Looking at protocol efficiency from a new angle: stability—delay analysis

Path stability is a very critical issue in resource-constrained environments as frequent route discoveries can easily congest the network and also unnecessarily exhaust the battery power of nodes. We quantify path stability in terms of the number of route transitions a routing protocol incurs to continue the data exchange between a particular source-destination (s-t) pair. End-to-end delay of an s-t session is another equally important performance metric, particularly for real-time applications. Aiming for optimum end-to-end delay can lead to unnecessary route transitions and vice-versa. In this paper, we introduce the idea of Stability-Delay Tradeoff (SDT) - as a measure of the efficiency of a MANET routing protocol. In a two-dimensional space of stability and delay, SDT refers to the proximity of the routing protocol's actual stability and delay with respect to the optimal stability and delay under the same history of network topology changes. We show that the theoretical optimum for path stability i.e., the number of route transitions is efficiently computable in polynomial time. We also propose a (distance, weight)-based assessment technique to quantify the SDT of a routing protocol.