Performance Evaluation of a Proposed On-Demand Recharging Policy in Wireless Sensor Networks

In order to tackle the energy hole problem in wireless sensor networks, various recharging policies have been proposed attempting to keep the average energy level high and the recharging distance (i.e., the distance covered by a mobile recharger) low. As shown in the literature, the recharging distance is minimized when the basis of the mobile recharger is located at the solution of a median problem that takes into account both distance and traffic demands. In this paper, a novel on-demand recharging policy is proposed based on local information, where the mobile recharger moves-upon request-to a target node of reduced energy level and replenishes its battery. Under the proposed policy, the mobile recharger moves in a hop-by-hop manner to the neighbor nodes of the lowest energy level, starting from the target node. The effectiveness of this policy is investigated here using simulation results and compared against an existing well-known on-demand recharging policy that exploits global knowledge (i.e., knowledge of both the energy level of all nodes and the network topology). It is shown that the proposed policy, even though based on local information, maintain the average energy level and termination time higher than that under the existing one that exploits global knowledge. Furthermore, it is observed that the network's lifetime is maximized when the basis of the mobile recharger is located at the solution of the mentioned median problem for all studied policies. Index Terms-Recharging Policy, Local Information, Wireless Sensor Networks.