Link layer assisted mobility support using SIP for real-time multimedia communication

Abstract

Real-time multimedia applications are expected to be popular in wireless Internet as well as wired Internet. Session Initiation Protocol (SIP) was standardized for real-time applications and extended to support terminal mobility by Internet Expert Task Force (IETF). However, SIP terminal mobility suffers from the considerable handoff latency which is unsuitable for the real-time communications. Most of the handoff latency comes from allocating a new IP address using Dynamic Host Configuration Protocol (DHCP) and updating a session with the new address. Another drawback of SIP terminal mobility is the connection error due to simultaneous movement of both communicating peers. In this paper, we propose an approach that supports soft handoff with SIP terminal mobility to achieve real-time multimedia communications over wireless networks. The proposed scheme, Predictive Address Reservation with SIP (PAR-SIP), decreases handoff delay by proactively processing the address allocation and session update using link layer information of wireless networks. We demonstrate the practicability and feasibility of PAR-SIP with the experimental results from implementation on the testbed. PAR-SIP terminal mobility reduces handoff latency during a call below a hundred milliseconds. It also reduces the probability of connection error due to simultaneous movement of peers. These results illustrate that PAR-SIP is appropriate to the real-time multimedia applications in the wireless Internet.