1、3404583 0070272 T30 ETSI/TC SMG Date : January 1993 Issued BY : ETSI/PTl2 UPDATE NOTE ETSI Technical Specification GSM 03.45 Technical Realization of Facsimile Group 3 - Transparent Previously Released version : 3.1 .O (Release 92, phase 1) New Updated version : 3.2.0 (January 1993) 1. Reason for ch
2、anae Changes agreed at SMG#5, as listed in section 2, are included. 2. Details of chame The following CRs were approved at SMG#5. CR Sections Title of CR , Ref Modified SMG Doc 03.45-03 all Editorial 03.45-05 6, Handling of tonal signalling by fax figures adaptors 11-5 to 11-9 03.45-07 5.2.3 Loss of
3、 V. 1 1 O synchronization 12/93 12/93 12/93 END OF UPDATE NOTE 3404583 0070273 977 . TS GSM 03.45 - version 3.2.0 - page 1 ETC I / SMG Jssued bv: ETSI PT12 - Date : January 1993 Recommendation: GSM 03.45 Title: TECHNICAL REALIZATION OF FAX GROP 3 - TRANBPARENT List of contents: O. SCOPE 1. SERVICE D
4、EFINITION 2. NETWORK ARCHITECTURE 3. REFERENCE CONFIGURATION AT THE MOBILE STATION 4. CONNECTION TYPES 5. USE OF TERMINAL ADAPTATION FUNCTIONS 6. SIGNALLING ASPECTS 7. INTERWORKING TO FIXED NETWORKS ANNEX References, definitions, abbreviations APPENDIX I Protocol entities from CCITT T.30 and T.4 II
5、Procedure examples Oriuinal L anuuaue: English Number of Daues: 39 TS 8H 03.4s 3404583 0070274 803 -version 3.2 O- page 2 Oe SCOPE This specification deals with the procedures allowing the technical realization of the Group 3 facsimile Service within the GSM PLMN using transparent Network support, a
6、ccording to the definition of Teleservice 61 and 62 specified in the TS GSM 02.03. 1. SERVICE DEFINITION The fixed network Group 3 Facsimile service, as basically defined in CCITT Recommendation F.160, is an international telematic Service for IS0 A4 document transmission between two facsimile stati
7、ons. The service specification is comprised of two parts: the control protocol described in CCITT Recommendation T.30, and the document transmission coding described in CCITT Recommendation T.4. The GSM facsimile Teleservice is intended to allow facsimile connections between group 3 apparatus using:
8、 - a GSM PLMN as a stand alone facility, for mobile to mobile communication; - a GSM PLMN to gain access to fixed networks PSTZJ and ISDN,for mobile to/from land communication. For this Teleservice, the document coding is as XITT Recommendation T.4 with no modifications. The protocol used is CCITT R
9、ecommendation T.30 modified within the PLMN as detailed in this Specification. The interworking between different networks is based on CCITT Recommendation X.300. The particular features of thio Teleservice are: - it uses point-point communication; the information transfer capability is lua1 speech/
10、facsimile; both mobile originated and terminated calls are suppcrted; the information transfer mode is circuit, Ap:ex, synchronous and symmetric; different end-to-end transfer rates are used with.: Ehe same call to take advantage of the better radio path .arror rate; use of a standard synchronous te
11、rminal adaptation fL;riction (as per TS GSM 07.03) within the MS. 340Y583 0070275 74T TS GSM 03.45 -version 3.2.0- page 3 f 2, NETWORK ARCHITECTURE FAX 1 The network architecture applicable to this Teleservice is shown in Fig 1/03.45, below. Adapt. Fig. 1/03-45 Network architecture y MT1 This shows
12、the case of mobile to fixed For mobile to mobile calls, there would effectively be a loop network interworking. back within the PLMN, using two IWFs. 3. REFERENCE CONFIGURATION AT THE MOBILE STATION The mobile reference configurations described in this section are defined as per TS GSM 04.02. Mobile
13、 Station I I I I I l Adapt. FAX : I TA MT1 Fig. 2/03.45 Reference configurations W 3404583 0070276 b8b W TS GSM 03.45 -version 3.2.0- page 4 The Teieservice definition in TS GSM 02.03 regards the group 3 facsimile terminal as a 2-wire analogue terminated equipment.In order to connect this to the MT2
14、 a separate “Fax Adaptor“ device is necessary. This configuration, shown in Fig. 2a03.45, has to be considered as the standard configuration, so that all the existing Group 3 facsimile apparatus can be connected to the PLMN. An alternative realisation would be to combine a standard group 3 facsimile
15、 machine and the Fax Adaptor into a specially developed “GSM facsimile machine“, directly providing a digital output. Although such a device must appear to the MT2 as identical to the Fax Adaptor (i.e.with an identical interface and protocol), it would allow for a significantly smaller and simpler f
16、acsimile machine. This configuration is shown in Fig 2d/03.45 and is regarded as a desirable alternative. In addition of course, it is always possible to realice an mo, as per Fig 2f/03.45, where both the facsimile and mobile termination functions are considered to be part of one integrated unit. Th
17、e remaining configurations concern the use of an S interface and Their use is for further study are considered as optional configurations. The particular terminal adaptation functions used are chose detailed in TS GSM 07.03 and the interface to the MTS *;sed is synchronous -V.24 with an option for s
