Cell-Free Terahertz Massive MIMO: A Novel Paradigm Beyond Ultra-Massive MIMO

TL;DR

This paper proposes using cell-free massive MIMO architecture at THz frequencies as an alternative to ultra-massive MIMO, demonstrating superior spectral and energy efficiency through simulations.

Contribution

It introduces cell-free massive MIMO for THz communications, offering a new paradigm that outperforms ultra-massive MIMO in key efficiency metrics.

Findings

CFmMIMO outperforms UMMIMO in spectral efficiency

CFmMIMO achieves better energy efficiency at THz frequencies

Simulation results validate the proposed approach's advantages

Abstract

Terahertz (THz) frequencies have recently garnered considerable attention due to their potential to offer abundant spectral resources for communication, as well as distinct advantages in sensing, positioning, and imaging. Nevertheless, practical implementation encounters challenges stemming from the limited distances of signal transmission, primarily due to notable propagation, absorption, and blockage losses. To address this issue, the current strategy involves employing ultra-massive multi-input multi-output (UMMIMO) to generate high beamforming gains, thereby extending the transmission range. This paper introduces an alternative solution through the utilization of cell-free massive MIMO (CFmMIMO) architecture, wherein the closest access point is actively chosen to reduce the distance, rather than relying solely on a substantial number of antennas. We compare these two techniques through simulations and the numerical results justify that CFmMIMO is superior to UMMIMO in both spectral and energy efficiency at THz frequencies.