基于WMN的P2P流媒体组播若干关键技术研究

发布时间：2018-04-15 17:50

本文选题：无线Mesh网络 + P2P　；参考：《北京交通大学》2014年博士论文

【摘要】：随着互联网的发展,流媒体业务逐渐增多。视频点播、网络电视、远程会议、远程教育已成为互联网的热门应用。P2P (Peer to Peer,对等端到对等端)技术的产生使互联网的工作模式从以客户端/服务器为代表的集中式走向了分布式,为流媒体应用带来了新的发展空间。与此同时,无线Mesh网络(Wireless Mesh Networks, WMN)和移动通信设备的飞速发展使得人们对P2P流媒体业务的需求由有线网络转移到了无线网络。这种用户需求推动了基于WMN的P2P流媒体技术的发展,而WMN的广泛应用前景也吸引了P2P流媒体技术向无线网络的移植。基于WMN的P2P流媒体系统是P2P流媒体在WMN支撑下的应用层实现,由于WMN网络的特殊性,P2P技术在WMN中面临着许多挑战与问题。例如,由于无线网络终端种类繁多造成的网络异构性问题、P2P覆盖层网络与底层网络的拓扑不匹配问题、无线网络链路干扰问题、无线频谱资源有限问题和缺少系统级实验平台的问题。针对上述研究背景和P2P流媒体技术在WMN环境中遇到的问题,本论文在传统的有线网络P2P流媒体组播技术的基础上,从理论和实验两个方面对WMN中的P2P流媒体组播技术进行了研究。论文的主要研究内容和创新点包括： (1)针对覆盖层网络与底层网络的拓扑不匹配问题和无线网络节点异构性问题,提出了一种无线网络通用的应用层组播成员管理协议。该协议通过采用“闲谈”机制、局部概率择优策略和去中心化管理策略,构造了一个稳定的、无标度的覆盖层网络,实现了组播组成员的动态加入与退出管理。基于复杂网络理论对所提协议进行的数学分析证明了其构造的覆盖层网络是稳定的。仿真结果表明,所提出的协议在一定程度上能缓解拓扑不匹配问题,而且比已有的协议模型更能适应异构无线网络环境。 (2)针对无线链路干扰问题,提出了一种低代价最少中继树组播路由算法。该算法由组播树构造算法和信道分配算法两部分组成。组播树构造算法在保证中继节点数目最少的同时尽量选择低代价路径进行数据转发,从而充分利用无线链路的一跳广播属性并且降低了端到端时延。信道分配算法通过扩大干扰优化范围、引入更精确的衡量干扰的参数,优化了已有的信道分配算法,从而减少了链路干扰。算法分析和仿真结果表明,所提出的低代价最少中继树组播路由算法降低了已有组播树算法的时间复杂度和组播树代价,减少了用户时延,提高了系统吞吐量。 (3)针对无线频谱资源有限和客户端资源受限问题,提出了一种基于SNR(Signal Noise Ratio,信噪比)反馈的多信道组播调度机制。该机制通过SNR反馈判断信道容量的大小,采用将优先级较高的数据块放在信道容量较大的信道上进行传输的策略,减小了流媒体启动时延和下载时间,提高了信道利用率。仿真结果表明,所提出的调度机制与原有调度机制相比,在用户时延、下载时间和带宽利用率方面的性能都有所提高,但其耗费的缓存空间略大于原有调度机制。经分析,在硬件技术日趋发达的今天,存储空间的获取对用户来讲并不困难。而在存储空间充足的条件下,用户对时间的敏感度明显高于对空间的敏感度,因此用少量空间换取时间的做法是可取的。 (4)针对缺少系统实验平台的问题,实际搭建了基于WMN的P2P流媒体系统。为了客观和精确地评估WMN中的P2P流媒体性能,启发与流媒体性能相关的下一步研究,在搭建的系统平台上通过现场实验的方式测试了流媒体编解码方式、编码速率、P2P方式的采用与否、跳数和网络拓扑结构五个因素对流媒体性能的影响。实验结果表明,编码方式、编码速率和网络拓扑都是影响视频质量的重要因素;跳数与视频质量没有必然的联系；P2P技术与WMN结合是可行的,但是采用P2P方式对WMN中流媒体质量的影响有利有弊。实验结果对今后的理论创新和实践部署都具有很好的参考意义。
[Abstract]:With the development of the Internet, streaming media business gradually increased. VOD, IPTV, teleconferencing, remote education has become a popular Internet application.P2P (Peer to Peer, peer to peer) technology makes the Internet work mode from client / server on behalf of the centralized to distributed, bring the new space for the development of streaming media application. At the same time, the wireless Mesh network (Wireless Mesh Networks, WMN) and the rapid development of mobile communication devices for people to make P2P streaming media business needs by wired network to wireless network. The user needs to promote the development of WMN P2P based on streaming media technology, and extensive the application prospect of WMN has also attracted the P2P streaming media technology to the wireless network transfer.
WMN P2P streaming media system is the realization of the application layer of P2P streaming media based on WMN support, because of the particularity of the WMN network, P2P technology faces many challenges and problems in WMN. For example, due to a wide variety of heterogeneous wireless network terminal network problems caused by the P2P overlay network and the underlying network topology does not match the problem, link interference in wireless network, wireless spectrum resources are limited and lack of experimental platform.
Based on the above research background and P2P streaming media technology in the WMN environment encountered problems, this paper based Streaming Media Multicast in wired network P2P on the traditional studies from two aspects of theory and experiment on WMN P2P Streaming Media Multicast Technology. The main research contents and innovations include:
