1、 ETSI TR 102 927 V1.1.1 (2010-11)Technical Report Speech and multimedia Transmission Quality (STQ);Packet Loss Concealment (PLC)performance measurement setup for home networksETSI ETSI TR 102 927 V1.1.1 (2010-11) 2Reference DTR/STQ-00177 Keywords analysis, quality, voice ETSI 650 Route des Lucioles
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8、I ETSI TR 102 927 V1.1.1 (2010-11) 3Contents Intellectual Property Rights 4g3Foreword . 4g31 Scope 5g32 References 5g32.1 Normative references . 5g32.2 Informative references 5g33 Definitions and abbreviations . 6g33.1 Definitions 6g33.2 Abbreviations . 6g34 Application area . 6g34.1 Codecs 6g34.2 D
9、evices . 6g35 Test environments 7g36 Detailed description of the test bed 7g36.1 For DSL home gateways 7g36.2 For FTTH home gateways 8g36.3 For VoIP applications on PC and IP-phones 8g36.4 For wireless terminals with embedded VoIP application . 10g37 Test procedure 10g37.1 PLC performance assessment
10、 (in terms of resulting voice quality) . 10g37.2 PLC behaviour analysis 12g3Annex A: Examples of test results 14g3History 17g3ETSI ETSI TR 102 927 V1.1.1 (2010-11) 4Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The inform
11、ation 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: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the E
12、TSI Secretariat. Latest updates are available on the ETSI Web server (http:/webapp.etsi.org/IPR/home.asp). 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 00
13、0 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This Technical Report (TR) has been produced by ETSI Technical Committee Speech and multimedia Transmission Quality (STQ). ETSI ETSI TR 102 927 V1.1.1 (2010-11) 51 Scope The
14、 present document describes the principles of performance measurement of PLC mechanisms for Voice over IP, based on a simulation of mastered degradations (IP packet loss with growing importance), assessment of QoS (through MOS-LQO scores) at the output of PLC. It defines the measurement setup needed
15、 and describes the detailed analysis of its behaviour. The present document presents a detailed and practical description of the corresponding test setup and procedure. Annex A provides examples of results of measurements done according to the test procedure defined in the present document. 2 Refere
16、nces References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Ref
17、erenced 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 in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. 2.1 Normative references
18、 The following referenced documents are necessary for the application of the present document. Not applicable. 2.2 Informative references The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area
19、. i.1 ITU-T Recommendation G.711: “Pulse code modulation (PCM) of voice frequencies“ (with Appendix I). i.2 ITU-T Recommendation G.722: “7 kHz audio-coding within 64 kbit/s“. i.3 ITU-T Recommendation G.729: “Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear predict
20、ion (CS-ACELP)“. i.4 ITU-T Recommendation P.862: “Perceptual evaluation of speech quality (PESQ): An objective method for end-to-end speech quality assessment of narrow-band telephone networks and speech codecs“. . i.5 ITU-T Recommendation P.862.1: “Mapping function for transforming P.862 raw result
21、 scores to MOS-LQO“. i.6 ITU-T Recommendation P.862.2: “Wideband extension to Recommendation P.862 for the assessment of wideband telephone networks and speech codecs“. i.7 ITU-T Recommendation P.862.3: “Application guide for objective quality measurement based on Recommendations P.862, P.862.1 and
22、P.862.2“. i.8 ETSI EG 202 425: “Speech Processing, Transmission and Quality Aspects (STQ); Definition and implementation of VoIP reference point“. ETSI ETSI TR 102 927 V1.1.1 (2010-11) 63 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and
23、definitions apply: home gateway: gateway between the Access Network (AN) and the Customer Premises Network (CPN) 3.2 Abbreviations For the purposes of the present document, the following abbreviations apply: DSLAM Micro-DSLAM ADSL Asymmetrical Digital Subscriber Line AMR Adaptive Multi-Rate codec DE
24、CT Digital Enhanced Cordless Telecommunications DSL See ADSL. DSLAM Digital Subscriber Line Access Multiplexer DTMF Dual Tome Multi Frequency FTTH Fibre to the home FXS (port interface) POTS interface of home Gateways GSM Global System for Mobile communication HATS Head and Torso simulator IP Intern
25、et ProtocolMOS-LQON Mean Opinion Score - Listening Quality, objective, Narrow-band PC Personal computerPLC acket Loss ConcealmentPOTS Plain old telephone service PSTN Public Switched Telephone Network SIP Session Initiation Protocol VoIP Voice over Internet Protocol WiFi Wireless Fidelity 4 Applicat
26、ion area 4.1 Codecs In the present document, we focus on PLC mechanisms associated with G.711 i.1 decoders only. In next revisions of the present document, the declination of this method for other codecs with optional PLC, like G.722 i.2 and AMR codec family, will be presented. Since PLC has been by
27、 default embedded in newer standardised decoders (like G.729 i.3), the performance of PLC mechanisms does not need to be assessed for these other codecs. 4.2 Devices The present document addresses all the following types of Home network devices likely to implement PLC: DSL home gateways FTTH home ga
28、teways VoIP applications on PC or IP phones Wireless terminals (WiFi, Bluetooth, DECT) with embedded VoIP application ETSI ETSI TR 102 927 V1.1.1 (2010-11) 75 Test environments The tests can be done in laboratory environment or in live situations. Both approaches are considered in the present docume
29、nt. It may also be sometimes difficult to make the tests: e.g. some test laboratories may not have the relevant tools for initiating the connection, or on real networks the performance may not be guaranteed. 6 Detailed description of the test bed Since PLC is meant to compensate for lost packets, th
30、e principle is to simulate such losses and to monitor the output signals. For this purpose a dedicated IP degradation simulation tool is used. This simulation is performed on the IP flow and requires: 1) to be done as close as possible to the measurement point (in order to avoid IP packet losses bet
