| The sustainable energy supply of Internet of things terminals is an important challenge in the popularization and application of Internet of things.Simultaneous Wireless Information and Power Transfer(SWIPT)technology aims to achieve the cooperative transmission of information signal and energy signal through far-field wireless electromagnetic signals,achieving energy transmission,saving spectrum resources and reducing repeated investment in infrastructure.As the transmission power of broadband signal is strictly limited,the energy transmission range of the traditional single broadband signal system SWIPT system is greatly restricted.Therefore,the SWIPT system of the hybrid signal system(HSS)produced.Its transmitter signal consists of high-power narrow-band energy signal and low-power wide-band information signal,sharing the same frequency band and transmitter infrastructure.HSS-SWIPT system can effectively expand the range of energy transmission,but it also brings a new problem of nonlinear distortion of power amplifier at the transmitter.In this paper,the nonlinear distortion of HSS-SWIPT system is studied.The main research contents and contributions are as follows.1.Considering Saleh and polynomial nonlinear distortion models of class A and class B power amplifiers,SNDR and conversion efficiency of transmitter power amplifiers are used as performance indexes of information transmission quality and energy transmission efficiency,respectively.The theoretical formulas of the two performance indicators are derived and the compromise relationship is obtained through simulation.It is found that every 5dB increase of SNDR will bring about 5%to 10%loss of energy efficiency,and the loss is more when SNDR is lower.2.For the receiver of SWIPT system,assuming the OFDM sum multitone sinusoidal signal system,the determinate interference signal elimination and naive interference avoidance are regarded as the upper and lower bounds of the interference elimination function of information receiver.The relationship between the BER of the information receiver and the SNR of the information signal,the power ratio of energy signal and information signal and the frequency interval of multitone signal under the polynomial power amplifier is analyzed.The study found that BER is mainly affected by SNR,and the effect of energy information signal power ratio is limited,and the better BER performance can be achieved when the frequency interval of multitone signal is large.3.For the complete transceiver system of SWIPT,the end-to-end energy transfer efficiency from the power amplifier energy consumption at the transmitter to the energy harvesting at the receiver is calculated.The trade-off relationship between BER and end-to-end energy efficiency is analyzed,and the trade-off area between BER and energy efficiency is defined.It is found that the highest value of energy efficiency mainly depends on the frequency interval of multitone signal,while the slope of the eclectic curve mainly depends on the SNR value of information signal.In the middle and low SNR range(SNR<10dB),a small BER loss can exchange for a large energy efficiency gain.The analysis of this paper clarifies the trade-off relationship between the key performance indicators in the hybrid signal system of SWIPT,which can provide useful guidance for system engineering design. |
PDF Full Text Request