Enabling SIP-Based Session Setup in Ad Hoc Networks

The deployment of infrastructure-less ad hoc networks is suffering from the lack of applications inspite of active research over a decade. This problem can be alleviated by porting successful legacy Internet applications and protocols to the ad hoc network domain. Session Initiation Protocol (SIP) is designed to provide the signaling support to multimedia applications such as Voice over IP (VoIP), Instant Messaging etc. However, SIP relies on an infrastructure for service discovery as well as message routing, which is unavailable in ad hoc networks. In this paper, we propose two approaches to solve this problem and enable SIP-based session setup in ad hoc networks (i) a loosely coupled approach where the SIP service discovery is decoupled from the routing procedure and (ii) a tightly coupled approach which integrates the service discovery with a fully distributed cluster based routing protocol that builds a virtual topology for efficient routing. Simulation experiments show that the tightly coupled approach performs better for (relatively) static multihop wireless networks than the loosely coupled approach in terms of the latency. The loosely coupled approach, on the other hand, performs better in networks with random node mobility. The tightly coupled approach, however, has lower control overhead in both the cases.