Model of downloading strategy from peers and server for saving server bandwidth in P2P VoD system

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.     

Research on grouping strategy of SIP-based streaming media P2P live broadcast network

The rapid development of Internet has led to the explosion of information sharing, and how to supervise the sharing is a main research topic on current Internet. Aiming at the disadvantage that the current Peer-to-Peer （P2P） is hard to manage and control, this paper presents a Session Initial Protocol （SIP）-based P2P network of three-level architecture. SIP middleware is introduced to the middle level of the three-layer architecture. By the connection function of the SIP signaling, the P2P transmission on media-level can be controlled. Using SIP＇s register and authentication function, the manage layer can manage the whole P2P network. Based on the aforementioned architecture, this paper investigates the grouping strategy on a live broadcast application in P2P network. Combined with the function of SIP register, the paper works on several grouping strategies, sets up models to manage users by grouping them, presents a weight-based K-means IP address grouping algorithm, and realizes it. The experiment shows that the grouping strategy presented in this paper can solve the problem of group sharing of network resource, and can realize the efficient-sharing, reasonable-distributing of network resource     

Novel two-layer motion estimation for video coding

In this paper,we proposed a novel Two-layer Motion Estimation （TME） which searches motion vectors on two layers with partial distortion measures in order to reduce the overwhelming computational complexity of Motion Estimation （ME） in video coding.A layer is an image which is derived from the reference frame such that the sum of a block of pixels in the reference frame determines the point of a layer.It has been noticed on different video sequences that many motion vectors on the layers are the same as those searched on the reference frame.The proposed TME performs a coarse search on the first layer to identify the small region in which the best candidate block is likely to be positioned and then perform local refined search on the next layer to pick the best candidate block in the located small area.The key feature of TME is its flexibility of mixing with any fast search algorithm.Experimental results on a wide variety of video sequences show that the proposed algorithm has achieved both fast speed and good motion prediction quality when compared to well known as well as the state-of-the-art fast block matching algorithms.     

Data management solutions based on the data distribution service communication model

This article presents a data management solution based on the data distribution service （DDS） communication model. The basic DDS communication model consists of a unidirectional data exchange where applications that publish data ＇push＇ the relevant data, which is updated to the local caches of co-located subscribers to the data [1]. DDS has no specified center node to forward data packets and maintain the communication data. This type of publish-subscribe （P/S） model presents integrity and consistency challenges in data management. Unlike peer-to-peer （P2P） distributed storage, DDS applications have a hard real-time environment and fewer data features, and the core problem is ensuring the integrity and consistency of data in distributed systems under this hard real-time environment. This article begins with a brief introduction of the communication model used by DDS, then analyzes persistent data management problems caused by such model, and provides an appropriate solution to these problems. This solution has been implemented in a prototype system of the real-time service bus （RTSB） of Tsinghua University.     

P2P:Development Situation and Operation Solutions

The rapid development of Peer-to-Peer (P2P) technologies and applications has a great impact on telecom services and operations. Operators should refine the pipeline operation and develop characteristic P2P services. They must comply with the rule of Internet services, and design manageable and operational P2P solutions combining the advantages in network, resource and subscriber, providing users with better P2P service experience. ZTE’s manageable and operational P2P solution provides operators with customized authorization and accounting functions. Its development is based on the broadband service management platform widely used in the live networks. ZTE’s P2P system is stable and reliable.     

Service Customized Space-Air-Ground Integrated Network for Immersive Media: Architecture,Key Technologies,and Prospects

The space-air-ground integrated network(SAGIN) is regarded as the key approach to realize global coverage in future network and it reaches broad access for various services. Being the new paradigm of service, immersive media(IM) has attracted users’ attention for its virtualization, but it poses challenges to network performance, e.g. bandwidth, rate, latency. However, the SAGIN has limitations in supporting IM services, such as 4 K/8 K video, virtual reality, and interactive games. In this paper, a novel service customized SAGIN architecture for IM applications(SAG-IM) is proposed, which achieves content interactive and real-time communication among terminal users. State-of-the-art research is investigated in detail to facilitate the combination of SAGIN and service customized technology, which provides endto-end differentiated services for users. Besides, the functional components of SAG-IM contain the infrastructure layer, perception layer, intelligence layer, and application layer, reaching the capabilities of intelligent management of the network. Moreover, to provide IM content with ultra-high-definition and high frame rate for the optimal user experience, the promising key technologies on intelligent routing and delivery are discussed. The performance evaluation shows the superiority of SAG-IM in supporting IM service.Finally, the prospects in practical application are high-lighted.     

