1、 ETSI TR 102 702 V1.1.1 (2010-03)Technical Report Access, Terminals, Transmission and Multiplexing (ATTM)Study of issues related to POTS injection in the customer wiring from xDSL VoIP Home GatewayETSI ETSI TR 102 702 V1.1.1 (2010-03) 2Reference DTR/ATTM-06016 Keywords ADSL, VDSL, POTS, splitter ETS
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6、n. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2010. All rights reserved. DECTTM, PLUGTESTSTM, UMTSTM, TIPHONTM, the TIPHON logo and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3
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8、 the GSM Association. ETSI ETSI TR 102 702 V1.1.1 (2010-03) 3Contents Intellectual Property Rights 4g3Foreword . 4g3Introduction 4g31 Scope 5g32 References 5g32.1 Normative references . 5g32.2 Informative references 5g33 Definitions, symbols and abbreviations . 6g33.1 Definitions 6g33.2 Symbols 7g33
9、.3 Abbreviations . 7g34 The background: from the PSTN to VoIP telephony . 8g34.1 Customers plants with centralised splitter 8g34.2 Customer plants with distributed filtering 10g35 Technical issues of POTS re-injection . 11g35.1 Speech transmission quality . 12g35.1.1 Frequency response characteristi
10、cs . 13g35.1.2 Return Loss . 16g35.2 xDSL transmission integrity . 24g35.3 Safety considerations 30g36 Conclusive remarks 30g3Annex A: AC terminating impedances . 31g3A.1 ZDSL: xDSL transceiver related impedances 31g3A.2 ZR: CPE and POTS interface off-hook impedance 31g3A.3 ZOnHo: Impedance On-hook
11、. 31g3Annex B: Optimisation of the input and balance impedances of the POTS interface of Home Gateways intended for re-injection applications 32g3B.1 Balance impedance optimisation 32g3B.2 Input impedance optimisation 37g3B.3 Conclusions on impedance optimisation 40g3History 41g3ETSI ETSI TR 102 702
12、 V1.1.1 (2010-03) 4Intellectual 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 available for ETSI members and non-members, and can be found in ETSI SR 000 314: “In
13、tellectual 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 server (http:/webapp.etsi.org/IPR/home.asp). Pursuant to the ETSI IPR Policy, no inv
14、estigation, 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 become, essential to the present document. Foreword This Technical Repo
15、rt (TR) has been produced by ETSI Technical Committee Access, Terminals, Transmission and Multiplexing (ATTM). It addresses the major issues related with the performances of VoIP customer installations exploiting the re-injection of the POTS service locally generated by the Home Gateway in the custo
16、mer premises wiring, without electrically disconnecting it from the external line. The present document is fully in line with the initiative “eEurope 2002 - An Information Society For All“, under “The contribution of European standardization to the eEurope Initiative, A rolling Action Plan“ especial
17、ly under the key objective of a cheaper, faster and secure Internet. Introduction Current ETSI standards on POTS/xDSL filters are based on the assumption of a classic xDSL deployment, either from the exchange or from the cabinet, with the POTS signals respectively injected at the central office or a
18、t the cabinet side of the local loop. Voice over IP (VoIP) technology is however progressively replacing the traditional telephone service provided from the Central Office. This technology, originally mainly used by IP Operators to complement their “triple play“ offer, is now being increasingly adop
19、ted also by the incumbent Operators to significantly cut the costs of the Central Office Switching Equipment and of the copper access network and to integrate the telephone service provision into the multimedia IP transmission and management platforms. In the VoIP telephony provision scenario the PO
20、TS signals are typically locally generated from the POTS interface of the Home Gateway. However, despite having abandoned the access network existing infrastructure, VoIP operators are still willing to take advantage of the existing customer wiring and POTS terminals, in order to achieve the seamles
21、s transition from the traditional POTS service to IP telephony. To this purpose, the POTS signals are locally re-injected in the user premises networks. To allow the self-installation by the customer for minimising the deployment time and costs, and to accommodate the constraints implicit in distrib
22、uted architectures, the re-injection technique is used for distributed architectures without galvanically separating the customer wiring from the external line. The resulting operating conditions of distributed filters when used in these applications are quite peculiar and differ substantially from
23、those assumed as a basis for their standardisation. The present document addresses the associated technical issues. ETSI ETSI TR 102 702 V1.1.1 (2010-03) 51 Scope The present document identifies the major issues affecting the speech and xDSL performances of customer installations exploiting the VoIP
24、 telephony provision through the re-injection of the analogue telephony service, as generated at the POTS interface of the xDSL Home Gateway, in the customer premises network without electrically disconnecting it from the external line. 2 References References are either specific (identified by date
25、 of publication and/or edition number or version number) or non-specific. For a specific reference, subsequent revisions do not apply. Non-specific reference may be made only to a complete document or a part thereof and only in the following cases: - if it is accepted that it will be possible to use
26、 all future changes of the referenced document for the purposes of the referring document; - for informative references. Referenced documents which are not found to be publicly available in the expected location might be found at http:/docbox.etsi.org/Reference. NOTE: While any hyperlinks included i
27、n this clause were valid at the time of publication ETSI cannot guarantee their long term validity. 2.1 Normative references The following referenced documents are indispensable for the application of the present document. For dated references, only the edition cited applies. For non-specific refere
28、nces, the latest edition of the referenced document (including any amendments) applies. Not applicable. 2.2 Informative references The following referenced documents are not essential to the use of the present document but they assist the user with regard to a particular subject area. For non-specif
