1、 ETSI TR 126 922 V15.0.0 (2018-07) Universal Mobile Telecommunications System (UMTS); LTE; Video telephony robustness improvements extensions; Performance evaluation (3GPP TR 26.922 version 15.0.0 Release 15) TECHNICAL REPORT ETSI ETSI TR 126 922 V15.0.0 (2018-07)13GPP TR 26.922 version 15.0.0 Relea
2、se 15Reference RTR/TSGS-0426922vf00 Keywords LTE,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 Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important
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14、echnical 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 between GSM, UMTS, 3GPP and ETSI identities can be found under http:/webapp.etsi.org/key/quer
15、yform.asp. Modal verbs terminology In the present document “should“, “should not“, “may“, “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 allo
16、wed in ETSI deliverables except when used in direct citation. ETSI ETSI TR 126 922 V15.0.0 (2018-07)33GPP TR 26.922 version 15.0.0 Release 15Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 References 5g33 Definitions and abbreviations . 5g
17、33.1 Definitions 5g33.2 Abbreviations . 6g34 Background 6g35 Overview of video robustness improvements extensions (VTRI_EXT) tools . 7g35.1 Introduction 7g35.2 Retransmission . 7g35.3 Forward error correction 7g35.4 Reference picture selection. 7g36 Test cases and conditions . 7g36.1 QoS requirement
18、s for conversational video services 7g36.2 Channel conditions . 9g36.3 Error profiles 10g36.3.1 Introduction. 10g36.3.2 QoS LTE . 10g36.3.3 LTE-OTT 10g36.3.4 WiFi 10g36.3.5 Summary . 10g36.4 Test Content . 11g37 Evaluation criteria 12g37.1 Testing configuration . 12g37.2 Performance metrics . 12g38
19、Results 13g38.1 Test cases 13g38.2 Simulation (RTT= 100 ms) 13g38.3 Simulation (RTT= 200 ms) 16g38.4 Simulation (RTT= 300 ms) 17g38.5 Simulation (RTT= 400 ms) 19g38.6 Summary 22g39 Conclusions and recommendations 22g3Annex A: Error patterns . 24g3A.1 IMS-QoS 24g3A.2 VT-LTE OTT . 24g3A.3 VT-Wifi 26g3
20、Annex B: Change history 30g3History 31g3ETSI ETSI TR 126 922 V15.0.0 (2018-07)43GPP TR 26.922 version 15.0.0 Release 15Foreword This Technical Report has been produced by the 3rdGeneration Partnership Project (3GPP). The contents of the present document are subject to continuing work within the TSG
21、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 in version number as follows: Version x.y.z where: x the first digit: 1 presented to TSG for informat
22、ion; 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, corrections, updates, etc. z the third digit is incremented when editorial only changes have been inco
23、rporated in the document. ETSI ETSI TR 126 922 V15.0.0 (2018-07)53GPP TR 26.922 version 15.0.0 Release 151 Scope The present document reports the study on video telephony robustness improvements extensions in Multimedia Telephony Service for IMS (MTSI) and provides recommendation on their applicabil
24、ity for MTSI video telephony applications. 2 References The following documents 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-
25、specific. - For a specific reference, subsequent revisions do not apply. - For 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
26、 Release as the present document. 1 3GPP TR 21.905: “Vocabulary for 3GPP Specifications“. 2 3GPP TS 22.105: “Services and service capabilities“. 3 3GPP TS 26.114: “IP Multimedia Subsystem (IMS); Multimedia telephony; Media handling and interaction“. 4 IETF RFC 4588: “RTP Retransmission Payload Forma
27、t“, July 2006. 5 IETF RFC 6865: “Simple Reed-Solomon Forward Error Correction (FEC) Scheme for FECFRAME“, February 2013. 6 IETF RFC 5109: “RTP Payload Format for Generic Forward Error Correction“, December 2007. 7 IETF RFC 4585: “Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-B
28、ased Feedback (RTP/AVPF)“, July 2006. 8 K. Yamagishi, T. Hayashi, “Parametric Packet-Layer Model for Monitoring Video Quality of IPTV Services“, IEEE ICC 2008, pp. 110-114, May 2008. 9 Q. Huynh-Thu, M. Ghanbari, “Impact of Jitter and Jerkiness on Perceived Video Quality“, Proc. of the Second Interna
29、tional Workshop on Video Processing and Quality Metrics for Consumer Electronics (VPQM), 2006. 10 C. Wang, X. Jiang, Y. Wang, “Video Quality Assessment Models for IPTV Services“, JDCTA, April 2013. 11 Pierre Ferre, Dimitris Agrafiotis, Tuan Kiang Chiew, Angela Doufexi, Andrew Nix, David Bull, “Packe
30、t Loss Modelling for H.264 Video Transmission over IEEE 802.11g Wireless LANs“, IEEE WIAMIS 2005. 12 S. Holmer, M. Shemer, M. Paniconi, “Handling Packet Loss in WebRTC“, pp. 1860-1864, ICIP, 2013. 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the terms and
31、 definitions given in TR 21.905 1 apply. ETSI ETSI TR 126 922 V15.0.0 (2018-07)63GPP TR 26.922 version 15.0.0 Release 153.2 Abbreviations For the purposes of the present document, the abbreviations given in TR 21.905 1 and the following apply. AV Audio Video AVC Advanced Video Coding AVPF Audio-Vide
32、o Profile with Feedback ER Error Resiliency FPS Frames Per Second HEVC High Efficiency Video Coding IMS-VT IP Multimedia Subsystem Video Telephony KB Kilo Byte MTSI Multimedia Telephony Service for IMS OTT Over The Top PLI Picture Loss Indication PLR Packet Loss Rate QVGA Quarter Video Graphics Arra
