Scalable Live Streaming Service Based on Interoverlay Optimization

In order to provide scalable live-streaming services, we propose an Inter-Overlay Optimization scheme, IOO. Instead of selecting better paths in the same overlay, IOO constructs efficient paths using peers in different overlays, so as to (i) improve global resource utilization of P2P streaming networks; (ii) assign resources based on their locality and delay; (iii) guarantee streaming service quality by using the nearest peers, even when such peers might belong to different overlays; and (iv) balance the load among the group (streaming overlay) members. We compare the performance of IOO with existing approaches through trace driven simulations. Results show that IOO outperforms previous schemes in terms of resource utilization and the QoS of streaming services. IOO scheme has been implemented in an Internet based live streaming system, called AnySee. AnySee was successfully released in the summer of 2004 in CERNET of China. Over 60,000 users enjoy massive entertainment programs, including TV programs, movies, and academic conferences videos.     

Fast-Mesh: A Low-Delay High-Bandwidth Mesh for Peer-to-Peer Live Streaming

Peer-to-peer (P2P) technology has emerged as a promising scalable solution for live streaming to a large group. In this paper, we address the design of an overlay mesh which achieves low source-to-peer delay, accommodates asymmetric and diverse uplink bandwidth, and continuously improves delay based on an existing pool of peers. By considering a streaming mesh as an aggregation of data flows along multiple spanning trees, the peer delay in the mesh is then its longest delay (including both propagation and scheduling delay) among all the trees. Clearly, such delay can be very high if the mesh is not designed well. In this paper, we propose and study a mesh protocol called Fast-Mesh, which optimizes such delay while meeting a certain streaming bandwidth requirement. Fast-Mesh is particularly suitable for a mildly dynamic network consisting of proxies, supernodes, or content distribution servers.      

Dynamic overlay multicast for live multimedia streaming in urban VANETs

Infotainment service has been a foreseeing trend in VANETs (Vehicular Ad Hoc Networks), and multimedia streaming has a high potential in VANET infotainment service. This paper considers the scenario of live multimedia streaming multicast to vehicles of the same group using a dynamic application layer overlay. Due to the willingness for cooperation of non-group nodes, application layer overlay multicast is more feasible than other kinds of multicast such as network-coding-based multicast and network-layer multicast. To adapt to high mobility and full of obstacles in urban VANETs, we propose an effective dynamic overlay multicast scheme for multimedia streaming, called OMV (Overlay Multicast in VANETs). The proposed OMV enhances an overlay’s stability with two strategies: (1) QoS-satisfied dynamic overlay and (2) mesh-structure overlay. The QoS-satisfied strategy to adjust the overlay selects potential new parents based on their streams’ packet loss rates and end-to-end delays. The mesh-structure strategy allows a child to have multiple parents. We evaluate the proposed OMV in urban VANETs with obstacles using two real video clips to demonstrate the feasibility of the OMV for real videos. Evaluation results show that comparing the proposed OMV to Qadri et al.’s work, which is a static mesh overlay and is the best method available in VANETs, the packet loss rate is reduced by 27.1% and the end-to-end delay is decreased by 11.7%, with a small control overhead of 2.1%, on average. Comparing the proposed OMV for tree overlays to ALMA, which is for dynamic tree multicast overlays and is also the best method available in MANETs, the packet loss rate is reduced by 7.1% and the end-to-end delay is decreased by 13.1%. In addition, to address the problem of obstacle-prone urban VANETs, we also derive feasible stream rates and overlay sizes for city maps with different road section sizes. To the best of our knowledge, how to organize and dynamically adjust an application layer multicast overlay for live multimedia streaming have not been studied in existing VANET literatures. In summary, to deal with highly dynamic topologies in urban VANETs, we propose a QoS-satisfied strategy for group nodes to switch to new parents that can offer better QoS. The proposed OMV is feasible for live multimedia streaming applications, such as emergency live video transmission and live video tour guides for passengers in different vehicles that belong to the same multicast group.     

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.     

P2P流媒体的数据调度算法

数据驱动型覆盖网络中的数据调度算法是影响P2P流媒体系统性能的重要因素,为了解决当前算法未能有效利用数据块和节点的特性导致流媒体服务质量差的问题,提出了一种基于数据块优先级和节点能力度的数据调度算法。该算法能够根据数据块的稀缺性、紧迫性得到块的优先级大小,根据节点的上行带宽、在线时间、相对距离得到节点能力度的大小,使优先级高的数据块和能力度大的节点优先被请求,减少了数据块的播放等待时间。在OPNET网络仿真实验表明该算法能够有效降低流媒体播放系统的启动延时和服务器的负载。     

