Frequency-Selective Hybrid Beamforming Based on Implicit CSI for Millimeter Wave Systems

TL;DR

This paper proposes a low-complexity hybrid beamforming scheme for millimeter wave systems that uses implicit channel information derived from coupling coefficients, simplifying the process while maintaining high data rates.

Contribution

It introduces a novel hybrid beamforming method leveraging implicit CSI from coupling coefficients, reducing complexity in high-dimensional millimeter wave channels.

Findings

Effective channel matrices identified by Frobenius norm maximize beamforming performance.

The proposed scheme achieves comparable data rates with lower computational complexity.

Implicit CSI-based approach simplifies hybrid beamforming implementation.

Abstract

Hybrid beamforming is a promising concept to achieve high data rate transmission at millimeter waves. To implement it in a transceiver, many references optimally adapt to a high-dimensional multi-antenna channel but more or less ignore the complexity of the channel estimation. Realizing that received coupling coefficients of the channel and pairs of possible analog beamforming vectors can be used for analog beam selection, we further propose a low-complexity scheme that exploits the coupling coefficients to implement hybrid beamforming. Essentially, the coupling coefficients can be regarded as implicit channel state information (CSI), and the estimates of these coupling coefficients yield alternatives of effective channel matrices of much lower dimension. After calculating the Frobenius norm of these effective channel matrices, it turns out that the effective channel having the largest value of the Frobenius norm provides the solution to hybrid beamforming problem.