卫星广域网组播技术分析

卫星本身固有的广播特性为组播传输提供了一种经济有效的方法。该文针对卫星环境特点简要讨论了卫星广域组播技术,分析了卫星可靠组播特点和未来应用需求可能面临的技术挑战。     

可靠的组播通信

随着IP应用对组播可靠性的要求不断提高,国际上很多大学和研究机构在一定的应用背景下提出了可靠组播通信,并开发了各自的解决方案。本文系统地介绍了常见的实现方法并进行分析。     

基于IPv4的可靠移动组播技术

移动组播技术是近几年来无线互联网领域的一个研究热点,其相当一部分应用要求移动环境下也能提供相当于有线链路的可靠性。但是移动环境下的突出特点就是链路差错率高,组播成员位置动态变化,这给移动组播尤其是可靠移动组播提出了很大的挑战。基于IPv4的可靠移动组播算法具有两种不同的设计思想,其中一部分算法是针对现有的移动组播算法存在的问题,进行可靠性方面的改进,另一部分算法是专门用于实现可靠移动组播的,它们大都引入了新的功能实体来保证可靠性。     

基于卫星的可靠组播协议研究

卫星组播是未来网络通信发展的方向之一,卫星由于其自身独特的特点内在地支持组播,但另一方面又因为大时延和相对复杂的无线信道特性降低了组播业务的可靠性。针对这一问题,在单向链路卫星组播结构基础上,融合分组级FEC和自适应速率技术,提出了一种新的可靠组播协议,经过理论分析可知,新的协议具有较好的差错控制和拥塞控制能力。     

可靠组播传输协议设计

本文根据SRM(Scalable Reliable Multicast)协议中阐述的原理,详细叙述了IP组播中可靠性的实现原理以及实现机制,并自行设计了一套实现方案,论述了此方案的可行性。     

组播技术在卫星DVB系统中的应用

本文论述了组播技术与卫星DVB—S技术结合应用问题，解释了组播技术，卫星DVB-S技术优点，分析了二者技术结合应用特点及带来的市场前景．同时．对应用方法，应用中出现的主要技术问题如何解决作了阐述，对存在的问题也作了说明．     

适于低轨卫星IP网络的特定源组播算法

为了解决低轨卫星IP网络中现有特定源组播算法的信道资源浪费问题,本文提出了一套新的特定源组播算法,即基于核心群的特定源组播算法(CSSM)和加权的CSSM算法(w-CSSM).CSSM算法以源节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,所得的树代价最小,从而大大提高了网络的带宽利用率和传输效率.在w-CSSM算法中,加权因子可以自适应调整以适度增大树代价、降低端到端传播时延,以支持某些有严格端到端时延要求的实时组播业务.通过与低轨卫星IP网络中典型特定源组播算法MRA的仿真比较,可以看出CSSM和w-CSSM算法的树代价性能比MRA有较大改善,不过端到端传播时延略高.     

基于卫星网络的移动可靠组播技术

本文首先介绍了基于卫星网络的可靠组播的优势,然后详细讨论了移动可靠组播及卫星网络可靠组播所面临的新的问题,最后提出了卫星网络中移动可靠组播的解决方案。     

基于EPON的可控组播技术

以太无源光网络( EPON)作为光纤到户的理想解决方案之一,凭借其带宽优势非常适合承载组播业务.EPON可控组播技术结合EPON的特点,从安全性和可维护性考虑,提出了一套可控组播实现方案,包括组播源管理、用户认证和组播流量控制等内容,以满足组播业务可维、可控的运营管理需要.     

组播技术在IPTV中的应用

随着网络技术的发展,IP技术已经成为核心网络承载技术的事实标准。传统业务在IP网络中的开展日趋成为广大研究人员以及各大运营商关注的热点。本文简要介绍了承载在IP网络上的电视业务(网络电视)的基本概念,重点研究了组播技术在网络电视中的应用．并从组网方式、频道快速切换方法、安全、计费以及源特定组播五个方面进行分析并给出了相应的解决策略。     

Probabilistic reliable multicast in ad hoc networks

When striving for reliability, multicast protocols are most commonly designed as deterministic solutions. Such an approach seems to make the reasoning about reliability guarantees (traditionally, binary, “all-or-nothing”-like) in the face of packet losses and/or node crashes. It is however precisely this determinism that tends to become a limiting factor when aiming at both reliability and scalability, particularly in highly dynamic networks, e.g., ad hoc networks. Gossip-based multicast protocols appear to be a viable path towards providing multicast reliability guarantees. Such protocols embrace the non-deterministic nature of ad hoc networks, providing analytically predictable probabilistic reliability guarantees at a reasonable overhead.