18、upport of .25bis procedures for autocalling and autoanswering. 3-1 Fax AUaptor functionality The Fax Adaptor block, Fig. 3/03.45, is intecisi to specifically complement the Group 3 facsimile apparatus ir. :=der to be able to communicate over a GSM PLMN. I COMPOSITE TONE HANDLING MONTORIN * handling
19、of the signalling on the 2-wire path to the facsimile machine, including autocalling and autoanswer functions where necessary (see section 6). - a digital section, dealing with: * monitoring and where necessary, manipulation of the T.30 protocol as detailed in the rest of this Specification; * overa
20、ll control of the adaptor; * connection over the synchronous V.24 interface to the MT as described in TS GSM 07.03; * where necessary, autocalling and autoanswering functions in the following this specification will reference cF.e Fax Adaptor functionality, considering the most general case :;?ere i
21、t operates as a full-featured (see Fig. 3/03.45) separaro clock (see Fig. 2a/03.45), as this reference configuratl-E is implicitly or explicitly exhaustive of all service :?:Aced technical aspects. according to V.25bis. 3.2 GSM Facsimile Machine functionality The special GSM facsimile machine shown
22、in - - MS configuration of Fig 2d/03.45 has a similar functionalic;. - -he digital part of the Fax Adaptor, but without any of the i:. ,-:gue port ions. It appears over the V.24 interface as identical to -:.? Fax Adaptor, 1.e. the MT2 needs to have no knowledge The particular configuration used. Whe
23、n necessary this reference configuration, will be e:;. - .: :ly referenced to in the following; otherwise all technical . ;-ts relevant to the configuration implicitly apply. 4. CONNECTION TYPES Table 1/03.45 shows the connection elements ar-: .: .tes applicable to this Teleservice!), adapted from T
24、S GSM C3 () Teleservice 61 includes both speech and data connecticn - -i. but Teleservice 62 only the data connection type W 3404583 0070278 459 W GSM 03.10 Model 6:Cpeech TS GSM 03.45 -version 3.2.0- page 6 Station RA1 to RA2 element CCITT A-law - Speech/GSM - Protocol type Access to TAF Radio inte
25、rface of fig.6 TC of the Mobile connection element Model 5 : Facsimile Group 3 C/D/S UD1 C/D/C UD1 C/D/S UD1 C/D/S UD1 - 9.6kbit/s - 12.0kbit/s - 16kbit/s - 64kbit/s - 4.8kbit/s - 6.0kbit/s - 8kbit/s - 64kbit/s - 2.4kbit/s - 3.6kbit/s - 8kbit/s - 64kbit/s (“1 The Fig. 4/03.45 shows the scheme of a t
26、ypical GSM PLMN connection for this Teleservice, considering respectively R and S access at Network Termination. To grant full support to the CCITT Rec. T.30, requiring different transmission speeds, the following strategy shall be implemented: - PLMN provides for three Access Rate only, that is 960
27、0 bit/s, 4800 bit/s, 2400 bit/s; - radio channel modification procedures are used for switching between Speech phase and facsimile phase, as well as to select the suitable Access Rate (9600/4800/2400 bit/s) within the facsimile phase, as resulting from the preliminary end-to-end negotiation between
28、the terminals; - to transport Binary Coded Signaling (BCS) requiring a synchronous 300 bit/s bit-rate, speed conversion will be used at both the PLMN ends. DTE FAX idaptor Fig. 4a/03.45 DCE - MT2 MSCAWF P L: M !Adapto m N: a I * - Standard Teleservice connection (“1 The highest Access Rate actually
29、supported in this Teleservice will be consistent with the highest Transparent Bearer Service provided by the Network Operator, according to the classification ( E3 / A 1 fixed in GSM Rec. 02.02. m 3404583 0070277 395 m TS GSM 03.45 -version 3.2.0- page 7 Fig. 4b/03.45 Optional Teleservice connection
30、 (F.F.S) 4.1 Information transfer protocol model The Fig. 5/03.45 depicts the protocol model for this Teleservice, deduced from model 5 of Fig. 6/03.10. The main point to be underlined is that all the protocol modules specific for this Teleservice are confined in the Fax Adaptation functions at both
31、 the MT and IWF ends. Mobile Station Base Station MSCAWF RVF Fax -; Adapt. I Radio VF BSS-MSC VF I I I I I I I I I I I I Fig. 5/03.45 Information transfer protocol model 4.2 Interactions with T.30 The philosophy of this Specification is to allow the T.30 protocol to pass transparently wherever possi
32、ble, through the Fax Adaptors at both ends of the PLMN channel. Manipulations are only made to the protocol where necessary to overcome problems resulting from the differences between the PSTN and the GSM system. Basically, these problems fall into four categories: - supporting facsimile on a digita
33、l connection type; 3404583 0070280 007 TS GSM 03.45 -version 3.2.0- page 8 - bit errors during transfer of BCS frames; - the need to change speed to reduce the impact of bit errors during transfer of Fax encoded Messages; - inability to support some features of T.30. 4.2.1 Link control strategy Thou
