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DENG Guang-qing WEI Ting CHEN Chang-jia ZHU Wei WANG Bin WU Deng-rong .School of Electronic Information Engineering Beijing Jiaotong University Beijing China 《中国邮电高校学报(英文版)》2011,18(6):78-88
In a peer-to-peer(P2P) live streaming system,each peer uses greedy strategy to download chunks as many as possible so as to assure smooth playback and promote the chunk propagation.However,diversity of video playback rate,heterogeneity of peer downlink bandwidth and no prefetching limitation determine that greedy strategy is not the best strategy for P2P video-on-demand(VoD) system though this strategy performs well in P2P live system.To reasonably assign upload bandwidth among peers,we first present a stochastic model to relate expected downloading speed(EDS) with buffered data amount(BDA,the amount of data has been fetched in buffer,however has not been played yet by the peer),video playback rate and fluency(the probability of no interruption in a viewing process).On the base of this model,we design an equal fluency bandwidth assigning algorithm(EFBAA).In this algorithm,requesting peers compute EDS according to several local parameters(such as BDA,video playback rate and fluency) dynamically and independently and send the EDS to neighbor peers together with buffer map.Then the neighbor peer proportionally partitions and assigns its upload bandwidth to requesting peers according to their EDS.Extensive simulations demonstrate that EFBAA outperforms greedy strategy in terms of server load and startup latency. 相似文献
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WEI Ting DENG Guang-qing CHEN Chang-jia ZHU Wei .School of Electronic Information Engineering Beijing Jiaotong University Beijing China 《中国邮电高校学报(英文版)》2011,(5):76-86,101
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. 相似文献
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针对P2PVoD系统中怎样有效地管理和使用节点所缓存的媒体内容的问题,本文提出了一种基于分布式的缓存管理架构。在这一架构中每个节点存储系相应的媒体分块,所存储的媒体分块可以组合成一个完整的媒体文件的所有节点分布在一个环内。因此在一个环内可以快速定位到这个媒体文件的不同分块,提高了资源搜素的效率。仿真证明这种架构可以有效地管理和使用节点所缓存的媒体内容支持用户的VCR操作。 相似文献
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基于P2P流媒体播放模型的内容发布策略 总被引:1,自引:0,他引:1
P2P流媒体播放软件的出现对现阶段的电视与网络行业产生巨大的影响,它使得在网上远程实时观看播放节目成为可能。阐述了基于P2P流媒体播放模型的几种内容发布策略,并经过计算与模拟仿真得到了最佳内容发布策略。 相似文献
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基于P2P应用的校园网安全策略及防护技术 总被引:4,自引:0,他引:4
首先介绍了P2P网络模型及特征。其次,分析了P2P应用突破校园网安全体系的可能性及目前典型的旁路技术。在P2P应用与传统应用对比分析的基础上,提出了基于P2P应用的入侵检测模型及校园网安全的防护技术,以及配置安全防火墙与入侵检测系统等安全构件相结合的安全策略。 相似文献
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基于双重特征的P2P流量检测方法 总被引:4,自引:0,他引:4
P2P流量逐渐成为了互联网流量的重要组成部分,精确地识别P2P流量对于有效地管理网络和合理地利用网络资源都具有重要意义.首先提出了在特定网络拓扑结构下的P2P流量表现出的流量特征,然后结合P2P流量的payload特征,设计了一种基于双重特征的P2P流量检测方法.该方法既克服了基于流量特征的检测方法应用级分类能力弱的缺点,又克服了基于payload特征的方法不能检测加密和未知P2P应用且检测效率不高的缺点.实验结果显示该方法比传统的基于payload特征的方法具有较高检测效率和合适的检测精度. 相似文献
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在非结构化P2P网络中,降低消息冗余,提高搜索的效率,一直是资源搜索的关键问题.目前非结构化P2P网络均采用生存时间(Time-To-Live)机制控制搜索算法的深度,但是同时产生了大量的冗余消息,严重影响了网络的利用率.为了能够在保持高搜索效率的前提下减少冗余消息的数量,提出了一种基于预算机制的非结构化P2P网络分段搜索策略DBudgetSearch.DBudgetSearch将搜索过程分为两个阶段,并在每个阶段中使用预算机制来控制消息转发的数量和导向,根据邻居节点的连接度大小来选择消息的转发对象.分析和试验结果表明,DBudgetSearch导向性好,算法搜索效率高,能够有效减少冗余消息. 相似文献
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随着信息技术和网络技术的飞速发展以及人们的应用需求,产生了网络视频会议系统.针对P2P网络技术协同网络会议系统的需求,分析流媒体传输与控制技术、Java Media Framework (JMF)媒体框架技术、RTP/RTCP流媒体传输与控制协议、P2P结构分析和P2P工作原理,建立P2P结构的系统框架和基于时间戳的RTCP流媒体同步机制,设计了基于JMF类及P2P结构的网络视频会议系统. 相似文献
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与有线网络相比,目前移动互联网的带宽普遍较低.这种情况下,如果移动P2P流媒体系统中用户节点上行带宽的利用率不高,将会极大地加重视频源服务器的负载,增加播放延时.为了充分地利用移动节点的上行带宽,缩短播放延时,文中提出了服务感知的视频片调度算法,它由请求算法和服务算法两部分组成.请求节点会根据最近的服务状况动态地调整请求的片数,减少服务拥塞的发生.服务节点会根据请求的优先级合理地安排上传顺序,提高服务的效率.仿真结果表明,该算法很好地适应了移动网络带宽低的情况,能够提高上行带宽的利用率,缩短播放延时. 相似文献
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E. Mousavi Khaneghah S. L. Mirtaheri M. Sharifi B. Minaei Bidgoli 《International Journal of Communication Systems》2014,27(10):2190-2214
Peer‐to‐peer (P2P) systems have been developed with the goal of providing support for transparent and efficient sharing of scalable distributed resources wherein size scalability is limited by the costs of all types of transparencies, especially data access transparency, which are due to the need for frequent data exchanges between peers and other related communication overheads. We present a model that formulates the relationship between scalability and data access transparency in P2P distributed systems to figure out how large these systems can be scaled up, given the overheads of establishing data access transparency. To validate our model and show how our model can be deployed in real life, we consider a real P2P distributed system as a case study and evaluate how CPU utilization, bandwidth, and data request frequency parameters of our model relate to the amount of effort required by the system management to establish data access transparency. We then calculate the strength of the coefficient of correlation of scalability and data access transparency in the system. The degree of strength of this coefficient allows the system designer to decide at design time whether to allow the use of the model in the management of system at runtime or not. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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An agent-based incentive mechanism for P2P systems 总被引:2,自引:0,他引:2
1 Introduction P2P systems differ from the traditional distributed computing systems. They are self-organizing, distributed resource-sharing networks. In P2P systems, there is no central authority that controls or manages the various components. Nodes can… 相似文献
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有效的资源查询是P2P应用所面临的关键问题之一。通过对结构化Pastry进行研究,将性能稳定的超级节点组织成一个主Pastry环,普通节点根据自身的物理位置关系动态地加入到某个子Pastry环中,主环和子环通过超级节点相互连接构成覆盖网络。仿真结果表明:改进后的模型查询性能优于Pastry,更好地适应动态的网络环境。 相似文献
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Anti-worm is an effective way to fight against malicious worm and has been followed closely by malicious worm researchers recently.However,active and passive confronting technologies in peer-to-peer (P... 相似文献