Delay-bounded adaptive power saving for ad hoc and sensor networks

An important performance concern in ad hoc and sensor networks is the duration of time the network remains connected without requiring a battery replacement at any node. This duration, commonly known as the network lifetime, is often limited by a set of nodes that deplete their energy faster than others and cause parts of the network to be disconnected. Existing techniques can only partly compensate for such critical nodes that bound the overall network lifetime. We introduce a methodology to further reduce the energy consumption of such nodes by adjusting their behavior when the network is dormant. In this dormant network condition, nodes put their radio in a power-saving mode. We propose a scheme to select the settings of this power-saving mode to optimize the network lifetime. While putting nodes in power-saving mode conserves their energy it can cause additional delay in transmission. We rind the optimal power-saving mode setting after imposing an upper bound on the end-to-end delay of routes in the network The disparity in the energy levels of the nodes can result from the network topology as well as differences in the hardware or the quality of the wireless links. Our adaptive power-saving scheme increases the lifetime of a network up to 30% when variation in energy profiles of the nodes is solely due to the network topology. It can result in even higher performance gain when considering other factors that differentiate the energy levels of the nodes.