Using sigcomp and ROHC in wireless networks

The deployment of interactive services such as instant messaging, Internet telephone calls, videoconferencing and other multimedia connections has increased the use of bandwidth. The session initiation protocol (SIP) used for these applications is text-based with long signaling messages. Using SIP in wireless networks will result in significant transmission delays because of the large message size and relatively low data rates across the radio interface. SigComp (SIP signaling compression mechanism) provides a solution to this problem by offering a robust, efficient and loss-less compression of SIP messages. SigComp requires UDVM (universal decompressor virtual machine), which provides decompression functionality and is one of the most essential parts of SigComp. UDVM gives an edge to SigComp over other compression architectures by providing a flexible choice of compression algorithms. UDVM allows the applications to choose any appropriate compression algorithm of their choice. Besides signaling overhead, there is protocol header overhead due to the use of IP protocols by multimedia applications. The robust header compression (ROHC) scheme has been developed to reduce the header overhead over wireless links. This paper discusses the collective usage and deployment of SigComp and ROHC schemes in wireless networks to reduce the signaling and the protocol header overhead, respectively. We performed experiment chat sessions on our SIP platform to analyze the overhead due to long SIP messages. We present results for the performance of SigComp compression used to compress SIP messages for different compression algorithms.