Research On Doppler Effect Technology Under Full-duplex Communication

With the rapid development of high-speed railways,there is growing demand that the train operation control system realizes the concept of “anytime,anywhere” communication.Full-duplex communication technology creates the conditions for fast and secure communication.At the same time,with the continuous application of full-duplex communication technology,some problems to be studied have also been discovered.If the user is in motion,the system will be affected by the Doppler shift.Therefore,this paper mainly studies the influence of Doppler shift on full-duplex massive multiple-input multiple-output(MIMO)systems.The specific research contents are as follows:Firstly,this paper studies the influence of Doppler shift on system performance in single-cell massive MIMO systems.The system model is mainly established with known channel state information(CSI)situation and unknown CSI situation.For the case of known CSI,by modeling the channel and applying MRC/MRT processing and the law of large numbers,the uplink asymptotic achievable rate and the downlink asymptotic achievable rate of full-duplex massive MIMO under the influence of Doppler shift is finally derived.And the system performance under the corresponding parameters is obtained through numerical simulation.Also the system performance under different parameters is compared,which also proves the correctness of the theoretical analysis.For the case of unknown CSI,besides analyzing the system performance during MRC/MRT processing,an ZFR/ZFT processing is used to compared with it.Then,this paper studies the influence of Doppler shift on system performance in multi-cell massive MIMO systems.The research was carried out from two cases of known CSI and unknown CSI.For the case of known CSI,by modeling the channel and applying MRC/MRT processing,the uplink asymptotic achievable rate and downlink asymptotic achievable rate of full-duplex massive MIMO under the influence of Doppler shift are finally analyzed.For the case of unknown CSI,the uplink asymptotic achievable and downlink asymptotic achievable rate of full-duplex massive MIMO under the influence of Doppler shift by applying MRC/MRT processing are also analyzed.From numerical simulation,it can be visually seen the impact of Doppler shift on multi-cell full-duplex massive MIMO systems.Finally,this paper considers the practical application scenarios of the research.The design scheme of full-duplex system in high-speed rail application is studied.Considering the influence of Doppler shift,the full-duplex relay system is introduced and analyzed.The relay station uses MRC/MRT to process the signal,and obtains the expression of the system reachable rate through mathematical analysis,What's more,the performance under different parameters is compared.The simulation results can visually reflect the influence of Doppler shift on the high-speed rail system.When the train speed increases,the system speed decreases due to the influence of Doppler shift.Simulations show that the system rate can be maintained and the influence of Doppler shift can be reduced by increasing the number of antennas.