Power-aware routing in sensor networks

In wireless sensor networks, every sensor communicates with other sensors directly or indirectly through intermediate sensors within its transmission range. Since each sensor is battery operated, power aware routing is very important in sensor networks. In this dissertation, we study power aware routing to maximize network lifetime in an asymmetric model and to minimize the total power consumption in a symmetric model. We develop effective heuristics for the aforementioned power-aware routing problems. First, we consider the problem of broadcasting messages in a wireless energy-limited network so as to maximize network lifetime. An O( e log e) algorithm to construct a broadcast tree that maximizes the critical energy of the network following the broadcast is developed. Additionally, we propose two new greedy heuristics to construct minimum energy broadcast trees. Second, we show that the problem of routing messages for point-to-point communication so as to maximize network lifetime is NP-hard. In our online model, each message has to be routed without knowledge of future route requests. We developed also a heuristic to maximize network lifetime. Finally we study the problem of power assignment for symmetric communication. We show that two incremental power heuristics for power assignment have an approximation ratio of 2. Enhancements to these heuristics are proposed. For the aforementioned power-aware routing heuristics, we give simulation results comparing new heuristics and previously published heuristics. Our extensive simulations show that our heuristics improve network lifetime significantly in the asymmetric model and reduce total energy consumption in the symmetric model.