33、y RPS Reference Picture Selection RPSI Reference Picture Selection Indication RTT Round Trip Time VGA Video Graphics Array VT Video Telephony VTRI_EXT Video Robustness Improvements Extensions Wifi Wireless Fidelity Note: Wifi is synonymous with Wi-Fi as defined by the Wi-Fi Allicance 4 Background Th
34、e present document reports the study on video telephony robustness improvements extensions in Multimedia Telephony Service for IMS and provides recommendation on their applicability for MTSI video telephony applications. These extensions target error robustness for higher bitrate MTSI video telephon
35、y as well as inter-working with WLAN use cases where error resiliency is more important. In order to be technically competitive, e.g. to some proprietary systems, MTSI should have the capability to employ mechanisms that can offer different trade-offs between rendering delay, video rendering jitter
36、(smoothness) and video quality that can adapt to varying channel conditions for better user experience. Retransmission, Forward Error Correction (FEC), and complementary reference picture selection indication (RPSI) AVPF feedback mechanisms offer these trade-offs. The present document first provides
37、 an overview of the additional error resiliency (ER) tools that could improve the performance of the Multimedia Telephony Service for IMS (TS 26.114 3). Then test conditions representative of error conditions experienced in IMS Video Telephony are presented. Following the description of the test con
38、ditions, evaluation criteria for determining the benefits of proposed tools and mechanisms is presented. Performance of the proposed ER tools is evaluated under the defined testing conditions that take into account packet loss rate/pattern, end to end delay, bitrate overhead and video smoothness (dr
39、opped frames, rendering jitter). Based on the performance results, conclusions are made in terms of recommendations for support of proposed ER tools and mechanisms for Multimedia Telephony Service for IMS. ETSI ETSI TR 126 922 V15.0.0 (2018-07)73GPP TR 26.922 version 15.0.0 Release 155 Overview of v
40、ideo robustness improvements extensions (VTRI_EXT) tools 5.1 Introduction Multimedia Telephony Service for IMS (MTSI 3GPP TS 26.114 3) defines MTSI clients sender and receiver behaviour utilizing IETF RFC 4585 7 AVPF Generic NACK and Picture Loss Indication (PLI) feedback messages for ER. Current er
41、ror correction scheme provides basic error correction through codec level error resiliency (ER) mechanisms. Transport and application level error resiliency schemes such as Retransmission (NACK), Forward Error Correction (FEC) along with advanced codec level ER schemes such as Reference Picture Sele
42、ction (RPS) provide alternative error correction mechanisms that offer different performance trade-offs. The performance of error correction schemes varies with end-to-end delay, channel bandwidth and packet loss rate. 5.2 Retransmission Retransmission (NACK) scheme 4 provides efficient error correc
43、tion in terms of bandwidth under short round-trip-time (RTT) cases with low packet loss rates. The efficiency of retransmission scheme becomes more pronounced at higher bitrates since selective retransmission of lost packets instead of entire pictures are needed. Under low RTT scenarios it can provi
44、de low video rendering jitter dependent on the de-jittering mechanism at the cost of additional delay. If additional delay cannot be accommodated, then retransmission can still provide recovery from error with video freezes during recovery similar to the existing error resiliency scheme in TS 26.114
45、. 5.3 Forward error correction Forward Error Correction (FEC) schemes 5 and 6 provide a mechanism that balances video quality and end-to-end delay. FEC schemes can adapt to varying channel error conditions. FEC is suitable for high RTT channels with high packet loss rates where retransmission leads
46、to high video rendering delay and codec based recovery mechanisms like RPSI, PLI lead to frequent video freezes and/or corruptions. FEC schemes are complemented by retransmission (NACK) or RPSI, PLI feedback mechanisms to address FEC failure cases. 5.4 Reference picture selection Reference picture s
47、election indication (RPSI) feedback message in AVPF 7 that is currently not supported in TS 26.114 offers establishment of common reference point for recovery between the sender and the receiver. In essence it provides codec level ER mechanism similar to the transport layer ER mechanism supported by
48、 the generic NACK message in TS 26.114. 6 Test cases and conditions 6.1 QoS requirements for conversational video services Specification TS 22.105 2 defines the range of QoS requirements and end user QoS requirements for conversational video services. According to TS 22.105, the following requiremen
49、ts should be supported. ETSI ETSI TR 126 922 V15.0.0 (2018-07)83GPP TR 26.922 version 15.0.0 Release 15Table 6.1-1: Range of QoS requirements copied from TS 22.105 (clause 5.4) Real Time (Constant Delay) Non Real Time (Variable Delay) Operating environment BER/Max Transfer Delay BER/Max Transfer Delay Satellite (Terminal relative speed to ground up to 1000 km/h for plane) Max Transfer Delay less than 400 ms BER 10-3 - 10-7 (NOTE 1) Max Transfer Delay 1200 ms or more (NOTE 2) BER = 10-5 to 10-8 Rural outdoor (Terminal relative speed