无线Mesh网络中基于业务价值的组播带宽分配方案

高延迟及低效益是无线Mesh网络中开展流媒体业务面临的主要问题。为解决该问题,首先赋予组播业务价值,该值反映了业务的网络优先级及效益优先级,并提出一个基于组播价值优先级的组播带宽分配方案。该方案第一阶段实施基于价值优先级的不区分业务类型的静态分配,通过对高价值业务的优先调度,实现了组播价值最大化及带宽效益最大化。在拥塞时,实施第二阶段的基于业务带宽需求调整及抢占的动态分配,保证了低时延约束业务的服务质量。仿真与常见算法的比较表明,所提出的方案在保证业务网络服务质量的同时,能实现带宽效益最大化。     

满足带宽的实时流覆盖组播算法

面对实时多媒体组通信应用中带宽瓶颈及用户对服务质量的不同需求,通过对带宽、时延、抖动等网络性能指标施加约束,设计一个满足大规模用户带宽需求的覆盖组播算法(BOM),用于构建层次化的覆盖组播树,平衡服务代理节点间的负载和链路间的流量.通过基于GT-ITM的网络仿真实验,证明该方法在实时流传输中具有较低的延迟、较小的抖动性和良好的可扩展性.     

基于IP网络的自适应QoS管理方案研究

目前实时音频、视频多媒体应用已经开始进入IP网络,但还有许多问题没有得到很好地解决,其中一个关键问题是多媒体服务的QoS问题、TCP／IP协议本身只提供一种“Best-effort”级别的服务,对QoS支持很少,“Best-effort”级别的服务往往会导致实时应用出现延迟抖动、分组丢失率高,从而极大的影响了实时应用的运行效果,因此必须研究可行的、高效的基于IP网络的QoS控制机制。IP网络QoS已成为分布式多媒体和网络通信的重要研究热点和难点课题。本文在IEＴＦ Intserv与Diffserv相结合的体系结构基础上,提出了一种适用于IP网络的自适应QoS管理框架,与Intserv或Diffserv模型不同的是,该QoS管理框架引入优先级节和自适应概念,QoS俦权处理采用基于多媒体优先级节的算法,在传输控制上采用了自适应QoS控制算法。它在应用层上完成,因此独立于底层网络协议。本文首先讨论了基本概念和函数,然后提出一种基于优先级节的自适应QoS管理框架和优先级调度流程。提出一种基于IP的自适应QoS协商机制,基本思想是基于RSVP（资源预留协议）。在提出QoS请求时进行QoS映射,然后启动适应性函数和资源管理函数进行协商,直到获得一组在当前资源状况下最佳的QoS指标。最后,本文还讨论了此方案的有效性并在自行开发的实验平台GUT上进行的QoS实验。实验表明应用该方法可以根据网络当前状态自适应地整多媒体实时应用的QoS需求。     

Resource allocation for multimedia streaming over the Internet

This paper addresses the resource allocation problem for multiple media streaming over the Internet. First, we present an end-to-end transport architecture for multimedia streaming over the Internet. Second, we propose a new multimedia streaming TCP-friendly protocol (MSTFP), which combines forward estimation of network conditions with information feedback control to optimally track the network conditions. Third, we propose a novel resource allocation scheme to adapt media rate to the estimated network bandwidth using each media's rate-distortion function under various network conditions. By dynamically allocating resources according to network status and media characteristics, we improve the end-to-end quality of services (QoS). Simulation results demonstrate the effectiveness of our proposed schemes     

基于网络编码的P2P流媒体

本文提出了一种基于网络编码的P2P流媒体直播方案。在该方案下，Peer节点对流经它的数据先进行网络编码，再进行转发，以提高Peer节点实际的下载速率以及对网络资源的利用率。仿真实验表明，采用网络编码后节点的播放质量得到了普遍性的增强。     

MFPQT:IPv4-IPv6过渡阶段的一种流媒体调度算法

为了解决在IPv4向IPv6过渡期间使用现有的基于IPv4环境的流媒体调度算法和策略导致的质量下降问题,提出基于细分播放通道类型和细分传输数据包类型的流媒体调度算法和策略．当所在网络中同时存在纯IPv4节点和IPv6节点时,通过在调度算法中细分IPv4和IPv6的播放节点、接收节点和多播通道,分别对其加以处理和调度,从而提高了面向不同类型用户节点进行节目流调度的效率和总体性能．     

