COMMUNICATIONS STANDARDS REVIEWISDN terminals (referred to hereafter as ISDN data terminals) that use digital bearer services. The new Recommendations cover interworking arrangements

April, 1991 Vol. 2.2 Copyright © CSR 1991 1

COMMUNICATIONS STANDARDS

REVIEW

Volume 2, Number 2 April, 1991

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.

Standardization of Provisions for Interworking of Data Terminals on an ISDN with DTE on Existing Networks...... 2TR-45.3, Digital Cellular Subcommittee, February 25 - March 1, 1991, Bellevue, WA.................................... 8

TR-45, Cellular Systems Committee............................................................................................ 8TR-45 WG1, Systems Engineering............................................................................................. 8TR-45.0.1, Joint Experts Meeting.............................................................................................. 8TR-45 WG2, Program Management............................................................................................. 9TR-45.3, Digital Cellular Subcommittee....................................................................................... 9TR-45.3 WG1, User Needs and Services........................................................................................ 9TR-45.3 WG2, Dual-Mode Standards........................................................................................... 10TR-45.3 Roster, February 25 - March 1, 1991, Bellevue, WA............................................................. 15

TR-41 Telephone Terminals, March 4-8, 1991, Baltimore, MD................................................................. 15TR-41.1 PBX and ISDN Terminating Equipment.............................................................................. 15TR-41.1.1 Loss/Level.............................................................................................................. 16TR-41.1.2 Private Network Synchronization................................................................................. 17TR-41.3 Telephones and ISDN Terminals...................................................................................... 17TR-41.4 NCTE...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18TR 41.7 Environmental and Safety Considerations.......................................................................... 19TR-41.OV Over Voltage Working Group....................................................................................... 19TR 41.8 Building and Wiring..................................................................................................... 19TR 41.9 Regulatory Considerations............................................................................................. 20TR-41 Roster, March 4-8, 1991, Baltimore, MD............................................................................. 20

TR-30.3 Ad Hoc, March 13 - 14 , 1991, Redbank, NJ............................................................................. 21TR-30.3 Ad Hoc Roster, March 13 - 14 , 1991, Redbank, NJ.............................................................. 22

CCITT Study Group VIII, Telematic Terminals and Protocols , March 18 - 27, 1991, Geneva, Switzerland............. 23Group 3 facsimile (Q3, Q18)...................................................................................................... 23Facsimile (Group 3/Group 4) Interworking (Q.4, Q18):..................................................................... 24Group 4 Facsimile (Q.4)........................................................................................................... 24Modulation Techniques for Telematic Services (Q.5)........................................................................ 24Terminal Characteristics for Mixed Mode and Processable Mode (Q.6).................................................. 24Coding of Alphanumerical Characters and Associated Control Functions (Q.8)........................................ 25Protocols for Interactive Video Services( Q.9)................................................................................ 25Teletex (Q.10) ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Conversion/Image Conversion Rules (Q.11).................................................................................. 25Telematic Interworking (Q.12)................................................................................................... 25Videotex (Q.14).... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Protocol Aspects of Interactive Videotext (Q.15)............................................................................ 26Common Components for Image Communications (Q.16)................................................................. 26Telematic Interfaces to ISDN (Q.17)............................................................................................. 26Session Control Procedures for Telematic Services (Q.21)................................................................. 26Audiographics Teleconferencing (Q.23)........................................................................................ 26Communication Application Profiles (Q.24).................................................................................. 26Document Application Profiles (Q.26)......................................................................................... 26Document Architecture, Transfer and Manipulation (Q.27)................................................................. 27Roster of CCITT Study Group VIII, March 18 - 27, 1991, Geneva, Switzerland........................................ 27

Meeting Schedules as of April 12, 1991.............................................................................................. 28

COMMUNICATIONS STANDARDS REVIEW

2 Vol. 2.2 Copyright © CSR 1991 April, 1991

STANDARDIZATION OF PROVISIONS FOR INTERWORKING OFDATA TERMINALS ON AN ISDN WITH

DATA TERMINALS ON EXISTING NETWORKS

1. INTRODUCTION

The provision for the interconnection of terminals on an Integrated Services Digital Network (ISDN) with terminalson existing networks is essential to the evolution of ISDN. While ISDNs will grow on the basis of applicationsthat take advantage of their end-to-end digital connectivity and robust signaling capability, many applications willrequire continued connectivity to terminals on existing networks. Provision for such interworking is being givenincreasing attention in the standards arena, both nationally and internationally.

The primary focus of this paper is on the status of standards for the interworking of data terminals using circuit-modeservices. The existing network of primary concern is the public switched telephone network (PSTN). The conceptsdiscussed are equally applicable to scenarios where either or both the ISDN and existing network is private.

Provisions in the existing ANSI standards and CCITT Recommendations in the 1988 Blue Books for theinterworking of non-voice terminals (including data and facsimile), where the ISDN terminal uses the 3.1 kHz audiobearer service, and for the interworking of voice terminals are described first. This is followed with a discussion ofprovisions in evolving new Recommendations for interworking with terminals on existing networks of non-voiceISDN terminals (referred to hereafter as ISDN data terminals) that use digital bearer services. The newRecommendations cover interworking arrangements that include a layer 1 interworking function (IWF) as well asnew signaling protocols to support terminals that use 64 kbit/s bearers for intra-ISDN connections and 3.1 kHzaudio bearers for ISDN/PSTN interworking. It is suggested that growth in the use of ISDN circuit mode services fordata applications will involve the use of digital bearers as opposed to 3.1 kHz bearers for intra-ISDN connections andthat ISDN terminal configurations of the latter type are likely to be of greatest importance in the near term.

Finally, with the necessary provisions for interworking with terminals on existing networks in place, theavailability of economical ISDN user access technology and new developments in facsimile terminals can be ex-pected to be a major stimulant to the deployment of ISDN during the next few years.

2. BASIC ISDN/PSTN INTERWORKING -3.1 KHZ AUDIO BEARER SERVICE

The ISDN/PSTN circuit-mode interworking scenarios covered by existing standards are illustrated in Figure 1. Theconnection of a voice and a data terminal to an ISDN basic access, using a passive bus or other means of supportingmultiple terminals on a single ISDN basic access, is illustrated. Voice (telephone) and data (DTE with modem)terminals are shown connected to the PSTN.

The overlay of the ISDN on the PSTN in Figure 1 illustrates that, during the evolution to ISDN, PSTN service willcontinue to be available everywhere. A variety of economic and service considerations will determine when and if aPSTN user moves to ISDN (and the extent to which ISDN circuit mode services will be used). The availability ofsuitable provisions for interworking with terminals on the PSTN will be an important consideration.

The interworking of the terminals in Figure 1 is relatively straight forward. The ISDN terminals (voice or data) use"Speech" or "3.1 kHz audio" bearer capabilities and standard pcm coding consistent with the coding of analog signalsin the telephone network. (The essential difference between the two types of bearers is that bandwidth compressioncapabilities that are incompatible with modems (including G3 facsimile terminals) are not permitted in 3.1 kHzaudio connections.) Where analog transmission facilities are encountered in either ISDN/ISDN or ISDN/PSTNconnections, the appropriate A/D conversion is automatically provided.

Figure 1 goes here. Please see inserted page

Figure 1. ISDN/PSTN interworking using Speech and 3.1 kHz audio bearer capabilities



* Whether the terminals are connected at an interface located at reference point S or T is not important to the discussion inthis paper - neither is the fact that the interface with the public network is normally on the network side of the NT1,commonly referred to at the "U" reference point (not shown).

Connections are established for calls from terminals on the ISDN to the terminal associated with the called directorynumber, whether it is for a terminal on the ISDN or the PSTN.

Calls to data terminal(s) on an individual ISDN access are to be distinguished (according to CCITT Rec. I.333) fromcalls to the voice terminal(s) on the same access by the assignment of different directory numbers. For calls fromthe PSTN, the signaling doesn't provide for carrying such a distinction. Given the assignment of different directorynumbers, the establishment of calls from the PSTN to the ISDN is as straight forward as for calls between terminalson the PSTN.

The capabilities available for the selection of a terminal from among multiple terminals on an ISDN basic access forintra-ISDN calls include the ISDN signaling Information Elements (IEs): Bearer Capability (BC), Low LayerCapability (LLC) and High Layer Capability (HLC). However, during the evolution of ISDN, applications requiringinterworking of terminals on ISDN with terminals on different networks will be common; the use of individualdirectory numbers, for terminals on the same ISDN access, to facilitate the selection of the desired terminal can alsobe expected to be common. However, provision in terminals to examine the three IEs will still be important.

3. ISDN/PSTN INTERWORKING - 64 KBIT/S BEARER SERVICES

During the initial stages of the development of standards for ISDN, there was considerable discussion of the supportof interworking for ISDN data terminals that take full advantage of the 64 kbit/s digital connectivity of ISDN, inboth the national and international standards' arenas. There has recently been renewed interest in related interworkingissues; efforts are being made to solidify provisions for such interworking in CCITT Recommendations.

3.1 ISDN Data Terminal Configurations

Interworking scenarios for the three basic ISDN data terminal configurations are illustrated in Figure 2. Terminalconfiguration (a) is the same as illustrated in Figure 1 and uses the 3.1 kHz audio bearer.

Figure 2 goes here. Please see inserted page

Figure 2 ISDN Data Terminal Configurations - ISDN/PSTN Interworking Scenarios * The designation TE2 is used in ISDN standards to denote a terminal with a non-ISDN interface. POTs telephones and DTEs

with interfaces conforming to TIA/EIA 232 C (or D or E) are the most common TE2s. TE1s have ISDN standarduser/network interfaces.

Terminal configuration (b) uses ISDN digital bearers (normally unrestricted [clear] 64 kbit/s bearers; such terminalscould also use restricted or 56 kbit/s bearers). Such terminals can take full advantage of the digital connectivity ofISDN, but, as illustrated in Figure 2, they require a layer 1 interworking function (IWF) for interworking withterminals on the PSTN. The IWF includes modem and terminal adaption functionality. The IWF can also providefor the interworking of such terminals with terminals of configuration (a). The IWF is a shared resource. Its use isgenerally most attractive where it is shared by a large number of terminals and where the usage by individualterminals is small. However, the factors that would be considered in any decision to provide (by a network) or use(by a customer) such a function are far too complex to be summarized by a single sentence. The interworkingscenario is being covered by a proposed CCITT Recommendation (I.516) concerning IWFs that include modempools. It will cover provisions for interworking of DTEs on PSTNs with ISDN terminals that use packet-mode aswell as circuit-mode ISDN services.

Terminals of configuration type (c) are capable of using either 64 kbit/s digital bearers or 3.1 kHz audio bearers. Theconfiguration provides for taking full advantage of the digital connectivity of ISDNs while not requiring layer 1IWFs for connections to terminals on the PSTN. Although this capability is achieved at the expense of increasedterminal complexity, the increased complexity is not significant for many terminals. (By integrating the CODEC



and modem function [creating a "digital modem"], the costly conversion function can be omitted although terminaldesigners may choose to include the functionality necessary to permit to alternate use of the terminal in PSTNapplications.)

G4 (and planned G3 64 kbit/s* ) facsimile terminals are expected to be very important examples of type (c)terminals. However, facsimile terminals do not require the terminal adaption function in the digital mode.It is important to note that all three configurations can take the form of a TE1. As noted above, plans for facsimileterminals would have the adaption function built in; such facsimile terminals would therefore be TE1s. Theimplementation of TE1s compatible with configuration (b) terminals had been assumed in the development ofterminal adaption Recommendations V.110 (I.463) and V.120 (I.465). This was a major consideration in thedevelopment of a Recommendation V.120.

