Research On And Design For Control Of Handoff Based SIP And UA With Presence Service

With the extensive application of Internet, the conventional telephoneservice was impacted by IP Phone as its low cost and prospect of market.H.323has widely applied in the IP Phone in China. At the same time, the merits ofSession Initiation Protocol should be seen in simple, flexible, and so on, furthermore, Session Initiation Protocol can quickly develop with the improvement ofsoft switch technology and the performance of Internet.Nowadays, the IP phone competes with PSTN telephone thought provid-ing the free or low charge voice service. Its advantage still does not carried outservice of transfer of multimedia data and management of session. Thepresence service is the basic of the realization of the intelligent and multimediaservice and all-important task.Moreover, SIP has the ability to support mobility, but the undesirabledelay and packet loss are produced during the process of session handoff.The above problems are researched in this dissertation. Main work issummarized as the following.Firstly, the correlative protocol such as Session Initiation Protocol, Sess-ion Description Protocol and Real-Time Transport Protocol is discussed. Theformat of the message, the field for the message and the meanings of all thefields are analyzed.Secondly, the cause of handoff delay in wireless SIP network is analyzed.The mobile management system of wireless IP network is designed to avoidhandoff delay, in the system Back-to-Back User Agent is induced as it has copyand forward function. The feasibility of the solution is analyzed.Finally, according to the demand of user agent with presence service, theVoIP UA with presence service is designed and realized based on oSIP. thefunction module including multimedia module, parsing module, affairmanagement module and user logic affair management module. Theexperiment demonstrates that this designed software can accomplish the basicfunction of presence service.