Simultaneous Beam and User Selection for the Beamspace mmWave/THz Massive MIMO Downlink

TL;DR

This paper proposes low-complexity algorithms for simultaneous user and beam selection in beamspace mmWave/THz massive MIMO systems, leveraging dirty paper coding to optimize sum rate and reduce computational complexity.

Contribution

It introduces a novel joint user and beam selection approach using DPC properties, enabling efficient selection based on partial beamspace channels and providing theoretical sum rate bounds.

Findings

Algorithms outperform prior solutions in sum rate.

Proposed methods significantly reduce computational complexity.

Simulation results confirm effectiveness and superiority.

Abstract

Beamspace millimeter-wave (mmWave) and terahertz (THz) massive MIMO constitute attractive schemes for next-generation communications, given their abundant bandwidth and high throughput. However, their user and beam selection problem has to be efficiently addressed. Inspired by this challenge, we develop low-complexity solutions explicitly. We introduce the dirty paper coding (DPC) into the joint user and beam selection problem. We unveil the compelling properties of the DPC sum rate in beamspace massive MIMO, showing its monotonic evolution against the number of users and beams selected. We then exploit its beneficial properties for substantially simplifying the joint user and beam selection problem. Furthermore, we develop a set of algorithms striking unique trade-offs for solving the simplified problem, facilitating simultaneous user and beam selection based on partial beamspace channels for the first time. Additionally, we derive the sum rate bound of the algorithms and analyze their complexity. Our simulation results validate the effectiveness of the proposed design and analysis, confirming their superiority over prior solutions.