Performance of VoIP Call Set-Up Over Satellite-UMTS Using Session Initiation Protocol
Session Initiation Protocol (SIP) is an application layer signalling protocol used in the IP-based Universal Mobile Telecommunication Systems (UMTS) network for establishing multimedia sessions. With a satellite component identified to play an integral role in UMTS, there is a need also to support SIP-based session establishment over Satellite-UMTS (S-UMTS) to achieve end-to-end seamless IP-based terrestrial/satellite network integration. Due to the inherent characteristics of SIP, the performance of SIP-based session set-up is largely compromised when transported over an unreliable wireless link with a large propagation delay. This paper presents the work done in incorporating a link layer retransmission based on the UMTS Radio Link Control acknowledgement mode (RLC-AM) mechanisms to improve the call set-up performance.