An Analytical Model for a Class of Receiver-Initiated MAC Protocols for Energy Harvesting Wireless Sensor Networks

In this paper we propose an analytical model for a general class of receiver-initiated MAC protocols for energy-harvesting wireless sensor networks. The aim is to evaluate the system occupancy of a sensor node and the average delay a packet in a node experiences, taking into account the energy that is consumed by the radio using the stored energy in a capacitor. Packets are generated by the node itself but may also arrive from neighbor nodes using a receiver-initiated MAC protocol. The radio switches between Transmit, Receive and Sleep states. During the Sleep state, energy is harvested and stored in a capacitor. The sensor node is modeled by means of a finite capacity queue with repeated server vacations of different types and the available energy is modeled by means of an extra variable. The system occupancy and the available energy are observed at inspection instants (i.e., the end of a service or the end of a vacation), resulting in a discrete-time Markov Chain. Closed form formulas for the system occupancy distribution at at arbitrary time instants together with the mean response time are derived. The model is applied to evaluate the sensor node’s performance for various parameter values.