A hybrid MAC with dynamic sleep scheduling for wireless sensor networks

In this paper, we present Hybrid MAC (H-MAC), a novel low power with minimal packet delay medium access control protocol for wireless sensor networks (WSNs). H-MAC achieves high energy efficiency under wide range of traffic load. It ensures high channel utilization during high traffic load without compromising energy efficiency. H-MAC does it by using the strength of CSMA and TDMA approach with intelligence. The novel idea behind the H-MAC is that, it uses both the broadcast scheduling and link scheduling. Depending on the network loads the H-MAC protocol dynamically switches from broadcast scheduling to link scheduling and vice-versa in order to achieve better efficiency. Furthermore, H-MAC uses Request-To-Send (RTS), Clear-To-send (CTS) handshakes with methods for adapting the transmit power to the minimum level necessary to reach the intended neighbor with a given BER target or packet loss probability. Thus H-MAC reduces energy consumption by suitably varying the transmit power. The simulation results corroborate the theoretical idea, and show the efficiency of our proposed protocol.