UMTS中的IP多媒体子系统及其业务架构

在未来的移动通信网中。基于IP的多媒体业务将成为通信网的主要业务，为了适应未来移动通信网的发展。必须在核心网中增加专门处理IP多媒体业务的功能实体。本文先介绍UMTS的R5中引入的IP多媒体子系统。然后讨论该系统的业务架构。     

UMTS中的IP多媒体子系统及其业务架构

在未来的移动通信网中,基于IP的多媒体业务将成为通信网的主要业务,为了适应未来移动通信网的发展,必须在核心网中增加专门处理IP多媒体业务的功能实体。本文先介绍UMTS的R5中引入的IP多媒体子系统,然后讨论该系统的业务架构。     

从传统移动通信网向全IP网络的演进

目前在国际上,各国都在积极研究“全IP网络”技术。简单地说,就是未来移动通信网是建立在IP技术的基础上,其中包括无线接入网和移动核心网都采用IP技术。整个移动通信网都将IP化,所以叫做全IP网络。     

从运营角度看IMS业务的发展

1引言 IMS（IP Multimedia Subsystem，IP多媒体子系统）是对IP多媒体业务进行控制的网络核心层逻辑功能实体的总称，为固定用户和移动用户提供IP多媒体业务。IMS作为NGN网络业务控制层面的一个组成部分，为未来的多媒体应用提供了一个通用的业务平台，用于提供包括PSTN／ISDN仿真业务、PSTN／ISDN模拟业务、IP多媒体业务（如Presence，Messaging，Conferencing，PoC等）、固定移动融合业务等在内的NGN业务。     

ATM技术在未来移动通信网中的应用

多媒体业务是人们对移动通信网提出的一个新要求。现有的移动通信网不能有效支持多媒体业务。ＡＴＭ作为Ｂ－ＩＳＤＮ的主干技术,可以用到移动通信网中使之能够提供多媒体业务。本文分析了移动ＡＴＭ网络的机理,预测了未来基于ＡＴＭ的移动通信网的发展过程,并对ＡＴＭ移动通信网当前存在的问题进行了讨论。     

下一代无线IP移动通信网中的IP微移动性协议

与Internet无缝连接和IP基的移动性是下一代移动通信网的重要特点。为了减少移动IP中的时延和信令开销，减少包丢失，提出了支持快速、 可靠切换和IP寻呼（IP paging)的IP微移动性（micro-mobility)协议。本文研究了提交到IETF移动IP工作组（MIP WG)的几种关键IP微移动性协议，分析了协议的动机、特点，比较了性能、信令复杂度和实用性，给出了可能的优化途径。     

NGN中的移动多媒体业务平台

IP多媒体子系统作为下一代网络的重要平台实现了固定网络与移动网络的无缝业务传递,丰富了移动多媒体的各种增值业务.IP多媒体子系统具有控制功能与承载能力分离、呼叫与会晤分离、应用与服务分离、业务与网络分离、移动网与互联网业务融合的主要特征,既适用于基于IP的移动多媒体业务,也适用于传统语音、数据和视频业务,是未来移动多媒体业务的发展方向.     

移动因特网及移动IP中的组播技术

移动因特网是因特网和移动通信网未来发展的一个重要方向。本文从因特网协议的层次出发,分析了移动因特网的无线物理和数据链路层、移动IP层等的特点,分析了几种移动IP支特组播的机制。比较了它们与有线因特网层次之间的区别。     

未来移动多媒体网络之间无缝切换的挑战

第三代移动通信系统的主要目标是提供多媒体业务，在移动多媒体通信系统中的切换问题非常重要，本介绍了多媒体业务的特点，移动多媒体业务切换的特殊要求，不同网络间的切换协议。重点介绍了基于IP网络的移动多媒体网络之间无缝切换的各种水平切换和垂直切换方式以及无线TCP的优化。     

IMS标准化取得明显进展

IP多媒体子系统（IMS）由第3代移动通信合作计划（3GPP）组织在R5版本中提出，是对IP多媒体业务进行控制的网络核心层逻辑功能实体的总称。IMS作为融合固定接入和移动接入的统一架构，是电信网发展和演进的未来方向，它提供的丰富业务能力将使电信网的发展打开新的篇章。目前，国际标准化组织高度重视IMS标准化问题。     

3G UMTS中的IP多媒体子系统探析

下一代的移动通信系统将基于全IP的网络构架,提供开放的业务生成环境。3GPP在其UMTSR5版本中首次引入了IP多媒体子系统(IMS)的概念,作为下一代网络的重要平台,IMS不仅实现了固网与移动网业务的无缝融合,还有利于运营商快速、灵活地开发更加丰富多彩的移动多媒体业务,从而吸引大量的终端用户。文章在描述IMS体系结构的基础上,特别针对IMS中几个关键要素点进行了重点分析。     

利用上下文转移实现移动IPv6上的IMS无缝切换

Mobility support for the next generation IPv6 networks has been one of the recent research issues due to the growing demand for wireless services over internet. In the other hand, 3GPP has introduced IP Multimedia Subsystem as the next generation IP based infrastructure for wireless and wired multimedia services. In this paper we present two context transfer mechanisms based on predictive and reactive schemes, to support seamless handover in IMS over Mobile IPv6. Those schemes reduce handover latency by transferring appropriate session ＇information between the old and the new access networks. Moreover, we present two methods for QoS parameters negotiations to preserve service quality along the mobile user movement path. The performances of the proposed mechanisms are evaluated by simulations.     

