Performance Analysis Of Full-Duplex Massive MIMO Systems With Low Resolution ADCs/DACs

Low power consumption,the lack of spectrum resources,high speed,and high coverage have long been urgent problems for wireless communication systems.Compared with the traditional multiantenna system,the large-scale multi-input multi-output(MIMO)system effectively develops space resources and improves resource utilization in the time and frequency domain,bringing great capacity gain to the system.Full-duplex technology uses simultaneous bi-directional transmission mode to achieve two-way communication,using the same channel resources in the communication process.Therefore,if full-duplex communication can be effectively applied,that is,the transceiver simultaneously performs signal transmission and reception on the same frequency resource,it is possible to theoretically achieve double the spectral efficiency of the half-duplex system.In order to enable the system to have the benefits of both technologies,we have studied a system that combines both massive MIMO technology and full-duplex technology.However,considering that the base station of a massive MIMO system is equipped with hundreds of antennas,the use a digital-to-analog converter(DAC)unit on the transmitter and an analog-to-digital converter(ADC)on the receiver in each antenna significantly increases the hardware cost of the system and power consumption,which becomes the main bottleneck for large-scale MIMO system applications.One way to solve this problem is to use a low resolution ADC.Therefore,this paper further studies the performance of fullduplex massive MIMO systems with low resolution ADCs / DACs.Firstly,this paper proposes a full-duplex massive multiple-input multiple-output(MIMO)system,and applies the maximum ratio combining/maximum ratio transmission(MRC/MRT)signal processing method to derive the approximateachievable rate expressions for uplink and downlink over Rayleigh and Ricean fading channel.Then,based on the derivedrate expressions,we propose four power scaling schemes to further investigate multi-user interference(MUI),loop interference(LI),inter-user interference(IUI)and additive white Gaussian noise(AWGN)on the system performance.The results show that the adverse effects of MUI,LI and AWGN on system performance can be compensated by increasing the number of base station antennas and applying the power scaling law appropriately.Then,this paper studies a full-duplex massive MIMO system based on low-resolution ADCs /DACs.Based on the Rayleigh and Ricean fading channel,we use the additive quantization noise model(AQNM)to derive the uplink and downlink approximate achievable rates of the system under both perfect channel state information(CSI)and imperfect CSI.Based on the derived rate expressions,we analyze the impact of three factors on the rate performance,including the number of antennas,the number of quantization bits,and the transmission power of the base station and each user.The theoretical results show that as the number of ADC quantization bit increases,the uplink and downlink rates tend to be constants,which means there is a limit to improving the system performance by increasing the number of ADC quantization bits.This point proves that using low resolution ADCs / DACs in a full-duplex massive MIMO system is a reasonable choice.Finally,we studied a full-duplex massive MIMO system based on a mixed ADC architecture.A small number of antennas are equipped with high-precision ADCs,and most of the remaining antennas are equipped with low-resolution ADCs.This architecture has the potential to significantly reduce hardware costs and power consumption while still maintaining most of the performance improvements promised by traditional architectures.Based on the Ricean fading channel and the MRT/MRC signal processing method,we derive the approximate uplink and downlink achievable rates of the proposed system.Finally,we conclude that the mixed ADC architecture can achieve a larger sum rate than the low resolution ADC architecture.By using a mixed ADC architecture,the full-duplex massive MIMO can achieve considerable performance.