P2P网络流媒体播放系统研究

介绍了一种基于P2P网络平台上新的流媒体播放技术,它将P2P网络技术和流媒体技术结合起来,充分利用网络闲置的带宽资源和存储资源,突破了传统的流媒体播放系统带宽瓶颈.它采用多点下载和文件分块重组方法,一边下载一边播放,能够保持节目流完整而流畅地播放.     

Modeling and application of moderate prefetching strategy based on video slicing for P2P VoD systems

In peer-to-peer (P2P) video-on-demand (VoD) streaming systems,each peer contributes a fixed amount of hard disk storage (usually 2 GB) to store viewed videos and then uploads them to other requesting p...     

Modeling analysis of server loading in large-scale P2P-VoD systems with actively collaborative helpers

Through moving a significant fraction of uploading from the servers to the peers, using P2P approach can effectively alleviate server loading in VoD deployments. However, users’ asynchronism dilutes their ability to assist each other. We develop a theoretical model to conduct an in-depth study of average server loading in large-scale P2P-VoD systems. This model captures many of the essential features of average server loading in large-scale P2P-VoD systems. Based on the in-depth study on average server loading, we introduce actively collaborative helpers into systems for alleviating server loading. The model of peers is further developed to a hybrid model for studying the optimal download amount of helpers from perspective of the entire network including peers and helpers. We show there exactly exists the sweet point of download amount of homogeneous helpers. With downloading the sweet amount, helpers can contribute the bandwidth around twice than they consume, when they do not assist each other, and even approximately 4 times when they assist each other.     

P2P计算模型探讨

随着P2P文件下载和P2P语音通信的崛起,P2P成为互联网应用最大的热点之一.P2P成功的根本在于建立了新的计算模型.本文从P2P计算模型入手,通过分析P2P计算模型和互联网的同构性,指出P2P计算的核心优势和目前存在的缺点,并探讨了解决这些问题的方法和P2P技术发展的趋势.     

Smart-blacklisting:P2P文件共享系统假块污染攻击对抗方法

在当前十分流行的P2P文件共享网络中,假块污染攻击严重地干扰了正常的文件下载过程。提出了基于概率统计及多轮筛选的对抗假块污染攻击策略——Smart-blacklisting,从理论上证明了该策略的有效性。仿真实验结果表明,该策略可以保证目标文件成功下载并降低假块污染攻击对下载时间及带宽消耗的影响。当攻击强度为0.2时,下载时间仅为eMule系统黑名单方法的13%,在带宽消耗方面也仅为其50%。     

SeekStream: adapting to dynamic user behavior in P2P video‐on‐demand

In recent years, the users' perceived quality of experience (QoE) in streaming services has gained a lot of attention. Particularly, a number of research efforts have focused on providing live streaming and video‐on‐demand (VoD) services using peer‐to‐peer (P2P) architectures. However, in these proposed architectures, the heterogeneity of users and their dynamic behavior has not been sufficiently studied. In a real life scenario, where users have highly heterogeneous bandwidth resources (cable, DSL, 3G networks, etc) and can arbitrarily decide to perform a VCR function (stop, fast forward and seeking), ignoring this behavior can significantly deteriorate the system's efficiency and the perceived QoE. In this paper, we present SeekStream, a scalable P2P VoD architecture that ensures the stable delivery of the video stream to every participating user even in cases of high heterogeneity and frequent seeking operations. Specifically, SeekStream is a set of algorithms that optimize the P2P overlay dynamically and in a distributed fashion, making it adaptive to users dynamic behavior and bandwidth changes. The available bandwidth resources of the participating users are optimally exploited, keeping the contribution from the media server(s) to a minimal level. To illustrate the performance of the proposed algorithms, we are using a centralized overlay network manager that discovers the optimal network graph as a reference. We have developed an extensive P2P VoD simulator that shows the efficiency, scalability, and stability of our system under variant and dynamic conditions. The algorithms of our proposed system introduce less than 4% bandwidth overhead while we achieve high offloading of the media server(s). SeekStream guarantees a high block reception rate for the users, even under extreme seeking patterns. Copyright © 2016 John Wiley & Sons, Ltd.     

云辅助P2P-VoD系统中一种邻居选择算法

提出了一种邻居选择算法,包括节点选择和块选择2个子算法。前者保证请求节点能够以较低的被拒绝概率发现提供视频数据的邻居节点;后者为节点以何种方式下载数据块提供依据,保证系统中视频数据块的高可用性。实验结果表明,提出的算法能进一步降低服务器带宽开销和节点请求拒绝率,并提升节点的下载速率。     

服务感知的移动P2P流媒体系统视频片调度算法

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.     

