A Low Call-Setup-Delay PoC System Based on SIP Compression and Procedure Simplified

Push-to-Talk over Cellular (PoC) is one of most attractive value-added services of mobile communication, which has more advantages than traditional trunk communication system, especially in coverage and flexibility. The long call-setup-delay is one major issue in PoC researching activities because it affects the user experience and blocks many application of PoC service. This paper tries to solve this problem with a proposed method based on Session Initiative Protocol (SIP) compression and call-setup procedure simplified. After comparison of several common used compression algorithms, the paper brings forward Deflate based on Static Dictionary (DSD) Algorithm to enhance the compression ratio of SIP messages. It analyzes the standard call-setup procedure of PoC and designs a simplified call-setup procedure to grant the Talk-Burst to the caller in advance. Simulation results support the efficiency of the proposed method. The average call-setup-delay value of 1.8s is got by the proposed method which combines DSD with the simplified call-setup procedure.