Optimization On Mobile Charging Path In Wireless Sensor Networks Among Obstacles

A comprehensive scheme of joint data collection and energy replenishment by utilizing mobile charger is a new breakthrough in energy-limited wireless sensor networks(WSNs),which can prolong network lifetime and improve network performances.Considering the presence of obstacles leads to communications barriers in the monitoring area,so the network can be divided into several disconnected subnets,the nodes in the subnet can communicate with each other,while the nodes in different subnets cannot communicate.Furthermore,the obstacles will block the movement of mobile charger.Therefore,we present optimal strategies on path planning by utilizing mobile charger in wireless sensor networks among obstacles.The main contents are as follows:1)Optimization problem on charging path is researched in wireless sensor networks among obstacles.The conceptions of connectivity matrix,shortest hop matrix and node fitness are presented to describe the connected relationship and distance relationship among nodes.2)For the path optimization problem based on energy constraint,low delay mobile charging strategy(LDMC)is presented to achieve the shortest path;considering residual energy of sensor nodes,optimal residual energy mobile charging strategy(REMC)is presented to charge nodes timely;finally,optimal mobile charging strategy based on charging weight(CWMC)is studied to make a balance between energy consumption and data collection delay.3)The optimal problem on mobile charging path among obstacles is proved to be NPC problem.Performances of the strategies are analyzed by simulation.Results show that CWMC presents better performances than LDMC and REMC by comparing path length,average charging latency and the number of residual nodes.For the three strategies,the path length of the mobile charger remains unchanged with the moving velocity of mobile charger increasing,while the average charging latency and the energy consumption show a descending trend.The path length of the mobile charger and the energy consumption are increasing with more nodes in the network,while the average charging latency shows a descending trend.