Hierarchical Codebook Design for Near-Field MmWave MIMO Communications Systems

TL;DR

This paper proposes a hierarchical near-field codebook design for mmWave MIMO systems, addressing spherical wavefront effects in large antenna arrays to improve beamforming accuracy.

Contribution

It introduces a novel hierarchical codebook design tailored for near-field conditions, including steering gain calculation and beam placement methods.

Findings

Enhanced beam coverage in near-field scenarios

Superior performance of the proposed codebook in simulations

Effective beam rotation and relocation techniques

Abstract

Communications system with analog or hybrid analog/digital architectures usually relies on a pre-defined codebook to perform beamforming. With the increase in the size of the antenna array, the characteristics of the spherical wavefront in the near-field situation are not negligible. Therefore, it is necessary to design a codebook that is adaptive to near-field scenarios. In this letter, we investigate the hierarchical codebook design method in the near-field situation. We develop a steering beam gain calculation method and design the lower-layer codebook to satisfy the coverage of the Fresnel region. For the upper-layer codebook, we propose beam rotation and beam relocation methods to place an arbitrary beam pattern at target locations. The simulation results show the superiority of the proposed near-field hierarchical codebook design.