Multi-Carrier Waveform Shaping For Wireless Information And Energy Provision

With the advent of the Internet of everything(Io E)era,large-scale Io E devices are deployed to the environment.They interact with each other to provide great convenience for people's life.However,the traditional battery supply method is difficult to meet the increasingly energy needs of equipment,and wireless information and energy provision(WIEP)technology came into being.The WIEP system uses radio frequency(RF)signals for energy transmission,and an energy divider is set at the receiving end to provide wireless information provision(WIP)services and wireless energy provision(WEP)services at the same time.However,due to the high energy loss of RF signal in wireless channel,how to improve the conversion efficiency of RF signal in energy transmission link has become the key to the application of WIEP technology.Some scholars have found that after nonlinear modeling of the energy collection circuit,the multi carrier transmission scheme can improve the conversion efficiency of signal RF to direct current(DC).Compared with the random frequency division multiplexing modulation signal,the RF-DC conversion efficiency can be further improved by using the deterministic multitone sine wave without modulation.This thesis presents a multi carrier WIEP system scheme.The traditional orthogonal frequency division multiplexing signal is used to provide WIP service,and the determined multi tone sine wave signal is superimposed on the modulation signal to further improve the WEP performance of the system.The orthogonality between carriers is realized by the change of fast Fourier transform.At the same time,because the WEP signal is known to the receiver,it does not affect the information demodulation at the receiver.Based on the proposed multi carrier WIEP system,the waveform reconstruction design under carrier frequency offset(CFO)is considered.Because the appearance of CFO will destroy the orthogonality between carriers,the intercarrier interference will seriously damage the performance of WIP.After analyzing the impact of CFO on system performance,this thesis carries out physical modeling to reduce the adverse impact of CFO.By reshaping the amplitude and phase of WIEP,the received DC energy can be maximized under the condition of ensuring the user's information rate.Geometric programming and swarm intelligence algorithm are used to solve the problem,and the effectiveness of the algorithm is verified.Based on the proposed multi carrier WIEP system,the waveform reconstruction in time-varying channel is further considered.The frequency response of time-varying channel changes with time and has time correlation.By using the statistical characteristics of time-varying channels and using outdated channel state information(CSI)for signal reconstruction,the number of channel estimation can be reduced and a lot of communication resources can be saved.Considering the existence of CFO and time-varying channel,the average DC energy of a transmission block is maximized.Geometric programming and artificial bee colony algorithm are used to solve the optimization problem.Finally,the reconstruction of multi carrier integrated digital energy signal in multiuser scenario is considered,in which different users use frequency division multiplexing technology to access the base station.By optimizing the access control matrix and WIEP waveform,we can reasonably allocate resources and improve the digital performance of the overall WIEP system.