A limited resource vector load-balancing algorithm for softswitch-based heterogeneous clustered media server

I. Introduction NGN (Next Generation Network) that can sup- port multimedia services has become a research hotspot in telecom and computer field in recent years. In the NGN architecture, multimedia service platform includes many kinds of devices[1]. As the device to provide media resource data and multime- dia operation environment under the control of softswitch device, media server is a key device on multimedia service platform. The media server un- der the control of softswitch device i…     

The Progress of P2P IPTV

1 Limitation of IPTV System with Client/Server Architecture IPTV services generally refer to theaudio/video contents transmittedthrough IP networks and received byTV. At present, telecom operatorsuse the manageable IP networkssupporting multicast to offer IPTVservices, including Live TV, Time- shiftedTV, Video on Demand (VOD) andinteractive data services.IPTVsystems in China are adoptingthe client/server architecture to offerunicast and on- demand (includes VoDand Time- shifted…     

Progress of Internet Video Technology

In China, currently there are more than 100 million videos being watched everyday on the Internet. There are three kinds of Internet videos: video sharing, Video on Demand (VoD), and Peer-to-Peer (P2P) streaming media. Video sharing is based on browser/server mode, severing user generated content. VoD is based on client/server mode and needs to be paid for. P2P streaming media is based on P2P mode service for hot content. To address P2P traffic optimization and content regulation, China National Information Technology Standardization Technical Committee sets up P2P working group to make relevant standards.     

A Cooperative QoS Management Scheme Based on DiffServ Network for Real-Time Service

In this paper,an improved scheme based on DiffServ network is proposed to provide a decentralized coopera-tive QoS management for real-time services'admission control and resources'monitoring.The proposed scheme consists of aQoS Control Server(QoSCS),a Service Management Server(SMS),a Network Management Server(NMS)and routersin the concerned management domain.When an application asks for a service with specific QoS requirements,a series ofcooperation are initiated among these components by means of a suit of signaling protocol.Once a service is admitted,itcan provide required QoS services more effectively than original DiffServ network.Monitoring per-flow states are movedfrom edge routers to the QoSCS server.The prototype implementation and experimental results show that this scheme canprovide enhanced manageability and scalability for providing per-flow management in such a distributed way.     

一种新的基于P2P-SIP分布式结点发现的网络电话研究与设计

通过对P2P技术和SIP协议的详细分析,充分发挥P2P技术分布式特性,采用CHORD结点搜索算法,设计出一个基于P2P-SIP的分布式结点发现的网络电话系统,克服了SIP网络电话系统需要集中式目录服务器的缺点,方便网络电话的管理,降低网络电话组建费用。     

基于JXTA的P2PSIP软电话原型系统设计

结合当前SIP、P2P以及P2PSIP技术的现有方案。以JXT和RTCClient为基础,设计并实现了P2PSIP软电话原型系统。依据JXTA的管道通告发布和查询功能,给出了系统的模块结构,并设计了适配协议。最后通过测试和数据包截获,对呼叫过程的数据流进行了分析,验证了原型系统的功能。     

基于P2P架构和SIP协议的多媒体邮件网络研究

文中提出了一种在P2P架构上的基于SIP协议的多媒体邮件网络,他可以克服IP网络上的服务器瓶颈问题和H.323协议的繁琐及低效率问题.同时介绍了本网络采用该P2P架构和SIP协议的优势所在.在此基础上,还介绍了本网络如何对多媒体信息流的获取、存储管理以及播放.最后,对各个功能模块进行了总体介绍.     

P2P流量的精细化识别方法研究

目前,已有多种方法可高效准确地完成对P2P流量的粗识别,但对P2P流量的精细化识别研究较少。该文首次将近邻传播(Affinity Propagation, AP)算法引入该领域,在Hi-WAP算法的基础上融合半监督聚类思想提出了一种基于分层加权半监督近邻传播(Hierarchical Weighted Semi-supervised AP, Hi-WSAP)算法的P2P流量精细化识别方法。该方法仅利用10个可快速计算获取的网络流特征对P2P流量按应用进行半监督聚类。两组数据集下的实验结果表明,该方法识别准确率高,时间复杂度低,为P2P流量的实时精细化识别提供了一种实现思路。     

P2PSIP原理和应用

SIP协议是当前VoIP和IM等多媒体协议的呼叫建立协议。P2P技术提供了分布式的网络架构中通信节点之间得对等通信能力,P2P网络架构经历了集中目录式网络架构、纯P2P网络架构、混合式P2P网络架构和结构化P2P网络架构。通过引入P2P技术,SIP网络的能力可以得到增强。P2PSIP网络主要有两个重要的操作:对P2P节点的操作和用户层面的操作。     

P2PSIP测试探讨

P2PSIP系统结合了P2P技术和SIP协议的优势,是当今网络技术领域的热门应用之一。本文首先介绍了P2PSIP系统的基本原理,基于现有的P2PSIP系统的体系结构,提出了P2PSIP系统测试主要内容,并分析和探讨P2P重叠层和SIP应用层的测试重点。     

对P2P与SIP结合的初步探讨

P2P和SIP是如今互联网、IT和通信界最热门的话题,P2P带来了思想和计算模式的革命,而SIP有望在通信和呼叫信令层面一统天下.本文就P2P和SIP系统架构和两者之间可能的结合点进行了分析,并提出两者可能的结合方案以及亟待研究的问题.     

SIP视频会议中服务器的研究与改进

视频会议系统中会议服务器决定着会议的稳定性、规模和质量.通过研究SIP协议、SIP协议实体和SIP视频会议中服务器的结构等,对现有结构和服务器进行了改进和设计.采用负载均衡方法,提高了系统动态自适应能力,扩大了视频会议的规模.利用SIP消息分发以及优先处理机制,进一步提高了视频会议服务器的消息处理效率,以解决消息并发和消息拥塞的问题,提高系统的可靠性.