Model of downloading strategy from peers and server for saving server bandwidth in P2P VoD system

作     者：WEI Ting DENG Guang-qing CHEN Chang-jia ZHU Wei 

作者机构：School of Electronic and Information Engineering Beijing Jiaotong University Beijing 100044 China Department ofPPLive P2P-CDN R＆D Shanghai 201203 China 

出 版 物：《The Journal of China Universities of Posts and Telecommunications》 (中国邮电高校学报（英文版）)

年 卷 期：2011年第18卷第5期

页      面：76-86,101页

核心收录：

学科分类：0810[工学-信息与通信工程] 1205[管理学-图书情报与档案管理] 080904[工学-电磁场与微波技术] 0809[工学-电子科学与技术（可授工学、理学学位）] 0839[工学-网络空间安全] 08[工学] 080402[工学-测试计量技术及仪器] 0804[工学-仪器科学与技术] 081001[工学-通信与信息系统] 0811[工学-控制科学与工程] 0812[工学-计算机科学与技术（可授工学、理学学位）] 

基　　金：supported by PPLive company, and the National Basic Research Program of China (2007CB307101-1) the National Natural Science Foundation of China (60672069, 60772043) 

主　　题：P2P VoD downloading server load 

摘      要：In peer-to-peer （P2P） video on demand （VoD） system, once the P2P downloading rate cannot satisfy the need of playback, server is quickly referred to for help in providing enough bandwidth. Thus the switch of downloading from other peers （P2P） and server （HTTP） exists. This paper uses the proportion of P2P downloading amount （PPDA） during the video watching process to measure server load. This article is interested in finding a better strategy or switch rule between P2P and HTTP downloading for saving server bandwidth. The authors suggest and model a kind of switch rule based on local buffer amount, using mathematical theory of Brownian motion. It can effectively alleviate the impact of P2P rate fluctuation, reduce the switch times and improve the PPDA by at least 3%-5% on the basis of the former switch rule, which means substantial cost can be saved. Particularly the PPDA is related with the ratio of playback bit rate to the HTTP downloading rate which means the PPDA can be restricted by controlling the ratio in the real-world system. Though the result comes from constant bit rate （CBR） video supposition, it provides perspective and method for variable bit rate （VBR） application, and valuable insights for the future development of P2P VoD system.