Research And Performance Analysis Of Cooperative Relay Transmission Scheme Based On Simultaneous Wireless Information And Power Transfer System

With the development of communication technology and the increasing demand for higher transmission rate,lower transmission delays and wider communication coverage,the energy consumption of devices in wireless network(such as sensors,mobile terminals,etc.)is also increasing day by day.Therefore,the energy supply of wireless communication nodes has become a research hotspot.At the same time,spectrum and energy efficiency are one of the most important design indicators in the wireless communication system,and the problem of spectrum resource shortage and low utilization has become more and more serious.Simultaneous wireless information and power transfer(SWIPT)technology transmits energy and information simultaneously through a wireless link by use of the dual physical characteristics of the radio frequency signal that are both carriers of information and energy,which provides a new solution for energy constrained system.And spectrum sharing technology can effectively alleviate the problem of spectrum resource shortage.Therefore,this paper focuses on the efficient utilization of energy in SWIPT relay cooperative system and spectrum sharing of cognitive cooperative relay network based on SWIPT.Reasonable energy utilization can improve the energy utilization efficiency of the relay nodes and the performance of the system.In SWIP-based relay cooperative system,in order to solve the problems of high outage probability and poor service quality caused by too little energy harvested by the relay nodes after a transmission,and to improve the energy utilization efficiency of the relay nodes and the reliability of the system,an energyaware retransmission(EAR)strategy was adopted in this paper.In this scenario,the source transmitter is allowed to perform a retransmission operation within the allowed number of retransmissions,to ensure that the relay harvests a certain minimum amount of energy before the second phase is started.Firstly,for the dual-relay SWIPT syetem,we derive the expression of the probability density function of the signal-to-noise ratio under the traditional and EAR scenarios,respectively.Then,the ergodic capacity of the system was analyzed theoretically and simulated according to the system model.The simulation results show that the EAR scheme is superior to the conventional transmission pattern,and boosts the dependability and power using efficiency of SWIPT relay system.Considering that spectrum and energy efficiency are the most important design indicators in wireless communication system,this paper further introduces cooperative spectrum sharing in SWIPT cognitive radio network to improve spectrum utilization and energy efficiency.For the SWIPT-based cooperative cognitive relay network,this paper firstly investigates the outage probability and throughput of the primary user system and the secondary user system respectively under the hybrid power-time split based relaying protocol(HPTSR),and gives their expressions.Then further analyzes the outage probability performance and throughput performance of the primary user system and the secondary user system under different system parameters,and compares HPTSR protocol with power splitting protocol(PSR)and time switching protocol(TSR).The analysis shows that this protocol is superior to the PSR and TSR protocols for the system based on HPTSR.