1、 ETSI TS 1Digital cellular telecoUniversal Mobile TelCellular Ge(3GPP TS 26.2TECHNICAL SPECIFICATION126 226 V13.0.0 (2016communications system (Phaelecommunications System (r text telephone modem; General description .226 version 13.0.0 Release 13GLOBAL SYSTEMOBILE COMMUN16-01) hase 2+); (UMTS); 13)
2、 TEM FOR ICATIONSRETSI ETSI TS 126 226 V13.0.0 (2016-01)13GPP TS 26.226 version 13.0.0 Release 13Reference RTS/TSGS-0426226vd00 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 A
3、ssociation 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
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7、film except as authorized by written permission of ETSI. The content of the PDF version shall not be modified without the written authorization of ETSI. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2016. All rights r
8、eserved. DECTTM, PLUGTESTSTM, UMTSTMand the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE are Trade Marks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM and the GSM logo are Trade Marks registered and owned
9、 by the GSM Association. ETSI ETSI TS 126 226 V13.0.0 (2016-01)23GPP TS 26.226 version 13.0.0 Release 13Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly
10、 available for ETSI members and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
11、 server (https:/ipr.etsi.org/). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may
12、become, essential to the present document. Foreword This Technical Specification (TS) has been produced 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 shoul
13、d be interpreted as being references to the corresponding ETSI deliverables. The cross reference 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“
14、, “need not“, “will“, “will not“, “can“ and “cannot“ are to be interpreted as described in clause 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 126 226 V13.0
15、.0 (2016-01)33GPP TS 26.226 version 13.0.0 Release 13Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 References 5g33 Definitions and Abbreviations 5g33.1 Definitions 5g33.2 Abbreviations . 6g34 General . 6g35 The problem . 6g35.1 US regula
16、tory issues . 6g36 The goals and objectives 7g37 Text Telephony architecture based upon CTM 7g37.1 Text Telephone devices 9g37.2 Error resilient transmission in the speech path . 9g37.3 Interworking with traditional Text Telephone devices . 9g38 Technical description of CTM . 10g38.1 Overview 10g38.
17、2 CTM transmitter . 10g38.2.1 Character set . 10g38.2.2 FEC error protection . 10g38.2.3 CTM burst structure 11g38.2.4 Periodic muting and insertion of resynchronization sequence 12g38.2.5 Interleaver and synchronization preamble 15g38.2.6 CTM modulator 16g38.2.7 Switching between speech and data 17
18、g38.3 CTM receiver . 17g39 CTM negotiation and inband signaling 17g39.1 Definition of control characters 18g39.2 CTM availability negotiation . 18g310 Functions in the CTM environment . 18g310.1 CTM to CTM communication 18g310.2 CTM between the mobile side and a gateway 19g310.3 CTM within the trans
19、coding equipment . 19g310.4 Cascading of CTM adapters in the speech path 19g310.5 Rerouting of a call from a CTM supported environment to a non-supported environment 19g3Annex A (Informative): CTM Receiver 21g3A.1 Demodulator . 21g3A.2 Synchronization and de-interleaver 21g3A.3 Puncture and resynchr
20、onization . 22g3A.4 FEC error correction . 22g3Annex B (informative): Change history . 23g3History 24g3ETSI ETSI TS 126 226 V13.0.0 (2016-01)43GPP TS 26.226 version 13.0.0 Release 13Foreword This technical description has been produced by T1P1. The present document is a description of the Cellular T
21、ext Telephone Modem solution for reliable transmission of a text telephone conversation via the speech channel of cellular or PSTN networks The contents of the present document are subject to continuing work within 3GPP and may change following formal 3GPP approval. Should the 3GPP TSG modify the co
22、ntents of this TD, it will be re-released by the 3GPP TSG with an identifying change of release date and an increase in version number as follows: Version x.y.z where: x the first digit: 1 presented to 3GPP for information; 2 presented to 3GPP for approval; 3 Indicates 3GPP approved document under c
23、hange control. y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections, updates, etc. z the third digit is incremented when editorial only changes have been incorporated in the specification; ETSI ETSI TS 126 226 V13.0.0 (2016-01)53GPP TS 26.226 versi
24、on 13.0.0 Release 131 Scope This Technical Specification (TS) concerns the Cellular Text Telephone Modem (CTM). CTM allows reliable transmission of a text telephone conversation alternating with a speech conversation through the existing speech communication paths in cellular mobile phone systems. T
25、his reliability is achieved by an improved modulation technique, including error protection, interleaving and synchronization. Together with recommendations ITU-T V.18 and T.140, CTM may serve for worldwide applications in text telephony. A general overview and explanations of possible implementatio
26、n architectures is provided. CTM is intended for use in end terminals (on the mobile or fixed side) and within the network for the adaptation between CTM and existing traditional text telephone standards. The CTM transmitter is fully specified and a bit exact C-code reference is provided. An impleme
27、ntation of an example CTM receiver is also described. 2 References This TS incorporates by dated and undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subs
28、equent amendments to or revisions of any of these publications apply to this TS only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies. 1 3GPP TS 26.231: “Cellular text telephone modem; Minimum performance requirements
29、“. 2 ITU-T Recommendation V.18 (2000-11): “Operational and interworking requirements for DCEs operating in the text telephone mode“. 3 3GPP TS 26.230: “Cellular text telephone modem; Transmitter bit exact C-code“. 4 ANSI TIA/EIA-825 (2000-03): “A Frequency Shift Keyed Modem for use of the Public Swi
