Modelling of S-MAC for Heterogeneous WSN

Wireless Sensor Networks (WSN) have experienced an important resurgence, especially through applications designed for the Internet of Things. In that sense, a WSN can be constituted of different classes of nodes, having different characteristics. On the other hand, S-MAC was the first Medium Access Control (MAC) protocol for WSN to implement the Duty Cycling (DC). DC is a popular technique for energy conservation in WSN, that allows nodes to wake up and sleep periodically. In this work, a performance evaluation study of S-MAC is performed considering heterogeneous scenarios and diverse medium access priorities. To accomplish that, an analytical model with a pair of two-dimensional Discrete-Time Markov Chains (DTMC) is developed. Scenarios with two classes of nodes forming the network were studied. Performance parameters such as packet average delay, throughput and consumed energy, are obtained and validated by simulation, showing accurate results.