Versatile low power media access for wireless sensor networks

We propose <i>B-MAC</i>, a carrier sense media access protocol for wireless sensor networks that provides a flexible interface to obtain ultra low power operation, effective collision avoidance, and high channel utilization. To achieve low power operation, <i>B-MAC</i> employs an adaptive preamble sampling scheme to reduce duty cycle and minimize idle listening. <i>B-MAC</i> supports on-the-fly reconfiguration and provides bidirectional interfaces for system services to optimize performance, whether it be for throughput, latency, or power conservation. We build an analytical model of a class of sensor network applications. We use the model to show the effect of changing <i>B-MAC</i>'s parameters and predict the behavior of sensor network applications. By comparing <i>B-MAC</i> to conventional 802.11-inspired protocols, specifically SMAC, we develop an experimental characterization of <i>B-MAC</i> over a wide range of network conditions. We show that <i>B-MAC</i>'s flexibility results in better packet delivery rates, throughput, latency, and energy consumption than S-MAC. By deploying a real world monitoring application with multihop networking, we validate our protocol design and model. Our results illustrate the need for flexible protocols to effectively realize energy efficient sensor network applications.