An Analysis Framework for Mobility Metrics in Mobile Ad Hoc Networks

Mobile ad hoc networks (MANETs) have inherently dynamic topologies. Under these difficult circumstances, it is essential to have some dependable way of determining the reliability of communication paths. Mobility metrics are well suited to this purpose. Several mobility metrics have been proposed in the literature, including link persistence, link duration, link availability, link residual time, and their path equivalents. However, no method has been provided for their exact calculation. Instead, only statistical approximations have been given. In this paper, exact expressions are derived for each of the aforementioned metrics, applicable to both links and paths. We further show relationships between the different metrics, where they exist. Such exact expressions constitute precise mathematical relationships between network connectivity and node mobility. These expressions can, therefore, be employed in a number of ways to improve performance of MANETs such as in the development of efficient algorithms for routing, in route caching, proactive routing, and clustering schemes

Cache timeout strategies for on-demand routing in MANETs

Varying the route caching scheme can significantly change network performance for on-demand routing protocols in mobile ad hoc networks (MANETs). Initial route caching schemes retain paths or links until they are shown to be broken. However, stale routing information can degrade network performance with latency and extra routing overhead. Therefore, more recent caching schemes delete links at some fixed time after they enter the cache. This paper proposes using either the expected path duration or the link residual time as the link cache timeout. These mobility metrics are theoretically calculated for an appropriate random mobility model. Simulation results in NS2 show that both of the proposed link caching schemes can improve network performance in the dynamic source routing protocol (DSR) by reducing dropped data packets, latency and routing overhead, with the link residual time scheme out-performing the path duration scheme.IEEE, South Australian Sectio