3.2 Terminal Configuration (c) Interworking

Considerable attention is presently being given to supporting terminals using configuration (c). For calls to suchterminals from similar terminals or type (b) terminals on the ISDN, the call would be answered using the 64 kbit/sbearer and the digital mode. For calls from G3 terminals on the ISDN or the PSTN, the call would be answeredusing the 3.1 kHz bearer and the corresponding mode.

For calls from the ISDN terminal, the call establishment procedure presently being considered is being developed inassociation with facsimile Recommendations in CCITT SG VIII. In this call establishment procedure, the terminalinitially originates the call specifying 64 kbit/s BC. If the call is rejected, the terminal automatically re-originatesthe call specifying a 3.1 kHz audio BC. The calling terminal would revert to G3 mode. If the call is rejectedbecause of a called terminal or network busy condition, the call could be re-originated, using the same bearer, at alater time. The specific conditions (e.g., BC not authorized) under which the call is re-originated using thealternative BC as opposed to re-originated using the same BC (e.g., user busy) are the subject of continued study ingroups responsible for interworking issues in CCITT SG XVIII and in groups responsible for signaling in SG XI.

Although this approach for call establishment does not require any special network capabilities, it does delay thecompletion of the call and uses network facilities and signaling resources twice when re-origination is required as aresult of terminal incompatibility. For these reasons, a proposal was developed in T1S1 to use a signaling proceduredefined for the 7 kHz audio bearer service for data applications. The procedure, which would use the BC presentlylabelled 7 kHz audio, would permit a call, initiated to a number, to be completed to a digital or a G3 facsimileterminal. The BC has the attributes of the 64 kbit/s BC, but (1) it is capable of having echo control and A/µ lawconversion* introduced to conform to the requirements of a 3.1 kHz audio or a Speech BC, and (2) it provides tonesand announcements. It is proposed that the 7 kHz audio BC be relabeled "Multi-Use" (MU) BC to reflect itssuitability for the data application. The MU-BC concept has been accepted in T1S1 and was tentatively accepted inSG XVIII at its December, 1990 meeting. It is expected to be considered at the Spring meetings of SGs I (Services)and XI (Signaling). Its capability to fall back to 3.1 kHz audio makes the BC attractive for the data application.(With clear digital transport rapidly becoming less expensive than those that support speech [for nationalconnections], the term "raise up" rather than "fall back" might be more appropriate.)

The procedure tentatively defined in SG XI for using the MU-BC, which would be relabeled MU, permits terminalsto specify two alternative BCs in the SETUP message. It provides for the call to be offered with both BCs specifiedand for the completion of a call to a terminal that uses either BC. It provides a means of indicating (in theCONNECT message) to the calling terminal the BC of the answering terminal. For the data application, the BCswould be 3.1 kHz audio and MU (as opposed to Speech and MU for the 7 kHz audio application). The networkwould introduce echo control and A/µ law conversion as appropriate. However, neither echo control nor A/µconversion are needed for most data applications. Most data terminals would disable echo control devices if theywere introduced. Many type (c) terminals would be designed for use in either A or µ law regions. For suchterminals, provision for automatically adapting to the coding law of the far terminal would be a minor addition.

Concerns were expressed by one interexchange carrier at the March meeting of T1S1 that the A/µ law conversionand echo control capabilities may be required when a 7 kHz audio connection falls back to a 3.1 kHz audio connec-tion. However, neither capability is required for the data application on North American connections. As stated

* G3-64 kbit/s (previously referred to as G3 bis or G3 ISDN) terminals would use the G3 facsimile algorithms but operate atrates of 56 or 64 kbit/s.* The need for the introduction of A/µ law conversion on international connections was recognized only recently and is notyet explicitly covered in the service definition or in the signaling procedures.



above, echo control is not required for most data applications, either nationally or internationally. Therefore, a delayin achieving standards agreements necessary for the full MU capability would not necessarily delay standardizing theprocedures for supporting the service on a national basis. Agreement on provisions for supporting the 2BC accessprotocol and the BC IE in the CONNECT message is all that appears to be necessary. And if digital facsimileterminals are priced as suggested below, there will soon be a stampede to complete agreement on the remainingprocedures or proprietary mechanisms will be introduced.

3.3 Terminal Configuration (b) Interworking

The standardization of provisions for interworking of type (b) terminals with terminals on the PSTN is not asadvanced but a draft of a new Recommendation (I.516) covering the required layer 1 IWF is under consideration in SGXVIII Working Party 2. The Recommendation will cover provisions for the interworking of both ISDN circuit- andpacket-modes with the PSTN. Clearly, such arrangements become most attractive where the intra-ISDN traffic islarge compared to the traffic between terminals on ISDN and terminals on PSTNs. However, other considerationsmay justify their introduction at an earlier stage in the evolution to ISDN.

The discussion here of this interworking scenario is limited to the most basic of the considerations. The detailedprocedures, including the various alternatives, are beyond the scope of this paper. The layer 1 IWF includes modemand terminal adaption functionality. The appropriate modem and terminal adaption functionality is application-dependent. In general, for every call originated by an ISDN type (b) terminal and for every call from the PSTN tosuch a terminal, the following tasks must be performed:i. Determine if the call requires a layer 1 IWF

ii. Select a modem/TA pair and associated parameters to ensure compatibility of modems across the PSTNsegment and commonality of TA protocols across the ISDN (digital) segment.

iii. Provide the necessary call setup and connection control and insert the layer 1 IWF in the connection.

iv. Provide for the establishment of the data circuit; i.e., the layer 1 transmission path between the DTE/DCEinterface of the DTE on the PSTN and the interface at the R reference point for the TE2 on the ISDN (or thelogical equivalent of this interface in a TE1).

There are two general approaches to determining the need to insert a layer 1 IWF in a connection for ISDN/PSTNinterworking:

i. Mechanisms that do not depend upon the calling terminal user knowing either the network (ISDN or PSTN) onwhich the called terminal is located or the called terminal characteristics, and

ii. Mechanisms that depend upon the calling terminal user providing this information.

The inclusion of "knowledge of terminal characteristics" as a factor in distinguishing (i) and (ii) recognizes the useof layer 1 IWFs in providing for the interconnections of type (a) and (b) terminals. In this case, the factor thatdistinguishes the called terminal is the BC it uses.

Category (a) mechanisms are compatible with a "single-stage" call establishment procedure. Category (b)mechanisms typically use a "two stage" call establishment procedure. The choice between single- or two-stage-call-establishment approaches is dependent upon a variety of factors, particularly application related factors. It is normal(common practice) in circuit mode data for users to be responsible for calling only terminals that are compatible.The PSTN user, however, is not accustomed to knowing whether the terminal is on the ISDN (and that an IWF isrequired) or on the PSTN. If the terminal is on the ISDN, the user must know the configuration of the calledterminal to determine use of a 3.1 kHz audio bearer or a digital bearer capability.

Maintaining information on the network on which a particular called terminal is located and the configuration ofeach called terminal would be difficult because terminals can be expected to migrate to ISDNs and the configurationof the terminals on the ISDN can be expected to change over time. This suggests that arrangements using the two-stage approach may not be suitable for many public-network, circuit-mode applications. The opposite may be truefor packet-mode applications. In any event, the two-stage call establishment approach is discussed only briefly here.



3.3.1 Two Stage Call Establishment

In two stage call establishment, the user indicates the need for the insertion of a layer 1 IWF by dialing a numberassigned to the IWF (note that PSTN signaling doesn't provide the user with the means of indicating the networktype of the called terminal). The number of the called terminal is signalled in the second stage. Different directorynumbers can be assigned to IWFs having different functionality (e.g., support of different modem types) therebyavoiding the need for other means of selecting IWF parameters.

3.3.2 Single Stage Call Establishment

• Layer 1 IWF location: The current draft of I.516 states that layer 1 IWFs are located in association with allISDN exchanges that serve ISDN data terminals that (i) use digital bearers and (ii) receive calls from terminals on thePSTN. It is also assumed that layer 1 IWFs are located in association with exchanges at the ISDN-PSTN boundaryfor calls from data terminals on ISDN to data terminals on the PSTN. Note that the ISDN boundary may not be atthe PSTN called terminal exchange. The draft of I.516 also notes that it may be inappropriate to locate IWFs inassociation with all boundary exchanges and that it may be more appropriate to locate IWFs in calling ISDNterminal exchanges. The issues involved are beyond the scope of this paper but it should be noted that provision forsupport of ISDN/PSTN interworking using a layer 1 IWF could require IWFs in all local exchanges.

The I.516 draft covers locations within a network (public or private) and on a customer's premises.

• IWF selection: For PSTN-to-ISDN calls, the I.516 draft notes that ISDN exchanges will also provide PSTNaccess and, therefore, that networks can determine that a call is for a terminal on an ISDN access at the called ter-minal exchange only. A determination of the need for the insertion of a layer 1 IWF can only be made on the basisof information concerning or provided by the called terminal. This information can be either the profile of the calledterminal (or the profile associated with the called number) or information in a message element, e.g., BC and/or LLCin the CONNECT message (or other message sent by the called terminal). Additional interworking alternatives maybe included in the draft Recommendation as it is developed. However, whether the exchange obtains the informationfrom a profile stored in the exchange or from a message from the called terminal, it recognizes that the call is for aterminal that uses a digital bearer and inserts the IWF.

For ISDN-to-PSTN calls, when a call leaves the ISDN and the appropriate call progress indicator is returned to thecalling terminal, a layer 1 IWF should be inserted and the call should progress as a PSTN call.

• Interworking function parameter selection: These parameters include: modem type, transmissionspeed, sync vs async and associated parameter, terminal adaption protocol and associated parameters, etc. A moredetailed list in given in the draft of I.516. The list depends upon the range of terminal types (particularly terminaladaption protocols) supported.

The procedures for IWF parameter selection discussed in the draft of I.516 are based on the same mechanismsspecified for the determination of the need for an IWF. The fundamental consideration is the dependence uponinformation provided by the ISDN terminal. However, it is proposed that modem selection can be simplified bylimiting modem types to those that can be implemented in a modem with Automode capabilities as specified inAnnex A of V.32 bis. This would limit modem types to FDX modems covering the rates from 1200 to 14,400bit/s, although the addition of provision for 100-series modems is possible. More importantly, this would not covermodems used by facsimile terminals. It is suggested that facsimile terminals may evolve directly from type (c)configurations to type (b) without the need for layer 1 IWF arrangements. Alternatives may be considered as themarket evolves.

Both the complexity of IWFs and associated signaling could be minimized by limiting the terminal adaptionprotocols supported. A major part of the support for the standardization in T1S1 of ANSI T1.612 (CCITT Rec.V.120) was the desire to avoid supporting multiple proprietary protocols in network-provided IWFs. However, therewill be applications where multiple terminal adaption protocols will be required; the draft of proposedRecommendation I.516 takes these applications into account.



• Connection Establishment: The draft of I.516 also provides guidelines for connection establishment anddata circuit establishment such that the connection would appear to the interconnected terminals the same as if theIWF were not needed.

4. CONCLUSIONS/COMMENTS

Standardization of provisions for ISDN/PSTN interworking for circuit mode applications is proceeding in Nationaland International standards forums. Existing standards provide for interworking of data terminals on an ISDN thatuse the 3.1 kHz audio BC. Because such terminal configurations use the ISDN essentially as an analog network(PSTN) and must include the modem function (which restricts their transmission rate), they cannot take fulladvantage of the digital transport of ISDNs and are therefore of an interim nature.

Standardization of provisions to support interworking for terminals that take full advantage of the digitalconnectivity of ISDNs is being actively pursued. The provisions, reflected in draft standards, cover the support ofterminals that provide for alternatively using digital (e.g., 64 kbit/s unrestricted) and 3.1 kHz audio bearers as well asterminals that use only the digital bearers. Terminals that provide for alternatively using 3.1 kHz audio as well asdigital bearers may be viewed as an interim arrangement; however, the interim terminal configurations can beexpected to be used for various applications for an indefinite period of time. It is clearly the most attractiveconfiguration at this time.