31、ween the simulation and the measurement points), 2) on an Ethernet link (or any similar physical support where IP packets can be directly processed). It is also necessary to ensure, as far as possible, that the link on which tests are performed is clean, that is exempt of degradations likely to caus
32、e packet losses before the simulation is performed. This is generally the case in a laboratory environment, as well as in live network under unstressed conditions. At the other end of the connection, a reference end-point is also necessary in order to send reference signals without extra impairments
33、. 6.1 For DSL home gateways On DSL architectures, it is difficult (and most of the time impossible) to perform test in an isolated test laboratory environment, since the gateway must be registered by a service plat-form to be allowed to set up calls. The simulator has then to be inserted in series o
34、n the link between the phone plug on the wall inside home and the residential gateway. Since this link is not using Ethernet and does not allow access to the raw IP traffic, it requires having a derivation to do so, composed by an ADSL modem router and micro-DSLAM and an Ethernet link between them,
35、as shown in Figure 1. The output signal for measurement and analysis purposes are captured at the output of the FXS port of the home gateway under test. In this case, the far-end reference point is a PSTN access, allowing a full G.711 i.1 communication. This set up has one drawback: it is based on t
36、he assumption that the IP CORE and DSL access networks are not causing any packet loss. Therefore an analysis of the contribution of these networks to the end-to-end packet loss rate is highly recommended in prior to the start of the test measurement procedure. ETSI ETSI TR 102 927 V1.1.1 (2010-11)
37、8PSTNIP NetworkADSL Modem-routerIP impairmentssimulatorDSLAMGateway under testGatewayReference signalDegraded signalAnalogueADSLEthernetFigure 1: Test set up for ADSL home gateway 6.2 For FTTH home gateways For further study. No test method is currently ready to be proposed. 6.3 For VoIP application
38、s on PC and IP-phones In fact, a distinction has to be done here between two situations: VoIP clients requiring a registration process on a commercial platform to be allowed to use the service Other VoIP clients The first case is in fact similar to the one of home gateways, in the sense that it requ
39、ires access to real networks, with possible resulting degradation of the IP flow. But the test set up is simpler, since the IP flow is directly accessible at the input of the PC or of the IP-phone. The extra modem-router and the DSLAM are not necessary; the IP degradation simulation can be performed
40、 directly in series with the PC or the Ip-phone, as illustrated by Figure 2. It should be checked that PC client on reference access is not creating unexpected impairment (e.g. packet jitter). Its performance should be in line with EG 202 425 (VoIP reference point) i.8. ETSI ETSI TR 102 927 V1.1.1 (
41、2010-11) 9Reference signalDegraded signalIP NetworkIP impairments simulatorPC with VoIP client under testVoIP service plat-formFigure 2: Test set up for VoIP on PC with registration on commercial platform The second case is much simpler, and can be implemented in a fully controlled environment in la
42、boratory. The test set up, as shown in Figure 3, is then simply composed by the PC or IP-phone under test, the IP simulator and an optional PC where the registration and authorisation functions are hosted (SIP proxy, for instance). It should be checked that PC client on reference access is not creat
43、ing unexpected impairment (e.g. packet jitter). Its performance should be in line with EG 202 425 (VoIP reference point) i.8. Reference signalDegraded signalIP impairments simulatorPC with VoIP client under testLocal registration plat-form (optional)Local IP switch or hub (optional)Figure 3: Test se
44、t up for VoIP on PC without registration on commercial platform In both cases: the output signal for measurement and analysis purposes are captured at the output of the sound card of the PC under test or at an electrical output of the IP-phone (jack or handset plug), the far-end reference point is a
45、nother PC or IP-phone embedding the same VoIP client with the same G.711 i.1 codec. ETSI ETSI TR 102 927 V1.1.1 (2010-11) 106.4 For wireless terminals with embedded VoIP application We are dealing here specifically with devices attached to the home network, that is their radio base station (whatever
46、 radio technology is used) is located inside home (i.e. it cannot be a WiFi hostpot around the next corner). The radio base station is therefore a peripheral unit of a central IP termination point. This central point can be any of the terminals presented in the cases above. The output signal is capt
47、ured at the corresponding electrical interface of the device, generally a headset jack plug. If the test facilities are also equipped with acoustical recording tools (HATS, etc.), it is also a possibility. The far end reference points remains also the same. Therefore the test set up for this case is
48、 similar to the one exposed above, with the only extension of the radio link. In Figure 4 we show the example with the DSL gateway. PSTNIP NetworkADSL Modem-routerIP impairmentssimulatorDSLAMGateway + radio base stationGatewayReference signalDegraded signalAnalogueADSLEthernetWireless terminal withV
49、oIP application under testFigure 4: test set up for wireless terminal with embedded VoIP application and base station attached to an ADSL home gateway 7 Test procedure The test procedure is based on the comparison of the device performance with two reference performance (one with reference PLC implementation and one without). These reference performance are made available in Table 1 and Figure 5, and can be used by the test lab as references. 7.1 PLC performance assessment (in terms of resulting voice quality) Test scenarios a
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