SIP Multicast-Based Mobile Quality-of-Service Support over Heterogeneous IP Multimedia Subsystems

The Universal Mobile Telecommunications System (UMTS) all-IP network supports IP multimedia services through the IP multimedia subsystem (IMS). This paper proposes a mobile quality-of-service (QoS) framework for heterogeneous IMS interworking. To reduce the handoff disruption time, this framework supports the IMS mobility based on the concept of session initiation protocol (SIP) multicast. In our approach, the mobility of a user equipment (UE) is modeled as a transition in the multicast group membership. With the concept of dynamic shifting of the multicast group´s members, the flow of actual data packets can be switched to the new route as quickly as possible. To overcome mobility impact on service guarantees, UEs need to make QoS resource reservations in advance at neighboring IMS networks, where they may visit during the lifetime of the ongoing sessions. These locations become the leaves of the multicast tree in our approach. To obtain more efficient use of the scarce wireless bandwidth, our approach allows UEs to temporarily exploit the inactive bandwidths reserved by other UEs in the current IMS/access network. Analytic and simulation models are developed to investigate our resource reservation scheme. The results indicate that our scheme yields comparable performance to that of the previously proposed channel assignment schemes.