The completion of standards will depend upon the pressure from industry, which in turn depends on the growth ofapplications and the availability/cost of ISDN services. While comments about the relatively slow growth in ISDNare common, it has been relatively rapid considering the major changes in technology required. And we are only onthe threshold of realizing the benefits of the new ISDN technology. Although important new switching andsignaling capabilities are being put in place, an equally fundamental change required for ISDN is the digitalsubscriber line. ISDN will provide more economical digital connectivity to the customer. Standardization of thetechnology for the basic access digital subscribers line was completed in 1988 and product announcements by siliconhouses have become common. Competition in the provision of this silicon is driving down its cost and should re-sult in ISDN basic access costs below the cost of two POTS lines. Since ISDN basic access provides for two 64kbit/s channels, usable for voice or data, and a 16 kbit/s channels, used for signaling and packet-mode data, thismeans that, for many users, ISDN will be less expensive than POTS and can provide dramatically enhanced datatransport capabilities.

The rapidly developing facsimile market and the enhanced facsimile capabilities provided by digital facsimileterminals designed to use ISDN (and pre-ISDN switched digital network capabilities) will be significant stimulantsto the evolution of ISDN; the evolution of ISDN digital circuit mode services should enhance the growth of thefacsimile market.. The expected competition between the G4 and G3 64 kbit/s implementers is already resulting intalk of digital facsimile terminals comparable in cost with quality G3 terminals and able to provide a many-foldenhancement of performance. The combination of lower basic access costs and the development of digital facsimileterminals should result in a major increase in demand for ISDN. The standardization of the new MU bearerservice to provide interworking of the new digital terminals (particularly facsimile) withexisting terminals will be an important factor in assuring that the service provided isattractive .

The general availability of ISDN at a reasonable cost can also be expected to stimulate new applications which maybecome more important than presently known applications. While it would be pure speculation to argue thatprovisions for interworking will be essential for the ISDN circuit-mode data applications of the mid-90s, having theappropriate standards in place will be important to assure the smooth evolution of ISDN.

Larrabee M. Smith, Holmdale, NJ.Mr Smith is a consultant specializing in ISDN and Data Communications Technology. He retired from AT&T BellLaboratories in 1989 and has been active in ISDN standards nationally and internationally for ten years. He isRapporteur for the question concerning the adaption of existing terminals to an ISDN in CCITT Study Group (SG)XVII and Editor of proposed Recommendation I.516 in SG XVIII. He was Chairman of T1D1.3 (T1S1.4) during thedevelopment of the ISDN basic access "U" interface standard (ANSI T1.601-1988), the corresponding S/T interfacestandard (ANSI T1.605 -1989) and the terminal adaption standard (ANSI T1.612-1990) which corresponds to CCITTRec. V.120.

Acknowledgments: The author wishes to acknowledge the helpful comments of Dr. R. M. Ephraim of Bellcore andDr. H. R. Silbiger, Applications and Communications Consultant.



REPORT OF TR-45.3, DIGITAL CELLULAR SUBCOMMITTEEFEBRUARY 25 - MARCH 1, 1991, BELLEVUE, WA

TR-45, CELLULAR SYSTEMS COMMITTEE

TR-45 did not meet in conjunction with TR-45.3; however, its two working groups did.

TR-45 WG1, SYSTEMS ENGINEERING

Many services supported by IS–54 are not supported by other cellular standards. Requirements need to becommunicated, via Service Descriptions, among TR-45 and its subcommittees. TR-45.0 .1 /91 .02.28.04(IMM) and TR-45.0 .1 /91 .02.28.05 (Synacom) propose a template for such service descriptions using CallingNumber Delivery as an example. The contributors will identify differences in the two proposals and present asummary of these differences to the next meeting.

Via TR-45.3 .A/91.02.26.01 , TR-45.2 (Intersystem Operations Subcommittee) submitted 10 questions onauthentication and privacy to the Ad Hoc Authentication Group. The contribution is the same as TR-45.0.1/91.02.07.03, submitted to TR-45.0.1’s previous meeting.

Once changes to IS–53 (Cellular Features Description) resulting from its ballot have been incorporated, the changeswill also be reflected in IS–71 (Cellular Mobile Telephone Service Descriptions — CMTSD).

TR-45.0 .1 /91 .02.28.03 (Hughes & McCaw) lists services in IS–71 and classifies each service as a bearerservice, teleservice, or supplementary service. It also shows the priorities GSM has assigned to their versions of theservices. The working group will develop service-priority recommendations and forward these recommendations toTR-45. Contributions are invited.

TR-45.0.1 agreed to subsume the functions of the Editorial Task Force, TR-45.3.3.3. As a result, the chairman ofTR-45.3.3.3 recommended to TR-45.3.3 that the Editorial Task Force be dissolved. TR-45.3.3 accepted therecommendation.

TR-45.0.1, JOINT EXPERTS MEETING

To assure that IS–41 (the intersystem operations standard), IS–54, and EIA–553 (the analog radio compatibilitystandard) support authentication and privacy, TR-45.0.1 sponsored a Joint Experts Meeting (JEM). Authenticationis a high priority since cellular carriers’ 1990 losses due to roamer fraud exceed $80 million. Carriers incurred theselosses despite their use of Positive Roamer Validation. The meeting generated user requirements, conclusions, andbroad recommendations which will be submitted to TR-45.0.1 in a report.

The JEM recognizes that smart-card technology is evolving. JEM recommended to the extent possible, that the TR-45 subcommittees should take no action which would preclude use of this technology. In the future, TR-45.0.1should study the smart-card concept.

Abbreviated user requirements are listed below:

1. Authenticate mobile stations whether they are assigned to an analog traffic channel or a digital traffic channel.

2. Authenticate roamers in the HLR/AC (Home Location Register / Authentication Center).

3. Detect fraud before a fraudulent roamer places his first call.

4. Provide voice privacy on the digital traffic channel.

5. Deter hijacking of traffic channels.

6. IS–54B shall support the above requirements.



7. EIA–553 shall support the above requirements to the extent possible.

8. IS–41C shall support the above requirements to the extent possible.

TR-45 WG2, PROGRAM MANAGEMENT

The group discussed its charter and recommended changes.

TR-45.3, D IGITAL CELLULAR SUBCOMMITTEE

TR-45.3 approved IS–55 and IS–56 for ballot. TR-45.3 also approved transmittal of a letter to PacTel (TR-45 .3 /91 .03 .01 .02 ). The letter, drafted by TR-45.3.4, deals with issues raised by PacTel in their ballot responseto IS–54A. The response is summarized below:

• Capacity. IS–54A provides tools to increase capacity, but system implementations determine actual capacity. Anew working group (System Performance) has been set up to deal with capacity issues.

• Quality. The voice coder selected for IS–54 provides better voice quality than analog FM.

• Carrier to Interference. Minimum standards for C/I performance are included in IS–55 and IS–56. This is thefirst time C/I performance has been specified in any North American cellular standard.

TR-45.3.A, AD HOC AUTHENTICATION GROUP

This group was set up to develop recommendations on subscriber authentication and voice privacy. As required bythe International Traffic in Arms Regulations, membership is limited to U.S. citizens, permanent legal residents ofthe U.S., and Canadians.

At the last two meetings, AT&T proposed new authentication and privacy schemes, but their proposals were notadopted. The authentication system is still based on a government-approved proposal from Ericsson GE.

B. Kratz (Ericsson) reported that the U.S. government has not yet recommended procedures for controllingdistribution of the encryption algorithms. Once the government has developed a procedure, TIA procedures should beeasy to establish.

K. Roeder (Uniden) volunteered to help prepare text on test procedures for IS–55 and IS–56. Tests must bedeveloped that do not compromise the authentication algorithms.

TR-45.3 WG1, USER NEEDS AND SERVICES

Working Group 1 started to verify and validate IS–71.

IS–71 , Ce l lu lar Serv ice Descr ipt ions (PN–2717)

IS–71 remains unchanged while TR-45.3.1 conducts a verification and validation. TR-45.3 .1 .1 /91 .01 .22 .01 isthe latest revision: Revision 10, 22 Jan 91.

TR-45.3 .1 /91 .02.27.05 presents the results of the CMTSD (Cellular Mobile Telephone Service Descriptions)review performed by TR-45.2.

Some services require more complete descriptions from the working group. These services are voice confidentiality,identity authentication, identity confidentiality, message handling (store and forward), user and signaling dataconfidentiality, user-to-user signaling, and vehicle location.



TR-45.3 WG2, DUAL-MODE STANDARDS

The Working Group received copies of PN–2216 (IS–55) and PN–2217 (IS–56) from the Chairmen of TF 1 andTF2, respectively. All outstanding Discrepancy Reports were cleared. The documents were forwarded to TR-45,where they were approved for ballot.

A motion was made to include digital-control-channel specifications in IS–54. It failed for lack of a second.TR-45.3 .2 .4 /91 .02 .28 .01 (Bell Cellular & Uniden) recommends that Message Waiting Notification beimplemented on the analog forward control channel (it now functions only on FACCH in dual-mode). The proposalraises a significant issue: Should dual-mode features be retrofitted to analog mobile stations, and if so, when?Migration of features back to analog will be discussed at the next meeting.

Assignment of message codes will have to be coordinated among all task forces in TR-45.3. The editor of IS–54will recommend a procedure.

IS–54A, Dual -Mode MS-BS Compat ib i l i ty (PN–2398)

IS–54A has been approved for publication.

IS–54B, Dual -Mode MS-BS Compat ib i l i ty (PN–2759)

IS–54B will be released for ballot when text on subscriber authentication and voice privacy has been incorporated. Itwill replace IS–54A. The following contributions were adopted.

TR-45.3 .A/91.02.25.04 , “No Prior Knowledge” Authentication Method Using Home-System GenericEncrypted Values with Existing Ericsson Algorithm (Beta Lab), proposes an authentication method that does notdepend on real-time links between the visited MSC and the home MSC. Two new inputs to the authenticationalgorithm replace A-key (Personal Identification Number) and ESN (Electronic Serial Number) when the mobilestation is roaming. The proposal was adopted in that the new baseline text incorporates a similar scheme using C-key.

The contribution also proposes adding stand-alone authentication to the analog control channel. This allows suitablyequipped analog systems to authenticate IS–54B mobile stations.

TR-45.3 .A/91.02.25.07 , Second Base Line Text Proposal for Authentication and Privacy (Ericsson GE),proposes second draft of text for IS–54B to support authentication and voice privacy. The text includes a keyenhancement, Stand-Alone Authentication, which allows roamers to be authenticated without requiring real-timelinks to the home system.

TR-45.3 .A/91.02.27.02 , Untitled (Ericsson GE), adds a page of baseline text missing from TR-45 .3 .A/91 .02 .25 .07

TR-45.3 .2 /91 .03.01.01 , Modified Power Up/Down Registration (Ericsson GE & Bell Cellular), proposes amodified method (compared to earlier Bell Cellular proposals) for power-up/power-down registration. Since powered-down mobile stations do not have to be paged, power-up/power-down registration reduces paging traffic on theforward control channel. The proposed method supports the following types of registrations: time-based (REGID),location-based (LOCAID), or both. The contribution includes eight pages of proposed changes. Final text will beadopted at the next meeting of TR-45.3.2.

The following contributions were deferred:

TR-45.3 .A/91.02.25.08 , Proposed Use and Consequences of Allowing the Dialed Digits to Affect theAuthentication Response (Motorola)

TR-45.3 .2 /91 .03.01.02 , CPA Operation Text Enhancements (Ericsson GE)TR-45.3 .2 /91 .03.01.05 , Proposed new protocol to facilitate Base Station C/I measurement (NovAtel)

IS–55, Dual-Mode MS Performance (PN–2216)IS–56, Dual-Mode BS Performance (PN–2217)



IS–55 and IS–56 were approved for ballot. TR-45.3 .2 /91 .03.01.04 (IS–55) and TR-45.3 .2 /91 .03.01.03(IS–56) incorporate the adopted changes noted below.

