Energy and Distance Optimization in Rechargeable Wireless Sensor Networks

The aim of a mobile recharger operating in a wireless sensor network (WSN) is to keep the network's average consumed energy and covered distance low. As shown in the literature, the covered distance is minimized when the mobile recharger's base is located as per the solution of a median problem, while the network's average energy consumption is minimized as per the solution of a different median problem. In this work, the first problem is analytically investigated, showing that its solution depends on the traffic load and the topology characteristics. Furthermore, it is shown that, under certain conditions, the solution for both problems is identical. These analytical results motivate the introduction of a new on-demand recharging policy, simple to be implemented and depending on local information. The simulation results confirm the analytical findings, showing that the solutions of both median problems are identical under certain conditions in WSN environments. Additionally, the proposed recharging policy is evaluated against a well-known policy that exploits global knowledge, demonstrating its advantage for prolonging network lifetime. For both recharging policies, it is shown that energy consumption and covered distance are minimized when the mobile recharger is initially located at the solution of the said median problems.