使用轉碼伺服器之SIP視訊會議多播樹狀結構之研究

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

楊溫志(Wen-Chih Yang)

指導教授 ： 陳銘憲

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.02030

摘要

在此論文當中，我們提出在一個自SIP延伸出來，加入轉碼伺服器作為多媒體視迅會議的實作架構。有別於過去視迅會議的架構，如星狀架構或完全連結的多點架構，我們使用覆蓋多播樹狀的方式連結每位會議成員，以達成頻寬使用率最小化。在考慮到會議使用者的異質性，我們在樹狀架構中加入轉碼伺服器，執行多媒體資料流的轉碼工作，再傳送給異質網路的不同使用者裝置。我們將覆蓋多播樹的路由方式研擬成最佳化的問題，其中，樹狀架構中的每個點是由行動裝置、一般電腦使用者以及轉碼伺服器所組成。對每一個行動裝置的使用者而言，如何在樹狀架構下尋找適當的連結點，並在異質網路架構下選擇適當的轉碼伺服器，正是我們要解決的問題。並預期在此架構下，能降低視迅會議整體的頻寬使用率，並且能在異質網路使用者之間保有一定的QoS服務品質。我們針對此問題，設計了一個直觀式演算法與網路通訊協定架構。其中，我們採用的SIP的訊息格式作為溝通的網路協定，並與現今的SIP標準相容。我們亦有在異質網路整合的環境下，針對所提出的演算法與網路協定架構作模擬。

關鍵字

視訊會議 ； 轉碼伺服器 ； 樹狀 ； 多播 ； 群播

並列摘要

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.

並列關鍵字

SIP conference ； overlay multicast ； transcoding proxy

參考文獻

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