Route fragility: a novel metric for route selection in mobile ad hoc networks

A key factor deciding the performance of a routing protocol in mobile ad hoc networks is the manner in which it adapts to route changes caused by mobility. Exploiting the intuition that a less dynamic route lasts longer, we propose a new metric, the Route Fragility Coefficient (RFC), to compare routes. RFC estimates the rate at which a given route expands or contracts. Expansion refers to adjacent nodes moving apart, while contraction refers to their moving closer. RFC combines the individual link contraction or expansion behavior to present a unified picture of the route dynamics. We demonstrate that lower the value of RFC, more static (less fragile) the route. We then use this metric as a basis for route selection so that route discovery yields routes that last longer and hence increase throughput while reducing control overhead. We provide a simple distributed mechanism to compute RFC, so that a Route-Request (RREQ) packet contains the metric for the path it traversed, when it reaches the destination. The Dynamic Source Routing Protocol (DSR) is enhanced with the proposed metric in the NS-2 simulation environment. Simulation results are provided to demonstrate improvement in throughput and reduction in routing protocol overhead with increased mobility.