Stochastic Security in Wireless Mesh Networks via Saddle Routing Policy

The security problem in multihop wireless networks is more severe than that in wired networks since its transmission media is the unprotected air. In this paper, we show how to increase the effective throughput via carefully choosing the multi-path routing for given source and destination nodes, where we call the total packets from the mesh routers to the gateway nodes that are not attacked by an attacker as effective throughput. We assume that the attacker has limited resources for attacking while attacking a node or a link will incur some certain cost. We show that it is NP-hard to find an optimum routing policy even if the attacking strategy is given. We model the problem as a two-player game between the routing policy designer and the attacker and propose a multi-path routing protocol for several possible attacks. We propose several routing protocols that can approximately maximize the total throughput achieved by the gateway nodes. Moreover, we theoretically prove that our routing protocols can achieve an effective network throughput (with packets which are not attacked) within a constant factor of the optimum in the worst case. Our theoretic results are confirmed by extensive simulations studies.