The following contributions pertaining to IS–55 were adopted:

TR-45.3 .2 .1 /91 .02 .26 .04 , Modifications to Carrier Switching Time Measurement (HP)TR-45.3 .2 .1 /91 .02 .26 .06 , Statechart for PN2216 Test Mode (NovAtel)TR-45.3 .2 .1 /91 .02 .26 .07 , Revised Test Interface figure (NovAtel)TR-45.3 .2 .1 /91 .02 .26 .08 , Modifications to PN2216 (Motorola)TR-45.3 .2 .1 /91 .02 .26 .11 , Modifications to TR-45.3.2.1/90.6.19.09 (Motorola)TR-45.3 .2 .1 /91 .02 .26 .12 , Environmental Degradations in IS55 (Hughes)TR-45.3 .2 .1 /91 .02 .26 .13 , Response to Verifi-cation and Validation Groups Comments Concerning Speech

Transmission in PN2216 (McCaw). One substantive addition: A note is added to §3.5.2.2: “Acoustic conditionsfor the measurement of the echo loss of digital mobile speakerphone terminals is under study.” In other words,the section explicitly omits measurements for hands-free mobile stations; however, manufacturers should notethat requirements for hands-free units are likely to be similar, if not identical, to requirements for handset units.The issues under study involve test conditions, not performance requirements.

The following contributions pertaining to IS–55 and IS–56 were adopted.

TR-45.3 .2 .1 /91 .02 .26 .03 , Untitled (HP). A compendium of contributions. Each addresses an outstandingdiscrepancy report (DR) for IS–55, IS–56, or both.

TR-45.3 .2 .1 /91 .02 .26 .05 , Proposed modifications to phase correlation requirements for the Standard ChannelSimulator (NovAtel), specifies the theoretical phase autocorrelation function of the Standard Channel Simulatorand the Doppler frequencies to be used for simulating various vehicle speeds. The contribution was amended toshift the test channel from 366 to 367.

TR-45.3 .2 .1 /91 .02 .26 .10 , Modifications to TR-45.3.2.1/90.6.19.09 (Motorola), recommends that no changesbe made to the digital intermodulation sections. The sections were challenged by a discrepancy report.

TR-45.3.2 T ASK FORCE 3, VOICE-CODER TESTING

The Task Force received and adopted several contributions for IS–XX, the full-rate speech codec performance standard.By May, IS–XX may be ready for verification and validation.

IS–XX, Full-Rate Speech-Coder Performance (PN–2745)

An “IS” number has not yet been assigned for this standard. The following contributions were adopted.

TR-45.3 .2 .3 /91 .02 .27 .03 , Correction for Master Coder Software (Motorola). The original C source code canlead to twos-complement overflows at the output of the decoder. The bug is fixed by replacing the source code in“vselp.c” with the new code given in the contribution.

TR-45.3 .2 .3 /91 .02 .27 .04 , Decoder Accuracy (AT&T Bell Labs), provides baseline text for §2.1.4 on decoderaccuracy. The minimum performance standard is a threshold in the cumulative probability distribution of segmentalSNR: F(16 dB) < 5%.

The task force noted that another approach proposed by Teknekron is useful for identifying specific coder problems,but is overly complex for simple go/no-go evaluation. To help members analyze their coders, a Technical ServiceBulletin may be issued on the alternative method.

TR-45.3 .2 .3 /91 .02 .27 .06 , Draft Text for PN 2745 (Motorola), contains new baseline text for §1 and §3.5.The first section is a general introduction to the standard. The second section is a description of the master-codersoftware.

TR-45.3 .2 .3 /91 .02 .27 .07 , Untitled (BNR), contains text for §2.2.2.6 (Listeners), §2.2.4 (Expected Results forReference Conditions), and §3.1.2 (Subjective Test Equipment). It also corrects Exhibit 2.2.2.8-2 (Example SASprogram for Analysis).

TR-45.3 .2 .3 /91 .02 .27 .08 , Speech Source Material (IMM), provides a description of how the speech sourcematerial for PN–2745 is derived from the TIMIT data base, including the details of sampling, filtering,



concatenation, and file-naming. Yet to be resolved is how to concatenate speech material while avoiding theinclusion of zero padding at the ends of file blocks.

TR-45.3.2 T ASK FORCE 5, DATA SERVICES

TR-45.3 .2 .5 /91 .02 .26 .06 is the data-services matrix as of the previous meeting. The first column of thematrix lists the aspects of the data services that must be specified. The first row lists the services that will initiallybe considered: G3 Fax, STU III, and Asynchronous Data (300, 1200, 2400, 4800, and 9600 bits/s). The cells of thematrix will contain each contributing organization’s proposals. Once all the proposals are in, a final consensusmatrix can be negotiated and the task force can document their recommendations.

TR-45.3 .2 .5 /91 .02 .26 .03 (NSA & GTE) describes the STU-III teleservice and provides entries for the matrix.The following amendment was made to the proposed entries: the value for Information Transfer Error Rate waschanged from “Approx. 0.001 BER” to “Approx. 10–2 BER.” Note that STU-IIID is a specification beingdeveloped for a new digital-cellular module. A column will be added to the matrix for a new bearer service: 13 kbit/sraw channel. STU-III is expected to use this bearer service.

TR-45.3 .2 .5 /91 .02 .26 .04 (OKI) proposes FACCH messages and channel-coding techniques for fax and data.The contribution was deferred until the next meeting. TR-45.3 .2 .5 /91 .02 .26 .05 provides Northern Telecom’sinputs to the matrix. Supporting notes are included.

Other contributions dealt with tutorial information on facsimile:

TR-45.3 .2 .5 /91 .02 .28 .01 (Murata) includes an annotated series of protocol records from actual faxtransmissions; CCITT T.30, Procedures for Document Facsimile Transmission in the General SwitchedTelephone Network; and a copy of a slide presentation on the structure of FAX machines.

TR-45.3 .2 .5 /91 .02 .28 .02 (National Semiconductor) is an Introduction to Modern FAX Design published byNational Semiconductor.

Since 300-bits/s data service is rapidly becoming obsolete, a proposal was made to drop it from the matrix. D.Sattler (Motorola) will recommend to TR-45.3.1 that the service not be supported. If TR-45.3.1 agrees with therecommendation, the service will be dropped.

TR-45.3 WG3, DIGITAL STANDARDS

TR-45.3 .3 Task Force 1 , Dig i ta l Control Channel Matr ix

TR-45.3 .3 .1 /91 .02 .28 .03 is the new version of the Matrix.

Two contributions dealt with the Digital Control Channel:

TR-45.3 .3 .1 /91 .02 .28 .04 (Ericsson) proposes the use of a reservation Aloha scheme. The proposed set-upprocedure moves the mobile station to a traffic channel as soon as possible. This minimizes control channelusage.

TR-45.3 .3 .1 /91 .02 .28 .05 (Northern Telecom) proposes the use of an enhanced reservation Aloha protocolusing a Central Retransmission Control Scheme (CRCS). The proposed set-up procedure moves the mobilestation to a traffic channel as late as possible. A higher capacity is claimed for this approach. Another claimedfeature is higher throughput of user packet data.

TR-45.3.3 Task Force 2 , Half-Rate Voice Coder

The Task Force continues to investigate methods for evaluating half-rate coders. To foster open discussion, aseminar has been scheduled for the June meetings in Toronto. The seminar will concentrate on three areas:• International standards activities, chaired by M. McLaughlin of Motorola.• Current state of the technology. A chairman has not yet been selected.• Systems issues, chaired by A. Angus of NovAtel.

Contributions to the seminar are invited.



TR-45.3 .3 .2 /91 .02 .26 .03 (American Mobile Satellite Corporation) describes the evaluation of a low-bit-ratecoder (5.6 to 6.4 kbit/s) for an Australian mobile satellite system. The winning coder from MIT was claimed to besuperior to VSELP at these low bit rates.

The technology evaluation will not be advertised. Word-of-mouth is expected to attract a sufficient number of codersfor evaluation.

TR-45.3 .3 Task Force 3 , Editoria l

At the recommendation of TR-45.3.3.3’s chairman, Task Force 3 was dissolved. TR-45.0.1 will take over editorialfunctions.

TR-45.3 .3 .3 /91 .02 .25 .03 (IMM) is a copy of “Statecharts: A Visual Formalism for Complex Systems,”Science of Computer Programming 8 (1987), pp. 231–274, by David Harel. It describes higraph statecharts using adetailed example. A. Sacuta (IMM) informed the task force that the author also recommends a paper published inIEEE Transactions on Software Engineering, Vol. 16, No. 4. The IEEE paper is a good companion to TR-45 .3 .3 .3 /91 .02 .25 .03 . For the next meeting, A. Sacuta will propose conventions to be used in developinghigraph statecharts.

TR-45.3 .3 .3 /91 .02 .25 .04 , TR-45.3 .3 .3 /91 .02 .25 .05 , and TR-45.3 .3 .3 /91 .02 .25 .06 (NovAtel)provide information on Statemate, a product of i-Logix. Statemate is a set of system-development tools based onhigraph statecharts. It was agreed that TR-45.3.3 would be informed of the contributions, and that individualorganizations may contact i-Logix if they are interested.

A. Angus (NovAtel) pointed out that if statecharts are adopted, the task force may also want to adopt othermethodologies, e.g., activity charts and module charts. (Activity charts describe the functions of a system. Modulecharts describe a system from a physical or structural perspective.) A. Angus will bring examples of state-descriptionlanguages to the next meeting.

TR-45.3 WG4, SYSTEM PERFORMANCE

TR-45.3 .4 /91 .02.27.02 is a copy of the working group’s charter adopted at the last meeting. “The workinggroup will perform a systems-engineering function focussed on the issues of capacity, quality, and complexity. Itwill make recommendations in these areas that will lead to the development of new or amended digital cellularstandards.”

Four companies made presentations on system capacity:

• TR-45.3 .4 /91 .02.27.04 , Extended TDMA Capacity Explanation (Hughes). ETDMA is based on IS–54,but uses half-rate coding and digital speech interpolation to achieve 10 or more times the capacity of existinganalog systems.

• TR-45.3 .4 /91 .02.27.05 , Capacity Considerations (IMM). The contribution provides some considerationsfor determining the capacity of cellular systems. It points out that capacity gain falls into two categories: spatialcapacity gain and spectral capacity gain. It recommends that proposals should be evaluated on three criteria:spectral gain, backward and forward compatibility, and degree of modularity.

• TR-45.3 .4 /91 .02.27.06 , Cellular System Capacity (NTI). NTI proposes that five factors must be evaluatedin determining system capacity: units of capacity, traffic characteristics, service quality, propagation model, andsystem-engineering model.

• TR-45.3 .4 /91 .02.27.07 , Capacity Predictions for IS–54 Dual-Mode Cellular (McCaw). McCaw proposes acapacity-assessment model and provides some preliminary results. For IS–54, the model shows that capacitypeaks at approximately 140 Erlang/km2 using a cell radius of 0.6 km.

The working group adopted a work plan that sees capacity recommendations being forwarded to TR-45.3 by August,1991 (TR-45.3 .4 /91 .02.27.03 ).

The working group adopted the following recommendation from Hughes Network Systems (TR-45 .3 .4 /91 .03 .01 .03 ): Any combination of techniques that provides 370 Erlang/cell or 408 voice circuits per cellshall be defined to meet the UPR capacity requirement.



The working group also adopted the capacity model proposed by McCaw in their presentation. The model isdescribed in TR-45.3 .4 /91 .03.01.04 . Contributions are invited on how to validate the model.

