Hybrid beamforming method in multiple-input-multiple-output multi-user communication system

The invention discloses a hybrid beamforming method in a multi-input multi-output multi-user communication system. The hybrid beamforming method comprises the following steps: (S1) solving complete digital beamforming B under multiple users; (2) according to the complete digital beamforming B, solving hybrid beamforming by adopting an alternating minimum algorithm; wherein the hybrid beamforming comprises an optimal analog beamforming matrix A and a digital beamforming matrix D. According to the method, firstly, the completely solved digital beam forming is expressed as an expression containing matrix inversion, and the matrix inversion is converted into an expression based on Neumann series solving, so that matrix singular value decomposition and matrix inversion with high calculation complexity are avoided. In the design of hybrid beam forming, the overall framework adopts an alternative minimization idea, and when the hybrid beam forming is solved, a gradient projection method is adopted, so that rapid con