Source and Channel Adaptive Rate Control for Multicast Layered Video Transmission Based on a Clustering Algorithm
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Source and Channel Adaptive Rate Control for Multicast Layered Video Transmission Based on a Clustering Algorithm ´ ome ´ ˆ Jer Vieron Thomson multimedia R&D, 1 avenue Bellefontaine - CS 17616, 35576 Cesson-S´evign´e, France Email: [email protected]
Thierry Turletti INRIA, 2004 route des Lucioles - BP 93, 06902 Sophia Antipolis Cedex, France Email: [email protected]
Kave´ Salamatian Laboratoire d’Informatique de Paris 6 (LIP6), 8 rue du Capitaine Scott, 75015 Paris, France Email: [email protected]
Christine Guillemot INRIA, Campus de Beaulieu, 35042 Rennes Cedex, France Email: [email protected] Received 24 October 2002; Revised 8 July 2003 This paper introduces source-channel adaptive rate control (SARC), a new congestion control algorithm for layered video transmission in large multicast groups. In order to solve the well-known feedback implosion problem in large multicast groups, we first present a mechanism for filtering RTCP receiver reports sent from receivers to the whole session. The proposed filtering mechanism provides a classification of receivers according to a predefined similarity measure. An end-to-end source and FEC rate control based on this distributed feedback aggregation mechanism coupled with a video layered coding system is then described. The number of layers, their rate, and their levels of protection are adapted dynamically to aggregated feedbacks. The algorithms have been validated with the NS2 network simulator. Keywords and phrases: multicast, congestion control, layered video, aggregation, FGS.
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INTRODUCTION
Transmission of multimedia flows over multicast channels is confronted with the receivers heterogeneity problem. In a multicast topology (multicast delivery tree in the 1 → N case, acyclic graph in the M → N case), network conditions such as loss rate (LR) and queueing delays are not homogeneous in the general case. Rather, there may be local congestions affecting downstream delivery of the video stream in some branches of the topology. Hence, the different receivers are connected to the source via paths with varying delays, loss, and bandwidth characteristics. Due to this potential heterogeneity, dynamic adaptation of multimedia flows over multicast channels, for optimized quality-of-service (QoS) of mul-
timedia sessions, faces challenging problems. The adaptation of source and transmission parameters to the network state often relies on the usage of feedback mechanisms. However, the use of feedback schemes in large multicast trees faces the potential problem of feedback implosion. This paper introduces source-channel adaptive rate control (SARC), a new congestion control algorithm for layered video transmission in large multicast groups. The first issue addressed here is therefore the problem of aggregating heterogeneous reports into a consistent view of the communication state. The second issue concerns the design of a source rate control mechanism that would allow a receiver to receive the source signal with a quality commensurate with the ban
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