Medium access and power control protocol for wireless sensor networks with directional antennas

The primary contribution of this paper lies in evaluating the potential benefits of using directional antennas in wireless sensor networks to reduce node power consumption and improve fairness and throughput. The protocol helps improve throughput and reduce energy consumption by maximising spatial reuse and with a strategy to deal with overlap between antenna patterns without any additional complexity at the sensor nodes themselves. The protocol uses packets from the hub to estimate the transmission power required by nodes, to avoid excess energy usage. The protocol is verified using RiverBed Modeler. Simulation results for fairness, throughput and node transmission energy requirement are presented, showing a reduction in average transmission power by a factor of two with respect to the protocol without power control. Good fairness is demonstrated and throughput for a 4-antenna system is 2.17 times that of a single antenna system. The antenna pattern overlap, which is often assumed negligible, is shown to have a significant effect on throughput.