Performance Optimization Of SWIPT System Based On Hybrid Energy Harvesting Protocol

With the development of communication technology,the demand for wireless communication grows faster and faster,a large number of wireless devices are connected to the network.At present,the devices in the wireless communication network are supplied by power grid or battery.The mobility and the maintenance of power grid is poor.Battery energy supply is relatively convenient,but it needs to be charged or replaced on time,which will cause the consumption of human and material resources.The introduction of Simultaneous Wireless Information and Power Transfer(SWIPT)technology can effectively alleviate this kind of problem.Based on the characteristics of radio frequency(RF)signal that can carry information and energy at the same time,SWIPT technology converts part of the collected RF signals into electrical energy,and the remaining part is used for information transmission.SWIPT technology can effectively prolong the service life of the devices and improve the performance of wireless communications systems.Based on the cooperative communication system with three-node relay model,the performance of SWIPT system with hybrid energy harvesting protocol is optimized and studied in the thesis.The specific research contents are as follows:1.For the SWIPT relay system based on hybrid energy harvesting protocol and linear energy harvesting(EH)model,the theoretical expressions of system throughput and energy efficiency are derived.In order to maximize the system throughput and energy efficiency,an adaptive scheme is proposed,in which the source transmission power,time switching factor and power splitting factor change adaptively according to the system parameters.(1)A throughput optimization model is established.Variable alternating optimization iterative algorithm is proposed to jointly optimize the transmitting power of source node,power splitting factor and time switching factor.(2)An energy efficiency optimization model is established inorder to improve the system energy efficiency.Iterative algorithm based on Dinkelbach is proposed to jointly optimize the power splitting factor and time switching factor.Simulation results show that the proposed scheme can effectively improve the throughput and energy efficiency of the system.2.There is direct communication link between the source node and the destination node,the SWIPT relay system based on hybrid energy harvesting protocol and nonlinear energy harvesting(EH)model is studied.The decode-and-forward(DF)scheme is selected at the relay node.The expressions of outage probability and throughput about the SWIPT system are derived,and the approximate closed-form expression is obtained by Gauss-Chebyshev integral.The Monte Carlo simulation is carried out by MATLAB to verify the expressions and approximate closed-form expressions.The influence of various parameters on the system performance is analyzed.The simulation results show that the system model studied has certain advantages in system outage probability and throughput.