Optimal Beaconing Control in Delay-Tolerant Networks With Multiple Destinations

The opportunistic contacts between nodes have important impact on the routing process in delay-tolerant networks, and they are related to the beaconing rate. In this paper, we study the optimal beaconing rates for the relay nodes and destinations at the same time. First, a theoretical framework, which can be used to evaluate the performance under different beaconing policies, is presented. Then based on the framework, we formulate an optimization problem. Through Pontryagin's maximum principle, we obtain the optimal beaconing policies for the relay nodes and destinations, respectively. In addition, we prove that both optimal policies conform to the threshold form. The optimal policy of the relay nodes changes its value from the maximal beaconing rate to the minimal one, but it is opposite for the destinations. The simulations show the accuracy of our theoretical model. Extensive numerical results show that the optimal policies are really better.