P2P网络中流媒体直播系统设计

在Internet视频直播服务中,受宽带限制,服务器难以支持大规模并发客户;针对该问题,该文设计了基于对等网络模式的流媒体直播系统。首先概述了基于P2P网络中的流媒体直播系统的过程,之后讨论了流媒体直播系统设计设计方案,最后阐述了流媒体直播系统中的关键技术。     

IMS 可管理P2P 流媒体应用服务器的设计与实现

基于IP多媒体子系统的流媒体系统采用的都是传统的客户端/服务器（Client/Server,C/S）架构,当大量用户同时请求流媒体服务时,中心媒体服务器将成为整个系统的性能瓶颈。在参考ETSI TISPAN制定的IMS-based IPTV架构基础上,给出了基于IMS的可管理P2P流媒体系统架构,并根据引入P2P技术的系统需求设计了可管理P2P流媒体应用服务器的软件模块结构及P2P分发树的构建算法。在原有基于C/S架构的流媒体应用服务器基础上,通过扩展集中管理和维护对等节点树P2P模块实现了媒体上传节点的选择,并以直播业务为例进行了原型系统验证。测试结果显示该系统能够有效地将终端节点组织成P2P流媒体分发网络,并有效地降低了媒体服务器的压力,提升了流媒体系统的性能。     

基于区域化的P2P流媒体直播系统模型

基于树状拓扑协议及扩展的模型和基于Gossip协议的模型在媒体数据分发方面存在缺陷。针对该问题,提出一种基于区域化的P2P流媒体直播系统模型,采用动态自适应的区域化自治机制,在大规模的流媒体直播网络系统中降低系统管理控制负载的开销,优化系统带宽和时延,提高了流媒体数据资源的利用率。     

P2P流媒体技术在远程教育中的应用研究

P2P技术在流媒体中的应用是目前研究的热点。该文提出了基于P2P流媒体技术的远程教学视频直播系统框架,并对其关键性技术进行了研究与分析。     

应用网络编码的P2P流媒体技术研究进展

P2P流媒体是一种极具潜力的流媒体内容分发技术。在P2P流媒体系统中采用网络编码,有利于进一步提升系统整体性能。针对目前流行的基于数据驱动覆盖网络的P2P流媒体系统框架,根据直播和点播这两种流媒体播送模式,深入讨论和分析了具有代表性的网络编码P2P流媒体技术方案的实现机制及其优缺点。最后,对该方向的研究趋势进行了展望。     

基于Gossip协议的P2P流媒体直播系统的研究

通过对当今P2P流媒体直播系统主流模型的对比分析,在Gossip协议的基础上,提出一种自适应Gossip协议P2P流媒体直播系统模型,针对节点的异质性实现动态的更新状态和查找节点的机制,充分利用节点的带宽,提高了系统的效率。     

面向P2P流媒体直播的数据分发机制研究进展

数据分发机制是P2P流媒体直播系统中的核心技术。根据流媒体数据分发过程中数据分发驱动因素的不同,将应用于P2P流媒体直播业务的数据分发机制分为3类,分别是路径驱动的、数据驱动的和混合驱动的。通过对以上3类数据分发机制的典型技术进行深入的研究与分析,概括并总结了现有技术的优缺点。最后,基于研究现状分析,指出了该领域未来的发展方向。     

结合IP组播的P2P流媒体直播系统

在流媒体系统中利用P2P技术与IP组播各自的优势,提出了一种结合IP组播的P2P流媒体直播系统,不仅能够充分利用用户节点的资源,减轻流媒体服务器与骨干网的负载,提高系统的可扩展性和可用性,而且有效地提高了P2P流媒体直播系统中视频流的服务质量。     

EPSS:可扩展的P2P流媒体模拟器

随着互联网上P2P流媒体服务的流行,P2P流媒体系统模拟器也成为实现和改进实际系统必不可少的工具.但是,现有的模拟器普遍存在功能扩充困难的问题,用户若想实现自己的研究目标,往往需要花费较多的时间和精力对模拟器进行定制.基于此,我们设计和实现了一款可以灵活扩展功能的P2P流媒体模拟器:EPSS.EPSS是一款事件驱动的报...     