An ad hoc group developed a list of factors that affect system capacity (TR-45.3 .4 / 91 .03 .01 .02 ). Four groupsof factors are listed: RF propagation-model factors, service-quality factors, system-engineering factors, and trafficcharacteristics.

Condensed from Cellular TechNotes, February, 1991. Next Generation Information Consulting, Alan Sacuta,V:403-251-1319, F:403-251-4414

THE CSR LIBRARY

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TR-45.3 ROSTER, FEBRUARY 25 - MARCH 1, 1991, BELLEVUE, WA

Peter Nurse (NovAtel) Chairman

Astronet Corp. David DeVaneyAstronet Corp. Tak ImamuraAT&T John MarinhoAT&T Phil TreventiAudiovox Lawrence HarteBellSouth Enterpr. Michael A. DanielBellSouth Mobility Thomas E. RichterEricsson GE John DiachinaEricsson GE Krister RaithEricsson Radio Barry KratzEricsson Walter MüllerGE Corp. R&D Howard LesterHughes Network Nancy NeigusHughes Network Mike ParrIMM D.R. BolgianoIMM Gil LaVeanIMM Al SacutaJapan Radio Co. Mat Kirimura

McCaw David HolmesMcCaw Rod NelsonMotorola Dave SattlerMurata Doug NeeleyNational Semi. Curtis SchmidekNEC America Stephen S. JonesNEC America Edward D. OrnelasNovAtel Allan AngusNTI Essam SourourNynex Corp. Erkin CubukcuPacTel Corp. Mo AliPacTel Corp. Jim ProffittPanasonic Sam McConougheySony Kazuhiko ShiraiSouthwestern Bell Terry WattsSynacom Tech Kirk CarlsonUS Govt DoD D. Nunley

REPORT OF TR-41 TELEPHONE TERMINALSMARCH 4-8, 1991, BALTIMORE, MD

TR-41.1 PBX AND ISDN TERMINATING EQUIPMENT

This was a joint meeting with CSA Technical Committee T512, Voice PBX and Key Telephone Systems. Themeeting was chaired by acting chairman J. Schick (Northern Telecom), the previous chairman having retired.

ETSI L IAISON

A number of ETSI documents were distributed by mail prior to the meeting. These included the Report of the BT2Meeting No. 4, September 10-14, Montreux, Switzerland (TR-41.1/91-01-002), the Basic Guide on the EuropeanIntegrated Services Digital Network (TR-41.1/91-01-003), Digital European Cordless Telecommunications (DECT) -Transmission Aspects [of] 3.1 kHz Telephony Interworking with Other Networks (TR-41.1/91-01-004), and Part 6of the DECT CI Specification - Speech Coding Transmission (TR-41.1/91-01-005). Unfortunately, the mailingfrom ETSI inadvertently omitted every second page of all but the second of these documents; therefore, discussionand response is deferred to the next meeting. It was noted that documents from this meeting will be forwarded to theBT2 chair.

Continuing the work of harmonizing North American and European PBX standards, two comparisons between DraftprETS 300 003 to 300 006 (PBX transmission requirements) and EIA/TIA 464 were made. For certainspecifications, TIA requirements are less stringent than ETSI over all or a portion of the parameter (frequency, inputlevel, etc.) range over which the specification is characterized (TR-41.1/91-03-010). (For North Americanmanufacturers, these requirements are of concern with respect to compliance with ETSI standards; presumably, whereTIA is more stringent, compliance exists). From the ETSI standpoint, it appears that, in general, TIA requirementsare more stringent than the ETSs (TR-41.1/91-01-001); however, with a few exceptions, dissimilarities arerelatively minor and can be rationalized by considering differences in the telecommunications environment(TR-41.1/91-03-013).

A new TIA project and working group to focus the work and coordination for TIA/ETSI standards harmonization wasproposed (TR-41.1/91-03-011). A formal project description will be prepared for the next meeting. J. Needham(Mitel) agreed to chair the working group.



CSA T512 LIAISON

D. Cheeseman (Alberta Gov't Tel) reported that CSA has sent out EIA/TIA 464 for letter ballot as a new T512standard. The current CSA T512 (Functional & Compatibility Standard for PBX) contains information onstatistical verification of compliance; this is not a currently included in EIA/TIA 464. CSA proposes(TR-41.1/91-03-009) that the update to EIA/TIA 464 currently in progress should incorporate this informationsince a sizeable number of requirements are stated in terms of percent compliance. Statistical verification provides analternate method to exhaustive testing which, in many cases (e.g., "95% of all possible connections) is impractical.

ANSWER SUPERVISION ON DID

As was noted in the report of the previous meeting (CSR, December, 1990), the new FCC ruling on returninganswer supervision on DID trunks for most call disposition scenarios implies incorporation of new answersupervision requirements in the PBX standard. A contribution to this meeting (TR-41.1/91-03-012) describes,in tabular form, the DID call scenarios subject to the PBX returning answer supervision. Briefly, the FCC rulingrequires DID answer supervision on calls which:

• Are answered by the called station, a forwarded-to station, an attendant, or a dialing prompt• Are routed to a recorded announcement (RAN) except for "number invalid", "not in service", or "not assigned"

recordings.• Are routed back to the PSTN and are answered or routed to a RAN

C. Berestecky (AT&T) gave a summation of the discussions which had been held with FCC; he noted that, althoughthe industry had pointed out the implementation difficulties, particularly with calls forwarded to the PSTN, FCCchose to proceed with adopting the rules. In AT&T's view, FCC appears to desire equity with Centrex. However,AT&T intends to present practical considerations to FCC in an upcoming meeting on April 18.

A related standard, ANSI T1.405-1989, contains requirements for returning answer supervision on DID calls whichreflect the FCC ruling but are not fully consistent with the TIA contribution. It is intended that the PBX standardwill be updated to harmonize with T1.405; however, J. Staats (Bellcore) will introduce the contribution tocommittee T1E1.1 (which formulated the T1.405 standard) for consideration as a basis for a coordinated industryposition.

INTERACTION WITH ISO/IEC JTC1

To maintain the overall liaison to JTC1, TR-41.1 appointed E. Polansky (AT&T) to be direct liaison with ANSIcommittee X3S3 which provides the interface and U.S. representation to JTC1.

UPDATE/RESTRUCTURE OF TIA-464-A

CSA further refined and updated the voiceband and digital data requirements proposal (TR-41.1/91-03-008). Onespecific addition concerns the continuity of permanent digital data connections; i.e., that such connections will notbe disrupted by (or will automatically be restored subsequent to) PBX restarts or normal maintenance actions. Sincethe proposed voiceband data requirements are related to the network allocation of voiceband data impairments, arevised version of the proposal will be sent to the T1Q1.1 SWG on Voiceband Data for review.

The chair noted that the planned update to TIA-464-A should consider the relevancy to current technology andemerging services such as new line-side services and wireless PBX. This would likely take the form of a majorrestructure of the document and the deletion of material no longer pertinent in today's telecommunicationsenvironment. Members of TR-41.1 were asked to be prepared to discuss and contribute to this topic at the nextmeeting.

TR-41.1.1 LOSS/LEVEL

Working Group TR-41.1.1 met in Boca Raton, FL on Feb 6-7 to review and edit Draft 2 of PN-1993, ISPBX LossPlan (TR-41.1.1/91-02-002). The outcomes of this meeting are reflected in the revised Draft 2.1 of thedocument (TR-41.1.1/91-03-006), reviewed on a page-by-page basis. Significant editorial changes subsequentto Draft 2 include a new Scope section (TR-41.1.1/91-03-004) presented by R. Frank (Siemens) and an explicit



caveat that the loss plan, while designed for compatibility with the North American network loss plan, is notinhibited by the North American coding law (µ-law) (TR-41.1.1/91-03-008).

Following the review and agreement to a number of editorial changes, TR-41.1.1 voted the document out toSubcommittee TR-41.1 for action and forwarding to TIA Committee TR-41 for approval. Subsequent action by TR-41.1 and TR-41 resulted in the document being submitted to TIA as SP-1993 for 60-day industry letter ballot.

Since the ISPBX loss plan provides options for digital trunk loss treatment, guidelines were needed for selecting theappropriate option. As reported in CSR, December 1990, a computer model comparison of the performance ofnetwork connections was used to define the benefits for each option (TR-41.1.1/91-02-003). The study waspresented by T. Schmalzried (AT&T) and resulted in a set of guidelines (TR-41.1.1/91-03-005) which areincorporated in SP-1993.

As a result of liaison with ANSI T1Q1.1, the echo control applications in the T1Q1.1 draft standard Loss Plan forEvolving Digital Networks have been reformulated so as to be less restrictive on private networks. This wascommunicated officially to the TR-41.1 and TR-41.1.1 chairs (TR-41.1.1/91-01-007 , also TR-41.1/91-01-006 ) and acknowledged as acceptable to TR-41.1.1 (TR-41.1.1/91-01-001). In other T1Q1.1 liaison matters,R. Koester (Bellcore) reported on a contribution proposing that the concept of all loss insertion taking place at thelast digital-to-analog conversion point, though a long term desirable goal, is not always feasible and should not be arequirement on network connections.

TR-41.1.2 PRIVATE NETWORK SYNCHRONIZATION

Two negative votes on the SP-2198 (Private Network Synchronization Standard) were resolved (the negativecomments concerned application of SONET derived synchronization). Several "yes" votes with comments are to beresolved at a March 18 teleconference. Subsequent to this conference, the document will be submitted for re-balloting.

A letter (TR-41.1/91-01-007) had been sent from the ETSI/BT2/WP-2 (Synchronization) chair to TR-41.1acknowledging receipt of the previous draft of the TIA synchronization standard. Attached to the letter is a list ofBT2/WP-2 experts.

TR-41.3 TELEPHONES AND ISDN TERMINALS

ISDN TERMINALS STANDARD

SP-1920A, Acoustic-to-Digital and Digital-to-Acoustic Transmission Requirements for ISDN Terminals is approvedby ANSI to become ANSI/EIA/TIA-579-1991.

WIDEBAND AUDIO

An earlier Bellcore document, TR-41.3/90-09-017 , Experimental Determination of Loudness Differences between3- and 7-kHz Bandlimited Speech Signals, was reviewed. The main conclusion was that the apparent loudness of7-kHz speech is approximately 6 dB louder than those of the narrowband signals typical of the telephone network.This conclusion might lead to the development of a new CCITT formula for computing loudness loss ratings; such aformula would probably be adopted by IEEE for the reaffirmation of the IEEE standard 661-1979 .

CCITT SG XII has a number of activities underway on specifications for wideband (7 kHz) audio (TR-41.3/91-03-003). Among these are studies on measurement methods (specifically, the use of the IEC-711 artificial ear withpinna simulator* for handset receivers), development of algorithms for calculating loudness ratings (2 proposalsbeing considered), and drafting of the specifications document with separate specifications for handset and handsfreesend and receive characteristics.

There is also work ongoing in ETSI on wideband terminals.

* Pinna is the floppy part of the ear against which the receiver rests. A pinna-like simulator is generally a molded rubberreplica of the ear. A "telecom pinna" does not have the appearance of an ear but consists of a series of concentric rings withcontrolled leaks; these duplicate the characteristics as a telephone receiver against a real ear but in a more repeatable testset-up.



TIA TR-41.3 is deciding whether an ANSI standard on wideband audio in parallel with the CCITT and ETSIstandards is required; the chair requested submissions to that effect.

FCC DOCKET 90-2, NPRM FOR COMPLIANCE WITH THE AMERICANS WITH DISABILITIES ACT OF1990

An overview of the NPRM (TR-41.3/91-03-001) was presented by M. Hacker (Northern Telecom). This NPRMdeals with a number of topics, including limitations on protruding objects, accessibility, volume control handsets,TDD unit provisions at pay stations, and signage. It is proposed that TIA (UPE with TR-41 input) formulate anindustry response to the NPRM (comment cut-off date is March 25). The main points in proposed response:

• Resolve discrepancy in protruding objects allowance (guidelines are 4 inches max; however, accompanyingfigures show 16 inches for a coin set).

