Energy-efficient Cooperative Transmission For SWIPT In WSNs

With development of smart life wireless sensor networks,It are widely applied in various field.However,due to limitations of battery,sensor node energy is limited and restricted the development of sensor networks.Cooperation sensor networks optimize resource allocation by cooperation between nodes and power control,which can effectively improve the energy efficiency of the networks.Simultaneous wireless information and power transfer(SWIPT)provides stable energy source for sensor networks,and provides a new method for prolong the life of the energy-constrained networks.In the SWIPT based Cooperative sensor networks realize the simultaneously information and power transfer,which is an effective way to further improve energy-efficient and life.Most of existing cooperative sensor network based on SWIPT are aimed at improving the network throughput under nodes energy keeps constant and ignore dynamic changes of the energy in the long-term operation,Dynamic change in battery energy will not only affect the reasonable allocation of harvesting energy,and will affect the life of the wireless sensor network.Therefore,We develop energy management strategy to make average energy-efficient maximum.Firstly,the battery energy model of nodes in different time slots is established by using the Markov process to described the dynamic characteristics of the battery energy of the sensor nodes in the cooperative network with limited battery capacity.In order to solve the problem of unnecessary energy consumption in the process of relay selection and unfair load distribution caused by sensor node position.A relay selection strategy of the joint node's energy and channel state under dynamic energy is proposed.Secondly,an no-convex constrained optimization function is proposed to maximize the average energy efficiency for SWIPT in cooperative sensor network with limited battery capacity based on time division multiple access.By exploiting fractional programming and dual decomposition,We develop a distributed iteration algorithm for power allocation,power splitting and relay selection by solving convex optimization problem.Finally,the simulation results show that the distributed iteration algorithm converge within a few ierations.Moreover,the proposed cooperation transmission strategy can make energy-efficient maximum under certain throughput constrains.