Swarm mobility and its impact on performance of routing protocols in MANETs

In a mobile ad hoc network (MANET), node mobility has significant impact on the performance of routing protocols. In this paper we investigate the impact of the swarming behavior of mobile nodes on the performance of MANET routing protocols, analytically and through simulation. We propose a Markov swarm mobility model to characterize time-dependent changes in the network topology, based on which a quantized collaboration degree is obtained. The proposed Markov swarm mobility model is validated through statistical hypothesis testing of simulation data. Then the performance of MANET routing protocols is studied in terms of hop count, routing overhead, and average end-to-end delay of a data packet. We derive an exact probability distribution function of the hop count, and analytic expressions for approximating the routing overhead and the average end-to-end delay. Numerical and simulation results are used to demonstrate the validity of the theoretical derivations. Trends of these performance metrics are discussed based on numerical results. An important observation is that, when a swarm of mobile nodes moves in a more collaborative manner, both the routing overhead and the average end-to-end delay of data packets are significantly reduced. The analysis developed in this paper can help gain insight into the effect of group mobility on the performance of MANET proactive routing, and provide guidelines for designing appropriate routing techniques for MANETs with swarm mobility patterns.