应用层组播研究综述

组播是互联网研究的一个重要课题．最近的研究发现IP组播方案存在一些很难解决的问题．基于互联网的性质和应用的特点，在IP组播模型、Oveday Network和Peer-to-Peer等技术的基础上，发展出了应用层组播技术．本文总结了目前应用层组播领域的主要算法，重点分析了其中的主要研究问题，概括了应用层组播算法研究中主要使用的评价方法，并对应用层组播的相关研究问题进行了讨论．并对未来的研究作了展望．     

业务驱动的应用层组播系统模型研究

当前,应用层组播解决方案种类繁多,各有优劣,不同的方案适合不同的业务需求。本文在分析各种应用层组播机理和特性的基础上,提出利用中间件的技术来构建新的应用层组播体系结构．以自适应组播应用业务的需求。     

因特网上数字视频的组播传输

讨论了数字视频业务在因特网中的组播传输，重点对因特网中视频服务系统基于应用层组播传输的技术和体系进行了深入分析。     

传统IP组播面临的困境及源特定组播(SSM)

IP组播出现以来，尽管其技术上具有一定的优势，但并未得到广泛的应用。本文首先简要介绍IP组播的原理和体系结构．然后从ISP、用户、ASM模型等几个方面重点分析了传统IP组播没有得到大规模商业应用的原因，最后介绍了一种组播的改进模型——源特定组播(SSM)。     

IPIV承载网解决方案

IPIV业务是承载于IP网络的增值业务。文章详细讨论了IPIV业务对承载网的带宽、QoS、可靠性、安全性、组播等方面的技术要求，在骨干网、省干/城域网和拉入网3个层面讨论了IPIV承载网的总体结构，分析了承载网组播协议实现，最后对可控组播实现用户和业务管理的问题进行了探讨。     

组播业务在网络中的实施

IP组播技术实现了IP网络中点到多点的高效数据传送。由于能够有效地节约网络带宽、降低网络负载，IP组播技术在实时数据传送、多媒体会议、数据拷贝、游戏和仿真等诸多方面都拥有广泛的应用前景。但是，目前中国运营商开展组播业务的实例并不多，主要是因为在现网中实施组播技术还存在一些问题，下面就分别对这些问题进行论述。     

IPTV中组播技术的解决方案

文中介绍了IPTV业务的概念,分析了实现IPTV业务的播技术,并讨论了将组播隧道技术和应用层组播技术应用到IPTV中的解决方案.     

EPON中组播协议的实现

探讨了EPON中实现IP组播业务的方法,详细描述了OLT和ONU对IP组播业务数据报的处理过程,以及对EPON用户终端设备加入、离开组播组的IGMP协议帧的处理过程     

组播协议在GPON中的实现及应用

首先讨论了在GPON中实现组播的意义,在对现有的二层组播协议分析与比较的基础上提出采用IGMP SNOOPING协议在GPON上实现组播,并结合GPON自身的特点,提出了一种新的实现方案,描述了OLT和ONU对IP组播业务数据报的处理过程,以及对GPON用户终端设备加入、离开组播组的IGMP协议帧的处理过程.最后详细说明了基于IPTV业务的组播技术在GPON中的应用以及组播技术在GPON中应用的优势.     

DSLAM中IP组播的实现

利用ADSL开展IP TV业务的关键技术就是在DSLAM中实现IP组播.本文对IP组播原理、DSLAM中IP组播的实现方式、在DSLAM中实现IP组播的衡量和目前还存在的问题进行了探讨.     

Scalable QoS-based IP multicast over label-switching wireless ATMnetworks

A Mobile IP multicast prototype that integrates a label-switching wireless asynchronous transfer mode, the mobile core-based multicast architecture, and an Internet multicast infrastructure is presented. MCOM creates multiple core-based layer 2 multicast trees that are independently established in member networks. They are interconnected via the Internet using layer 3 multicast routing. Gateways on the border of the Internet and wireless ATM networks convert ATM multicast traffic to suitable IP packets as well as converting from IP packets to ATM cells for MCOM. To solve the cell interleaving problem that results, ATM block transfer/immediate transmission capability is reasonably modified. Additionally, class-based block buffer management for ATM multicast connections is built into wireless ATM switches for soft quality of service control. Dynamic group management, multicast channel rerouting, and reliable multicasting are also studied in relation to existing Internet protocols like Mobile IP, Internet group management protocols, and multicast routing protocols     

组播技术及其在光层的实现

带宽密集型的多媒体应用对现有网络提出了新的要求,组播技术有助于解决其在网络带宽和服务质量方面的问题,而在光层实现组播具有更简单、高效的特点.然而,光层组播由于光缓存、光分束和光波长变换等光器件的限制,呈现出和IP层组播不同的特点.对IP层和光层组播进行了讨论,分析了光层组播模型,并对稀疏光分束和稀疏波长变换的光网络组播路由提出了重路由到源和重路由到相关节点两种重路由方式.     

