Research And Design Of Scheduling Algorithm Of Mobile Charge In Wireless Sensor Network

With the progress of the wireless communication technology and hardware technology, wireless sensor networks has been developed rapidly in recent years.Applications of wireless sensor networks spread from the American military field to all aspects of life, such as home automation, forest fire detection, health monitoring and rained agriculture. However, the limited energy of the sensor node has become one of the most critical factors, which stunts the development of WSN. Affected by the volume of node, the sensor nodes powered by battery can only store the energy with the minimum capacity. In addition, the sensor networks usually consists of a large number of sensor nodes, which are distributed randomly in dangerous, harsh and even the original environment where no person can reach. And once developed, it is extremely difficult to maintain and even can not be maintained. Based on these limits,the way of replacing the battery for sensor nodes to continue for powering can completely unrealistic. The limited energy problem has become one of the core issues in WSN research, which needs to be solved urgently. How to solve the problem of energy limitation of sensor nodes is very strategic significance. In terms of energy management, domestic and foreign researchers are devoted to these two areas of the energy harvesting and energy conservation, and have made good progress. However,the energy conservation can only prolong the lifetime of sensor nodes, and the technology for obtaining energy from the environment is still unstable and unreliable.Recent breakthroughs in wireless energy transfer and rechargeable lithium batteries provide a promising support for the energy problem of WSN: a mobile vehicle or robot which carried a high volume battery as a mobile charger to periodically deliver energy to the sensor nodes.In this thesis, the wireless sensor network is briefly summarized from the aspects of the system structure and features firstly. Then, it introduces the related technologies involved in the field of mobile charging, include the energy conservation technology,the energy harvesting technology and the wireless charging technology. By introducing the concept of the upper and lower bounds of energy, the problem of mobile charging in wireless sensor networks is transformed into the vehicle routing problem with time windows, which is a classic problem of multiple traveling salesman problem.Simplebut, on the premise of each sensor node of the network has different energy consumption rate, and based on the fact that all sensor nodes own their time windows,the mobile charge based on time windows aims to design the most reasonable schedule algorithm to complete the charging of sensor nodes by defining the required upper bound and lower bound of time windows reasonably. Subsequently, this thesis analyzes the quantitative relationship between the network radius,the number of mobile charger and the number of sensor nodes, the energy of the mobile charger quantitatively. On the basis of this, an approximate algorithm is proposed. By adding virtual node, the multiple traveling salesman problem can be transformed into the single traveling salesman problem,and then a feasible solution can be constructed through approximation algorithm; On the structure of the feasible solution, using 2-opt local optimization method to optimize the, and at the same time, considering the mutual cooperation between the mobile chargers.Finally, through the experiment and simulation, the feasibility and superiority of the proposed mobile charging algorithm are proved.