P2P直播平台网络设计

互联网开始进入了视频时代,今后的互联网将以视频为主要特征,视频需要高带宽,使得掌握网络资源的运营商们具有了相对的优势,从而使得他们在视频媒体领域内有了施展身手的机会。运营商们拥有布遍各地区的光纤网和“全球眼”监控系统,由数千台服务器组成的,并且采用了先进的P2P技术,使得用户数越多观看的效果越好。本文提供了一个完整的P2P直播平台网络设计方案,以供同行们交流。     

基于ConferenceXP的P2P视频会议系统设计与实现

通过分析现有视频会议系统存在的问题,并结合P2P网络的技术特点,提出了一种基于P2P的视频会议系统体系结构。同时分析音视频同步和带宽自适应传输两个关键问题,并给出了解决方案,重点叙述基于Conference XP平台的P2P视频会议系统的设计实现过程。ConferenceXP融合了音频视频和网络技术中的新发展,在该平台上实现的视频会议系统具有很好的实用价值和市场潜力。     

P2P业务流量特性及其对Web业务的影响

近年来各种P2P应用不断出现及演进,P2P应用正逐渐成为下一代互联网的杀手级应用。但同时P2P消耗了Internet的大部分带宽,造成了网络技术服务商(ISP)接入网络的拥塞,从而使传统Internet应用性能受到严重影响。从P2P流数量、服务器负载、网络瓶颈点分布、往返时间(RTT)的异构特性等方面可以看出,P2P流量消耗了巨大的网络带宽,影响了传统Internet业务的性能,增加了运营成本。利用P2P流量和Web流量的集成模型,可以量化分析P2P流对Web流的影响,使网络运营商可以在网络瓶颈点对P2P连接数进行优化和调整,从而有效地控制P2P流量。NS2仿真结果较好地验证了该模型的有效性。     

基于分簇P2P的多跳无线mesh网络资源检索与分发算法

针对多跳无线mesh网络中拓扑结构和不同类型节点的特征,将多跳无线mesh网络建模成分簇P2P结构.为了降低资源发布的开销,在进行资源共享设计时,利用布鲁姆过滤器作为资源表示和消息在网络中传输.以布鲁姆过滤器为基础,提出了一种基于资源密度敏感的多跳无线 mesh 网络资源检索和分发算法,将移动客户端的资源下载请求转发到拥有资源副本最多的P2P分簇,利用该分簇的多个资源副本备份提供资源下载服务,最大化降低节点移动性产生的资源下载中断.仿真结果表明所提出的资源检索和分发算法能有效提升资源的下载性能.     

P2P技术在IPTV中的应用

IPTV是基于宽带高速IP网的流媒体服务，提出基于对等网络模式的IPTV系统，从而克服了现在IPTV系统的“瓶颈”问题，对P2P技术存在的问题进行分析并提出对策。     

MSPnet： MANAGEABLE SIP P2P MEDIA DISTRIBUTION SYSTEM

The letter proposes a three-layer manageable media distribution network system archi- tecture called MSPnet, which is based on Session Initiation Protocol[1] and Peer to Peer (SIP P2P) technology. MSPnet performs application-level structured DHT routing and resource location among domains and unstructured ones in domain. Except for media distribution, it can be used to support a variety of P2P applications, including video broadcasting, video on demand, VoIP, etc. MSPnet is composed of three layers, namely, the signal control layer, the management layer, and the media transportation layer. The MSPnet prototype consists of the SIP server, the management server, the media server, and the node User Agent (UA). Results from a prototype experiment in a large-scale Internet environment show that MSPnet is feasible, scalable and manageable.     

基于移动P2P网络的Mobile TV的实现方案

Mobile TV已经成为人们广泛关注的增值业务之一。本文提出一种基于移动P2P（Mobile P2P，MP2P）技术的Mobile TV业务的实现方式，为了能更好地支持多种类型的移动终端，在网络中加入编码变换服务器，提供实时视频编码变换功能。     

Distributed upload bandwidth assigning algorithm in P2P VoD system

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.     

构建G2P结构IPTV新网络

当前主流的传统C／S架构的IPTV网络存储成本巨大，即使是采用H．264这样的高性能编码器，可以节省的存储费用也是有限的，而且服务器的响应时间长，服务器性能和带宽“瓶颈”严重。提出一种P2P（PeertoPeer）和C／S（Client／Server）混合的用于存储和传送IPTV（Intemet Protoeol based Television）数据的网络新结构G2P（Groupto Point），并详细介绍G2P结构中媒体服务器的分布以及分布式差异化存储和组对点分片数据分发方式，分析比较采用G2P技术发展IPTV业务的特点，并针对不足之处提出改进方向。     

下一代广播电视网（NGB）环境下VOD业务模型

针对目前广电网络中第二代视频点播系统（VOD,Video-On-Demand）相对于上一代VOD系统的改进和存在的不足,本文提出在中国下一代广播电视网络（NGB）环境下的一个VOD业务模型,用以满足大规模实时点播以及高清晰度播放的需求。骨干网采用内容分发网络（CDN）,接入网采用P2P策略。本文论述了该模型的设计思路。