基于P2P技术的流媒体直播系统的研究与实现

本文介绍了P2P技术和流媒体的技术框架,并对它们进行研究和分析,并在此基础上设计和实现了一个高质量的流媒体直播系统。     

基于P2P的流媒体直播系统研究与设计*

根据当前流媒体播放系统存在的问题,设计了基于对等网络模式的流媒体直播系统,其中每个节点既是服务的消费者同时又是提供者,克服了当前流媒体系统在大规模用户时存在的服务器瓶颈问题,具有对网络带宽和服务器处理能力要求低,容易部署和扩展性高的特点。     

面向嵌入式机顶盒终端的P2P网络电视直播系统的设计与实现

针对当前IPTV直播应用中,集中服务模式对服务器性能和网络设施要求较高、可扩展性较差的问题,提出了一种基于P2P(点对点)技术的直播系统Clear Live。与现有的P2P视频系统只针对PC终端的情况不同,该系统主要面向IPTV应用,面向嵌入式机顶盒终端,并兼容PC终端。Clear Live针对机顶盒终端的特点和IPTV应用的环境做了适当的和针对性的设计。实际系统测试结果表明,Clear Live系统能在较低的硬件配置下为大量用户提供高质量的直播服务。     

A P4P-integrated data-driven P2P system for the live multimedia streaming service

The Proactive network Provider Participation for the P2P (P4P) architecture deploys central servers, which perceives network status and provides peering suggestions to P2P systems in order to achieve better network resource utilization while supporting best possible application performance. However, P4P alone may not be able to make appropriate peering suggestions for live multimedia streaming since it does not include mechanisms to reflect some of the parameters that are important to the QoS of live multimedia streaming such as upload bandwidth and stability of a peer as a stream deliverer. Furthermore, peer synchronization and parent replacement in the middle of a session, which are critical issues to the QoS of live multimedia streaming, are also left as the matters to be dealt with by the P2P systems alone. Most of the existing data-driven P2P systems leverage periodic information exchanges among neighboring peers in order to cope with these problems, which may incur long delay and high control overhead. In this paper, we proposed P4P-integrated data-driven P2P system for live multimedia streaming service. The proposed system includes not only the peering suggestion mechanism appropriate for live multimedia streaming but also the peer synchronization and parent replacement mechanisms, which exploit the centralized P4P framework and do not require periodic control information exchanges. We implemented the system in NS-2 simulator and compared its performance to the P4P and existing data-driven P2P systems. The results from experiments show that the proposed system enhances QoS compared to the existing data-driven P2P systems while maintaining the same level of network efficiency of the original P4P.     

Towards efficient video chunk dissemination in peer-to-peer live streaming

There are substantial differences in chunk dissemination manner between P2P live streaming and BitTorrent, and inappropriate algorithms will result in inefficiency of live streaming systems. In this paper, we study the chunk dissemination of P2P live streaming, and introduce a discrete and slotted mathematical model to analyze chunk selection algorithms, including rarest first algorithm and greedy algorithm. Moreover, we present a performance metric to evaluate chunk selection algorithms, as well as the optimization function for the exploration of chunk dissemination strategies. We point out the causes of poor performance of these algorithms, and propose a service request randomization mechanism to promote the use of peer resources, which can prevent chunk requests from rendezvous on a few of peers. Simultaneously, we employ weight assignment strategies to avoid excessive requests for rare chunks. Besides, we present an enhanced model, which adds node degree constraint, to improve our model. We revisit the chunk selection algorithms based on the enhanced model. The results of simulation experiments validate our theoretical analysis and indicate that the weighted randomization mechanism is resilient to flash crowd and peer churn, and can improve the performance of P2P live streaming.     

