基于网络编码的P2P流媒体传输技术研究

发布时间：2018-07-21 11:09

【摘要】：随着计算机的普及与网络的迅猛发展,网络视频成为人们的主要娱乐方式。传统的C/S策略已无法满足用户需求,P2P技术应运而生,节点(peer)不需依赖中心服务器,各节点之间的地位是平等的,它们可以相互直接进行通信和数据交换,每个节点既可以请求服务也可以提供服务,兼任客户机和服务器两种身份,具有可扩展性高、部署成本低等特点消除了流媒体系统瓶颈,具有很好的扩展能力。网络编码融合了路由与编码的信息交换技术,为提高网络的传输容量指明了一个新的发展方向。使用网络编码可以对网络中间节点对数据编码组合之后再转发,可以提高网络的吞吐量,减少启动延迟改善网络负载均衡等。将网络编码与P2P技术相结合,能够减少系统的数据传输延时,增强系统的鲁棒性。本文首先介绍了P2P技术,流媒体技术、P2P流媒体技术及网络编码,着重讨论了网络编码在P2P流媒体中的应用,详细分析了现有基于网络编码的P2P流媒体系统,并指出存在问题,容易产生冗余数据和系统延时大。针对此问题,本文着重从减少数据冗余和传输延时两方面加以改进,设计了基于网络编码与综合因素调度算法相结合的P2P流媒体直播系统NCCFS (Network Coding with Comprehensive Factors Scheduling),调度算法同时考虑数据的紧急性和稀缺性来确定数据段的优先级,并对邻居节点网络带宽进行有效估算,根据数据段优先级和各邻居节点带宽确定数据传输次序和方向,数据调度采用推拉结合策略,节点刚加入系统时,主动向邻居定制少量数据,主动准确的获取所需要的播放数据段,同时邻居节点记下发送数据段的序号,一旦这些段成功解码后,节点进入稳定播放阶段,节点就不再主动发送请求的数据报文,节点通过推策略获得需要的数据段。若当节点的数据段临近播放截止时间还不能解码时使用拉策略,节点转为主动向邻居节点请求数据,避免数据播放画面出现停顿现象,此时拉策略作为一种修补措施来满足播放的连续性。仿真结果表明,NCCFS有效减少了系统的播放延迟和控制开销,提高了流媒体的播放质量。
[Abstract]:With the popularity of computer and the rapid development of network, network video has become the main entertainment. The traditional C / S strategy can no longer meet the needs of users. P2P technology emerges as the times require. The node (peer) does not need to rely on the central server, so the status of each node is equal, and they can communicate and exchange data directly with each other. Each node can request service as well as provide service, both client and server identity. It has the characteristics of high scalability and low deployment cost, which eliminates the bottleneck of streaming media system and has a good ability to expand. Network coding combines the information exchange technology of routing and coding, and points out a new development direction for improving the transmission capacity of the network. The network coding can be used to combine the data encoding to the middle nodes of the network and then forward, which can improve the throughput of the network, reduce the startup delay, and improve the network load balance, and so on. Combining network coding with P2P technology can reduce the delay of data transmission and enhance the robustness of the system. This paper first introduces P2P technology, streaming media technology, P2P streaming media technology and network coding, emphatically discusses the application of network coding in P2P streaming media, analyzes in detail the existing P2P streaming media system based on network coding, and points out the existing problems. Easy to generate redundant data and system delay. In order to solve this problem, this paper focuses on reducing data redundancy and transmission delay. A P2P streaming media streaming system NCCFS (Network coding with Comprehensive factors scheduling) based on network coding and comprehensive factor scheduling algorithm is designed. The scheduling algorithm considers the urgency and scarcity of data to determine the priority of data segment. The network bandwidth of neighbor node is estimated effectively. According to the priority of data segment and the bandwidth of each neighbor node, the order and direction of data transmission are determined. A small amount of data is ordered to the neighbors actively and accurately, and the neighbor node notes the serial number of the sending data segment. Once these segments are decoded successfully, the node enters the stage of stable playback. The node no longer actively sends the requested data packet, and the node obtains the required data segment by pushing the policy. If a pull strategy is used when the data segment of the node cannot be decoded, the node turns to request data from the neighbor node actively, so as to avoid the pause of the data playing screen. The pull strategy is used as a repair measure to satisfy the continuity of playback. The simulation results show that NCCFS can effectively reduce the playback delay and control overhead of the system and improve the playback quality of streaming media.
【学位授予单位】：广西师范大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP393.02

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