29、ic references, the latest version of the referenced document (including any amendments) applies. i.1 ETSI TS 102 971: “Access and Terminals (AT); Public Switched Telephone Network (PSTN); Harmonized specification of physical and electrical characteristics of a 2-wire analogue interface for short lin
30、e interface“. i.2 ETSI TR 102 021: “Terrestrial Trunked Radio (TETRA); User Requirement Specification TETRA Release 2“. i.3 ETSI TBR 038: “Public Switched Telephone Network (PSTN); Attachment requirements for a terminal equipment incorporating an analogue handset function capable of supporting the j
31、ustified case service when connected to the analogue interface of the PSTN in Europe“. i.4 ETSI ES 203 038: “Speech and multimedia Transmission Quality (STQ); Requirements and tests methods for terminal equipment incorporating a handset when connected to the analogue interface of the PSTN“. ETSI ETS
32、I TR 102 702 V1.1.1 (2010-03) 6i.5 ETSI ES 201 970: “Access and Terminals (AT); Public Switched Telephone Network (PSTN); Harmonized specification of physical and electrical characteristics at a 2-wire analogue presented Network Termination Point (NTP)“. i.6 ETSI TS 101 952-1: “Access network xDSL t
33、ransmission filters; Part 1: ADSL splitters for European deployment; Sub-part 1: Generic specification of the low pass part of DSL over POTS splitters including dedicated annexes for specific xDSL variants“. i.7 ETSI TS 101 952-1-5: “Access network xDSL transmission filters; Part 1: ADSL splitters f
34、or European deployment; Sub-part 5: Specification for ADSL over POTS distributed filters“. i.8 EN 60950-1: “Information technology equipment - Safety - Part 1: General requirements“. i.9 IEEE 802: “IEEE Standard for Local and metropolitan area networks“. i.10 IEEE 802.11: “IEEE Standard for Informat
35、ion technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications“. i.11 Broadband Forum TR-127: “Dynamic Testing of Splitters and In-Line f
36、ilters with xDSL Transceivers“. 3 Definitions, symbols and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: access network: network connecting the Local Exchange with the customer wiring. Often referred to as “local loop“ Customer Pre
37、mises Network (CPN): in-house IP network connecting the Home Gateway to the customer IP devices distributed filter: low pass filter that is added in series with each of the parallel connected POTS TEs NOTE: Each of the parallel connected filters (in the in-house cabling) is known as a distributed fi
38、lter. These filters are also known as In-line filters or microfilters. far end echo: speech that is fed back to the talker in a telephony connection with a round trip delay (i.e. the delay between talking and hearing the feedback) greater than 5 ms, resulting in a distinguishable echo FXS port (inte
39、rface): POTS interface of Home Gateways home gateway: gateway between the Access Network (AN) and the Customer Premises Network (CPN) NOTE: For the purposes of the present document the Home Gateway, besides implementing the xDSL and networking functionalities allowing the customer access to IP servi
40、ces, also features a local POTS interface allowing the access to the VoIP telephony services by means of plain POTS terminal equipment. hybrid: circuit used in the POTS transmission link in COs and HGs (provided with POTS interface) for implementing the four wires/two wires transition between the sp
41、eech codec and the POTS interface NOTE: This circuit operates as a bridge with an internal balance impedance which is intended to match as well as possible the impedance presented by the POTS line. local loop: See access network. microfilter: distributed filter off-hook: state of the POTS equipment
42、at either end of a loop connection when the NTP terminal equipment is in the steady loop state ETSI ETSI TR 102 702 V1.1.1 (2010-03) 7on-hook: state of the POTS equipment at either end of a POTS loop connection when the NTP terminal equipment is in the quiescent state passive splitters: splitters co
43、ntaining exclusively passive components POTS re-injection: delivery scheme by which the POTS service, as locally generated from the POTS interface of the xDSL Home Gateway, is injected into the customer premises telephone wiring without electrically disconnecting it from the external line POTS/xDSL
44、splitter: circuit separating the transmission of POTS signals and DSL signals, enabling the simultaneous transmission of both services on the same twisted pair sidetone: speech that is fed back to the talker in a telephony connection with a round trip delay (i.e. the delay between talking and hearin
45、g the feedback), of less than approximately 5 ms, making it indistinguishable from the original utterance triple play services: services combining Data, Voice and Video unbundling: process whereby a local loop owned and operated by a providing operator is made available in whole or in part to a requ
46、esting operator for the provision of services to a user xDSL: covers ADSL and VDSL families only NOTE: E.g. SDSL is not covered by this abbreviation in the present document. 3.2 Symbols For the purposes of the present document, the following symbols apply: RLCOReturn loss at the POTS interface of th
47、e POTS/xDSL splitter at the CO side RLTEReturn loss at the POTS interface of the TE microfilter for the traditional xDSL deployment RLRIReturn loss at the POTS port of the microfilters for the re-injection scheme ZACGeneric name for the AC POTS impedance models ZDSLImpedance model of the input filte
48、r of a particular xDSL ZOnHoImpedance modelling multiple parallel on-hook phones ZREuropean harmonized complex reference POTS impedance 3.3 Abbreviations For the purposes of the present document, the following abbreviations apply: AC Alternating Current ADSL Asymmetric Digital Subscriber Line CO Cen
49、tral Office NOTE: Local Exchange LE. CPE Customer Premise Equipment NOTE: Terminal Equipment TE. CPN Customer premises network NOTE: See definition. DC Direct Current DSL Digital Subscriber Line DSLAM Digital Subscriber Line Access Multiplexer ERL Echo Return LossETH Ethernet interface NOTE: See IEEE 802 i.9. ETSI ETSI TR 102 702 V1.1.1 (2010-03) 8FXS Foreign eXchange Station HG Home Gateway IP Internet ProtocolLE Local Exchange NOTE: Central Office. NTP Network Termination Point OLO Other Licensed Operator PLT Power Line Telecommunicatio