• Specification of hand set receiver amplification criteria acceptable to the telephone industry, including range,mode of control (step or continuously variable), reset capability. Note that CSA T515 specifies a range of 17 dBabove nominal set ROLR.

• Industry consensus on signage.• Include TIA RS-504, Hearing Aid Standard, in the Rules.

TR-41.3 will prepare a written input to TIA for response to FCC. TR-41.3 also will recommend that the NPRMproposed rules be incorporated into FCC Part 68.

HEARING AID COMPATIBILITY

Magnetic coupling requirements for telephone handset to hearing aids in the current standard, RS-504, include testprocedures for analog sets . To be compatible with digital terminals such as those described in SP-1920A, a testprocedure using an appropriate input level which recognizes the differences in receiver sensitivity is needed. P.Coverdale (Northern Telecom) discussed a contribution (TR-41.3/91-03-002) which provides a check on anearlier recommended level and verifies that the input test level should be changed from -10 dBV to -3 dBV.

John Schick, Northern Telecom

TR-41.4 NCTE

The meeting notes of the previous meeting, TR-41.4/91-03-002 , were approved after a minor modification:

TR-41.4/91-03-003 , Meeting Notes and editorial comments on PN-2023, from D. Curtis (Bellcore), wasaccepted for information by the editor.

TR-41.4/91-03-004 , Input to the editor of PN-2023 on previously agreed changes, from E. Polansky, AT&T,was accepted by the editor and incorporated in the revision 5 document on PN-2023.

TR-41.4/91-03-005 , Draft 5 of PN-2023: Network Channel Terminating Equipment for Public Switched DigitalService, from R. Callahan, Editor, (Bellcore) was reviewed page by page. Minor corrections only were made andnoted by the editor.

In discussing this document, the following issues arose:

• The echo canceler capability of these devices. D. Rittenhouse, NTI, pointed out that the standard refers to using asteady tone for disabling cancelers. It does not address the phase reversal method of disabling echo cancelers.AT&T may deploy some circuits that require the phase reversal. E. Polansky was asked to investigate whetherAT&T's network and equipment were compatible with CCITT G.164 and G165. The assignment was given toall participants to investigate CCITT G.164 and G.165 in addition to the TR-30 standards that also mention echocanceling. It was also pointed out that the draft was not formally compared with T1E1 and T1X1 digital non-switched interface standards. All members are asked to examine this capability.



• It was agreed to take the table of contents in draft 5 and reduce it down to only three levels (from five or six). Itwas also agreed to grant the editor the right to move all the figures to the back and to change the PN-2023 to anSP designation, giving it a proposed standard number. Any changes to the document not agreed to at thismeeting would have to be addressed by ballot comments. There was still reference in the text to "T-link" whichis a proprietary designation of NTI. It was agreed to delete this reference.

• It was agreed by the members present to examine section 8 in the ballot process to consider how it would workwith Type 1, Type 2, and Type III equipment. Section 8 has to do with the DTE connection of the switched 56kbit devices. This is the V.35/EIA-530 interface, which now includes a pin assignment table.

TR 41.7 ENVIRONMENTAL AND SAFETY CONSIDERATIONS

TR 41.7/91-03-001 , Actual Copy of the Tentative Interim Amendment approved by the NFPA, from the TIAStaff, cleared up the wording and pointed out that equipment intended to be electrically connected to a Telecomnetwork shall be listed. This listing requirement shall become effective on October 1, 1990, for premises wiringcomponents, such as plugs, jacks, connectors, terminal blocks,and cross connect assemblies. The listingrequirements for all their equipment shall become effective on July 1, 1991. This was to allow inventory itemsalready in distributors' hands to be sold. Exceptions to this procedure did not apply to wiring componentsmanufactured before October, and all other equipment manufacturer before July 1, 1991. Also, another exceptionwas granted to test equipment that is only temporarily connected to the network for maintenance.

ANSI/EIA/TIA 571-1991, Environmental Considerations for Telephone Terminals, was formally approved by TIA.Copies of this standard will be available from the TIA within several months.

TR 41.7 will be forming an EMC sub-working group to provide input to CISPR, an international groupestablishing electromagnetic emanation standards.

TR 41.7/91-03-003 , Proposals re: issues in the National Electrical Code, submitted by C. Chamney, NorthernTelecom, were denied. They included modifications for a new section of the electrical code for telecommunicationsequipment based on TR 41.7/91-03-001 .Anyone may write the NEC to comment on all proposed changes to the NEC. The comment period is still open.To request changes to the code, obtain copies from the Secretary of Standards Council of the NFPA, Battery MarchPark, Quincy MA, 02269. Comments on these proposals will be accepted until June 1, 1991.

R. Ivans, U.L., pointed out that the CSA and the U.L. will be having meetings to harmonize the documents. Therewas a request from the FCC as to what recommended voltage telephones should be able to withstand. It was adifficult question to answer in that for most telephones, they felt the circuit should withstand 300v DC and allphones must be able to handle 600v DC. They did not have statistics as to what the break-out was, and asked forcontributions at the next meeting.

TR-41.OV OVER VOLTAGE WORKING GROUP

A special meeting was held with over 45 participants. The main issue was U.L. requirements (UL1459 revision 2).They could be met by putting a fuse into a product, but when the fuse blows, the product would be out of service. Itwas pointed out by the participants that with the phone out of service, somebody would not be able to dial 911 andthis might represent a greater hazard than the fire hazard that the fuse is trying to protect.

All the manufacturers in attendance were asked to make a proposal on how they would like to deal with this. Therewas also a letter from a device manufacturer (EFI Electronics) who complained that his device couldn't rigorouslymeet the U.L. requirements and simultaneously be robust and withstand lightening hits.

TR 41.8 BUILDING AND WIRING

Working Group TR 41.8.1, Commercial Premise Wiring, did not meet. SP-1907B (Industrial and CommercialBuilding Wiring Standard) is out for a default ballot which closes on March 17, 1991. The "SP" is to be presentedto the Engineering Council at their meeting in April. Issuing of the standard for EIA/TIA-568 should occur shortlyafter that.



TR 41.8.2, Residential and light commercial standard, resolved all ballots on SP-1558B. It will become EIA/TIA-570.

The Ad Hoc TR 41.8.3, Telecommunications Pathway and Spaces, met to discuss a draft document. The scope ofthis work is becoming defined, and will be more extensive than previously thought.

The ISO/IEC JTC-1/SC25/WG3 met in Las Vegas to review a consolidated standard. The Europeans need a 120ohm cable requirement. Much of their installed base is 120 ohms. The U.S. delegation reluctantly indicated thatthey may agree to this.

The US TAG will meet in late April. Any contributions should be submitted to the TAG. There are contributionsproposed for a Fiber Optic (Generic) contribution and Installed Wire Characteristics contribution.

TR 41.9 REGULATORY CONSIDERATIONS

There were two joint meetings with TAPAC since the last TR 41 meeting. The issues addressed were safety,environmental, and leakage, and all three appear to be resolved in terms of harmonizing CSA and FCC Part 68requirements.

TR-41.9 will be working on signal power at the next meeting. There will be a new sub-committee chaired byGeorge Lawrence of AMP that will convert all the dimensions for all the connectors in FCC Part 68 from U.S.measurements to metric, as requested by the FCC.

The next TR-41.9 meeting will be in Edmonton on May 15-17, hosted by AGT Limited. Further harmonizationbetween TAPAC and FCC Part 68 will be attempted. TR-41.9 will not meet in Park City with the exception of thenew metric conversion committee.

William Buckley, Verilink

TR-41 ROSTER, MARCH 4-8, 1991, BALTIMORE, MD

Victor Boersma (Northern Telecom) Chairman, TR-41John Schick (Northern Telecom) Acting Chairman, TR-41.1LeRoy Baker (Reliance Comm/TEC) Chairman, TR-41.3Bill Buckley (Verilink) Chairman, TR-41.4T. Killam (Siemens) Chairman, TR-41.7George Lawrence (AMP) Chairman, TR-41.8Chuck Berestecky (AT&T) Chairman, TR-41.9

Alberta Gov't Tel Don CheesemanAT&T Ed PolanskyAT&T Terry SchmalzriedAT&T C. TenorioB.C. Telephone Terry GillBell Atlantic Trone BishopBell Canada Frank McCauheyBell Canada Anthony SkucasBellcore Fred BreemBellcore Dave CurtisBellcore Bob KoesterBellcore Jim StaatsBellcore Rolyn CallahanCertelecom Labs Inc David DulmageComm. Cert. Lab Ann WrideDep't of Comm (Can) Henry MarFujitsu Jay FarrellGTE Testmark Labs Charles MosgraveIBM Thomas TolerINC Fred WeberMitel Bob Hamilton

Mitel John NeedhamNorth Am. Telecom Mary BradshawNorthern Telecom Paul CoverdaleNorthern Telecom Jorge del RioNorthern Telecom Ed ErhlichNorthern Telecom Severin GodoNorthern Telecom Mel HackerNorthern Telecom Erik HanssonNorthern Telecom S. HorneNorthern Telecom Dennis RittenhouseNorthern Telecom Ron RobinsonRacal-Milgo Stephen WinterRedcom Labs Mike MyersRolm Systems Tailey TungSiemens Richard FrankSouthwestern Bell Hal HolzwarthTelecomm. Tech. Bernard WorneTIA Hal BergeU.L. Randy IvansUnited Telecom Cliff Chamney



REPORT OF TR-30.3 AD HOCMARCH 13 - 14 , 1991, REDBANK, NJ

This special interim Ad Hoc Meeting was called to focus on creating a Technical Bulletin on Network TransmissionSimulation for Evaluating Modem Performance.

The scope for the proposed Technical Bulletin was discussed. It was felt that the bulletin should cover bothmodeling the network and application notes on modem testing issues (such as test duration, data patterns, through-put testing, test setup and calibration, interpretation of results, etc.) although application notes on testing modems isreally a TR-30.1 issue. The Chairman of TR-30.1 agreed that TR-30.3 should create the application notes, thenhave TR-30.1 review them before releasing them. The committee decided to break the work into two technicalbulletins: one covering network simulation and the other covering application notes on modem test methodology. Itwas decided that this meeting should concentrate on network transmission issues first; then, if time permitted,discuss the application notes.

M. Turner (PTT) presented TR-30.3/90-02004, since portions of it were relevant to the technical bulletin. Twoapproaches to simulation were discussed. The first approach is one in which the loop simulation is "orthogonal" tothe other impairments. The second approach is one in which the loop would follow other impairments. The looptherefore affects these impairments as happens on the real telephone network. The advantages of having the loopfollowing the other impairments are as follows:

• Compatible with approaches used in other standards (e.g., NET 20).

• More accurate modeling of noise shaping by the loop and attendant noise enhancement by the modem.

• More accurate near end echo levels, and dispersion.

Comments were made that the contribution didn't include arguments in favor of the orthogonal architecture. It wasgenerally agreed that loops should follow the other impairments and that the bulletin should use this approach.

TR-30.3/91-02010 reviewed the proposed title and scope for the technical bulletin as defined at the last meeting.The committee decided to use an O-PAD, instead of an H-PAD, to buffer the modem impedance from port A, andsimplify the test set-up and calibration. It was also decided that only port B will use external loop models. Oneloop in the simulator would be placed on port B and the other loop in the simulator would be placed on the hybridbalancing input for port B. However, it is expected that 496-B will include loops at both ends.

M. Kalb's proposed Impairment Combination Table (TR-30.3/91-02003) and TR-30.3/91-04011-AH(extracts from SG XVII TD-237) were used as the starting point for creating a new impairment combination tablethat was representative of the US PSTN. The committee modified each impairment combination using thefollowing criteria:

1. Since it is unlikely that more than two impairments would be stressed on a real line at the same time, it wasdecided to avoid stressing more than two impairments on one impairment combination.

