P2P流媒体关键技术研究

探讨在Peer节点服务能力的异构性、节点的动态性以及流媒体本身的特殊性下,使P2P流媒体系统保证服务质量的关键技术.从拓扑构建、调度策略、缓存机制三个方面总结P2P流媒体系统涉及的节点选择算法、节点定位方法、数据调度算法、缓存的替换和中继算法等关键技术,分析其存在的问题,指出P2P流媒体关键技术的未来研究方向,对P2P流媒体系统的研究和开发具有重要意义.     

P2P流媒体系统关键技术概述

主要从资源定位和数据传输两个方面概述P2P流媒体系统的关键技术。资源定位主要介绍结构化和非结构化资源索引及节点选择方法,节点选择则从节点物理位置和节点异构性讨论。数据传输主要讨论数据拓扑结构、数据调度模式、数据片选择策略及与SVC、MDC视频编码的结合。     

基于P2P技术的流媒体分发模型分析

点对点(P2P)流媒体通过在流媒体服务系统中引入P2P技术,在不增加成本的同时有效提升服务能力,并有效避免了P2P应用的诸多弊端,是当前网络条件下一种较理想的多媒体分发技术。文章将介绍主要的几种P2P流媒体分发模型,并对不同模型的优缺点进行比较讨论。     

P2P大规模流媒体调度技术研究

随着宽带、IPV6、3G等技术的日渐成熟,流媒体应用已成为Internet承载的重要业务.调度技术是保证大规模可信流媒体服务质量的关键问题之一.对典型流媒体调度和分发技术进行综述,归纳分析了基于P2P网络环境下树型、网状以及混合拓扑结构的流媒体技术的优缺点,对mesh网下的资源发布于查找、服务节点选择、数据块调度等进行了重点分析和评述.依据流媒体应用的发展趋势,预测了P2P大规模可信流媒体调度技术在适应复杂网络,及结合云技术等方面的研究方向与内容.     

P2P流媒体服务质量关键技术的研究

流媒体应用已成为当今互联网承载的主要业务之一,如何支持大规模用户在线使用流媒体,并保障流媒体的服务质量(QoS)尤为重要。依据P2P技术的特点和流媒体系统的发展,对比分析了典型流媒体系统的流服务策略,总结归纳了系统的优点与不足。以节点选择机制、数据调度机制、缓存机制、容错机制、激励机制为评价指标,重点对当前流媒体系统服务质量研究进行评述。最后对保障大规模可信流媒体服务质量的研究方向进行了展望。     

基于P2P技术的流媒体应用探讨

通过对数字媒体在互联网环境下传播应用的探讨,深入理解P2P技术与流媒体技术的完美融合而产生的互联网新型应用的工作机制和特点,最后,提出流媒体应用未来发展方向和待解决的技术问题。     

P2P网络流媒体关键技术

P2P网络流媒体技术一直是学术界和产业界的研究热点.本文围绕覆盖网络拓扑结构,对现有的P2P流媒体系统作了全面的归类总结,深入介绍和分析了覆盖网络构建、数据块调度策略等P2P流媒体核心技术,并概要讨论视频编码、网络编码、覆盖网络拓扑优化、安全与激励机制等P2P流媒体相关增强技术.对典型P2P流媒体系统的性能进行了比较,...     

P2P流媒体模型的资源传输机制

针对流媒体的点播和直播服务,提出了基于P2P的流媒体应用层多播和点播的解决方案,构建了基于超级节点和普通节点的两层体系结构的视频流媒体模型.描述了模型的总体结构,分析了资源传输机制.基于校园网对模型进行了测试,测试结果表明,模型能够实现基于流媒体应用的多点数据快速互传.     

