Research On Precoding Design Of Co-frequency Co-time Full-duplex Millimeter Wave Massive-MIMO Relay

One of the key features of the new generation of mobile wireless communications systems is the unprecedented demand for high-throughput data transmission.The worldwide monthly traffic of smartphones is expected to be about 50 petabytes in 2021.The most immediate method to satisfy these demands in wireless communication systems is to increase the spectral efficiency(SE)and the available bandwidth.In mobile communication networks,the available bandwidth in conventional sub-6GHz band is almost saturated.In the millimeter wave(mm Wave)band(approximately 30 GHz-300 GHz bands),more than 150 GHz bandwidth is available.Simultaneous in-band full duplex(FD)transmission can achieve transmitting and receiving signals simultaneously.It can realize twice the spectral efficiency of the conventional half-duplex(HD)system in ideal conditions.FD mm Wave system improves the transmission bandwidth and spectral efficiency.In addition,the configuration of massive multiple input multiple output(MIMO)can reduce the small scale fading,transfer energy and achieve interference suppression.Wireless relay backhaul is an important application scenario of FD mm Wave system.On one hand,wireless relay backhaul is of low cost and flexible to deploy,and on the other hand,FD mm Wave relay extends the coverage of the system and achieves high transmission rate.Therefore,it is of great significance to study the precoding method of FD mm Wave massive-MIMO relay system.The precoding scheme and asymptotic performance of FD mm Wave relay system with hybrid analog-and-digital structure is intestigated,aiming at suppressing the FD self interference(SI)and providing reasonable power allocation mathod,so as to improve the SE and energy efficiency(EE)of the system.Based on an FD mm Wave hybrid analog-and-digital structure relay system model and its energy consumption model,the decoupled precoding design and system performance are investigated.Aiming at the special precoding structure of mm Wave system and FD SI,the decoupled interference suppression precoding schemes of the fully-connected structure and the sub-connected structure are designed,respectively.Based on the power consumption model,the effects of the number of antennas,the number of radio frequency(RF)links and the transmitting power of each node on the energy efficiency of the system are analyzed.For the relay system with fully-connected structure,the joint precoding scheme is further studied.On the basis of making full use of millimeter wave channel characteristics and RF precoding structure,an orthogonal matching pursuit(OMP)based joint precoding iterative algorithm is proposed.By utilizing the channel structure and properties of the precoding design,a simplified expression of the SE is obtained under certain approximate conditions.Next,the simplified SE and energy consumption model are used to optimize the EE of the system in order to obtain the EE optimization method under the constraint of the minimum SE and transmitting power.By transforming the non-convex fraction problem into iterative parametric convex optimization,an EE optimization algorithm with minimum SE requirement and transmitting power constraint is proposed to improve the EE on the basis of ensuring the minimum SE requirement of the system.Aiming at the particularity of channel and hybrid antenna structure in mm Wave communications,the asymptotic orthogonality of mm Wave massive MIMO channel is analyzed.Then,the asymptotic spectral efficiency of the relay system with massive MIMO is derived.The ability of massive MIMO to suppress the relay SI and the influence of imperfect SI channel state information on precoding performance are analyzed.In this thesis,an interference cancellation hybrid precoding algorithm is designed to suppress the SI of each node in the two-way relay(TWR)system.The asymptotic orthogonality of antenna response vectors is utilized to deduce the asymptotic spectral efficiency of the FD mm Wave TWR system with massive MIMO,which proves that FD SI,TWR SI and noise in the TWR system can be suppressed by massive MIMO.The imperfect channel state information FD SI can also be effectively suppressed by massive MIMO.The asymptotic SEs of the system under different power scaling schemes(PSS)are derived.In addition,when the two nodes of the system are only equipped with a limited number of antennas,the interference suppression ability of the large-scale antennas of the relay node on the system is analyzed.The corresponding asymptotic performance is derived,and the feasible power allocation strategy under the current system configuration is discussed.For the FD mm Wave integrated access and backhaul(IAB)relay system,the asymptotic SE of the system with large-scale antennas configuration is derived and the interference suppression ability is analyzed.The corresponding baseband precoding is proposed to deal with the residual multiuser interference.In order to suppress all the interference without considering the large-scale antennas,a block diagonalization(BD)based interference cancellation precoding design is proposed,which eliminates the interference by utilizing the null space of the channel matrix.In addition,a signal to leakage and noise ratio(SLNR)based precoding scheme is proposed.By transforming the generalized Rayleigh quotient into Rayleigh quotient and utilizing Rayleigh-Ritz theorem,a precoding scheme composed of generalized eigenvectors is obtained.Finally,the schemes illustrated above are discussed.The characteristics of RF and baseband precoding schemes and the abilities of each scheme to suppress different interference and noise are analyzed.The results in this work show that using reasonable antenna configuration,power allocation strategy and precoding design can suppress the interference in the FD mm Wave relay system and improve the SE and EE of the system.