On Performance Modeling of Ad Hoc Opportunistic Routing Protocols

Since the inception of opportunistic routing in ad hoc networks, a number of OR protocols have been proposed. The performance measure of these protocols is predominantly based on simulation. Although simulation provides a simple and economical mechanism to test complex routing algorithms, they have been reported to produce inconsistent results. Simulation-based evaluation of ad hoc routing protocols should, therefore, be complemented with mathematical modeling and verification. OR protocols try to restrict the number of transmissions, therefore, the most important performance evaluation metric of OR protocols is packet transmission. In this chapter we examine the various mathematical evaluation models available in literature. During our study we found that these models do not consider retransmitted packets. We, therefore, propose an analytical model which account for packet retransmissions. The mathematical models are validated using prominent OR protocols. The performance of OR protocols depend not only on design issues like candidate selection and forwarder prioritization but also on network parameters like node topology, node density, etc. While the user has no control on the network parameters the performance of the protocol can be improved by carefully tuning the design issues. As a proof of concept we propose an OR protocol that minimizes packet retransmissions.