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  1. 1. INTERNATIONAL TELECOMMUNICATION UNION FOCUS GROUP ON IPTV TELECOMMUNICATION FG IPTV-IL-0058 STANDARDIZATION SECTOR STUDY PERIOD 2005-2008 English only WG(s): 4 4th FG IPTV meeting: Bled, Slovenia, 7-11 May 2007 INCOMING LIAISON STATEMENT (Ref.: COM 16 – LS 191) Source: Rapporteur Q22/16 Title: Reply LS to FG-IPTV on multicast aspects (FG IPTV-OL-0030Rev.1) Attention: This is a document submitted to the work of ITU-T and is intended for use by the participants to the activities of ITU-T's Focus Group on IPTV, and their respective staff and collaborators in their ITU-related work. It is made publicly available for information purposes but shall not be redistributed without the prior written consent of ITU. Copyright on this document is owned by the author, unless otherwise mentioned. This document is not an ITU-T Recommendation, an ITU publication, or part thereof.
  2. 2. -2- FG IPTV-IL-0058 INTERNATIONAL TELECOMMUNICATION UNION COM 16 – LS 191 – E TELECOMMUNICATION STANDARDIZATION SECTOR English only STUDY PERIOD 2005-2008 Original: English Question(s): 22/16 Shenzhen, China, 12-16 March 2007 LIAISON STATEMENT Source: Rapporteur Q22/16 Title: Reply LS to FG-IPTV on multicast aspects (FG IPTV-OL-0030Rev.1) To: FG IPTV (cc: SG 17, SG 13) Approval: Q22/16 Rapporteur meeting (Shenzhen, 12-16 March 2007) For: Information Deadline: 20 June 2007 Contact: Noah Luo Tel: +86-755-28786346 Rapporteur Q22/16 Fax: +86-755-28789166 Huawei Technologies Co.,Ltd. Email: P.R. China Contact: Seong-Ho Jeong, Tel: +82 31 330 4642 Rapporteur Q24/16 Fax: +82 31 333 4256 HUFS E-mail: Korea (Republic of) First of all, SG 16 would like to thank FG IPTV for your LS on multicast aspects (our TD 314/Gen, your FG IPTV-OL-0030Rev.1) in response to the original LS from SG 16 (COM 16-LS-158). It provides useful information and thus a good understanding for SG 16 of what you are doing on multicast. We discussed it at our Rapporteur meeting in Shenzhen, China (12-16 March 2007), and have the following suggestions for you to consider. 1 Our understanding of multicast’s relations with IPTV Multicast is an important enabling factor for IPTV. It has great impacts on IPTV requirements, architecture, security, performances and user experiences. SG 16 is working and will still work on technologies related to IPTV, therefore multicast is one of our areas of interest. The current state of the arts of multicast, according to our understanding falls short of being able to support IPTV in a satisfactory way. As a result, work in areas like security, performances and media encapsulation and transport using multicast is in rather urgent need to be done. Since you are working on a new working document entitled “IPTV Multicast Frameworks” as you informed us in your LS, we hope that our information can be of some use to you.
  3. 3. -3- FG IPTV-IL-0058 2 SG 16 work on IPTV services emulation IPTV services emulation is a name given to a mechanism that provide content-based services to traditional TV users in such a way that the users may feel as if they are using traditional TV. We identify this kind of services as being important to IPTV and having close relations with IPTV. Contributions had been received on this subject at the last several meetings and discussion had been conducted based on these contributions. Experts in SG 16 tend to think this may be an area of potential importance. Based on such understanding, we sent out a LS to FG IPTV to inform you about our initial work on this subject. We also agreed amongst us that to proceed the work in this area and to facilitate a better understanding, further contributions are needed. Thanks to those contributors of the original contributions on IPTV services emulation, more contributions can be expected as they promised. 3 Security aspects of multicast Multicast has the potential of causing risk to contents protection in IPTV. In order to counter such risks, multicast duplication nodes need to have the capability of admitting a multicast group join request based on the authentication information of the host sending this request; in other words, multicast need to be controllable in the sense that an authentication mechanism can be incorporated. 4 QoS support for multicast Multicast is useful to enable the network to transport multimedia data to many endpoints compared to unicast. However, the multicast tree makes resource reservation difficult since resource should be reserved considering the number of multiple endpoints. SG 16 sees QoS as a very important subject for emerging multimedia applications, e.g. IPTV, and therefore we would like to be informed of your work related to this aspect. We are also willing to carry out study on this area within SG 16. We look forward to any possible cooperation between FG IPTV and SG 16 regarding the multicast QoS aspect. 5 Channel zapping and multicast Channel zapping has direct impacts on users’ perception of IPTV services, thus is of top importance for service providers. There have been a lot of research being done in this area and many ways have been worked out in an effort to solve this problem. On the one side, it has close relations to multicast, shortening multicast join and leave time may greatly improve channel zapping performances. On the other side, channel zapping can also be tackled by introducing media coding related techniques, such as scalable coding, use of an auxiliary video stream consisting of thumbnail images. In this case, it is in the scope of SG 16. ____________