VSS BASED SESSION SETUP MECHANISM IN IMS

This paper proposes a novel session setup mechanism in IMS(IP Multimedia Subsystem) by introducing the functional entity termed VSS(Visitor Subscriber Server) which is used to provide registration and location management.The new mechanism aims at improving session setup procedure by a betterment of location management in IMS.Through the use of two-tier subscriber information database constituted by the HSS(Home Subscriber Server) and the VSS, the new mechanism seperates the registration procedure and location management from the S-CSCF(Serving-Call'Session Control Function), and makes them be handled by the VSS.At the same time, the new mechanism updates the signaling procedure of registration and session setup.With VSS based location management, the cost of registeration and session setup procedure as well as the delay of session setup procedure become lower.The cost and delay functions of the new session setup mechanism as well as the cost function of new registeration are deduced.Then, simulations and analysis verify that the performance of this new mechanism gets the benefit in cost and time.

IMS网络中一种基于组的业务触发算法

该文研究了IMS(IP Multimedia Subsystem)中的呼叫建立流程,以确定可以优化的信令流量,研究结果显示:S-CSCF(Serving Call Session Control Function)是IMS中的瓶颈点。为了降低会话建立时延,提高系统性能,提出了一种基于组的业务触发算法(Group based Service Triggering Algorithm,GSTA),然后对现有3GPP(3rd Generation Partnership Project)提出的业务触发算法(3GPP STA,3GPP Service Triggering Algorithm)和GSTA进行了性能建模,理论分析和仿真结果表明GSTA可以有效地降低S-CSCF的信令流量,增加了整个系统的吞吐量,同时显著减少了会话建立时延,提高了IMS网络的服务质量。

IMS网络中业务触发数据的研究

分析了现有 IP 多媒体子系统(IMS)业务触发数据存在的问题,给出了一种业务键的实现方式,业务键的存在可以使多个应用服务器(AS)之间的初始过滤准则(iFC)互不干扰,从而不会因为新业务的部署而引发新旧业务之间的冲突。接着对第三代合作伙伴计划(3GPP)业务触发和基于业务键的业务触发进行了性能建模,理论分析和仿真结果表-明,通过增加业务键数据,可提高服务呼叫会话控制功能(S-CSCF)和 AS 的匹配效率,使S-CSCF 在一次业务触发中可以触发多个业务,从而简化业务触发流程。基于业务键的业务触发方式可以有效地提高业务触发效率,增加系统的吞吐量,降低会话建立时延,提高IMS 网络的服务质量(QoS)。

Parlay多业务环境中SSDB机制的性能分析

主要研究在Parlay多业务环境中,在不同负载情况下,由软交换发起的业务和由Web服务器发起的业务之间性能的相互影响,提出了在这些业务间动态分配系统资源的方法,并在保证系统稳定性的前提下,提出使用会话建立时延约束(SSDB)机制确保各业务的吞吐量、请求响应时间等性能指标.仿真结果表明,结合SSDB机制的系统资源动态分配能有效地满足下一代网络多业务环境中各业务性能的要求.

远程教育环境中会话发起机制的研究

在基于多播的紧密控制的多媒体会议系统中,会话的发起经常采用发送会话公告信息的方法,但是在这样的会话发起框架中仍然存在一些问题,由于会话公告协议限制全局会话的公告报文带宽上限为4Mb/S,再加上多播信息的不可靠传送,客户端的会话目录工具经常需要等待10-20分钟才能得到特定会话的公告信息。讨论了远程教育环境中的会议发起机制以及与之紧密相关的会话目录服务,并在此基础上对上述的启动延迟问题进行了分析,提出了使用会话目录代理的方法来解决该问题。

CDMA2000中连接建立的分组延时分析

分组的RLP(无线链路协议)传送延时是连接建立延时的一个重要组成部分.已有的研究一般假设满负荷的条件计算该部分延时,但该假设在连接建立的过程中不成立.本文分析连接建立过程中分组的RLP传送延时,通过考察组成一个分组的所有数据帧在不同轮次的传送状态,提出了一种迭代计算方法.仿真结果表明,提出的方法可以准确地计算连接建立条件下的分组延时.满负荷条件下的延时和连接建立条件下的分组延时相比较,前者的延时可比后者的延时多达到100ms.

P2PSIP系统子网间会话建立延迟的研究

为了解决由于网络节点的大量增加引起的分层P2PSIP系统中子网间用户会话建立的高延迟问题,提出了利用上层覆盖网采用单跳HDT算法的解决方案。对现有的P2PSIP网络进行了研究,把会话建立时用户定位的延迟分为在子网内部和上层覆盖网中两个部分。利用单跳DHT算法来减少子网间用户定位时消息在上层覆盖网中路由的跳数,从而可以降低平均延迟时间。通过对该方案的可行性分析和延迟的比较,表明了该方案是可行的。

An rFC based service triggering algorithm for IMS network

To reduce the potential signaling traffic in IP multimedia subsystem(IMS),the session establish-ment procedures were investigated.The serving call session control function(S-CSCF)is the major bot-tleneck in IMS and the existing 3GPP service triggering algorithm(STA)based on initial filter criteria(iFC)increases the end-to-end session setup delay remarkably.To reduce the session setup delay andimprove the system performance,a SIP response message based filter criteria(rFC)was proposed.Basedon the rFC,a SIP response message based STA(RSTA)was further proposed.The modeling and theoret-ical analysis of 3 GPP STA and RSTA were presented.Simulation results show that,compared with 3 GPPSTA,the RSTA can avoid the additional signaling traffic load of the S-CSCF and application server(AS)effectively,reduce the session setup delay considerably,increase the throughput of the S-CSCF and im-prove the quality of service(QoS)of IMS network.

ON PERFORMANCE OF APPLICATION TRIGGERING ARCHITECTURE IN IMS NETWORK

The modeling of Application Triggering Architecture (ATA) in the IP Multimedia Sub- system (IMS) is presented. The session setup delay and system throughput are employed as the measurement to investigate the performance of ATA and the Serving Call Session Control Function (S-CSCF). With theoretical analysis and simulation results, we find that, the number of the ASs (Application Servers), the use of the subsequent Filter Criteria (sFC) and the arrival rate have heavy impact on the session setup delay and the S-CSCF is the major bottleneck in IMS network. The results are useful in constructing IMS network. At last, we propose several possible solutions to reduce the session setup delay and decrease the load of the S-CSCF.

CDMA2000 1X EV-DO无线环境下IMS会话建立时延分析

针对CDMA2000 1X EV-DO无线接入环境,采用数学分析方法试图对互联网协议多媒体子系统(IMS)中的用户会话建立时延进行定量分析.详细分析了无线链路协议在数据链路层上产生的传输时延,同时分析了上层重传机制对传输时延的影响.分析结果表明,数据链路层使用无线链路协议、传输层使用用户数据报协议、应用层使用会话初始化协议所产生的会话建立时延最小.