LAUSR

To reduce the energy waste caused by idle listening, sensor nodes in wireless sensor networks (WSNs) usually work with low-duty-cycle mode. However, such mode brings many new challenges, especially for broadcasting applications. This paper proposes to exploit the broadcast nature of wireless media to further save energy for broadcasting in low-duty-cycle WSNs, by adopting a novel opportunistic broadcasting transmission model. The key idea is to allow nodes to defer their wake-up time slots to opportunistically overhear the broadcasting messages sent by their neighbors, improving the energy efficiency at the cost of the increase of average broadcasting delay. Instead of regarding delay or energy as the single optimization objective, in this paper, we present a broadcasting cost function, which provides an adaptive control on the tradeoff between delay and energy to cover various performance requirements. Our target is thus to find the optimal broadcasting schedule to minimize the broadcasting cost, based on the opportunistic broadcasting transmission model. To this end, we first model the target problem under the single-hop case as a dynamic programming problem and prove it is solvable in polynomial time, then extend it to the multi-hop case and come up with an efficient solution. Extensive simulation results reveal that our solution always has a better performance over the other solutions under whatever configurations.