Research On Mobile Charger Based Charging Strategy In Wireless Rechargeable Sensor Network

Wireless sensor network is a distributed self-organizing network composed of wireless sensors.The sensor node is usually powered by a dry battery,and the energy carried by the battery is very limited.Therefore,the energy of sensors becomes an obstacle of the development of wireless sensor network.In order to solve the energy bottleneck problem,researchers usually work on energy consumption optimization and energy supply.Due to the advancement of wireless energy transmission technology,wireless rechargeable sensor networks have become the new trend in the future,and the mobile charging strategy has become the focus of current research.Most of the existing research works adopts the charging mode that separates moving and charging,in the model the charger moves to the charging spots,and then starts charging the sensor nodes.The defect of this model is that the sensors only obtain energy when the charger stays at the charging spots.A more reasonable charging method is “charging while moving and staying” which means that the charger can charge the node both when it is moving and stays at the spots.The research objective of this paper is to improve the overall charging efficiency of the network by planning the traveling route,moving velocity and stay time of the mobile charger.First,based on the assumption of “charging while moving and staying”,this paper proposes a path planning problem that takes speed variations into account,and proves that the problem is NP-hard.We divides the problem into two sub-problems: path planning and velocity control.For the path planning problem,this paper first designs a greedy construction algorithm,and then uses genetic algorithm to optimize it.For the velocity control problem,this paper formulates the problem of charging delay calculation as a linear programming problem,and adds the velocity as a variable into the linear programming.Secondly,in order to explore the superiority of the charging model based on Traveling Salesman Problem with Neighborhood(TSPN)over that based on Traveling Salesman Problem(TSP),this paper proposes a TSPN-based charging strategy based on the “moving and charging separation”model.Then,for the multi-charger scenario,we designs a charging strategy under a multi-charger model,including the calculation of the number of chargers and the network partitioning strategy.Finally,this paper evaluates the performance of the proposed algorithm.The simulation results show that compared with the fixed moving velocity algorithm,the charging algorithm considering velocity variation improves the network charging efficiency by about 24 %.And the path planning algorithm based on the TSPN model improves the network charging efficiency by approximately 29 % compared with the algorithm based on the TSP model.