Research On Adaptive Tracking Technology Based On Hybrid Beamforming

The next generation of mobile communications has also put forward diverse requirements for application scenarios while pursuing ultra-high transmission rates.With the popularization of transportation methods such as aircraft and high-speed rail,people hope to obtain the same communication services under high-speed motion scenarios.Millimeter wave communication has attracted much attention due to its rich spectrum resources,and it also needs to combine multiple antenna beamforming techniques to compensate for the severe propagation loss.Fortunately,the extremely short wavelength associated with millimeter wave enables a large antenna array to be easily installed in a small physical dimension.However,conventional beamforming poses a multitude of diverse challenges due to the increase in the number of antennas and unique millimeter wave channel characteristics.A hybrid beamforming technology combining digital beamforming with high performance and analog beamforming with low power consumption has emerged.This paper takes the communication under high-speed moving objects as the research background,and studies the fast and effective adaptive beam tracking technology under the hybrid beamforming architecture of millimeter wave system.The main contents of this paper are as follows:Firstly,this paper studies the beamforming algorithm based on codebook search.That is,in the pre-defined beam set,we choose the beam that can obtain the maximum spectral efficiency as the beamforming matrix of the transmitter and receiver.This method can avoid complex estimation of channel state information,and simplify the calculation of forming matrix into the the multivariate function for the optimal value.In particular,we use the warm start strategy to perform initialization,which can avoid a large number of random test to save searching overhead.After obtaining a relatively good initial value,we perform alternative optimization over the precoder and combiner,and the discrete stochastic optimization is used to optimize the precoder and combiner,respectively.In this paper,the idea of stream by stream optimization is also proposed in view of the rapid increase of the codebook in the application of the three-dimensional planar array.Communication under multiple data streams independently trains the shaping vector of each data stream,which can greatly reduce the number of searches and greatly reduce the beam training time.Simulation results show that the proposed algorithm can achieve almost the same spectrum efficiency as the exhaustive search,and it reduces the search complexity significantly.Then this paper studies a blind adaptive beamforming algorithm.The algorithm is applied to a hybrid beamforming system with separate subarray partition structures.The arrival angle information of the desired signal beam can be extracted by using the delay relationship of the received signals between adjacent subarrays,and the algorithm theoretically eliminates the influence of Doppler shift on the angle estimation and can be well applied to high-speed motion.The algorithm is highly applicable in different sub array division.Simulation shows that the algorithm can get good estimation of the DOA and the convergence speed of the algorithm can be improved by increasing the number of subarrays.Finally,this paper researches and optimizes the digital forming matrix to obtain a higher output signal-to-interference and noise ratio,and has better anti-jamming performance.We propose two hybrid beamforming algorithms adapted to separate subarrays based on the linearly-constrained minimum variance criterion.Compared with the classical MVDR algorithm,the computational complexity of the algorithm is reduced.The hierarchical MVDR algorithm converts the solution of the high latitude forming matrix into two low-latitude matrix solutions.The sub-beam domain MVDR algorithm converts the solution of the antenna element weight vector into a solution to each beam direction weight vector.Simulation results show that the proposed algorithm has a stronger robustness and improves the error tolerance ability of the direction of desired signal.