34、gh the T.30 procedure is plain half-duplex, between the FAs at both the GCM PLMN ends a full-duplex mode connection will be established. Information transfer is structured in fixed length blocks, carrying either data received from the local modem, or idle synchronization patterns. Establishment, mai
35、ntenance and release of the data circuit is performed autonomously by each FA, by properly handling the physical interface to its local modem. Due to the rigid timeout constrains in T.30 protocol procedure, which will be actually concatenated to the procedure defined here for the GCM connection part
36、, a strictly forward- only approach is adopted for data link control; that is no retransmission means are explicitly introduced to recover corrupted information blocks. Although in the majority of cases the T.30 protocol can take care of lost frames and easily recover, there are some particularly cr
37、itical points where two consecutive segments in the procedure, without any interposed acknowledgement, require different transmission speeds (BCC speed/Message speed). In these cases, to grant that a correct change-over from one modem type to another takes place at both the PLMN ends, some additiona
38、l protection is necessary in the GSM environment. This protection, actually at the beginning and at the end of the Fax page transmission, is given by means of a confirmation mechanism, whereby the originating FA waits while transmitting a fixed pattern until an explicit acknowledgment is received fr
39、om the terminating FA. In these cases an interruption of the normal T.30 information flow may eventually result. Aiming at minimizing any possible delay in the end-to-end transmission between the two facsimile apparatuses, the FAs will pass on information without error control of the message integri
40、ty To this regard, however, it is worth underlining that an essential requirement in this procedure is the detection of some key messages exchanged between the terminals, carrying basic control information. Hence, in parallel to the primary information passing process, a continuous monitoring of the
41、 information flowing across the FA is necessary, to detect these messages, fully checked in their logical integrity. (.) All V.21 modems in the FAs shall use the faster response time provided by CCITT Rec. V.21 (see Table 2/V.21) for OFF to ON transition of CT109 and CT106. = 3404583 OD70281 T43 m T
42、S GSM 03.45 -version 3.2.0- page 9 In addition, as detailed below, some fields in some frames may need to be changed. 4.2.1.1 Message detection While in BCS, the following frames have to be detected: - DIS/DTC, to monitor all operationai parameters proposed to the sender terminal by the receiver ter
43、minal; - DCS, to realize (see Table 2/T.30) the actual message transmission speed accepted by the sender terminal; - NSF, to inhibit Non-Standard Facilities, if explicitly required by the user Fax Adaptor configuration; - DCN, to initiate the Call release procedure. During the Message phase (C phase
44、 of T.30) a single bit pattern has to be detected, the EOL character, a unique codeword that can never be found within a valid line of Fax coded Data (see CCITT Rec. T.4, section 4.1.21, and therefore used to control the buffer level in each FA, as detailed in the following section 5.2.6. 4.2.2 Spee
45、d conversion for BCS phases Given the signalling load caused by the Channel Mode Modify procedure, rather than changing the radio channel speed to 300 bit/s to carry the BCS frames, a speed conversion mechanism is exploited at both the PLMN ends, allowing to maintain the Channel rate of the Message
46、phase (9600/4800/2400 bit/s) during BCS phases. A speed conversion factor can be defined as: Fax Message speed (9600 or 4800 or 2400 bit/s) Standard BCS speed (300 bit/s) which will assume the value 8 or 16 or 32, depending on the actual Message speed negotiated between the terminals. In the origina
47、ting FA up-conversion to Message speed will be performed on the basis of a plain “n times“ repetition algorithm. In the terminating FA, down-conversion to the BCS speed will require a “by nil decimation algorithm; this algorithm is assumed implementation dependent, and hence its actual definition is
48、 beyond the scope of this Specification. 4.2.3 Compatibility checking Some features of T.30 cannot be supported in the GSM PLMN environment. Fax Adaptation function is in charge of dealing with such compatibil.ity checking. 340Ll583 0070282 98T TS GSM 03.45 -version 3.2.0- page10 4.2.3.1 Group 1 and
49、 Group 2 support Group 1 and Group 2 equipments are not supported by the Teleservice as described in this Specification. TO this purpose, any tonal signalling specific to the above kind of Fax ap2aratus will be ignored by the Fax adaptation function at MS and IWF. 4.2.3.2 2400 bit/a handshaking Only standard 300 bit/s Binary Coded Signalling is supported. To this purpose the FA will ignore this capability within the B segment of T.30 procedure, looking for DIS frame, by default, from V.21 modem only. 4.2.3.3 Non-standard facilities Non-standard facilities are suppo