30、tched Telephone Network“. 5 ITU-T Recommendation T.140 (1998-02): “Protocol for multimedia application text conversation, Feb. 1998“. 6 ISO/IEC 10646-1: “Information technology Universal Multiple-Octet Coded Character Set (UCS) Part1: Architecture and Basic Multilingual Plane“. 7 ITU-T Recommendatio
31、n H.248 (2000-11), Annex F: “Text Telephony, Text Conversation, Fax and Call discrimination packages“. 3 Definitions and Abbreviations 3.1 Definitions Cellular Text Telephone Modem: modem (consisting of transmitter and receiver) that allows the reliable transmission of text via the speech channel of
32、 cellular phone systems or PSTN networks Baudot Code: modem signal and character coding scheme of the North American Text Telephone, as specified in ITU-T V.18 2, Annex A.1 (“5-bit operational code“) and in ANSI TIA/EIA-825 4 Text Telephone Code: modem signal and character coding scheme of any of th
33、e PSTN Text Telephone types supported by the harmonizing ITU-T Recommendation V.18 2 ETSI ETSI TS 126 226 V13.0.0 (2016-01)63GPP TS 26.226 version 13.0.0 Release 133.2 Abbreviations For the purposes of this TS, the following abbreviations apply: BP Band Pass CER Character Error Rate CTM Cellular Tex
34、t Telephone Modem FCC Federal Communications Commission FEC Forward Error Correction GSM Global System for Mobile communications HCO Hearing Carry Over Alternating transmission of speech and text. ITU-T International Telecommunication Union Telecommunication standardization sector (former CCITT) LP
35、Low Pass PCM Pulse Code Modulation PSTN Public Switched Telephone Network TTY Text Telephone UCS Universal Multiple-Octet Coded Character Set UMTS Universal Mobile Telecommunications Systems VAD Voice Activity Detection VCO Voice Carry Over alternating transmission of speech and text 4 General Deaf,
36、 hard of hearing, and speech-impaired persons have been using specific Text Telephone (referred to as TTY in North America) equipment in the fixed network for many years to transmit text and speech through ordinary speech traffic channels. Modern digital cellular systems, however, do not provide sat
37、isfactory character error rates for text transmitted in the speech channel with the traditional modulation developed for the fixed network. The FCC under the US Government has required an urgent solution for all emergency (911) calls for one specific text telephone protocol called Baudot Code. This
38、TS addresses these FCC requirements, and specifies a solution for the GSM and UMTS and potentially other cellular technologies. The goal is to provide a solution that can support all traditional text telephony systems worldwide. Internationally, PSTN text telephony is standardized in ITU-T V.18 2 an
39、d ITU-T T.140 5. 5 The problem Due to the fact that digital cellular phone systems are optimized for speech signals and the radio transmission may be subject to relatively high error rates, the transmission of text telephone modem signals via the speech path in cellular networks is in some cases uns
40、atisfactory: i.e. received messages show an unacceptably high character error rate (CER). One reason for this is that the digital cellular phones use speech coding in order to compress the signal. Since this coding is optimized for speech-like signals, modem signals are more or less distorted. A fur
41、ther problem is in the transmission errors and the applied error concealment in digital cellular phone systems in case of poor channel conditions. The repetition of speech frames results in character errors or even in error propagation. The traditional text telephone modulation technique, designed y
42、ears ago for PSTN lines, was not developed for these sophisticated, speech-optimized transmission channels. Data transmission methods exist in the wireless services, but for various reasons, a text telephone transmission method for the speech path is desired. Two reasons are: 1: text telephony is ac
43、knowledged as a way to contact the emergency services, and emergency services in wireless networks are so far only defined for speech calls. 2: Alternating speech and text in a call is desired, and one simple way to accomplish that without special service support (like multimedia) is by alternating
44、the use of the speech channel. 5.1 US regulatory issues The FCC under the US Government has required an urgent solution for all emergency (911) calls for one specific text telephone protocol of the ITU-T V.18 standard, called “Baudot Code“. This TS addresses these FCC requirements and this section p
45、oints out specific US regulatory issues. ETSI ETSI TS 126 226 V13.0.0 (2016-01)73GPP TS 26.226 version 13.0.0 Release 13The minimum performance requirements for the CTM transmission are included in 1. That specification shall be applied for verifying performance. The FCC requires that the solution f
46、or cellular systems is fully compatible to traditional text telephone standards, at least it shall support Baudot modulation at 45.45 baud in the landline end. 6 The goals and objectives CTM is developed to provide a solution that: - meets the FCC Emergency Call (911) requirements for Text Telephony
47、; - meets the requirements for a Global solution for Text Telephony; - works with GSM AMR, EFR, and FR codecs, as well as future codecs; - is applicable for existing and future speech traffic channels in GSM and UMTS; - minimizes the impact to existing or future cellular networks; - allows roaming b
48、etween networks of different operators; - provides a transmission rate of 10 characters per second according to a net bit rate of 80 bit/s; - does not introduce an additional delay of more than 800 ms for text transmission; - does not have any impact for voice transmission, i.e. speech signals must
49、not be distorted or delayed. 7 Text Telephony architecture based upon CTM An overall architecture for supporting traditional text telephone communication via cellular telephone systems is depicted in figure 1. This Technical Specification covers the gray shaded transmission and receiving parts of the Cellular Text Telephone Modem (CTM). The text telephone detector may act as specified in V.18 2. This section provides an overview of the CTM transmitter and the CTM receiver. The Cellular Text Telephone Modem is fully specified in the following
