Routing for Maximum System Lifetime in Wireless Ad-hoc Networks

An ad-hoc network of wireless static nodes is considered as it arises in a rapidly deployed, sensor based, monitoring system. Information is generated in certain nodes and needs to reach some designated gateway node. Each node may adjust its power within a certain range that determines the set of possible one hop away neighbors. Traac forwarding through multiple hops is employed when the intended destination is not within immediate reach. The nodes have limited initial amounts of energy that are consumed in diierent rates depending on the power level and the intended receiver. We propose algorithms to select the routes and the corresponding power levels such that the time until the batteries of the nodes drain-out is maximized. The algorithms are local and amenable to distributed implementation. When there is a single power level, the problem is reduced to a maximum ow problem with node capacities and the algorithm converges to the optimal solution. When there are multiple power levels then the achievable lifetime is within 90% of the optimal (that is computed by linear programming) most of the time. It turns out that in order to maximize the lifetime, the traac should be routed such that the energy consumption is balanced among the nodes in proportion to their energy reserves, instead of routing to minimize the absolute consumed power.