A contention window adaptive MAC protocol for Wireless Sensor Networks

Wireless Sensor Networks (WSNs) have been widely applied in many domains. Medium Access Control (MAC) protocols, the bottom part of the WSNs´ protocols, have a significant influence on the performance of the network. Considering the deficiencies of back off mechanism in SMAC, we modify the RTS frame as well as the contention window. Then we put forward an improved back off algorithm which adopts the adjustable contention window instead of the constant contention window. In the algorithm, the node not only concerns the competition of the medium by setting two counters, but also takes the neighbors´ competition of the channel into account to evaluate the busy-idle condition of the medium. Simulation results on ns-2 show that our MAC protocol has better energy efficiency and lower latency compared to SMAC protocol.