Due to the fact that sensor nodes are untethered and unattended, energy management is a critical issue in communication mechanism of a wireless sensor network. In this paper, we address this problem and propose a novel solution based on media access control technique. Our protocol DE-MAC exploits the inherent features of TDMA to avoid the main sources of energy wastage: collision and control packet overhead. It uses the concept of periodic listen and sleep in order to avoid idle listening and overhearing. However, unlike existing MAC-layer protocols, DE-MAC treats the critical nodes differently in a distributed manner. Motivated by the fact that a weaker node should be used less frequently in a routing in order to accomplish load balancing, DE-MAC performs a local election procedure and chooses the worst-off node/nodes as the winner/winners and makes them sleep more than the other neighboring nodes. Since the election procedure is fully integrated with the TDMA slot assignment, our protocol suffers no extra throughput loss. We evaluate DE-MAC and present the simulation results which explicitly show the gain in performance.
