Energy-Aware Adaptive MAC Protocol for Real-Time Sensor Networks

One of the important objectives in Wireless Sensor Networks (WSNs) is to minimize energy consumption while satisfying delay constraints. Although, several energy-aware MAC layer protocols exist, the absence of channel adaptation and load adaptation results in energy wastage due to retransmissions and low success rate. In this paper, we propose an Adaptive- CSMA/CA protocol which accounts for varying channel and load conditions at a node by influencing the selection of either low energy or low delay transmission option. We devise an energy-delay metric that helps a node select the best message and modulation to obtain joint reduction in energy and delay at the time of transmission. Our simulation results show that our proposed Adaptive-CSMA/CA scheme results in upto 87% improvement in energy consumption under varying channel conditions and upto 150% higher success ratio under varying load as compared to the CSMA/CA specified in IEEE 802.15.4.