2. The levels of Phase Jitter were reduced because it was generally felt that the modern PSTN (mainly digitalnetwork) has less phase jitter.

3. Five different unloaded loop models were used at port B.

4. A 6.1 dB loss O-PAD was used at port A on all impairment combinations to buffer the modems impedance andsimplify the test set-up and calibration.

5. Realistic echoes were modeled by choosing appropriate values for THL, trunk loss, and delay.

6. A subset of the 496-A EDD and Attenuation Distortion curves were selected.

7. Values of Intermodulation Distortion and frequency offset that reflect the modern network were used.



8. PCM and ADPCM were not included in the test suite since this would require major upgrades to currentlydeployed test equipment.

M. Turner (PTT) presented his contribution on limiting the impairments in the reverse direction to a subset of theimpairment in the forward direction (TR-30.3/91-04013-AH). This limitation was only intended for thetechnical bulletin to maximize the usage of currently available equipment. He gave the following reasons forlimiting the reverse direction impairments:

1. Less costly to many modem testers to use a limited impairment set, because many of the existing test-sets do notinclude the full set of impairments in both directions.

2. It is not likely that worse case impairment combinations would occur simultaneously in both directions.

3. Omission of reverse path frequency offset, nonlinear distortion, and phase jitter would not have a significant effecton the simulation since the far end echo would still encounter these impairment in the forward path.

The committee decided that all impairments should be placed in both directions since the economic impact would beminimal (only some systems don't have full bi-directional capability), and it is not known how this limitationwould affect the test results.

J. Douglass revised the Impairment combination tables based on committee discussions. In TR-30.3/91-04015A-AH , three lines were added to support more EDD curves and include impulse noise. The committeediscussed whether the EDD combinations that were selected reflected the modern network. TR-30.3/91-04015A-AH also included a table that could be used for characterizing each impairment as "low stress", "moderate stress," or"high stress." The committee filled in the table based on survey information. One of the EDD lines was droppedafter checking the End Office Connection Survey, because it was found to be inconsistent with the available data.An impairment combination using the "stand-ard impulse" as specified in IEEE 743 was included in the tests. Theimpulse noise will be placed on the output of the simulator and be shaped by the loop, because this is what is cur-rently available on simulation equipment.

D. Moon (GDC) prepared TR-30.3/91-04014-AH , a draft version of the text for the technical bulletin. It wasdecided that Appendix B, covering application notes on modem testing, would be put into the second technicalbulletin. Several sections of the document were discussed. Wording changes were made in a number of areas. Itwas decided that the editing could be better completed offline by D. Moon and J. Moran. Members were requested toprovide input to them on suggested modifications.

The committee developed a cover sheet to go with the technical bulletin that provided guidelines under whichchanges in the parameter values could be changed. It was stated that changes should only be made as necessary toreflect a more accurate model of the network, rather than being made simply on the results of modem performancetests.

A lengthy discussion ensued on how to handle signal-to-noise ratio in the technical bulletin. It was decided that boththe receive level and the noise level should be controlled parameters and that adjustments for trunk loss should bemade to compensate for variations in modem transmit level. D. Moon and J. Moran were requested to include this inthe editing of the draft of the technical bulletin.

Jack Douglass, UDS Motorola

TR-30.3 AD HOC ROSTER, MARCH 13 - 14 , 1991, REDBANK, NJ

Jack Douglass (UDS Motorola) Chairman, TR-30.3

AT&T Horace HagenAT&T Mike KalbAT&T Bell Labs Tayfun CataltepeAT&T Bell Labs Bhavama ShahGeneral Datacomm Dave MoonHayes Dave Rife

IMC Laura PreeceMotorola Codex Jack MoranPTT Larry OwensPTT Mike TurnerTAS Steve MooreTAS Dave Tarver



REPORT OF CCITT STUDY GROUP VIII, TELEMATIC TERMINALS ANDPROTOCOLS , MARCH 18 - 27, 1991, GENEVA, SWITZERLAND

GROUP 3 FACSIMILE (Q3, Q18)

The rapporteur's report (B. Revillet), TD-567 , includes a document list.

G3 Higher Resolutions: Most discussion revolved around whether pel conversion is required when a G3terminal sends a document in normal resolution (196x203 pels/inch) to a terminal having an even resolution(200x200 pels/inch, or 300x300 pels/inch). While this results in some distortion from the original image, acontribution with examples and subjective test results shows this distortion to be practically not perceptible. Nodecision was made on this issue, and the test results will be sent to SG I. It now seems probable, based on thecomments of many delegates, that conversion will not be required. This will lead the way to migrating to the evenresolutions (multiples of 100 pels/inch) as the standard resolutions for G3. A contribution from the Q.16 rapporteur(TD-516) described a number of subjective test comparing the quality of faxed documents using variouscombinations of normal G3 and even resolutions. The results show the "distortions" to be imperceptible.

G3 Character Mode (see also Q.8): The French proposal (D-196) was presented to standardize on a Cyrilliccharacter set, in spite of the SG I request to just provide for a way of indicating which set (or sets) could besupported. A compromise on assigning four bits in the protocol to character sets was not accepted. Two were to beassigned to Latin sets (T.51, ISO 8859) one to Kanji, and one to "other." There is usually no end to discussions oncharacter sets; hopefully SG I will reemphasize its desire to indicate supported character sets by means of Object-Identifiers.

High Performance G3 Fax: HP G3 could be accomplished by specifying higher modem data rates, and/or bysome streamlining of the G3 protocol. TD-514 suggests revisions to T.4 and T.30 documents for the purpose ofdeveloping a HP G3 recommendation. It does not make a modulation proposal. Following on TD-514 ,preliminary terms of reference for a new modem were drafted. These include: higher performance than V.17 (Error-free document rate); maximum data rate significantly greater than 14.4 kbit/s; responsibility of data rate to chooserate with qualifiers (e.g. BER); half-duplex, but duplex is under study; connection training time less than 4 sec.;training time after turnaround objective of 200 msec.; reverse data transmission 2.4 kbit/s.

Interaction with FaxPADs: SG VIII has decided that it is responsible for specifying the access of G3equipment to such systems, which are being standardized in SG VII. A joint meeting will be held with Q8/VII,which is developing the Fax PAD recommendations, in September. This may result in further delay of the FaxPADrecommendations.

Use of Fax with DCME : Experts from SG XV attended the sessions which dealt with demodulation of faxsignals by network based equipment. The principal problem exists when proprietary features are used, especiallynon-standard modulation schemes. Various possibilities of indicating this to the network are being discussed,including the use of the CNG (Calling) tone, or the DIS/DTC. A special meeting (noted in TD-503) is planned inGeneva in July to discuss this issue with SG XV experts.

Access to Other Services: The AT&T contribution (D-257) on access to facsimile enhanced services wasreceived with interest. There was general agreement on the short term/long term approach, and on using X.400 typeservice elements. The contribution proposed to use DTMF signaling before starting the T.30 protocol in the shortterm. As a long term solution, the information would be communicated by inserting a "Facsimile ServiceInformation" file before any other facsimile information was transferred. The US contribution asking SG I todetermine a common DTMF user interface for all services was accepted. A liaison was sent to SG I (TD-587)asking their Human Factors Group to study this issue, and the AT&T contribution on access was annexed to theliaison statement as an example of the type of information to be communicated. A German contribution proposed toadd selective polling and optional subaddressing by means of new T.30 signals (TD-551). This will be studied asan alternative to the AT&T proposal.

G3 File Transfer: The US proposed FTAM-like Binary File Transfer (TD-591) was finally agreed to beconsidered a draft recommendation, and thus has moved closer to approval. There were some questions about the useof the diagnostic attributes, and a new contribution with more detail was requested. It was agreed that the Frenchwill draft another recommendation for "Document File Transfer" which is character based. Provisional bit



assignments (TD-590) were made for the file transfer capabilities, which also make provision for the FacsimileService Information (FSI) file.

G3 Fax and Automatic Answering Devices: The principal input document was from the Japanesemanufacturers (D-256). It was accepted in principle, with the flow diagram as modified in TD-553 . Principles tobe considered are:1. No additional facilities can be considered from the calling side2. Existing terminals have to be used after a connection box3. The calling party expects normal telephone conditions4. Synthetic generation of tones (such as ringing signal) should not be used, since the calling party may believe no

charging has started.

FACSIMILE (GROUP 3/GROUP 4) INTERWORKING (Q.4, Q18):

Group3-64 kbit/s: Study Group I, in their November meeting, sent a liaison to Study Group VIII requestingwork to satisfy a requirement for facsimile on the ISDN making full use of the 64 kbit/s capability. Theysuggested that this might be fulfilled by technical work on Group 3 and/or Group 4. Some delegates, especiallythose from Germany and France, questioned whether the liaison statement from SG I really authorized doingtechnical work on G3-64. It was decided remove this work from the Q3, Q18 rapporteurs group and to appoint A.Guiseppini as Special Rapporteur for 64 kbit/s facsimile on ISDN.

Guiseppini was given the charter to develop technical recommendations for both G3-64 and Group 4 Class 1. SG Iwill eventually have to decide whether one or both satisfy their requirements. He appointed R. Stadler (Swiss PTT)to lead the G3-64 group, and M. Mori (Ricoh Japan) to lead the G4 Cl 1 group. The G3-64 group used the US-UKcontribution (Draft Annex B to Rec. T.30) as their base text (D-246). There were some technical discussions onthis draft, but no technical problems were found with the proposal. The chair asked for an outline of the callestablishment procedures to be drafted, which was accomplished (TD-539Rev 1). The group's conclusion was thatthe two documents (protocol and call establishment) should be combined into a white contribution for the nextmeeting of SG VIII, since they appeared to meet all technical requirements. The call establishment procedure is, inthe short run, dependent on changing the meaning of the G4 Cl 1 HLC information element into a "Facsimile" HLCIE. In the long run, the Multi Use Bearer Capability (MU BC), under development by SG IX and XVIII, would beused for ISDN-PSTN interworking between G3-64 and normal G3.

In their report, the G4 Cl 1 group concluded that a combined G4-G3 machine would satisfy the SG I requirements oninterworking, although such a machine is not standardized. They also agreed that the G4 efficiency should beenhanced by concatenating the OSI layers. This would have to be done with SG VII cooperation. Guiseppini'sreport (TD-550) was eventually accepted, although Germany asked to be recorded as not agreeing. Several countrieshave already indicated that they plan to support the introduction of the proposed G3-64 contribution at the nextmeeting.

GROUP 4 FACSIMILE (Q.4)

A new draft recommendation describes the two high resolution monochrome test charts, which were developed in theUS (D-250). In order to improve the efficiency of Group 4, a proposal for layer concatenation was made by theFrench (COM VIII-133). This work will be moved to Q.17, which is responsible for Rec. T.90, Telematicterminal access to ISDN. Some work was done on color for G4, and it was agreed that the JPEG algorithm wouldbe used. The Q.4 report is in TD-532Rev. 1 .

MODULATION TECHNIQUES FOR TELEMATIC SERVICES (Q.5)

B. DeGrasse (Rockwell, US) is the rapporteur. A short train procedure for V.29 modems was drafted (D-231),principally for use by Videotex terminals. SG XVII was also requested to provide a short train option for V.17 (seeQ.15 report). Liaisons to SG VII on these subjects are included in the meeting report (TD-602). It was also agreednot to produce any amendments dealing with modem configurations for Group 3 in this study period.

TERMINAL CHARACTERISTICS FOR MIXED MODE AND PROCESSABLE MODE (Q.6)

This question (rapporteur: P. Maurice, France) is now discussing minimum implementation requirements forequipment intended for document transfer using the CCITT/ISO Document Application Profile (DAP) International



Standardized Profiles (ISPs). This would be a companion recommendation to the DAP recommendations. A newdraft Rec. T.500 was developed (TD-575). Editors were appointed for T.500, T.510, T.511, T.512 and T.515 inorder to have final documents for approval in this study period.