一种覆盖网多QoS约束均衡的路由算法

覆盖网服务质量（QoS）路由是覆盖网研究的关键问题,在多QoS约束均衡和网络资源优化的基础上,提出一种多QoS约束均衡的路由算法。该算法考虑包括节点和链路在内的多种QoS约束因素,使用层次分析、参数归一等方法解决多个QoS参数权值分配问题。同时根据覆盖网络特点采用资源均衡的方法,对链路带宽及节点计算能力2种QoS参数资源进行均衡。利用随机拓扑实验对时间、代价、资源利用率等性能指标进行验证,并与同类算法进行比较,结果表明,该算法所选择的路径在各项QoS指标都满足的情况下,能较好地均衡网络资源。     

在IPv4向IPv6过渡阶段的一种流媒体调度优化方案*

为了解决在IPv4向IPv6过渡期间使用现有的基于IPv4环境的流媒体调度算法和策略导致的质量下降问题,提出基于细分播放通道类型和细分传输数据包类型的流媒体调度算法和策略。当所在网络中同时存在纯IPv4节点和IPv6节点时,通过在调度算法中细分IPv4和IPv6的播放节点、接收节点和多播通道,分别对其加以处理,从而提高了调度不同性质节目流的效率。     

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.     

Dynamic QoS queuing control mechanism for multimedia differentiated services

An essential goal of communication networks is to provide multimedia services with QoS streaming. A properly designed multimedia QoS system must reserve requested resources according to user QoS requirements and the available network resources. However, the static resource allocation among priority queues in DiffServ networks leads to insufficient resource usage when a burst occurs in one priority queue while other queues starve. This study presents a User-Oriented QoS Streaming System to achieve perceptible satisfaction based on novel streaming and media differentiation policies in DiffServ networks. This study also proposes that the Dynamic QoS Queue Mapping (DQ²M) mechanism dynamically control queue scheduling by adaptively maximizing the utilization of queues and network resources according to the soft states of the DiffServ network. Evaluation results indicate that the proposed DQ²M algorithm can improve the fairness and efficiency of resource utilization for low-priority queues.     

A new scalable multicast routing algorithm for interactive real-time applications

Quality of service (QoS) provisioning generally assumes more than one QoS measure that implies that QoS routing can be categorized as an instance of routing subject to multiple constraints: delay jitter, bandwidth, cost, etc. We study the problem of constructing multicast trees to meet the QoS requirements of real-time interactive applications where it is necessary to provide bounded delays and bounded delay variation among the source and all destinations while keeping overall cost of the multicast tree low. The main contribution of our work is a new strategy for constructing multiconstrained multicast trees. We first derive mathematically a new delay-variation estimation scheme and prove its efficiency. Thereafter, we propose a simple and competitive (in terms of running time) heuristic algorithm, for delay and delay variation constrained routing problem based on the proposed delay-variation estimation scheme and using the Extended Prim-Dijkstra tradeoffs’ algorithm. Our contribution also extends previous works in providing some properties and analyses of delay bounded paths satisfying delay variation constraints. Extensive simulation results show that our algorithm outperforms DVDMR in terms of multicast delay variation with the same time complexity as DVDMR.     

面向QoS的域间实时流覆盖组播方法研究

针对跨域远程协作中的实时流通信质量问题,构建了实时流服务网格（LSSG）,这是一个可扩展的且面向用户QoS需求的覆盖组播通信中间件结构,LSSG服务由网络服务提供商策略部署的服务代理（SvB）提供。论文主要采用面向QoS的域间覆盖组播算法（QIOM）来组织SvB建立实时流组播服务树,根据用户服务质量请求提供跨自治系统的实时流组通信服务,将域间资源管理转变为流媒体应用的动态协同服务管理。仿真结果表明QIOM能有效地发现和提供QoS满意的覆盖服务及实现SvB间的覆盖流量负载平衡。     

具有小世界特性的语义覆盖网络模型

目前大多数的结构化覆盖网络模型忽略节点的聚类性和对称性,并且只能提供精确的资源查询机制。为此,给出一种具有小世界特性的语义覆盖网络模型。该模型采用显式分区机制、语义搜索链和组扩散机制。分析和实验结果表明,该模型比现有的覆盖网络模型Chord和CAN具有更好的网络性能,搜索效率更高,且具有较好的多匹配结果查询能力。     

CircleSearch：流媒体VoD环境下的P2P搜索算法

在基于P2P的流媒体VoD环境下,搜索机制是影响服务质量的关键因素之一。该文提出一种新的基于环状网络的分布式自适应概率搜索算法——CircleSearch。它依据节点本体内容生成结构化的环状拓扑网络,保证算法的可扩展性、健壮性和分布性。自发组织基于本体距离和连接可靠性的small world覆盖网络,减小消息的转发次数,采用自适应搜索算法提高文件定位的准确性。仿真实验表明,CircleSearch以其高成功率、低服务器负载和很小的平均搜索长度实现媒体流传输的即时、稳定、可控和连续,为VoD服务提供QoS保证。