基于BitTorrent的流媒体缓存及调度机制研究

发布时间：2018-01-14 06:22

本文关键词：基于BitTorrent的流媒体缓存及调度机制研究　出处：《燕山大学》2012年硕士论文　论文类型：学位论文

【摘要】：BitTorrent协议以大规模的分发，快速地下载的特点成为了最流行的P2P软件。BitTorrent系统与P2P流媒体系统的网状拓扑结构有很大的相似之处，但是BitTorrent乱序下载数据片段的方式并不适用于对时间敏感的流媒体文件。鉴于BitTorrent协议的高效性和开源性，本文对BitTorrent协议的节点调度机制进行改进，同时系统中引入媒体服务器，并设计媒体服务器的缓存和响应请求调度算法。本文在对国内外研究现状综合分析的基础上，，对流媒体系统的缓存机制和调度机制问题进行了深入的研究。首先，针对BitTorrent协议提出了基于滑动窗口的节点调度算法。节点对媒体片段的下载采用滑动窗口机制，区分片段的优先级，同时引入预取机制。另外，根据节点自身的情况对节点的滑动窗口大小进行优化。最后，对节点的邻居节点进行筛选，选取最优的几个为节点服务。其次，提出了基于媒体服务器的缓存和响应请求调度机制。系统中加入媒体服务器作为节点的补充流，对媒体服务器的缓存算法进行研究.综合考虑媒体片段的流行度和供求值来设计价值函数，并提出了基于价值函数的缓存替换算法CAVF(Caching Algorithm based on Value Function)。此外，在本文提出的缓存算法的基础上，设计媒体服务器的响应请求调度机制，根据节点请求的数据段的特征和节点的带宽，提出了基于数据段优先级的响应请求调度算法。最后，对本文提出的缓存和调度算法在通用P2P模拟器GPS(General Peer-to-PeerSimulator)中进行了仿真验证。分别从播放连续度、启动延迟、缓存命中率和服务器负载这四个性能指标方面来分析本文提出的算法和典型算法进行的对比。
[Abstract]:BitTorrent protocol to mass distribution, quickly download features to a network topology structure of P2P software of the most popular.BitTorrent systems and P2P streaming media system has a lot of similarities, but the BitTorrent of order to download the data fragment way does not apply to time sensitive streaming media files. In view of the efficiency and the open source BitTorrent protocol in this paper, node scheduling mechanism of BitTorrent protocol is improved at the same time, media server is introduced into the system, and design the media server cache and responds to the request scheduling algorithm. Based on the domestic and foreign research on comprehensive analysis of the current situation, this paper study of streaming media system caching and scheduling mechanism.
First of all, according to the BitTorrent protocol proposed a node scheduling algorithm based on sliding window. Download nodes on the media segments using the sliding window mechanism, distinguish the fragments of priority, while the introduction of prefetching mechanism. In addition, according to the characteristic of the node node of the sliding window size is optimized. Finally, the neighbor node of the node selection, several select the best service for the node.
Secondly, the media server caching and scheduling mechanism based on the response to the request. Join the media server as the node of flow system, research on the media server caching algorithm. To design the value function considering the popularity and demand of media segments, and puts forward the value function of the cache replacement algorithm CAVF (Caching based on Algorithm based on Value Function). In addition, based on the cache algorithm proposed in this paper on the design of the media server response request scheduling mechanism, according to the characteristics of the node and the requested data section of the bandwidth, proposes the response data segment priority scheduling algorithm based on request.
Finally, the caching and scheduling algorithm is proposed in this paper in general P2P simulator (General GPS Peer-to-PeerSimulator) was simulated. From the playback continuity and startup latency, the cache hit rate and server for comparative analysis of the proposed algorithms and algorithms of the load of the four performance indexes.

【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TN919.8;TP333

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