1、 International Telecommunication Union ITU-T G.1082TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (04/2009) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Multimedia Quality of Service and performance Generic and user-related aspects Measurement-based methods for improving t
2、he robustness of IPTV performance Recommendation ITU-T G.1082 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299
3、 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHON
4、Y G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSI
5、ON MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.1082 (04/2009) i Recommendation ITU-T G.1082 Measurement-
6、based methods for improving the robustness of IPTV performance Summary Recommendation ITU-T G.1082 provides a framework for improving the robustness of IPTV performance based on the results of real-time measurements. The primary application of this framework is to control the media and network resou
7、rces based on the measurement information and according to policy rules to support high quality of experience of IPTV services. For IPTV services, service providers and network providers may have separate monitoring systems. Measurement information is provided by the monitoring system. This Recommen
8、dation first describes the possible measurement information used in different monitoring domains and the information exchanged between providers. It then gives guidance on how to take these factors into account to adjust media and network resources in order to maintain the quality of experience for
9、IPTV services. Source Recommendation ITU-T G.1082 was approved on 29 April 2009 by ITU-T Study Group 12 (2009-2012) under Recommendation ITU-T A.8 procedure. Keywords IPTV, measurement, QoE, QoS, resource adjustment. ii Rec. ITU-T G.1082 (04/2009) FOREWORD The International Telecommunication Union (
10、ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and i
11、ssuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these
12、topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the express
13、ion “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicabilit
14、y) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Reco
15、mmendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability o
16、f claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this
17、Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2010 All rights reserved. No part of this publication may be reproduced, by any means whatso
18、ever, without the prior written permission of ITU. Rec. ITU-T G.1082 (04/2009) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 4 Abbreviations and acronyms 1 5 Conventions 2 6 Overview of the framework of measurement-based methods for improving the robustness of IPTV performance (MMRP) 2
19、 7 Process of end-to-end quality improvement. 3 7.1 Monitoring system 4 7.2 Measurement-based resource adjustment function 4 7.3 Resource control enforcement 5 8 Measurement information reporting. 5 8.1 Reported measurement information . 5 8.2 Intra-domain interactions 7 9 Information exchanged betw
20、een providers. 8 9.1 Information provided by SPs 8 9.2 Information provided by NPs . 8 9.3 Information exchanged between SPs and NPs . 8 9.4 Inter-domain interactions 9 10 Measurement-based adaptive resource control for IPTV services . 10 10.1 Media resource control. 10 10.2 Network resource control
21、 . 10 11 Security consideration 11 Appendix I QoE evaluation in mid-point 12 I.1 Introduction 12 I.2 Collaboration between SP and NP to evaluate QoE in mid-point 12 Appendix II Encoded bit rate adjustment in the head-end system 14 Appendix III Encoded layer adjustment . 16 III.1 Introduction 16 III.
22、2 Network device adjusts the encoded layer . 16 III.3 STB adjusts the encoded layer . 17 Appendix IV Delivery path adjustment 19 Bibliography. 21 Rec. ITU-T G.1082 (04/2009) 1 Recommendation ITU-T G.1082 Measurement-based methods for improving the robustness of IPTV performance 1 Scope This Recommen
23、dation describes some methods by which measurement information of IPTV service quality can be used to dynamically control the performance of an IPTV service such as network resource allocation, FEC redundant encoding, delivery path selection or media encoding bit rate if scalable encoding is employe
24、d. This Recommendation defines the subset of QoS/QoE performance parameters to be obtained from the IPTV monitoring system and methods for analysing them to provide media resource and transport network resource control in support of high quality end-to-end delivery of IPTV services. It also provides
25、 guidance on the collaboration between different providers and defines the metrics to be exchanged between them for resource management. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recom
26、mendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other refere
27、nces listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.1080 Recommendation ITU-T G.1080 (2008), Quality of experience re
28、quirements for IPTV services. ITU-T G.1081 Recommendation ITU-T G.1081 (2008), Performance monitoring points for IPTV. ITU-T Y.1540 Recommendation ITU-T Y.1540 (2007), Internet protocol data communication service IP packet transfer and availability performance parameters. 3 Definitions This Recommen
29、dation does not define any special terms. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: DiffServ Differentiated Services FEC Forward Error Correction GOP Group Of Pictures IP Internet Protocol IPDV IP packet Delay Variation IPLR IP packet Loss Ratio
30、IPTD IP packet Transfer Delay 2 Rec. ITU-T G.1082 (04/2009) IPTV Internet Protocol Television MMPAP Monitoring Management and Performance Analysis Platform MMRP Measurement-based Methods for improving the Robustness of IPTV Performance MOS Mean Opinion Score MPLS Multi-Protocol Label Switching NP Ne
