Proactive Charging Mechanism for Wireless Rechargeable Sensor Networks

Despite the fact that Wireless Sensor Networks (WSNs) are used in a variety of applications, the limited battery capacity of the sensor nodes is still considered the main challenge for WSN development. Recently, wireless power transfer technology (WPT), which uses a mobile charger (MC) to wirelessly charge the sensor nodes, has demonstrated a promising method for extending the lifetime of WSNs. Various wireless charging schemes have been proposed which are classified into two classes: periodic and on-demand. However, these two classes have a problem in which they don't take the variance in the consumption rates of sensor nodes into consideration. Moreover, we need to make sure that the sensor nodes don't run out of their power before the mobile charger reaches them. This paper proposes a new scheme for charging sensor nodes in WSNs where the time of recharging the sensor nodes is determined in prior according to some factors such as residual energy of the sensor nodes, energy consumption rate of the sensor nodes, and the distance between the sensor nodes and the MC. We call the proposed scheme a proactive charging. In the proposed scheme, the network area is divided virtually into hexagon cells. Then, based on the factors mentioned above, the MC identifies the appropriate cell to be visited for recharging the sensor nodes in that cell. Simulation results have shown that the proposed approach outperforms the on-demand First Come First Served (FCFS) scheme in terms of extending the network lifetime.