On bandwidth-efficient SIP conference with overlay multicast for heterogeneous users using transcoding proxy

• Main Authors: Wen-Chih Yang, 楊溫志
• Other Authors: Ming-Syan Chen
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/85390930402183968962

碩士 === 國立臺灣大學 === 電信工程學研究所 === 93 === In this work, we propose a SIP extension for static multimedia conference applications using transcoding proxies. Different from the previous mechanisms that use a star or a fully connected overlay network, we use an overlay multicast tree for each conference group to minimize the bandwidth consumption. To consider the heterogeneity of users, we include transcoding servers in a conference tree to transcode the multimedia streams to the users with the different devices in different networks. We formulate the routing of an overlay multicast tree as an optimization problem. For each end host, our problem is to find the neighbors in the overlay multicast tree and to select the proper transcoding server to serve in the heterogeneous environment. The objective function is to minimize the total bandwidth consumption in each overlay tree, and the constraint is the end-to-end perceived QoS of each heterogeneous end host. We design a heuristic algorithm and a network protocol for the problem. Our protocol uses only SIP messages and is backward compatible with the current SIP standard. We also conduct simulation for our algorithm and protocol in the heterogeneous networks.