P2P流媒体系统激励机制综述

本文基于当前P2P流媒体系统激励机制的研究与应用成果,分析并归类应用于P2P流媒体系统的典型的激励机制：基于直接互惠、基于信誉、基于货币交易和基于社会财富再分配的激励机制。对比分析不同激励机制的协作程度、公平性、对能力不同节点的影响,同时结合各机制目前存在的问题提出进一步的研究方向。     

移动P2P流媒体业务及市场分析

分析了移动P2P流媒体业务,阐述了移动P2P网络应用的业务、计费及运营模式,探讨了3G网络中移动P2P流媒体的应用。     

基于P2P流媒体直播系统的数据传输策略

针对P2P模式下视频流媒体直播系统的数据传输策略用改进的模拟退火算法进行了优化。以全局规划的思想建立了P2P视频流媒体的数据传输策略数学模型VMDTSA-P2P,模型充分考虑了可用出口带宽和可用性时间对播放连续性的影响,把它们作为获取最优解的目标函数因子,并用改进后的模拟退火算法进行解的寻优,相比于传统的数据传输策略,在具有大量用户的情况下加快了新节点从伙伴节点中选择数据块提供节点的速度,并且保证得到近似最优的数据块提供节点组合,减少了视频流媒体直播系统播放的延迟,从而提高了播放的连续性、流畅性,保证了视频播放的质量。通过该算法在模拟P2P系统中的实现,验证了该算法在P2P系统中对数据传输的准确性和高效性。     

异构环境下P2P直播流媒体调度算法研究

对节点上行带宽异构环境下的P2P流媒体系统数据块调度算法进行了研究,具体包括系统模型及相关标识,基于带宽感知的数据块调度算法研究和性能评价。通过研究发现,在设计数据块调度算法时充分利用带宽异构性,优先选择高上行带宽的节点,能有效地降低平均块延时。     

Proxy-based patching stream transmission strategy in mobile streaming media system

A mobile transmission strategy, PMPatching （Proxy-based Mobile Patching） transmission strategy is proposed, it applies to the proxy-based mobile streaming media system in Wideband Code Division Multiple Access （WCDMA） network. Performance of the whole system can be improved by using patching stream to transmit anterior part of the suffix that had been played back, and by batching all the demands for the suffix arrived in prefix period and patching stream transmission threshold period. Experimental results show that this strategy can efficiently reduce average network transmission cost and number of channels consumed in central streaming media server.     

P2broadcast: a hierarchical clustering live video streaming system for P2P networks

This work describes a novel live video streaming system for P2P networks, referred to as P2broadcast. The video streaming service has bandwidth requirements to guarantee presentation quality. Therefore, a scalable strategy to quickly find a path from a media server to a client with abundant bandwidth is very important. A common approach in the literature is the bandwidth first (BF) scheme, which allows a newcomer to adopt a BF tree traversal scheme to find its parent peer on the P2P overlay tree to retrieve the media content. The BF scheme is likely to build a deep overlay tree, resulting in long start‐up latency as the number of peers on the overlay tree grows. P2broadcast reduces start‐up latency by organizing peers into hierarchical clusters and making the overlay tree become a ‘short‐and‐wide’ tree. The hierarchical clustering structure enables a newcomer to find its parent peer among the set of peers that are more likely to provide large available bandwidth only. Limiting the set of potential parent peers not only reduces start‐up latency but also improves the system availability. Additionally, unlike the BF scheme that only concerns available bandwidth, P2broadcast utilizes a cost function to evaluate the appropriateness of a potential parent peer. The cost function considers the depth of the newcomer on the overlay tree, making the overlay tree become a short‐and‐wide tree. In addition to start‐up latency reduction, the short‐and‐wide tree feature also alleviates the service interruption probability due to the leaving or failure of a peer. Our simulation results show that P2broadcast greatly outperforms the BF scheme in terms of system availability, and achieves around 66% savings in start‐up latency and 10% decrement in service interruption probability. Copyright © 2005 John Wiley & Sons, Ltd.     

单码流场景下P2P流媒体直播数据调度方法

由于具有较高应对节点动态性的能力和较强的扩展性,Mesh-Pull P2P流媒体直播分发方法赢得了学术界和工业界的广泛青睐.提出了传统互联网单码流场景下Mesh-Pull P2P流媒体直播的数据调度算法.该算法采用TOPSIS方法来解决调度算法中数据块优先级的量化这一多属性决策问题,以降低节点的启动延迟.仿真实验表明,本算法可以在保证高视频播放质量的情况下降低用户观看视频的延迟.     

