基于分布式编码缓存的视频多播技术

发布时间：2018-05-28 06:57

本文选题：编码缓存技术 + 喷泉码　；参考：《西南交通大学》2016年硕士论文

【摘要】：编码缓存是最近几年才提出的一种新的缓存技术,在性能上和传统缓存方案相比有着显著的提升。它除了带来本地缓存增益以外,还带来了额外的全局缓存增益,这种增益来源于对本地缓存和发送阶段的共同优化来保证在服务器发送时,一些不同用户的请求可以通过线性编码多播传送给用户。具体来说,当用户请求文件时,服务器端将多个视频数据线性编码之后多播发送,客户端接收到服务器端发送的数据以后,将这些数据和本地的缓存数据联合解码恢复出请求的整个文件,从而达到服务器端发送一次数据就能满足多个用户的目的。本文首先介绍了编码缓存算法的背景及研究意义,然后重点介绍了Ali-Niesen编码缓存算法和PDA编码缓存算法。同时,用户优先级也是实际应用中的一个重要的因素,同时,本文将PDA编码缓存算法应用到考虑到用户优先级的场景中,以满足优先级较高的用户能够更快地获得请求数据的业务要求。基于中心化的PDA编码缓存技术,本文实现了一个包括一个服务器、六个用户的视频多播系统,这里假设服务器端有十个不同的文件数,每个文件的分块数为四,所有文件的1/2缓存在每个用户端。对于基于缓存的单播系统和基于编码缓存的多播系统,本文以服务器发送完所有文件的时间为评估参数进行对比。在无线环境中,由于系统丢包率过高,本文通过加入喷泉码减少系统的丢包率。论文的实验结果表明,在有线场景下,编码缓存方案可以大幅度降低服务器的发送时间。在存在20%-30%丢包率的无线场景下,与未加入喷泉码的编码缓存多播系统相比,加入喷泉码以后的系统可以大幅度降低丢包率。在考虑到用户优先级的情形下,以服务端发送次序为评估参数,论文的分析结果表明,考虑了用户优先级的PDA编码缓存算法可以根据用户的优先级选择发送次序,更好地满足优先级较高的用户能够更快的获得所需数据的业务要求。论文的相关分析结果表明,综合运用考虑用户优先级要求的编码缓存算法和喷泉编码,可以为无线网络环境下的多播传输技术方案提供切实可行的技术解决方案。
[Abstract]:Coding caching is a new caching technology that has been raised in performance over the last few years, compared with traditional caching schemes. In addition to bringing local caching gains, it brings additional global caching gain, which is derived from the common optimization of local caching and sending stages to ensure that the server is sent to the server. In particular, when the user requests a file, the server sends multiple video data linearly after the multiple video data is encoded, and the client receives the data sent from the server side and decodes the data together with the local caching data to recover the request. In this paper, the background and research significance of the coding caching algorithm are introduced, and then the Ali-Niesen coding caching algorithm and the PDA coding caching algorithm are introduced, and the user priority level is also an important factor in the practical application. At the same time, this paper applies the PDA coding caching algorithm to the user priority scene to meet the requirements of the higher priority users to obtain the request data faster. Based on the centralization of PDA coding caching technology, this paper implements a video multicast system including a server and six users, which is assumed to be served here. There are ten different numbers of files at the end of the traffic, four of each file, and the 1/2 of all files at each user side. For cached unicast and multicast based multicast systems based on the code cache, this article compares the time of all files sent by the server to the evaluation parameters. In the wireless environment, due to the system packet loss rate The result of this paper is to reduce the loss rate of the system by adding the fountain code. The experimental results show that the coding caching scheme can greatly reduce the sending time of the server in the wired scene. In the wireless scene with the 20%-30% packet loss rate, the system after the fountain code is added to the system after the fountain code is added to the coded slow memory multicast system without the fountain code. The packet loss rate can be greatly reduced. In the case of user priority, the server sending order is the evaluation parameter. The results of the paper show that the PDA coding cache algorithm considering the user priority can select the sending order according to the user's priority, and better satisfy the user with higher priority. The related analysis results of the paper show that the comprehensive application of the coding caching algorithm and fountain encoding considering the user priority requirements can provide a practical technical solution for the multicast transmission technology in the wireless network environment.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TP333

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