快速演进的IMS体系

在网络融合的大背景下,IMS(IP多媒体子系统)从无线网络架构中诞生开始就在不停地演进,先进的理念促使了多种业务网络选择IMS作为会话控制层的通用架构.本文从IMS的发展历史、应用场景、技术变化、标准环境等方面总结和分析了IMS体系的可能发展方向和热点问题.     

浅谈IP多媒体子系统业务平台

文章研究了3GPP在UMTSRel5、Rel6演进版本中提出的IP多媒体子系统(IMS),描述了IMS在基于分组域上提供电话和非电话业务的系统架构。IMS的提出对固网和移动网络的融合起到了很大的推动作用,研究基于IMS的统一业务平台对下一代业务平台体系架构具有一定参考意义。     

IP网络分组传送性能讲座 第1讲:IP网络性能参考模型

随着IP技术的发展,其应用领域不断扩大.现有的IP网络能够较好地支持非实时数据业务,为r使它也能够支持各种实时业务与多媒体业务,就必须研究和规范IP网络传送信息的性能.本讲座在研究和分析ITU-T关于IP网络性能的标准和实际解决工程技术问题的基础上,讨论和介绍了IP网络性能方面的有关内容.其中包括:IP业务性能描述的参考模型、IP业务性能测试的环境与条件、IP业务的性能参数、IP业务的可用性等.     

无线多媒体传感器网络QoS区分 服务路由机制

 无线多媒体传感器网络中多种类型数据并存,服务质量需求各异,因此如何提供服务质量保障机制是无线多媒体传感器网络研究领域的重点问题.本文提出了一种基于角度的区分服务路由算法,在该算法中,网络节点将各自的邻居节点按其偏转角度进行分类,为不同需求的数据流选择不同的转发区域,并结合邻居节点的地理位置、单跳通信负载、剩余能量等信息完成各数据流的区分路由.仿真结果表明,该算法在多媒体数据流传输的延迟、抖动、丢包率以及能耗等性能上均要优于已有算法.     

Design of a Link Control Protocol for Multimedia Services in Wireless Local Communication

The convergence of wireless systems with multimedia services is the challengeof future generation wireless networks. The large variety of QoS requirementsof different media as well as the maintenance of synchronization of thedifferent streams to be presented at receiver, demand from the Data link layersome extra functionalities. In this paper, we present an enhanced approach forthe efficient management of multimedia applications in third-generationwireless networks. We advocate the use of multiple connections, one for eachtraffic component of the application, as the effective solution for thetransport of multimedia applications in future-generation wireless networks.The effectiveness of this scheme is guaranteed by providing a new link controltechnique that works on top of a PRMA-type access protocol which jointlymanages different streams of a multimedia application. For this purpose, wepropose a two-level priority mechanism (static and dynamic priorities)specified by higher protocol layers for link activation, channel access, andadmission control procedures specific to a multimedia application and foroptimizing the sharing of radio channel resources and management of thereservation queue at the base station. We expect this priority-based mechanismto perform well, especially during periods in which system traffic load ishigh, and to react well to the deterioration of multimedia service quality,in terms of both QoS parameters and the synchronization of its trafficcomponents.     

IP网上的会议电视系统

ＩＰ网上的会议电视是当前多媒体通信技术研究的一个热点。文章介绍了ＩＰ网络会议电视系统的关键技术，并对整个系统的组成和工作过程作了较详细的阐述。     

Mobile and Multicast IP Services in PACS: System Architecture, Prototype, and Performance

Traditionally, wireless cellular communication systems have been engineered for voice. With the explosive growth of Internet applications and users, there is an increasing demand on providing Internet services to mobile users based on the voice-oriented cellular networks. However, Internet services add a set of radically different requirements on to the cellular wireless networks, because the nature of communication is very different from voice. It is a challenge to develop an adequate network architecture and necessary systems components to meet those requirements.This paper describes our experience on developing Internet services, in particular, mobile and multicast IP services, in PACS (Personal Access Communication Systems). Our major contributions are five-fold: (i) PACS system architecture that provides wireless Internet and Intranet access by augmenting the voice network with IP routers and backbone links to connect to the Internet; (ii) simplified design of RPCU (Radio Port Controller Unit) for easy service maintenance and migration to future IP standards such as IPv6; (iii) native PACS multicast to efficiently support dynamic IP multicast and MBone connectivity; (iv) optimization and incorporation of Mobile IP into PACS handoff mechanism to efficiently support roaming within a PACS network as well as global mobility between PACS networks and the Internet; (v) successful prototype design of the new architecture and services verified by extensive performance measurements of IP applications. Our design experience and measurement results demonstrate that it is highly feasible to seamlessly integrate the PACS networks into the Internet with global IP mobility and IP multicast services.     

QoS issues in the converged 3G wireless and wired networks

The Internet evolution delineated through the last years has urged the wireless network community to support the deployment of IP multimedia services with guaranteed quality of service (QoS) in 3G wireless networks. This article copes with the interoperability between 3G wireless networks and wired next-generation IP networks, for the provision of services with an a priori known quality level over both environments. More specifically, the UMTS architecture as well as a prototypical implementation of the next-generation Internet based on DiffServ are considered. The article focuses on the mapping among the traffic classes of the two networks at the point where the networks converge, and discusses the requirements and possible solutions for their proper interworking at the signaling and user levels. Simulations prove that proper mapping among the traffic classes of each world is necessary in order to achieve the desired end-to-end traffic characteristics.