Integrating SIP-Based Network Mobility into IP Multimedia Subsystem

The combination of SIP-NEMO and IMS brings benefits of power saving, low complexity and few handoff to both end users and service providers. In this article we investigate the integration of SIP-NEMO in the IMS, and propose two interworking architectures: loosely coupled and tightly coupled. We also present three basic scenarios: registration, session establishment and optimized handoff with context transfer in the two architectures, respectively. The loosely coupled architecture maintains the original characteristics of SIP-NEMO and IMS. Control signals for the call setup are passed through the interrogating network in the IMS. The tightly coupled architecture utilizes the network agent of SIP-NEMO as a back- to-back user agent to integrate SIP-NEMO into IMS with minor modification of the IMS network and provides the security offered by IMS. The discussions on deployment and security issues show that the proposed approaches achieve the integration with minimal changes to the existing standards.