Performance Analysis for Optimal Hybrid Medium Access Control in Wireless Sensor Networks

Sink´s vicinity is a hotspot area in a wireless sensor network, and has a significant impact on the normal operation and network performance of the entire network. A hybrid MAC protocol makes use of the advantages of both CSMA/CA and TDMA protocols and adaptively switches between the two protocols based on dynamic traffic load, and can thus improve the network performance within the sink´s vicinity. In this paper, we study MAC for the sink´s vicinity in a WSN. We develop performance models for CSMA/CA and TDMA systems and compare their performance under both non-saturation and saturation conditions based on the developed performance models. Through simulation results, we verify that the accuracy and correctness of the performance models. Moreover, the analytical results based on the performance models can be used as a guide for determining the optimal load point for protocol switch and designing an optimal hybrid MAC protocol for the sink´s vicinity.