On Signaling Efficiency for Call Setup in all-IP Wireless Networks

This paper analyzes the signaling efficiency for multimedia call (session) establishment in all-IP wireless networking infrastructures based on the Internet Multimedia Subsystem (IMS) standard framework and CDMA2000 Evolution Data Only Rev. A (EV-DOrA) standard for wireless link transmission. We present a comprehensive, bottom up analysis of signaling delay for setting up multimedia sessions and we evaluate system architecture alternatives to reduce it. Call setup time is particularly critical for interactive applications, such as gaming, push-to-X and Voice over IP (VoIP), where user experience of time that takes to start or join a session directly translates in user perception of service quality. Our analysis takes into account a large set of system design parameters across all layers, ranging from radio link properties to IMS processing and specific characteristics of the Session Initiation Protocol (SIP). For an example signaling flow between two mobile users, we derive an important set of numerical results for call set up time under various IMS design scenarios that consider effects of SIP compression efficiency, choice of transport protocols (TCP, UDP) and radio link quality. Based on the results obtained, we propose and discuss new methods to improve the signaling efficiency and to reduce the call setup time.