Cooperative Approach between ISP and P2P Users to Reduce Inter-AS Traffic

A peer-to-peer(P2P) network is a distributed application architecture which provides many attractive features,such as availability,self-organization,load-balancing,and anonymity.However,P2P network has created significant problems to network operators by generating large volumes of inter autonomous system(inter-AS) traffic.Focusing on the BitTorrent swarming protocol,this paper proposes an approach which aims to reduce P2P generated inter-AS traffic.In particular,the approach can reduce inter-AS traffic by 50% to 70%.Moreover,it can improve the downloading speed by 60% for the popular torrents.The evaluation shows that controlled regional-based contents replication can effectively achieve this goal.Furthermore,the approach is incrementally deployable.Network regions in which the system gets deployed can solve their P2P generated inter-AS traffic problems autonomously,i.e.,without any Internet service providers-collaboration and any requirement,the system can be deployed in the entire Internet.     

移动P2P视频流媒体体系下的帧位分配算法

针对移动P2P流媒体系统中存在多视频源的特点,提出了多视频源串行和并行调度算法。串行调度算法,接收Peer通过实时侦测的QoS变化触发视频源的更换,并通过流序列时间模型来同步各个视频源。并行调度算法,多个视频源同时提供服务,并通过帧位分配算法分配各视频源的传输任务。帧位分配算法首先将视频序列分成包含固定帧数的块系列,然后进行块级位分配以充分考虑帧间效应。对于单个帧块位分配问题,算法将其建模成了非线性规划问题,通过引入分段线性R-D模型将该问题进一步转换成了普通的线性规划问题,并提出了一个贪婪实现策略。实验结果显示流分配算法能获得高效、平稳的视频质量,而且时间效率也非常高,能较好的满足移动P2P视频流媒体系统的实时性。     

P2P环境下视频新闻发布系统设计

基于C/S模式的流媒体视频新闻播放需要占用大量网络带宽和服务器资源,限制了视频新闻网络发布业务的进展,而构建P2P环境下的视频新闻发布系统,可充分利用网络带宽资源和服务器处理能力,有效解决了用户大规模访问视频新闻发布系统时服务器存在的瓶颈问题.     

Scalable 3D video streaming over P2P networks with playback length changeable chunk segmentation

3D video distribution over P2P networks has been thought as a promising way for 3D video entering home. The convergence of scalable 3D video coding and P2P streaming can provide diverse 3D experiences for heterogeneous clients with high distribution efficiencies. However, the conventional chunk segmentation and scheduling algorithms originally aiming at the non-scalable 2D video streaming are not very efficient for scalable 3D video streaming over P2P networks due to the particular data characteristics of scalable 3D video. Based on this motivation, this paper first presents a playback length changeable 3D video chunk segmentation (PLC3DCS) algorithm to provide different error resilience strengths to video and depth as well as layers with different importance levels in the 3D video transmission. Then, a hybrid-priority based chunk scheduling (HPS) algorithm is proposed to be tied in with the proposed chunk segmentation algorithm to further promote the overall 3D video P2P streaming performance. The simulation results show that the proposed PLC3DCS algorithm with the corresponding HPS can increase the success delivery rates of chunks with more important levels, and further improve the user’s quality of 3D experience.     

基于超级节点的P2P信任模型的研究

提出基于超级节点的P2P网络信任模型—Super Trust。在Super Trust模型中,对节点的信任值采用了组内直接信任,组内间接信任和组间信任相结合的方式,从而提高了信任值计算的精确性;此外,通过引入超级节点机制,提高了系统交互的成功率。实验结果表明,与基于推荐信任传统模型和RBTrust模型相比,Super Trust具有较高的交易成功率,并且在不同的恶意节点攻击模式下具有较高的成功交易率。