Energy Efficiency Maximization of MIMO Systems through Reconfigurable Holographic Beamforming

TL;DR

This paper proposes a novel holographic beamforming approach using reconfigurable metasurfaces in MIMO systems to significantly improve energy efficiency, with a low-complexity optimization algorithm and analytical solutions for special cases.

Contribution

It introduces a new architecture with reconfigurable metasurfaces for energy-efficient MIMO communication and develops an efficient optimization algorithm with analytical solutions for specific scenarios.

Findings

Holographic beamforming with metasurfaces enhances energy efficiency.

The proposed algorithm converges to a first-order optimal point.

Significant energy efficiency gains over digital beamforming architectures.

Abstract

This study considers a point-to-point wireless link, in which both the transmitter and receiver are equipped with multiple antennas. In addition, two reconfigurable metasurfaces are deployed, one in the immediate vicinity of the transmit antenna array, and one in the immediate vicinity of the receive antenna array. The resulting architecture implements a holographic beamforming structure at both the transmitter and receiver. In this scenario, the system energy efficiency is optimized with respect to the transmit covariance matrix, and the reflection matrices of the two metasurfaces. A low-complexity algorithm is developed, which is guaranteed to converge to a first-order optimal point of the energy efficiency maximization problem. Moreover, closed-form expressions are derived for the metasurface matrices in the special case of single-antenna or single-stream transmission. The two metasurfaces are considered to be nearly-passive and subject to global reflection constraints. A numerical performance analysis is conducted to assess the performance of the proposed optimization methods, showing, in particular, that the use of holographic beamforming by metasurfaces can provide significant energy efficiency gains compared to fully digital beamforming architectures, even when the latter achieve substantial multiplexing gains.