Abstract

A key challenge for wireless sensor networks is how to extend network lifetime with dynamic power management on energy-constraint sensor nodes. In this paper, we propose two energy-efficient MAC protocols: asynchronous MAC (A-MAC) protocol and asynchronous schedule-based MAC (ASMAC) protocol. A-MAC and ASMAC protocols are attractive due to their suitabilities for multihop networks and capabilities of removing accumulative clock-drifts without any network synchronization. Moreover, we build a traffic-strength- and network-density-based model to adjust essential algorithm parameters adaptively. Simulation results show that our algorithms can successfully acquire the optimum values of power-on/off duration, schedule-broadcast interval, as well as super-time-slot size and order. These algorithm parameters can ensure adequate successful transmission rate, short waiting time, and high energy utilization. Therefore, not only the performance of network is improved but also its lifetime is extended when A-MAC or ASMAC is used.