a calling data device. A 1300Hz tone is suggested in V.25 to identify a calling data device to a manual answerer. There is some interest in this, but it needs to be supported by TR-30.1.

TR-30.4 ad hoc met on Monday February 12, 1990 to continue the work on PN-2120 (AT command set standard). This work continued revision of TR-30/89-04014R5 at Section 7.3 (S Register and other parameter definitions) which was not included in the R5 document. This work is moving very slowly and a large list of outstanding issues remain. There will be an additional ad hoc editing meeting hosted by Hayes, March 13 - 15, 1990 in Atlanta, GA. in an attempt to complete a draft of a US contribution to CCITT SGXVII. TR-30/89-04014R6 will be available after this meeting.

Ken Krechmer, ACTION Consulting

TR-30 ROSTER, FEBRUARY 13 - 16, 1990, FORT LAUDERDALE, FL.

ACT Jack MacCrisken Grid Systems Teodor Nitu ACTION Consult. Ken Krechmer Hayes Toby Nixon ADC Kentrox John Litster NSA Diane Gordon AMP Inc. Jack L. Bradbery Octocom Eldon Anderson AT&T Krishna Murti Octocom Ken Jones AT&T Paradyne Stephen Wilkowok Penril Datacomm Dick Stuart AT&T Paradyne John Law Winters PTT Mike Turner Codex Jack Moran Racal-Milgo Joe Carballosa Codex John Payton Rockwell Glen Griffith CSR Elaine Baskin R. Scott Associates Munther Qubain Cornel Electric Ray Kelly Telebit John Bingham dB Consulting Dick Brandt Telebit Sam Pai DEC M. Ralph Dieter TAS Steve Moore Everex Joe Decuir UDS Jay C. Bain Gen'l DataComm Fred Lucas UDS Steve Turner Gen'l DataComm Jim Tracy US Robotics Ron Martin

SEMI-ANNUAL REPORT TECHNICAL COMMITTEE TR-30 MARCH 1990

Technical Subcommittee TR-30.1 still is primarily focused toward the international standards arena. Its three most active projects involve working within the international standards community:

1. To draft CCITT Recommendation V.32 bis which will specify a 14,400 bit/s duplex modem for the Public Switched Telephone Network (PSTN) application; 2. To develop V.asym which will specify a 14,400 bit/s half-duplex modem for facsimile applications 3. To work within CCITT and ISO on Network Management issues.

Domestically, TR-30.1 decided to release the Automode Modem specification as an Interim Standard. This specifies interworking scenarios between new Automode V.32 (9600 bit/s) modem and other V.32, V.22bis(2400 bit/s) and V.22 (1200 bit/s) modems.

Technical Subcommittee TR-30.2, after completing its work on the new interfaces, is focusing on revising and updating EIA-422-A, EIA-232-D and EIA-334-A. It continues to be active in CCITT and ISO for the specification of an International version of EIA-530.

TR-30.3 continues to work on the revision of EIA/TIA-496-A, which will add transient impairments to the test channels for modems. Additionally, TR-30.3 is active in CCITT, proposing revisions to Recommendation V.56. Active liaison with T1Q1 is being maintained.

Technical Subcommittee TR-30.4 continues its work on a new USA standard for the "AT" command set based on the present defacto standard for serial dialing and control with modems. A preliminary version of this will be introduced in the CCITT this spring. TR-30.4 continues to have an open project for expanding Recommendation V.25 bis although the present efforts are focused on the AT work.

R. P. Brandt,Chairman Technical Committee TR-30, Data Transmission Systems, and Equipment

SG XVII SPECIAL RAPPORTEURS GROUPS ON V.32 ENHANCEMENTS (Q3) AND V.42 ENHANCEMENTS (Q5), FEBRUARY 26 - MARCH 2, 1990, ATLANTA, GEORGIA

V.32 ENHANCEMENTS

Two opposing rate negotiation proposals met head-on at this meeting. The first was A-3, "Why extending the rates in V.32 cannot be accomplished satisfactorily by simply allocating bits in the existing Rate Sequence -BT," the existing British Telecom proposal for a 24-octet rate sequence menu. Such a capabilty can provide signalling rate changes without retraining, asymmetric, and half duplex operation, as well as signalling of time division multiplexer configurations. The second proposal (A-1, "Proposed Modifications to V.32 for Extended Data Signalling Rates -USA") was the US proposal for a simple change to the existing 16-octet rate sequence V.32 to accommodate additional rates of 7200, 12000 and 14400 bit/s.

