Performance analysis of SIP-based push-to-talk service for GPRS/cdma2000 network

Push-to-talk service in GRPS/cdma2000 is a type of communications service that sets up a channel between two or more users without the need to dial a connection or set up a call, just like walkie-talkie or private mobile radio (PMR) system. This service is gaining in popularity in recent years due to its resource and cost efficiency and is thought as one of the perspective "killer application" in the digital public mobile data network (DPMDN). In this paper, we evaluate the structure and performance of the PTT service using SIP as call control protocol for present 2.5G DPMDN such as GPRS and cdma2000 1X , and present a improved call control protocol. By making use of the user\´s pre-knowledge of PTT talking model, this protocol applies a single way signaling structure and simplifies the setup procedure. The analysis result shows this call control scheme can significantly decrease the call delay time - one of the most key factor that influences the user\´s feeling