1、 ETSI TS 123 053 V15.0.0 (2018-07) Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); Tandem Free Operation (TFO); Service description; Stage 2 (3GPP TS 23.053 version 15.0.0 Release 15) TECHNICAL SPECIFICATION GLOBAL SYSTEM FOR MOBILE COM
2、MUNICATIONSRETSI ETSI TS 123 053 V15.0.0 (2018-07)13GPP TS 23.053 version 15.0.0 Release 15Reference RTS/TSGS-0423053vf00 Keywords GSM,UMTS ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Associa
3、tion but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice The present document can be downloaded from: http:/www.etsi.org/standards-search The present document may be made available in electronic versions and/or in print. The content of any electronic and/or print
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13、TSI, and conveys no right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks. Foreword This Technical Specification (TS) has been pr
14、oduced by ETSI 3rd Generation Partnership Project (3GPP). The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables. The cross reference
15、between GSM, UMTS, 3GPP and ETSI identities can be found under http:/webapp.etsi.org/key/queryform.asp. Modal verbs terminology In the present document “shall“, “shall not“, “should“, “should not“, “may“, “need not“, “will“, “will not“, “can“ and “cannot“ are to be interpreted as described in clause
16、 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions). “must“ and “must not“ are NOT allowed in ETSI deliverables except when used in direct citation. ETSI ETSI TS 123 053 V15.0.0 (2018-07)33GPP TS 23.053 version 15.0.0 Release 15Contents Intellectual Property Rights 2g3For
17、eword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 References 5g33 Definitions and abbreviations . 6g33.1 Definitions 6g33.2 Abbreviations . 6g34 Main Concepts 6g35 TFO Architecture and Transmission Mechanism . 6g35.1 TFO Access Interfaces and Reference Points . 6g35.2 General In-band
18、Transmission Mechanism for TFO 7g35.3 High-Level Functions Required for TFO . 7g36 Model of operation . 8g36.1 Overview 8g36.2 TFO establishment phase . 8g36.2.1 Sending of TFO_REQ message by a BSS 8g36.2.2 Monitoring of TFO_REQ by a BSS 9g36.3 Transparency of transmission equipments . 9g36.3.1 Loca
19、l disabling 9g36.3.2 Transparency to TFO negotiation messages . 9g36.3.3 Transparency to TFO speech frames 9g36.4 Modification of speech codec . 10g36.4.1 Introduction. 10g36.4.2 Exchanged parameters 10g36.4.3 Change of speech codec configuration in the BSS . 10g36.5 TFO operation 10g36.5.1 End to e
20、nd delay . 10g36.5.2 Synchronisation between TRAUs . 10g36.5.3 Monitoring in TFO operation 11g36.5.4 DTX aspects 11g36.5.5 Error concealment . 11g36.5.6 Management of UFE bit . 11g36.5.7 Handover management . 11g36.5.8 Other issues . 12g37 Compatibility Issues . 12g38 Interactions with Other Service
21、s 12g38.1 General . 12g38.2 Support of DTMF . 12g39 Operational Aspects . 13g3Annex A (informative): Change history . 14g3History 15g3ETSI ETSI TS 123 053 V15.0.0 (2018-07)43GPP TS 23.053 version 15.0.0 Release 15Foreword This Technical Specification has been produced by the 3rdGeneration Partnershi
22、p Project (3GPP). The contents of the present document are subject to continuing work within the TSG and may change following formal TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying change of release date and an increase
23、in version number as follows: Version x.y.z where: x the first digit: 1 presented to TSG for information; 2 presented to TSG for approval; 3 or greater indicates TSG approved document under change control. y the second digit is incremented for all changes of substance, i.e. technical enhancements, c
24、orrections, updates, etc. z the third digit is incremented when editorial only changes have been incorporated in the document. ETSI ETSI TS 123 053 V15.0.0 (2018-07)53GPP TS 23.053 version 15.0.0 Release 151 Scope The present document defines the stage 2 service description for Tandem Free Operation
25、 (TFO) in and between GSM and UMTS. Tandem Free Operation applies only to speech calls. NOTE: The TFO principles are built so that they could be used as well by other systems other than GSM and UMTS. In analogy with ITU-T Recommendations I.130 2 and with reference to ITU-T Recommendations Q.65 VI.1
26、(Stage 2 of the method for the characterisation of services supported by an ISDN), the second stage of the following three-level structure is derived from a stage 1 service description. - Stage 1 is an overall service description, from the service subscribers and users standpoints, that views the ne
27、twork as a single entity which provides services to the user. - Stage 2 identifies the functional capabilities and information flows needed to support the service described in stage 1. Furthermore, it identifies various possible physical locations for the functional capabilities. The output of Stage
28、 2, which is signalling system independent, is used as an input to Stage 3, the design of signalling system and switching Recommendations. - Stage 3 defines the signalling system protocols and switching functions needed to implement the service described in stage 2. 2 References The following docume
29、nts contain provisions which, through reference in this text, constitute provisions of the present document. - References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. - For a specific reference, subsequent revisions do not apply. - Fo
30、r a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document. 1 3GPP TR 01.04: “Digital cellular telecomm
31、unications system (Phase 2+); Abbreviations and acronyms“. 2 ITU-T Recommendations I.130 (1988): “Method for the characterization of telecommunication services supported by an ISDN and network capabilities of an ISDN“. 3 3GPP TS 22.053: “Tandem Free Operation (TFO); Service Description - Stage 1“. 4
