| The standard of WCDMA gets through R99, R4, R5 and R6 stages. The network of WCMA is divided into access network and core network. Connecting to users is the major function of access network. And core network is divided into two parts in R99 and R4, the two parts are CS (Circuit Switched Domain) and PS (Packet Switched Domain). The CS domain is responsible for narrow band operation. The call control part and bearer part is divided into MSC and MGW in CS domain in R4 standard. MSC is the software switched device, it should receive signal and explain the signal, and lastly it should control bearer and implement the operation according to the signal.As a signal, SIP (Session Initial Protocol) is introduced in R5. But if the software switched device adopts the SIP, it can upgrade from R4 to R5 smoothly.The thesis researches the function of software switched device that adopts SIP.The thesis discusses the three parts mainly: SIP and its extending protocol, the module designing of software switched device and the call flow that is based on the 23.205. Firstly it researches the SIP and its extending protocol. And then it discusses the module design of software switched device, whenever the board receives and sends the SIP message it can be load balance by the method of reattaching port, so according to this point the capability of software switched device can be improved; and it can implement the interworking between one signal and another signal by designing the middle signal, so the system can be reusable. Lastly the thesis discusses the call flow of IP bearer based on the 23.205 reference; it implements the SIP call flow and dynamic codec negotiation by using SDP protocol. |
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