Hybrid Precoding With Low-Resolution PSs for Wideband Terahertz Communication Systems in The Face of Beam Squint

TL;DR

This paper proposes a hybrid precoding approach using low-resolution phase shifters for wideband Terahertz MIMO systems, addressing beam squint and hardware limitations to improve performance in 6G communications.

Contribution

It introduces a heuristic algorithm for hybrid precoding with low-resolution PSs in wideband THz MIMO, applicable to fully connected, partially connected, and dynamic subarray architectures.

Findings

Outperforms existing methods in simulation results.

Effectively mitigates beam squint effects.

Enhances performance with low-resolution PSs in wideband THz systems.

Abstract

Terahertz (THz) communication is considered one of the most critical technologies for 6G because of its abundant bandwidth. To compensate the high propagation of THz, analog/digital hybrid precoding for THz massive multiple input multiple output (MIMO) is proposed to focus signals and extend communication range. Notably, considering hardware cost and power consumption, infinite and high-resolution phase shifters (PSs) are difficult to implement in THz massive MIMO and low-resolution PSs are typically adopted in practice. However, low-resolution PSs cause severe performance degradation. Moreover, the beam squint in wideband THz massive MIMO increases the performance degradation because of the frequency independence of the analog PSs. Motivated by the above factors, in this paper, we firstly propose a heuristic algorithm under fully connected (FC) structure, which optimize the digital precoder and the analog precoder alternately. Then we migrate the proposed heuristic algorithm to the partially-connected (PC) architecture. To further improve the performance, we extend our design to dynamic subarrays in which each RF chain is connected to any antenna that does not duplicate. The numerical results demonstrate that our proposed wideband hybrid precoding with low-resolution PSs achieves better performance to the comparisons for both FC structure and PC structure.