浅析IP多播的两种配置方案

IP多播是发生在IP层的点到多点的通信形式,是流媒体、远程教学等网络应用的基础,选择一个合适的多播配置实施方案对多播应用至关重要。介绍了分别使用路由器和三层交换机进行多播的配置方案,并从原理、性能及适用场合等方面分析比较这两种配置方案,为研究多播应用奠定基础。     

因特网多播拥塞控制机制研究

简述了目前多播拥塞控制机制的研究进展状况。首先,从公平性和可扩展性两个方面介绍了多播拥塞控制的基本要求;然后,分析了算法设计中的基本问题;最后,指出了未来的研究热点。     

基于监听的组播服务管理分析与研究

导致组播应用存在问题的原因之一是缺乏服务管理。现今，组播面临转折，服务管理是否有效将决定组播能否在专有网络和Internet中继续使用。分析近期组播服务管理方面的研究工作，全文关注点是：域内和域间组播服务管理存在的问题及解决方法；监听信源和信宿问的组播可达性；测定端到端路径上的组播存在性。     

基于RSVP的Internet QoS服务实现分析

Ｉｎｔｅｒｎｅｔ越来越成为人们信息交流的重要媒体，但是传统Ｉｎｔｅｒｎｅｔ基于ＩＰ协议的尽力（ｂｅｓｔ－ｅｆｏｒｔ）传送模型，满足不了实时业务的ＱｏＳ要求。根据当前技术的最新进展，介绍基于ＲＳＶＰ协议的资源预留机制，分析在Ｉｎｔｅｒｎｅｔ上采用ＲＳＶＰ协议实现有ＱｏＳ保障的业务时存在的问题和解决对策。     

WCDMA增强无线接入技术:从R5到R6

主要讨论了宽带码分多址系统中，从Release5到Release6协议版本增强的无线接入技术，包括高速下行分组接入、高速上行分组接入和多媒体广播和组播，考虑了一些技术实现的细节问题和对无线接入网的影响。     

Scalable team multicast in wireless ad hoc networks exploiting coordinated motion

In this paper, we study a new multicast paradigm for large scale mobile ad hoc networks, namely team multicast. In team multicast the multicast group does not consist of individuals, rather, of member teams. For example a team may be a special task force that is part of a search and rescue operation. The message must be broadcast to each member of each team in the multicast group. Team multicast is very common in ad hoc networks set up to accomplish some collective tasks, such as for emergency recovery or battlefield applications. A key problem in several of the above applications is scalability to large membership size as well as network size. Our approach exploits motion affinity (more precisely, team members’ coordinated motion) which is typically present when the set of nodes has a commonality of interests. Each team can be viewed as a logical subnet. Within the team a landmark node is dynamically elected. The addresses of and the paths to the chosen landmarks are propagated into the whole network so that a source of a multicast group can route to the landmark of a subscribed team.Our protocol, Multicast-enabled Landmark Ad Hoc Routing (denoted as M-LANMAR), uses tunneling from multicast sources to each landmark of the subscribed team and restricted flooding within the motion group. Simulation study shows that M-LANMAR provides efficient and reliable multicast compared with the application of a “flat” multicast scheme (e.g., ODMRP) that does not exploit team coordinated motion.This paper contains three contributions: a new model for team multicast, with the definition of team dynamics (join, merge, split); the exploitation of team mobility and of landmarks in order to achieve scalable multicast, and; the implementation and performance evaluation of M-LANMAR, a landmark based team multicast scheme.     

精细可分级编码技术及其应用

首先讲述精细可分级编码(FGS)的主要编码技术和它的精细分级特性,介绍了FGS几个先进特征和主要的改进方案;接着从网络视频应用特点的角度出发,讨论了在FGS抗误码方面和适应时变网络带宽方面的现有工作,并结合研究给出实例;最后描述了基于FGS的网络视频应用的单播和多播系统框架。     

QoS-aware minimum energy multicast tree construction in wireless ad hoc networks

Energy conservation is a critical issue in wireless ad hoc networks since batteries are the only limited-life energy source to power the nodes. One major metric for energy conservation is to route a communication session along the routes which require the lowest total energy consumption. Most recent algorithms for the MEM (Minimum Energy Multicast) problem considered energy efficiency as the ultimate objective in order to increase longevity of such networks. However, the introduction of real-time applications has posed additional challenges. Transmission of video and imaging data requires both energy and QoS-aware routing in order to ensure efficient usage of the networks. In this paper, we only consider “bandwidth” as the QoS in TDMA-based wireless ad hoc networks that use omni-directional antennas and have limited energy resources. We present a constraint formulation model for the QoS-MEM (QoS-aware Minimum Energy Multicast) problem in terms of mixed integer linear programming (MILP), which can be used for an optimal solution of the QoS-MEM problem. Experiment results show that in a typical static ad hoc network with 20 nodes, the optimal solutions can always be solved in a timely manner.     

IDBS系统中基于本地缓存的VOD组播方案

首先概述了交互式数据广播系统(IDBs)的结构特点及应用现状，然后主要介绍了一种在IDBs系统中使用的基于本地理存的VOD组播方案，主要阐述了它的工作过程和优点，并进行了简单的性能分析。     

一种新型多目发送保序机制及实现

本文提出了一种双层多中心多目发送保序机制，并在以太网和工作站环境中实现．通过将本方法与现有集中式、分布式和树型方式的比较以及对实验数据的分析，认为集中式虽然通信开销低、简单易实现，但坚定性差、并行度低；分布式方式虽然坚定性强，但并行度低、通信开销大、效率低；传播树方式效率虽然较前两种有所提高，但在根结点处同样并行度低、坚定性差，而且结构不灵活．本文提出的方法，避免了上述三种方式的缺点，并且具有坚定性强、并行度高和结构灵活、简单的特点．