An asynchronous low-power medium access control protocol for wireless sensor networks

Duty cycling is a fundamental approach used in contention-based medium access control (MAC) protocols for wireless sensor networks (WSNs) to reduce power consumption in sensor nodes. Existing duty cycle-based MAC protocols use either scheduling or low-power listening (LPL) to reduce unnecessary energy lost caused by idle listening and overhearing. This paper presents a new asynchronous duty-cycled MAC protocol for WSN. It introduces a novel dual preamble sampling (DPS) approach to efficiently coordinate channel access among nodes. DPS combines LPL with a short-strobed preamble approach to significantly reduce the idle-listening issue in existing asynchronous protocols. We provide detailed analysis of the energy consumption by using well-known energy models and compare our work with B-MAC and X-MAC, two most popular asynchronous duty cycle-based MAC protocols for WSNs. We also present experimental results based on NS-2 simulations. We show that depending on the traffic load and preamble length, the proposed MAC protocol improves energy consumption significantly without degrading network performances in terms of delivery ratio and latency. For example, for a traffic rate of 0.1 packets/s and a preamble length of 0.1s, the average improvement in energy consumption is about 154%. Copyright (c) 2011 John Wiley & Sons, Ltd.