Research On Relay Cooperative Hybrid Precoding Technology In High-speed Mobile Millimeter Wave Scenarios

With the rapid development of communication needs and the explosive growth of intensive wireless data services,low energy consumption,high capacity,highly reliable and resilient transmission capabilities pose higher challenges for high-speed mobile wireless communication.To meet the demand for high-quality link communication and energy-efficient transmission in high-speed mobile millimeter wave(mm Wave)networks,hybrid precoding and relay collaboration technologies have significant advantages in ensuring transmission link stability and improving system energy efficiency.The additional information links to compensate for mm Wave fading losses can be constructed by relay-assisted communication networks,and combining hybrid precoding techniques to further enhance the capacity and energy efficiency of the system.Hence,this dissertation focuses on the study of hybrid precoding techniques for relay collaboration in high-speed mobile mm Wave channels.Firstly,to improve the beamforming gain of the relay system in high-speed mobile mm Wave channel and reduce the hardware cost of the hybrid precoding architecture,the influence of the hybrid precoding with different precision phase shifters on the performance of the relay system under the known channel state is studied.In order to maximize the spectral efficiency of the system,the complexity of solving the optimal hybrid precoding matrix is reduced by decoupling the multi-node complex optimization problem,and the discrete orthogonal matching pursuit algorithm is used to solve the optimization of the relay hybrid precoding matrix.Numerical results have shown that the proposed discrete hybrid precoding scheme has lower quantization loss for the relay transmitter,and the spectrum efficiency of the low quantization precision phase shifter is close to that of the full precision phase shifter.Secondly,for the full-duplex relay system in imperfect mm Wave channel,the performance of a hybrid precoding system with different quantization bit phase shifters is studied.Considering the transmission process with residual self-interference noise,the optimization function with incomplete channel state information is transformed into a low complexity norm minimization formal equation.On this basis,a relaxation optimization algorithm based on quantization step size and alternating direction multiplier method is proposed.Under the condition of arbitrary quantization accuracy,the tradeoff between spectrum efficiency and energy efficiency is obtained.The numerical results show that the transmission power plays a positive role in the quantization loss compensation,but too high transmission power will reduce the energy efficiency.Finally,to further reduce the energy consumption of mm Wave communication systems and ensure successful communication when the direct view link is blocked,the design and optimization of the hybrid precoding scheme under the condition of multi-level link blocking are studied.Firstly,in order to maximize the spectral efficiency,an orthogonal matching codebook dictionary algorithm is proposed to design base station hybrid precoding for non-blocking cases.Secondly,for mild congestion,the radiation power in the beam range is optimized to compensate for the performance loss caused by congestion,and the base station hybrid precoding is designed through the updated codebook dictionary.Then,a multi-block alternating optimization algorithm framework is proposed to jointly optimize the base station hybrid precoding codebook dictionary,passive phase shift matrix and power allocation factor.Numerical results show that the proposed scheme can effectively deal with random congestion while ensuring the minimum Qo S required by users and that to obtain more economical system performance,users with different Qo S requirements need to provide transmission power with the gap.