Hybrid scheduling strategy of multiple mobile charging vehicles in wireless rechargeable sensor networks

Charging optimization is an important research issue in wireless rechargeable sensor networks. The current researches on wireless charging mainly consider a single mobile charger to replenish sensors. However, a single mobile charger is difficult to meet the energy request of a large number of sensors. In this paper, a multiple mobile chargers replenishment approach is studied. First, an optimization problem is formulated to reduce charging energy consumption and path cost for enhancing charging efficiency. Then, due to the difficult of the problem, an improved bee colony algorithm is designed to schedule multiple charging vehicles for sensor energy replenishment at each period. Further, in order to decrease the number of starved sensors, a dynamic insertion method is integrated to insert the sensors with real-time request into the charging queue. Finally, the validity and feasibility of the proposed algorithm are evaluated by simulation in terms of the length of charging path, the total energy consumption of charging and the number of nodes violating constraints. The results demonstrate that the proposed approach can obtain more excellent solution than the compared approaches.