As stated in their A-2 paper ("On V.32 Extension"), the UK delegates felt that the existing V.32 rate sequence was too restrictive. One of the arguments advanced by the UK for the rate change (without retrain) proposal was that it would allow starting up at a lower rate, then going to a higher rate after more information was available for a decision.

Asymmetric operation was represented as a way to take care of different performance capabilities of different modem implementations or different echo characteristics on the two ends of a connection. Time division multiplexing was presented as a dial backup answer. The UK delegates also stated that they saw potential backward compatibility problems with the proposal to change just V.32. When asked to rank order the desirability of these proposed new capabilites, they responded that the ability to change speeds without retrain was their number one priority.

The US delegates argued that the existing V.32 recommendation already provided for rate changes with the retrain capability. They agreed that it would take longer than the BT proposal anticipated, but did not see this as a problem based on their belief that it wouldn't occur that often. They contended that "shorter intial" start up times followed by rate changes which interrupted the user data flow was misleading; it would better to take the time in the beginning to establish the channel at the highest reliable rate.

The US delegates also stated concerns about allowing the modem to make decisions about changing speed which might be incorrect for the application. The example given was one in which the data flow in the main channel (high speed direction of data flow) was interrupted by the modem requesting a higher data rate in the lower speed direction where it was not needed.

After some fruitless discussion, the Rapporteur (Ken Miller of Codex) decided to examine one proposal at a time.

The following agreements were reached:

1) The outcome of this study will be a V.32 bis recommendation rather than a new version of V.32. This alleviated the UK concerns about backward compatibility. 2) The modulation technique specified will be the same as V.33. 3) Trellis coding will be specified for all speeds. 4) 2400 will be no longer be considered as a future V.32 data rate. 5) Half-duplex operation will be dropped from consideration. 6) The uncoded mode of 9600 bit/s will be dropped.

There was no consensus on

1) The need for rate change without retrain 2) The need for asymmetric operation 3) The need for the capability to transmit TDM configuration information in the rate sequence.

The need for a speedy resolution was expressed by the Chairman of the Study Group (K. Kern) as well as by the Rapporteur. In an effort to break the dead-lock, it was decided to produce a "Draft Recommendation V.32 bis", as

10 Vol. 1.2 Copyright © CSR 1990 March 1990 COMMUNICATIONS STANDARDS REVIEW complete as possible. This draft would reflect all points of agreement and leave blank or marked "for further study" those points where there was no consensus. It was proposed that this document be used as the basis for discussions at the April SG XVII meeting, where the blanks could be filled in once agreements were made. This proposal was accepted by the group and an editing group was formed. This editing group produced A-5, "Draft Recommendation V.32 bis - Editing Group."

One of the major changes in V.32 bis, in addition to higher data signalling rates, was that all data signalling rates will be required. It was noted in the present V.32 Recommendation, 4800 bit/s was not required, although the handshake must take place at this data signalling rate. It was decided to add this requirement in V.32 bis. The several large holes in the document can be filled in quickly when agreements are struck. During the meeting the Federal Republic of Germany and France both supported the USA position.

Document A-4 "Possible flaw in V.32 Automode procedure - USA" from Hayes notes a possible flaw in V.32 Automode Annex A. No discussion took place because no one was familiar with the paper.

At the end of the meeting, R.P Brandt, the chairman of WP XVII/1, announced that Dick Stuart (Penril-USA) had volunteered to take over the responsibilities of Rapporteur for this work. The official appointment will be made at the April meeting.

Document A-6 is the V.32 Rapporteur's (Ken Miller) minutes of this meeting.

V.42 ENHANCEMENTS

The V.42 Rapporteurs Group met February 28 through March 1. The goal of this meeting was to catch-up on previous work. The work was broken down into four areas: V.42 amendments, Forward Error Correction, Statistical Multiplexing, and V.42 bis (editorial) Amendments.

