Unified Mobility Manager - Enabling Efficient SIP/UMTS Mobile Network Control
01 August 2003
Internet telephony is viewed as an emerging technology not only for wireline networks, but also for third generation wireless networks. Although IP end-to-end is considered the eventual approach for future wireless voice services, there is still a long way to go before IP voice packets can be effectively transported over the air. Therefore, Internet telephony and today's circuit-switched wireless networks will coexist for years to come, and it is essential to effectively perform interworking between these networks. This paper proposes the Unified Mobility Manager (UMM) that achieves efficient interworking between traditional wireless networks and Internet-telephony networks. The main characteristic of the UMM is that it combines UMTS HLR and SIP proxy functionality in one logical entity, which helps eliminate the performance degradation due to interworking between SIP and UMTS. This paper identifies seven potential network architectures with and without the UMM and with varying degree of IP penetration in the wireless core networks, and performs comparative analysis in terms of their call setup signaling latency. Our performance results show that for SIP originated calls, the architecture with the UMM can achieve better performance when compared to existing UMTS networks without the UMM. Our results further show that when the backbone network is fully IP-enabled, dramatic performance gain can be accomplished with the UMM for PSTN originated calls as well as for SIP originated calls. The paper also demonstrates that the UMM allows for a graceful migration from today's circuit- switched wireless networks to hybrid SIP/circuit-switched wireless networks, and towards all-IP based wireless networks in the future.