31、twork Provider QoE Quality of Experience QoS Quality of Service RFC Request For Comments RTCP RTP Control Protocol RTP Real-time Transport Protocol SLA Service Level Agreement SP Service Provider STB Set-Top Box UDP User Datagram Protocol VoD Video on Demand 5 Conventions None. 6 Overview of the fra
32、mework of measurement-based methods for improving the robustness of IPTV performance (MMRP) In IPTV services, the QoE is a great concern to the end users. The user expects the perceptual quality of IPTV services to be as good as or even better than that of conventional TV service. In order to achiev
33、e the users expectation, a QoS/QoE monitoring system becomes an indispensable part of the IPTV services. In a conventional monitoring system, the measurement information is only used for evaluating network performance and QoE of end users. However, this information can also be valuable input for pro
34、viding media resource and transport network resource control in support of high quality of experience of IPTV services. The SP and NP can adjust the media and network resources based on the measurement information. The resource adjustment procedure includes the steps of reporting measurement informa
35、tion, exchanging information between SP and NP, and deciding resource adjustment methods by SP and NP. Figure 1 depicts a reference model for a MMRP system. Rec. ITU-T G.1082 (04/2009) 3 Figure 1 Reference model A monitoring system includes monitoring points (labelled PTs) and a monitoring, manageme
36、nt and performance analysis platform (MMPAP). MMPAP manages one or multiple domains and collects measurement data from the monitoring points. The MMPAP of the SP collects information from the head-end system and the end-user system. The MMPAP of the NP collects information from backbone and access n
37、etwork domains. Note that the monitoring points located in a service providers domain have different capabilities from those located in a network providers domain. Based on the measurement data collected from monitoring points, the MMPAP provides the QoE metrics and other information of IPTV service
38、s. If the QoE metrics are below a certain predefined value, which is defined in the policy, it may trigger a network resource adjustment procedure, a media resource adjustment procedure or both. Since one single provider has limited measurement information, the SP and NP may share a set of informati
39、on to decide on a resource adjustment method. During the procedures, the end users may not perceive the quality degradation of IPTV services. 7 Process of end-to-end quality improvement MMPAP is located in the SP and NP administrative areas. The measurement-based resource adaptive control function c
40、ollects the information from one or more MMPAP. The media and network resource is adjusted in a centralized model or in a distributed model. Centralized model A single resource adaptive control function is responsible for the management of media and network resources. It collects measurement informa
41、tion from all the MMPAPs. If a MMPAP is Analysis for media resource control Analysis for network resource control Policy VoD server Encoder Service server PT IP core network IP access network HGW STB PT PT PT Monitoring, Management and Performance Analysis Platform of SP Network Provider Service Pro
42、vider End user Policy Monitoring, Management and Performance Analysis Platform of NP 4 Rec. ITU-T G.1082 (04/2009) under a different administrative area, it is not easy to aggregate the information and control the resource of entire domains. Distributed model A number of adaptive resource control fu
43、nctions are responsible for the management of media and network resources. Each resource adaptive control function collects measurement information from its associated MMPAP and manages the resource of administrative domains. The measurement information is exchanged between adaptive resource control
44、 functions which collaborate with each other for the end-to-end quality maintenance. This Recommendation describes a distributed model. The SP and NP collect measurement information from their MMPAP and share a part of the measurement information with each other. Based on measurement and auxiliary i
45、nformation, SP and NP first decide which provider is responsible for adjusting the resource. Then, the media and transport network resource is adapted to maintain the end-to-end quality. Figure 2 illustrates this process. Figure 2 Resource control process 7.1 Monitoring system The monitoring points
46、collect measurement metrics. The MMPAP entities will process these metrics, e.g., correlate and aggregate metrics, etc., and generate measurement reports. The reporting information obtained by processing metrics extracted from a different domain is described in clause 8. 7.2 Measurement-based resour
47、ce adjustment function Based on the reported measurement information, the NP and SP first decide the status of the perceived quality. If the measurement information indicates a trend of degradation or occurring degradation, the NP and SP will analyse how to adjust the resource to maintain the percei
48、ved quality at an expected level. Because of the limited ability of the SP and NP, one single provider may not be able to obtain all the information needed for resource control. The SP and NP share information with each other. The SP needs the network resource and network performance information to
49、adjust the media resource. The NP needs the expected or experienced QoE of the user to make sure that the resource adjustment facilitates QoE. The information to be exchanged and methods for exchange are described in clause 9. The resource control policy instructs the SP and NP what to do. For example, if measurement information indicates mild quality degradation, one provider may adjust the network resource to Monitoring system Collect and analyse measurement data Report measurement information Collect measurement information from own monitoring