V.42 AMENDMENTS

The first session of the Rapporteurs group dealt with the backlog of papers proposing amendments to the Recommendation. The majority of these papers were either authored by Hayes or from Hayes sources. The exception was Temporary Document 71, "Proposed V.42 Text for Data Compression Negotiation" authored by Fred Burg (AT&T), editor for V.42.

Toby Nixon (Hayes) presented all of the papers with the exception of TD-71. A-107, "Proposed addition to R1 Annex 9" which modifies COM XVII R-1 Annex 9, ""Proposed modifications to V.42," was accepted. Delayed 36 ("Editorial Changes to Recommendation V.42") was accepted with minor editorial corrections. Discussion on Delayed 37 ("Assured delivery of data in V.42 DCEs") dealt with a graceful disconnect (sending all data already in buffer before disconnecting); Delayed 38 ("Operation of the DTE-DCE Interface after fall back to non-error correcting operation in V.42 DCEs-Hayes") dealt with a V.42 DCE interacting with a non V.42 DCE. Too many open issues need to be addressed to accept either of these proposals at the meeting.

Delayed 39 ("Transparent Character-based Flow Control in V.42 DCEs - Hayes") proposed an optional way of providing transparency on the DTE-DCE interface for X-ON/X-OFF characters. In this paper, Hayes proposed a method for encoding these characters (when they appear in user data during a file transfer) to prevent the local DCE from interpreting them as flow control requests. The group felt that ISO (the DTE people) should be consulted before any action is taken. A liaison was sent to ISO/IEC SC 6/WG 1&3 (A-108) asking their opinions on this matter.

FORWARD ERROR CONTROL (FEC)

Two new papers were presented by OKI (Japan): A-101, "Progress in Standardization of FEC Protocol" and A- 102, "Forward Error Correction Protocol Procedures.". These papers build on the proposals OKI has been bringing to CCITT over the past year (COM XVII No. 7, "Necessity of Standardization of Forward Error Correction Protocol" and D-35, Technical Investigation of V.42 procedures applying to FEC based protocol"). They propose the inclusion of an optional Forward Error Correcting (FEC) procedure to be added to Recommendation V.42, specifically addressing the use of modems on cellular connections. Discussion dealt with issues such as the long

March 1990 Vol. 1.2 Copyright © CSR 1990 11 COMMUNICATIONS STANDARDS REVIEW term prospects of analog cellular radio (D-44, "Data Transmission over Cellular Radio" from Racal Milgo Ltd. - UK) and the need for interworking with existing non-FEC modems.

In order to gain the benefit of this scheme, an interworking method that could be implemented at the interface between the cellular network and the Public Switched Telephone Network (PSTN) needs to be worked out. To gain the benefit of FEC on the majority of connections, the cellular site would have to implement a modem pool with FEC capability.

It was decided that the whole cellular issue would be better addressed in a separate Rapporteurs Group which would also deal with the use of alternative modulation techniques and interworking between modems on cellular networks and modems on the PSTN. Close liaison with SG XV (network terminals) was identified as a requirement for this new group.

STATISTICAL MULTIPLEXING

It had been anticipated that there would be rapid agreement on the previously-drafted changes to V.42 to accommodate a simple one-to-one mapped statatistical multiplexer (CCITT SG XVII R-1 Annex 10, "Proposed Modifications to V.42 for Statistical Multiplexing" and CCITT COM XVII No. 6, "Optional Statistical Multiplexer Option for V.42"). However, at the request of Racal-Milgo, an Editor's group was convened to study interconnection of ports at opposite ends of the connection. No resolution was reached.

V.42 BIS EDITORIAL AMENDMENTS

A-103/A-104, "Editorial Comments on V.42 bis" presented editorial corrections for V.42 bis (the recently- approved data compression recommendation). They were accepted without discussion. A-105 describes the status (in process) of ISO standards for the use of private parameters for negotiations of V.42bis data compression.

NEW PROPOSALS

As the last item on the agenda, Toby Nixon (Hayes) asked the group to consider the application of V.42 bis to Synchronous Operation in its future work. The problem of flow control was highlighted as an area for study. This proposal received wide support.