This paper presents the Route Driven Gossip (RDG) protocol, a gossip-based multicast protocol designed precisely to meet a more practical specification of probabilistic reliability in ad hoc networks. Our RDG protocol can be deployed on any basic on-demand routing protocol, achieving a high level of reliability without relying on any inherent multicast primitive. We illustrate our RDG protocol by layering it on top of the “bare” Dynamic Source Routing protocol, and convey our claims of reliability and scalability through both analysis and simulation.     

利用组播树优化VPLS组播功能的研究

RFCs 4761和4762描述了一种基于利用点对点或点对多点单播LSP承载组播流量的VPLS解决方案.对于某些VPLS组播流量配置,这种解决方案有一定局限性.例如,当有大量的组播流量需要传播时,会导致带宽利用严重非最佳化.本文描述的解决方案是为了克服现有VPLS组播解决方案中的一部分局限性.其中描述了在SP网络中利用组播树来实现VPLS组播的过程.该解决方案允许在多个VPLS实例间共享一个这样一棵组播树.此外,本文提出的解决方案还允许SP网络中的一棵单独的组播树承载来自一个或多个VPLS实例的,仅仅属于指定的一个或多个IP组播流集合的流量.     

视频会议系统中音频IP多播在局域网上的实现

介绍了一个模拟视频会议的流程设计和一个实用的利用Socket进行多播通信的实现流程,以在局域网上实现音频IP多播为例,说明多播技术的应用及其实现方法。     

多媒体通信的成组多点广播路由算法

多点广播是一源点传送信息到多个目的节点,成组多点广播是一组节点内部互相进行多点广播。成组多点广播的路由算法是为组内的每一个节点建立一棵路由树,用于点到多点的广播通信。本文提出一种新的成组广播路由算法,它比传统的成组广播路由算法在性能上有了一定的提高,同时更为简洁。     

Adaptive approach for FEC reliable multicast

An adaptive integrated forward error correction approach to provide reliability in a multicast environment is proposed. The proposed solution avoids the undesirable feedback implosion phenomenon regardless of the number of receivers and uses minimum bandwidth in the feedback channel     

Delay performance of VSAT-based satellite wide area networks

This paper studies the performance of VSAT-based satellite wide area networks. Very small aperture terminals are used as transport gateways to interconnect local area networks through satellites to form a wide area network. This paper concentrates on analysing the delay of the network, which is the time needed to send a packet from a station in the source LAN to a station in the destination LAN. Several access techniques are considered for comparison. It is observed through numerical examples that TDMA on the up-link and TDM on the down-link offers the best delay performance.     

一种改进的层次型移动组播协议

论文介绍了现有层次性移动组播协议——Mobi Cast协议,分析了该协议的优缺点。在Mobi Cast协议的基础上通过加入隧道技术,并减轻基站开销等方面进行了改进。仿真与分析表明,改进后的Mobi Cast协议具有组播数据丢包率低、网络维护开销小、切换延迟短等特点。     

Minimum coding nodes multicast tree for two-channel all-optical network coding scheme

A heuristic algorithm of establishing a minimum coding nodes multicast tree on which a two-channel all-optical network coding scheme can be performed is presented.To minimize the coding nodes,the heuri...     

Parity-based loss recovery for reliable multicast transmission

We investigate how forward error correction (FEC) can be combined with automatic repeat request (ARQ) to achieve scalable reliable multicast transmission. We consider the two scenarios where FEC is introduced as a transparent layer underneath a reliable multicast layer that uses ARQ, and where FEC and ARQ are both integrated into a single layer that uses the retransmission of parity data to recover from the loss of original data packets. To evaluate the performance improvements due to FEC, we consider different loss rates and different types of loss behavior (spatially or temporally correlated loss, homogeneous or heterogeneous loss) for up to 10⁶ receivers. Our results show that introducing FEC as a transparent layer below ARQ can improve multicast transmission efficiency and scalability. However, there are substantial additional improvements when FEC and ARQ are integrated