A contention-based energy-efficient MAC protocol for wireless sensor networks

Energy-efficient MAC protocols applied for WSNs can be classified into two main categories: con tendon-based and schedule-based protocols, according to their wireless media access strategy. In this paper, we propose an asynchronous energy-efficient MAC protocol: A-MAC from contention perspective. Through applying free-running method and rescheduling scheme, A-MAC does not require network time synchronization any more, which is necessary for existing energy-efficient MAC protocols. So our algorithm is more suitable for the system which is difficult to ensure high quality network time synchronization. Moreover, we present a traffic-intensity- and network-density-based model to yield essential algorithm parameters: power on/off duration and interval of schedule broadcasts. Simulation results show that our algorithm can acquire optimal values of these parameters successfully to increase energy utility, ensure successful transmission rate and decrease data packet average waiting time. Therefore, network performance can be improved and network lifetime can be extended by using our algorithm