Challenges and opportunities of delivering IP-based residential television services

This article describes the main challenges of implementing an end-to-end architecture for delivery of high-quality, IP-based residential TV services to residential customers. The IP-based approach can be implemented with an IP multicast overlay network with traditional routers or use IP-multicast-aware ATM switching systems. Both approaches use IP multicast to transport MPEG-2 broadcast video and can work on any access architecture, especially on copper-based architectures (xDSL) such as ASDL and VDSL. The main challenges met while implementing the IP-based architecture are competitive positioning relative to traditional CATV architectures, overall architecture, head-end architecture and quality issues, traffic engineering for stringent QoS requirements, IP multicast requirements, and business case considerations. The IP-based approach described leverages Internet technology advancements and capitalizes on the impacts of Internet on interactive entertainment. Video channel manipulation at the head-end is dependent on access bandwidth and affects video quality. Video traffic management to meet stringent QoS requirements is challenging at the IP layer. High-capacity, responsive IP multicasting is essential to achieving high service quality. Cost-effective IP multicasting is a critical component of the business case.     

Protection of MPEG‐2 Multicast Streaming in an IP Set‐Top Box Environment

The widespread use of the Internet has led to the problem of intellectual property and copyright infringement. Digital rights management (DRM) technologies have been developed to protect digital content items. Digital content can be classified into static content (for example, text or media files) and dynamic content (for example, VOD or multicast streams). This paper deals with the protection of a multicast stream on set‐top boxes connected to an IP network. In this paper, we examine the following design and architectural issues to be considered when applying DRM functions to multicast streaming service environments: transparent streaming service and large‐scale user environments. To address the transparency issue, we introduce a ‘selective encryption scheme'. To address the second issue, a ‘key packet insertion scheme’ and ‘hierarchical key management scheme’ are introduced. Based on the above design and architecture, we developed a prototype of a multicasting DRM system. The analysis of our implementation shows that it supports transparent and scalable DRM multicasting service in a large‐scale user environment.     

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.     

Investigation of multicast‐based mobility support in all‐IP cellular networks

To solve the IP mobility problem, the use of multicast has been proposed in a number of different approaches, applying multicast in different characteristic ways. We provide a systematic discussion of fundamental options for multicast‐based mobility support and the definition and experimental performance evaluation of selected schemes. The discussion is based on an analysis of the architectural, performance‐related, and functional requirements. By using these requirements and selecting options regarding network architecture and multicast protocols, we identify promising combinations and derive four case studies for multicast‐based mobility in IP‐based cellular networks. These case studies include both the standard any‐source IP multicast model as well as non‐standard multicast models, which optimally utilize the underlying multicast. We describe network architecture and protocols as well as a flexible software environment that allows to easily implement these and other classes of mobility‐supporting multicast protocols. Multicast schemes enable a high degree of flexibility for mobility mechanisms in order to meet the service quality required by the applications with minimal protocol overhead. We evaluate this overhead using our software environment by implementing prototypes and quantifying handoff‐specific metrics, namely, handoff and paging latency, packet loss and duplication rates, as well as TCP goodput. The measurement results show that these multicast‐based schemes improve handoff performance for high mobility in comparison to the reference cases: basic and hierarchical Mobile IP. Comparing the multicast‐schemes among each other the performance for the evaluated metrics is very similar. As a result of the conceptual framework classification and our performance evaluations, we justify specific protocol mechanisms that utilize specific features of the multicast. Based on this justification, we advocate the usage of a source‐specific multicast service model for multicast‐based mobility support that adverts the weaknesses of the classical Internet any‐source multicast service model. Copyright © 2006 John Wiley & Sons, Ltd.     

基于NR的5G多播/广播关键技术

交互式网络电视（internet protocol television，IPTV）、群组通信等应用具有明显的多播/广播业务特征，5G蜂窝移动通信系统需要高效支持这类应用数据的传输。首先，按照多播/广播业务数据从5G核心网经由基站到终端的不同传输方式分析了 5G 多播/广播系统的基本架构；然后，从无线空口协议栈、物理层与高层协议增强、业务过程与业务连续性等方面对5G多播/广播无线传输技术进行了详细分析；最后，对5G多播/广播技术的后续演进方向进行了展望。     

基于卫星网络的IP组播技术

IP组播技术是新兴的网络技术,依托卫星网络的组播业务更是下一代Internet为用户提供的主流服务。文章详细介绍IP组播技术,对其在卫星网络应用中存在的主要问题、解决方法及常用的卫星组播网络拓扑结构进行阐述和分析。