Stability and hop-count based approach for route computation in MANET

In this paper, we present an approach for MANET routing based on stability and hop-count, where the stability metric considered is the residual lifetime of a link. We view stability based routing not as a separate routing protocol but as an enhancement to a hop-count based routing protocol (e.g. DSR or AODV), so that the expected residual lifetime as well as hop count of a route are taken into account. First, we investigate how residual link lifetime is affected by parameters such as speed and mobility pattern using simulation. The result shows that residual link lifetime is a function of current link age, mobility speed and mobility pattern and does not vary monotonically with age. Therefore, intuitive idea such as older links are more stable, which is used in existing stability-based routing algorithms like associativity based routing (ABR), does not hold across a large spectrum of mobility speeds and models. Instead, the reverse can be true. We propose stability and hop-count based routing algorithm (SHARC) using DSR as the basic routing protocol. The stability of a path is calculated using a simple histogram based estimator. Simulation results show that SHARC performs better than a hop-count only algorithm (DSR) and a stability only algorithm for both throughout of long-lived TCP and response time of short data transfer. SHARC also performs close to an algorithm with perfect knowledge of link residual lifetime in many cases.