Low-Complexity Multicast Beamforming for Millimeter Wave Communications

TL;DR

This paper introduces a low-complexity multicast beamforming approach for millimeter wave communications, utilizing channel gain estimation and sub-array division to reduce computational load while maintaining performance.

Contribution

It proposes a novel channel gain estimation method and a sub-array division technique to simplify multicast beamforming design in millimeter wave systems.

Findings

Significant reduction in computational complexity.

Performance comparable to existing methods.

Effective use of phase factors for additional degrees of freedom.

Abstract

To develop a low-complexity multicast beamforming method for millimeter wave communications, we first propose a channel gain estimation method in this article. We use the beam sweeping to find the best codeword and its two neighboring codewords to form a composite beam. We then estimate the channel gain based on the composite beam, which is computed off-line by minimizing the variance of beam gain within beam coverage. With the estimated channel gain, we propose a multicast beamforming design method under the max-min fair (MMF) criterion. To reduce the computational complexity, we divide the large antenna array into several small-size sub-arrays, where the size of each sub-array is determined by the estimated channel gain. In particular, we introduce a phase factor for each sub-array to explore additional degree of freedom for the considered problem. Simulation results show that the proposed multicast beamforming design method can substantially reduce the computational complexity with little performance sacrifice compared to the existing methods.