Research On Transmission Protocol And Performance Optimization Based On Integrated SWIPT Communication System

With the rapid development of the information age,the scale of wireless networks continues to expand,and the number of nodes in the network has increased dramatically.In traditional networks,the energy of a node is provided by a battery with a limited capacity.This energy supply method determines the limited life of the node.At the same time,facing more and more nodes,frequent battery replacement will consume a lot of manpower and material resources.In recent studies,most scholars have ignored direct links in communication networks and only considered relay link transmission.This assumption is unrealistic,and it will cause waste of resources and limit system performance.However,the emergence and development of Simultaneous Wireless Information and Power Transfer(SWIPT)provides new ideas for solving this problem.SWIPT technology can collect energy for the passive nodes in the communication network through radio frequency signals,and can also use radio frequency signals to transmit information.This technology avoids the disadvantages of traditional energy supply methods and greatly extends the service life of network nodes.Therefore,the application of SWIPT technology in wireless networks has attracted much attention.This paper mainly studies the transmission protocol and performance optimization of SWIPT-based communication systems.This paper is mainly divided into the following two parts.1.A communication system that only considers relay link transmission will cause waste of resources and limit the improvement of system performance.Aiming at this problem,considering direct links in SWIPT-based networks,the TSR-DL protocol based on time switching strategy(TS)and the PSR-DL protocol based on power splitting strategy(PS)are proposed.The source node can not only transmit information to the destination node through relay forwarding,but also transmit information to the destination node through a direct link.The destination node combines the signals from the source node and the relay node by the Maximum Ratio Combining(MRC)method,the combined signal is used as the final information of the destination node.The functional relations of the TSR-DL protocol and the PSR-DL protocol's outage probability with respect to the TS coefficient and the PS coefficient are derived.The optimization problems of TS coefficients and PS coefficients of throughput are established and solved respectively,and the superiority of their throughput performance is proved.Finally,the numerical simulation results also show the improvement of system throughput performance of TSR-DL and PSR-DL protocols.2.When the relay is far away from the source node,the efficiency of collecting energy through the radio frequency signal of the source node will be low.To address this problem,three energy collection schemes are proposed,namely,S-WPH collects energy from the source node,and D-WPH collects energy from the destination node and SD-WPH collects energy from both the source node and the destination node.According to the known relay location,the optimal energy collection scheme can be selected.In the three schemes,the optimization problem of the TS coefficients of the throughput is established,and the optimal TS coefficients are calculated by numerical calculations(the SD-WPH also requires the optimal power allocation coefficient)to achieve the optimal Throughput.Finally,based on these three energy harvesting schemes,two energy harvesting strategies for different situations are proposed.