Research On The Cooperative Charging Scheduling For Mobile Wireless Rechargeable Sensor Networks

At present,due to the serious issue of insufficient energy storage of battery-powered sensor nodes,traditional wireless sensor networks have shortened their lifetime and reduced performance,and cannot meet people’s needs.With the development of wireless charging technology,wireless rechargeable sensor network has emerged as a new type of sensor network.Wireless Power Transmission(WPT)has been widely used to replenish energy for Wireless Rechargeable Sensor Networks.However,the charging service model,which is of the essence to commercial WPT,has not emerged so far.In this paper,we present an omnidirectional wireless charging service model from the perspective of cooperative charging economics,and formulate the Cooperative Charging Scheduling(CCS)problem for joint optimization of rechargeable devices’charging cost and moving cost.The business model of wireless charging services is critical to the further popularization of wireless charging technology.With the development of wireless charging technology,wireless chargers will become the infrastructure,which can provide paid energy for rechargeable devices.This thesis first proposes two intragroup cost sharing schemes:proportional cost sharing scheme and a Shapley cost sharing scheme to promote cooperation between equipment.By reducing the cooperative charging scheduling problem to the generalized facility location problem,it is proved that the problem proposed in this thesis is NP-hard.Then a (lnn+1)/(1-ε)-approximate algorithm of the CCS problem is proposed based on greedy approach and submodular function minimization,where n is the number of rechargeable devices,and?is the search precision.Furthermore,this thesis models the large-scale CCS problem as a coalition formation game,and present a game theoretic algorithm CCSGA.We show that CCSGA finally converges to a pure Nash Equilibrium.This thesis conducts simulations,and field experiments on a testbed consisting of 5 chargers and 8 rechargeable sensor nodes.The results show that the average comprehensive cost of CCSA is 27.3%lower than the noncooperation algorithm and is only 7.3%higher than the optimal solution on average.In field experiments,CCSA outperforms the noncooperation algorithm by 42.9%in terms of comprehensive cost on average.Moreover,CCSGA is much faster than the approximation algorithm and is more suitable for large-scale cooperative charging scheduling.