It was also decided that the (ODA) processable mode open interchange application should not necessarily be linkedwith Teletex, but should be part of a generalized document interchange service which SG I may specify.

CODING OF ALPHANUMERICAL CHARACTERS AND ASSOCIATED CONTROL FUNCTIONS(Q.8)

The rapporteur's (Y. F. Lum, Communications Research Centre Canada) report is TD-536 . Revisions were madeto T.51, Coded Character Sets for Telematic Services. D-197 will be the basis for the development of T.52, Non-Latin Character Sets for Telematic Services. D-215 is the first draft of T.53, Control Functions.

PROTOCOLS FOR INTERACTIVE VIDEO SERVICES( Q.9)

Rapporteur: B. Marti, France. Much of this work on multimedia and hypermedia communication is based on theISO SC 2 MHEG results, but only the ASN.1 version will be used by CCITT. The applicable parts are publishedin the meeting report (TD-588). Transfer protocols will be based on DTAM (D-212).

TD-444 is a liaison statement from SG XVIII titled Integrated Video Service Baseline Document. It proposes tocoordinate issues associated with video services and coding for B-ISDN across the various standards groups affected.

TELETEX (Q.10)

Programmable Communication Interfaces. The work on telematic application interfaces based on theFrench/German Appli/Com is progressing. A draft recommendation will be presented at the next SG VIII meeting(October 1991). It now seems likely that communications software providers will build to this programmablecommunication interface (PCI), and that the standard will be completed in March, 1992. A draft servicerecommendation for PCIs is in D-224 , and the draft technical recommendation is in D-226 . Changes to D-226agreed to at the meeting are described in Appendix II of TD-563 the Q.10 meeting report.

Recommendation T.60 was modified extensively (TD-566) to allow for the inclusion of T.561 and T.562 specifiedfunctions. T.61 enhancements, aligned with T.51 and T.52, were accepted and a White Contribution should beforthcoming at the next SGVIII meeting.

Existing Teletex terminals allow a simple file transfer on the basis of a "private use" function. A standardizedapproach is desired. D-225 describes the French proposal to support 4 file types, Basic Transfer Mode, DocumentTransfer Mode, Binary File Transfer and Edifact.

CONVERSION/IMAGE CONVERSION RULES (Q.11)

The rapporteur's (P. Talone, Fondazione Bordoni Italy) report is TD-597 and includes a draft proposal. However,this question is generating little interest.

TELEMATIC INTERWORKING (Q.12)

This question is now beginning to draw some attention because of the work on fax access to MHS. The rapporteuris M. Schumann from DBP Telekom. Discussions dealt with interworking between Group 3 fax and MHS, andwith interworking between DTAM based equipment and MHS. The technical aspects of interworking betweenGroup 3 fax and MHS were seen to belong to Q.12, and this was pointed out in a liaison statement to SG VII (TD-584 ). The Store and Forward Unit (SFU), as proposed by SG I Q.14 (Facsimile Store and Forward Service) wasseen to be a fax Access Unit (FAU) combined with an MTA (Message Transfer Agent). Q.12 will work on theFAU. The liaison also asks some questions regarding delivery notifications and receipt notifications. It wasproposed that receipt notifications be generated by the FAU after the message has been transmitted to the Group 3terminal. Discussions on interworking between DTAM based equipment and MHS resulted in the acceptance of anew draft recommendation based on a German contribution (D-240), which also is contained in the meeting report(TD-585). This recommendation would allow transfer of processable documents to and from MHS.



VIDEOTEX (Q.14)

The report of the meeting is contained in TD-537 . This meeting continued work on data syntaxes defined in T.101.Two new draft annexes (E & F) to Rec. T.101 on audio videotex data syntax (TD-554) and photographic videotexdata syntax (D-202) were agreed upon. TD-499 includes the Revisions to Annex B (Data Syntax 1 [used in theJapanese CAPTAIN system]) which were accepted.

PROTOCOL ASPECTS OF INTERACTIVE VIDEOTEXT (Q.15)

TD-527 is the rapporteur's (C. Dawkins, British Telecom) report. Included as Appendix 7 and 8 are two liaisonstatements to SGXVII requesting short training facilities in V.29 and V.17 for use in Videotext applications.Editing of T.102, Protocols for Syntax-based Videotex using ISDN (TD-529) and T.103, Protocols for Syntax-based Videotex using ISDN Packet Mode (TD-530) was accomplished. TD-528 , a draft of T.1xy, provides anoverview of the requirements (and some details of the PSTN interworking) that are driving this work, support ofVideotex systems over ISDN services. T.1xy indicates the protocols for Videotex and T.101 defines the datasyntaxes used.

COMMON COMPONENTS FOR IMAGE COMMUNICATIONS (Q.16)

The rapporteur's (Dr I. Sebestyen, Siemens) report is TD-596 . Draft T.JBIG (D-214) and T.JPEG (W-126)compression recommendations were reviewed. TD-555 includes proposed enhancements to JPEG. It is planned tocomplete approval of these recommendations in this study period.

TELEMATIC INTERFACES TO ISDN (Q.17)

A revision to Rec. T.90, which had been proposed for approval by Resolution 2 procedures at this meeting, waswithdrawn from consideration until at least October, 1991. The current version of T.90 with amendments is in TD-579 . The rapporteur, M. Matsumoto (NTT, Japan) and his collaborators found that there were still too manyunsolved problems. The problems were related to the code points to be assigned in the LLC IE for layer 2 and layer3 protocols. A liaison was sent to SG XI on this issue (TD-571). New work was started on defining a PCI forISDN terminal equipment based on a contribution from Germany (D-200). The Q.17 report is in TD-578 .

SESSION CONTROL PROCEDURES FOR TELEMATIC SERVICES (Q.21)

Proposed changes to T.62 and T.62bis were made. These changes are included in the rapporteur's report, TD-565 .Only two participants were present at these meetings.

AUDIOGRAPHICS TELECONFERENCING (Q.23)

The rapporteur for audiographics teleconferencing (AGC) is C. J. Starkey, (DataBeam, US). The report is in TD-589Rev . Four recommendations are being drafted for approval in March, 1992:• T.agc, Audiographics application and protocols• T.mcs, Multipoint data communications service and protocols• T.agc, Audiographics teleconferencing terminal application profile• T.mcu, Multipoint control unit (conference bridge) application profile for AGC

COMMUNICATION APPLICATION PROFILES (Q.24)

The revised version of T.532 Communication Application Profile BT1 for document bulk transfer is in TD-583 .TD-582 is the report of K. Nakao, rapporteur, (KDD, Japan).

DOCUMENT APPLICATION PROFILES (Q.26)

The reports by R. Hunter (British Telecom) are in TD-542 and TD-558 . The recently approved recommendationT.502 (Processable Mode 11) and T.505 (PM26) correspond to ISO pDISP (proposed Draft International StandardizedProfile) FOD11 and FOD26. To maintain better synchronization with the ISO process, it was decide to delayResolution 2 approval of draft Rec. T.506 (PM36) corresponding to ISO pDISP FOD36 until the ISO approvalprocess is complete.



DOCUMENT ARCHITECTURE, TRANSFER AND MANIPULATION (Q.27)

A first draft of a recommendation, Extensions to ODA for support of manipulation, was accepted (D-238). On thetopic of document transfer (DTAM protocols), it was agreed that DTAM should be extended to transfer not onlyoffice application data formats, but also the transfer of additional end user application formats such as SDIF (SGMLdocument interchange format), EDIFACT, and other file formats. DTAM is seen as an alternative to MHS baseddocument transfer. The rapporteur's (H. Silbiger, AT&T Consultant, USA) report is TD-586Rev .

Herman R. Silbiger, APPLICOM Application and Communication Consultants

ROSTER OF CCITT STUDY GROUP VIII, MARCH 18 - 27, 1991, GENEVA, SWITZERLAND

The total attendance (smaller than normal) was 121 delegates:

Germany - 20Japan - 17US - 16France - 15Italy - 8Norway - 5Switzerland - 5UK - 5Others - 30

Communications Standards Review

regularly covers the following committee meetings:

ANSI: X3L2.8

TIA (USA): TR-29 TR-41TR-30 TR-45.3

CCITT: SGVIII SGXVII

The next issue of Communications Standards Reviewwill be published late May, 1991.



MEETING SCHEDULES AS OF APRIL 12, 1991SUBJECT TO CHANGE WITHOUT NOTICE

1991

SG D Apr 16 Washington, DCT1Q1 Apr 22 - 26 Long Branch, NJJoint Rap. Apr 26 GenevaSGXVII Ap 29-May 3 GenevaTR-45.3 May 6 - 10 Dallas, TXT1S1 May 6 - 10 Atlanta, GATR-29 May 6 - 9 Washington DC areaT1E1 May 13 - 17 Buffalo, NYTR-30 Jun 10 - 14 Nashville, TNTR-45.3 Jun 10 - 14 Toronto, Ont.SGXVIII Jun 10 - 17 GenevaTR-41 Jun 17 - 21 Park City, UTSG D Jul 1 Washington, DCT1Q1 Jul 8 - 12 Boulder, COTR-45.3 Jul 7 - 11 Calgary, AlbertaTR-29 Aug 6 - 8 Yountville, CATR-30 Aug 12 - 15 San Francisco areaT1S1 Aug 12 - 16 Denver, CO

TR-45.3 Aug 12 - 16 Montreal, QueT1E1 Aug 26 - 30 Montreal, QueTR-41 Sep 9 - 13 Ottawa, ONTR-45.3 Sep 16 - 20 Albany, NYT1Q1 Sep 30 - Oct 4 ---TR-30 Oct 14 - 17 Raleigh, NCT1S1 Oct 14 - 18 ---WP VIII Oct 16 - 25 GenevaTR-45.3 Oct 21 - 25 Orlando, FLWP XVII Oct 29- Nov 6 GenevaTR-29 Nov 5 - 7 ---WP XVIII Nov 11 - 22 GenevaTR-45.3 Nov 18 - 22 San Francisco, CATR-41 Dec 2 - 6 New Orleans, LAT1E1 Dec 9 - 13 Williamsburg, VATR-30 Dec 9 - 12 Clearwater Beach, FL

1992

TR-45.3 Jan 6 - 10 San Diego, CAT1S1 Jan 19T1Q1 Feb 2T1E1 Feb 16T1S1 Mar 1TR-41 Mar 16-20 St. Augustine, FLSG VIII Apr 21-May 1T1E1 Apr 26T1S1 May 10T1Q1 May 17

TR-41 June 15-19 St. Johns, NFLDT1E1 Jul 19T1S1 Aug 2T1Q1 Aug 16TR-41 Sep 14-18 Vancouver, BCT1E1 Oct 25T1S1 Nov 8T1Q1 Nov 15TR-41 Dec 7-11 San Jose, CA

Communications Standards Review is published 6 to 8 times per year, within days after the latest, relatedstandards meetings. Editor: Elaine J. Baskin, Ph.D. Technical Editor: Ken Krechmer. Copyright © 1991,Communications Standards Review. All rights reserved. Copying of individual articles for distribution within anorganization is permitted. Subscriptions: $695.00 per year United States and Canada, $350.00 for each additionalsubscription to the same organization at the same address; $895.00 per year Foreign, $450.00 for each additionalsubscription to the same organization at the same address. Submit articles for consideration to: CommunicationsStandards Review, 757 Greer Road, Palo Alto, CA 94303 USA. Tel: +1-415-856-9018. FAX: +1-415-856-6591. 12902

Documents

COMMUNICATIONS STANDARDS REVIEWISDN terminals (referred to hereafter as ISDN data terminals) that use digital bearer services. The new Recommendations cover interworking arrangements