A new Media Access Control protocol for ad-hoc wireless sensor networks

This paper proposes a Media Access Control protocol,called CT-MAC, for ad-hoc wireless sensor networks. It is a contention-based TDMA scheme, which assimilates the valuable design philosophies of CSMA and TDMA while offsetting their weaknesses. Inspired by S-MAC[1], CT-MAC proposes a novel conception of contention/doze and communication/dormancy duty cycle. Unlike S-MAC where the durations of each cycle are fixed, CT-MAC makes these durations self-adaptive for energy efficiency. More importantly, CT-MAC originally adopts the protocol interference model to contend the noninterference channels for each time-slot, and extends the conventional IEEE 801.11 RTS-CTS scheme with stronger functions to successfully solve the exposed terminal problem, which is not well addressed before. We believe that the initial high overhead in the contention period would be eventually compensated by the improved throughput and energy efficiency subsequently. Simulations are performed among CT-MAC, S-MAC and simplified 802.11 DCF to demonstrate the efficiency and effectiveness of the proposed CT-MAC.