Determining Fuzzy Link Quality Membership Functions in Wireless Sensor Networks

Wireless Sensor Network routing protocols rely on the estimation of the quality of the links between nodes to determine a suitable path from the data source nodes to a data-collecting node. Several link estimators have been proposed, but most of these use only one link property. Fuzzy logic based link quality estimators have been recently proposed which consider a number of link quality metrics. In this work, we implemented the Fuzzy logic based link estimator in the WiseRoute routing protocol, which is a collection style protocol in MiXiM. We also present an experimental approach to determine a suitable fuzzy membership function based on varying the shape of the fuzzy set for a multipath wireless sensor network scenario and choosing an optimum shape that maximizes the Packet Delivery Ratio of the network. The computed fuzzy set membership functions were evaluated against an existing fuzzy link quality estimator under typical scenarios and it is shown the performance of the experimental optimal membership function was better in terms of packet reception ratio and end-to-end delay.