32、 3GPP TS 48.060: “Digital cellular telecommunications system (Phase 2+); In-band control of remote transcoders and rate adaptors for full rate traffic channels“. 5 3GPP TS 48.061: “Digital cellular telecommunications system (Phase 2+); In-band control of remote transcoders and rate adaptors for half
33、 rate traffic channels“. ETSI ETSI TS 123 053 V15.0.0 (2018-07)63GPP TS 23.053 version 15.0.0 Release 153 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: Tandem Free Operation: corresponds to the Mobile-to-Mobile call
34、s for which the speech is not transcoded two times but only one by the Mobile Stations For simplicity the term MS is also used when UE is meant for 3G systems. The same is valid for TRAU and TC analogously. 3.2 Abbreviations For the purposes of the present document, the following abbreviations apply
35、: IPE: In Path Equipment TFO: Tandem Free Operation Further abbreviations used may be found in 3GPP TR 01.04 1. 4 Main Concepts In-band TFO aims to remove the speech coding and decoding done in the BSS in MS-to-MS calls in order to improve the perceived speech quality. In-band TFO is established aft
36、er call set-up using in-band signalling. This signalling is therefore controlled by the TRAU. Using in-band signalling implies that the link between the TRAUs is transparent in the sense that the digital content of what is emitted by a TRAU is not modified. The so-called In Path Equipments must ther
37、efore be disabled or configured in such a way that the information (signalling and coded speech) required for Tandem Free is not altered. 5 TFO Architecture and Transmission Mechanism 5.1 TFO Access Interfaces and Reference Points The GSM BSS reference points for TFO are described in figure 1. GSM A
38、 interface reference point applies here with the exception that speech is not in the standard 64 kbit/s PCM format and between TFO TRAUs in-band signalling is used. For speech and in-band signalling the MSC is transparent. The UMTS core network reference points for TFO are described in figure 2. The
39、 UMTS Nb interface reference point applies here with the exception that speech is not in the standard 64 kbit/s PCM format and between TFO TRAUs in-band signalling is used. For speech and in-band signalling the Core Network is transparent. Additional transmission equipments are taken into account. T
40、hese equipments are all those which can process the PCM signal between the two peer BSS, e.g. echo cancellers, DCME. The BSS to BSS transmission is then considered transparent provided no transmission equipment along the circuit do not modify the 1 or more LSB or these transmission equipments implem
41、ent a TFO “transparency mode“. A specific signalling allows to remotely control in-band these equipments. BSS-MSC out-of-band signalling consists in this version of TFO of the normal BSSMAP signalling which carries the list of acceptable speech codec that may be used for the TFO negotiation mechanis
42、m. Use of TFO specific out-of-band mechanism is not foreseen in that version of the specification. ETSI ETSI TS 123 053 V15.0.0 (2018-07)73GPP TS 23.053 version 15.0.0 Release 15MS TRAUTRAUMSBTS BTSBSCBSC MSC MSC64 kbit/s Speech Samples carrying- TFO Frames on the LSB containing- Compressed speech s
43、amples- Control bits- TFO Messages- Original PCM speech samples on the MSBIPE IPEAbis AbisA AFigure 1 TCUENode BRNCMSC ServerMGw64 kbit/s Speech Samples carrying- TFO Frames on the LSB containing- Compressed speech samples- Control bits- TFO Messages- Original PCM speech samples on the MSBTCUENode B
44、 RNCMSC ServerMGwIPE IPEIuNbIu NbFigure 2 5.2 General In-band Transmission Mechanism for TFO In TFO establishment mode, one bit out of 16 LSB bits is regularly stolen of the 64 kbits/s circuit. This provides for a 0,5 kbits/s channel and has been selected so that the degradation on the speech qualit
45、y is inaudible. In TFO established mode bit stealing takes place on the LSB bit/s (bit 8, 7 9-N; N=1: number of stolen LSB bits) on each PCM sample. The number N of stolen LSB bit/s depends on the codec type. This provides for a N*8 kbits/s channel that allows to carry vocoded speech in TFO frames.
46、The contents of the “unstolen“ bits 1- (8-N) is normal A/-law information. 5.3 High-Level Functions Required for TFO The high level functions which apply to TFO are described hereafter. Not all these functions need necessarily to be covered by the first description of TFO since some issues may be to
47、o complex to solve in an initial stage or at all. ETSI ETSI TS 123 053 V15.0.0 (2018-07)83GPP TS 23.053 version 15.0.0 Release 15The list of functions which are applicable to the BSS follows: - signalling a request message (TFO_REQ) on the A interface that the TRAU supports TFO; - signalling an ackn
48、owledgement message (TFO_ACK) that the request message has been received from the peer entity; - monitoring request and acknowledgement messages on the A interface that the peer entity supports TFO; - remote control of echo cancellers, DCME, .; - signalling of current speech codec with acknowledgeme
49、nt message; - signalling of speech codec capability with acknowledgement message; - change of current speech codec within the BSS (optional); - sending of TFO speech frames to the A interface; - reception of TFO speech frames from the A interface; - conversion of a flow of TRAU frames into TFO speech frames; - conversion of a flow of TFO speech frames into TRAU frames. The following function applies to IPEs that may be along the 64 kbits/s circuit, such as DCME or echo cancellers equipments: - monitoring of TFO negotiation messages; - repetition of LSB bit 8 o
