SIP and 802.21 for Service Mobility and Pro-active Authentication

The IEEE 802.21 working group is designing a framework to facilitate handover between heterogeneous networks allowing mobile terminals to get information about nearby networks before performing the handover. The design of a transport protocol for 802.21 signaling is still an open issue and in this paper we propose a solution based on the Session Initiation Protocol (SIP) that is the most used standard signaling protocol for voice over IP services. In this paper we focus on the SIP features that allow service mobility, i.e., allow users to use their services regardless the access network they are using. We propose a signaling model in which the 802.21 framework is used to provide information that allow users to activate the SIP mobility procedures before the handover and the SIP messages used for service mobility are used as carriers of 802.21 signaling, too. This allows to reduce the complexity of the signaling infrastructure that performs both service mobility and discovery of information about nearby networks.