一种新的IMS分布式SCIM业务触发机制

IMS(IP Multimedia Subsystem)网络中，S-CSCF(Serving Call Session Control Function)逐次匹配过滤准则的业务触发机制使呼叫信令在S-CSCF与AS(Application Server)之间多次转发，增加了S-CSCF实体的负载压力和呼叫延迟时间。该文在现有IMS业务提供框架的基础上，提出分布式SCIM(DSCIM)业务触发机制，完成了业务流程中AS到AS的连续业务触发，避免了S-CSCF与AS之间信令的往返转发。通过Jackson排队网络理论对业务触发机制进行了数学模型分析和仿真实验，结果均表明DSCIM业务触发机制能够有效降低网络的平均呼叫时延，减轻S-CSCF的负载压力。

A Novel Distributed SCIM Service Invocation Mechanism in IMS

In the service invocation mechanism of current IMS (IP Multimedia System) network, the Serving-Call Session Control Function (S-CSCF) invokes each Application Server (AS) sequentially to perform user’s service profile. This mechanism makes SIP request be forwarded excessively among the S-CSCF and Application Servers (ASs), so it is easy to result in the heavy load of the S-CSCF entity and long call set-up delay. This paper proposes a novel Distributed SCIM (DSCIM) service invocation mechanism. It aims at reducing the call set-up delay in IMS service layer along with decreasing the load of the S-CSCF entity by invoking each AS consecutively without signaling being forwarded back to the S-CSCF. The service invocation mechanisms are modeled through Jackson network and the simulations of different scenarios verify that DSCIM service invocation mechanism can effectively reduce call set-up delay of the network and decrease the load level of the S-CSCF.