基于P2P的流媒体直播系统研究与设计

传统的流媒体系统建立在客户-服务器模式的基础上,系统伸缩性差,服务器常成为系统的瓶颈.根据当前流媒体播放系统存在的问题,设计了基于对等网络模式的流媒体直播系统,其中每个节点既是服务的消费者同时又是提供者,克服了当前流媒体系统的服务器瓶颈问题。     

一种分层分簇的P2P流媒体覆盖网络模型

提出一种新型的分层分簇结构的P2P覆盖网络模型HCPON。该模型根据能力对节点分层处理,分簇聚合,分别应用不同方案优化覆盖网络结构,兼顾了节点的能力差异性和位置特性。仿真实验表明,该模型具有很好的可扩展性和鲁棒性,能够满足大规模流媒体服务需求。     

Modeling and optimization of survivable P2P multicasting

Various solutions based on Peer-to-Peer (P2P) multicasting have been gaining much popularity in recent years, since P2P multicasting can effectively support live streaming of various content. In this work we assume that the P2P multicasting is used to distribute content with high reliability requirements, e.g., weather warnings, security updates, financial data, security warnings, etc. The main idea to provide protection of the system against network failures is to establish several (at least two) disjoint multicasting trees. Our discussion in this paper centers on the problem how additional survivability constraints to provide failure-disjoint trees impact the operation of P2P multicasting systems. As the performance metrics we propose to use: streaming cost, maximum delay and throughput. The possible failure scenario we take into account is a single failure of one of the following network elements: streaming server, overlay link, uploading node and ISP link. We examine the topic of survivable P2P multicasting applying offline optimization methods and simulations. In the former case we formulate Mixed Integer Programming (MIP) models and use the CPLEX solver to obtain optimal results. For the streaming cost objective we compare two MIP formulations in terms of the complexity and execution time. Results show that our formulation provides much better performance compared to the classical P2P multicasting formulation proposed in the literature. Moreover, in the case of the streaming cost problem we propose a new evolutionary algorithm that yields results for larger networks than the CPLEX solver. The simulations are run to emulate a distributed network environment, in which each node makes its own decisions. Results obtained using both research methods confirm that the survivability of P2P multicasting can be achieved with relatively low additional system overhead for all three considered performance metrics: streaming cost, maximum delay and system throughput.     

基于宽带城域网的P2P流媒体直播模型与方法

为了解决现行P2P直播系统存在启动延时长、画面质量差的问题,提出了一种基于分布式树状拓扑结构的模型架构及其实现方法。该模型由服务器组、超级节点组和普通节点组共同组成分布式P2P流媒体分发网络,通过采用非平衡的MDC编码方案和动态的普通节点服务请求策略,有效解决了启动延时过长的问题;通过优化节点缓冲区的基本结构,并采用推拉结合的缓冲区调度策略,大大提高了网络的分发效率,有效解决了节点播放不畅的问题。实验证明,与现行直播系统相比,该模型具有更短的播放启动延时和更好的播放体验。     

Measurement study on P2P streaming systems

Originally used as the default infrastructure for efficient file sharing, peer-to-peer (P2P) architecture achieved great successes. Now, the P2P model has been adopted for many other distributed applications, such as instant message and phone services, Internet gaming, and large-scale scientific computing. In recent years, P2P streaming systems experienced tremendous growth and became one of the largest bandwidth consumers on the Internet. Compared to standard file sharing systems, the streaming services show unique characteristics with more stringent time constraints and require much higher network bandwidth. It is extremely important to evaluate and analyze existing applications, and investigate the merits and weaknesses in these systems for future development. In this paper, we conduct a comprehensive measurement study on two of the most popular P2P streaming systems, namely, PPLive and PPStream. They are very popular P2P streaming applications, and serving millions of registered users with hundreds of live TV channels and millions of other video clips. In our measurement, we deploy our collectors in China, and both live TV and video-on-demand (VoD) channels are evaluated. We record run-time network traffic on the client side, compare and analyze the characteristics of these channels based on their popularity. For both categories, we perceive that, in general, the two measured P2P streaming systems provide satisfactory experience to the audiences for all channels regardless of popularity. However, the most of data are downloaded from the dedicated servers for unpopular channels. We also observe that live TV channels show better peer coordination than VoD channels. Beside the traffic, we have also collected cache replacement information for VoD channels, and these measurement results can help us understand the caching mechanism of P2P streaming systems. With the support of the cache, VoD channels perform better than their counterparts in the live TV category in terms of data transmission, workload distribution, and signal traffic overhead. Overall, our results reveal that although P2P streaming systems can usually provide excellent viewing experience for popular channels, there are still challenges to fully support unpopular channels. New designs and algorithms are in urgent need, especially for unpopular live TV channels.