Richard Brandt, dB Consulting

SG XVII S PECIAL RAPPORTEURS GROUPS ON V.32 ENHANCEMENTS (Q3) AND V.42 ENHANCEMENTS (Q5) ROSTER.

Apple Computer (V.42 only) Racal-Milgo AT&T (Comm) US Robotics AT&T (Paradyne) Fed Rep of Germany Deutsch Bundespost Telekom Cornel Electric Finland Nokia Datacomm General Datacomm France TRT Phillips, Hayes Microcomputer Products Japan OKI Electric Memotec Datacom UK British Telecom Motorola (Codex) Racal-Milgo Ltd. Motorola (UDS) Penril Datacomm R. Scott Associates (V.42 only)

On January 11, 1990, the Standards Council considered the request of the Telecommunications Industries Association and Electronics Industries Association for a Tentative Interim Amendment (TIA) to 800-51(i) of the 1990 edition of NFPA 70, National Electrical Code. The Standards Council agreed to issue the following TIA:

"(i) Equipment. Equipment intended to be electrically connected to a telecommunications network shall be listed for the purpose. This listing requirement shall become effective on October 1, 1990 for equipment comprising the premise communications wiring system from the point of demarcation up to and including the final outlet providing modular plug and jack connection (or equivlant). This listing requirement for all other equipment, shall become effective on July 1, 1991.

(FPN No. 1) The point of demarcation is defined by FCC Part 68. (FPN No. 2) One way to determine applicable requirements is to refer to Standard for Telephone Equipment, UL 1459-1987 or Communications Circuit Accessories, UL 1893-1990.

Exception: This listing requirment shall not apply to reinstalled equipment manufactured before July 1, 1991."

The condensed version: Modem manufacturers need to comply with applicable UL (or similar) regulations (currently UL 478 is effective; on March 15, 1992, UL 1950 becomes effective) for new modem installations commencing July 1, 1991.

Ken Krechmer, ACTION Consulting

The next issue of Communications Standards Review will be published mid-May, 1990.

MEETING SCHEDULES AS OF MARCH 8, 1990. SUBJECT TO CHANGE WITHOUT NOTICE TR-29 Aug 7 - 9 Yountville, CA T1E1 Mar 12 San Antonio, TX T1S1 (T1AG) Aug 27 --- TR-30.4 adhoc Mar 13-15 Atlanta, GA TR-30 Sep 4 - 7 Sunnyvale, CA SG VIII Mar 26 - Apr 4 Budapest WP VIII Sep 5-14 Geneva TR-30 Apr 2 - 5 Gaithersburg, MD. T1E1 Sep 24 Portland, OR SG D Apr 6 Washington, DC T1Q1 Oct 15 Dallas, TX T1S1 Apr 16 Dallas, TX SG XVII Oct 15-23 Geneva SG XVII Apr 19-27 Geneva T1S1 Oct 29 --- T1Q1 Apr 23 Boulder, CO TR-29 Nov 6 - 8 Tampa, FL TR-29 Apr 30 - May 3 Holmdel, NJ COMDEX Nov 12 - 16 Las Vegas, NV TR-30 Jun 11-15 Norcross, GA T1E1 Dec 10 Washington, DC T1E1 Jun 18 Chicago, IL TR-30 Dec 11 - 14 --- T1S1 Jun 25 San Francisco, CA T1Q1 Jul 30 Santa Clara, CA

Communications Standards Review is published 8 to 10 times per year, within days after the latest, related standards meetings. Editor: Elaine J. Baskin. Technical Editor: Ken Krechmer. Copyright © 1990, ACTION Consulting. All rights reserved. Copying of individual articles for distribution within an organization is permitted. Subscriptions: $695.00 per year United States and Canada, $350.00 for each additional subscription to the same organization at the same address; $895.00 per year Foreign, $450.00 for each additional subscription to the same organization at the same address. Submit articles for consideration to: Communications Standards Review, 757 Greer Road, Palo Alto, CA 94303 USA. Tel: 650-856-9018. FAX: 650-856-6591. 19002