(1) according to the topology of overlay network and the underlying network, and wireless network node heterogeneity problem, proposed application layer multicast membership management protocol for wireless network. This protocol by using the universal "chat" mechanism, the local probability selection strategy and decentralized management strategy, construct a stable, scale-free overlay network, realizes dynamic multicast group members to join and exit management. The mathematical analysis of the proposed protocol for complex network theory proved that the structure of the overlay network is based on stable. The simulation results show that the proposed protocol can alleviate the topology mismatch problem in a certain extent, but can adapt to the heterogeneous wireless network environment than the existing protocol model.
(2) for the wireless link interference problem, proposes a low cost minimum relay tree multicast routing algorithm. The algorithm consists of the multicast tree construction algorithm and channel allocation algorithm is composed of two parts. The multicast tree construction algorithm to ensure the minimum number of relay nodes and low cost path to forward data as far as possible, so as to make full use of. The broadcast property of wireless link and reduce the end-to-end delay. The channel allocation algorithm by expanding the range of interference optimization parameters to measure the interference introduced, more precisely, to optimize the channel allocation algorithms, thereby reducing the link interference. Algorithm analysis and simulation results show that the low cost of the proposed minimum relay tree multicast routing algorithm to reduce the existing multicast tree algorithm time complexity and the cost of the multicast tree, reduce user delay, improve the system throughput.
(3) according to the limited radio spectrum resource and client resource constrained problem, an algorithm based on SNR (Signal Noise Ratio, SNR) multi channel multicast scheduling mechanism. The feedback mechanism by SNR decision feedback channel capacity size, the transmission of higher priority data blocks on the channel capacity of the the strategy reduces the startup delay of streaming media and download time, improve the utilization rate of channel. The simulation results show that the proposed scheduling mechanism compared with the original scheduling mechanism, the user delay, download time and rate the performance of wide band are increased, but the cost of cache space is slightly larger than the original scheduling mechanism. After analysis, the hardware technology increasingly developed today, the storage space of the acquisition is not difficult for users. In adequate storage conditions, users of time sensitivity was significantly higher than that of It is advisable to exchange a small amount of space for time by a small amount of space.
(4) for the lack of experimental platform system, set up WMN based P2P stream media system. In order to objectively and accurately evaluate the performance of WMN P2P streaming media, streaming media and related inspiration performance the next step of the research, through field experiments in the system platform of the streaming media codec the test, encoding rate, and whether the adoption of P2P, effect of jump five factors of streaming media performance and network topology. Experimental results show that the encoding method, encoding rate and network topology are important factors that influence the quality of video; jump no connection number and video quality; P2P technology combined with WMN it is feasible to adopt P2P mode, but the effect on WMN streaming media There are both advantages and disadvantages. quality. The experimental results have a good reference value for the future of theoretical innovation and practical deployment.

【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TP393.02

【参考文献】