Hybrid precoding design for terahertz dynamic array-of-subarrays architecture

Abstract

Terahertz (THz) communication is a key technology to 6G wireless communication systems. Due to the extremely short wavelength of THz wave, ultra-massive multiple-input multiple-output (UM-MIMO) systems can be realized. The high array gain generated by UM-MIMO systems can overcome the limitation of THz communication distance. In UM-MIMO systems architectures, dynamic array-of-subarrays (DAoSA) architecture can dynamically adjust the connections between radio frequency (RF) chains and subarrays according to the channel state. In this paper, a hybrid precoding scheme of DAoSA architecture with low complexity and good performance is proposed. Hybrid precoding of UM-MIMO systems is optimized with the spectral-energy efficiency rate (SEER) maximization as the objective function. To reduce the computation complexity of optimization problem, the intractable original problem is decoupled into two subproblems that can be solved easily. Then, element-by-element (EBE) algorithm is proposed to solve the DAoSA hybrid precoding subproblem. Furthermore, to determine the connections of the switch es, a logistic chaotic searching algorithm (LCS) is proposed, which can obtain the global optimal solution without traversing repeatedly all connections under a fixed search space. Simulation results showed that the proposed DAoSA hybrid precoding scheme can achieve higher SEER than the existing papers.