Low cost routing in mobile ad-hoc networks: is it achievable?

Cache schemes that adopt timeout (i.e. lifetime) for removing stale information have its correct estimation as basic assumption. An incorrect value for the timeout highly reduces the effect of the cache scheme or, even worst, produces a severe performance degradation rather than an improvement. However, lifetime estimation in mobile ad-hoc networks is difficult to assure due to the rapid and random changes in the network topology as well as to dependency on the path length. In this paper we discuss the general issue of caching in the context of mobile environments as a means to achieve efficient routing protocols. We propose a class of cache schemes that adopt active topology monitoring to determine when cached routes become stale. The scheme requires explicit support from the routing protocol. We present an implementation of the scheme when using a ZRP-like routing protocol and present some preliminary performance results.