Extreme-MIMO Field Trials in 7 GHz Band: Unlocking the Potential of New Spectrum for 6G

TL;DR

This paper explores the use of extreme MIMO with 256 ports at 7 GHz for 6G, demonstrating high throughput in urban environments through simulations and field trials, and discusses deployment challenges.

Contribution

It introduces a 256-port X-MIMO prototype for 7 GHz, providing real-world field trial results and analyzing its potential for 6G high-capacity wireless communication.

Findings

Achieved over 3 Gbps for a single user in urban outdoor environments.

Validated the feasibility of 8-layer downlink single-user MIMO at 7 GHz.

Showed large digital aperture supports high-order spatial multiplexing.

Abstract

The frequency range around 7 GHz has emerged as a promising upper mid-band spectrum for 6th generation (6G), offering a practical balance between coverage and capacity. To fully exploit this band, however, future systems require substantially stronger beamforming and spatial multiplexing capability than today's 5G 64-port commercial deployments. This article investigates extreme multiple-input multiple-output (X-MIMO) with 256 digital ports as a practical 6G architecture for 7 GHz operation. First, through system-level simulations, we examine the throughput benefits and design trade-offs of increasing the number of base station (BS) and user equipment (UE) digital antenna ports, including comparisons between 128-port and 256-port configurations. We then present a 256-port 7 GHz BS and UE prototype and report field-trial results obtained in urban outdoor environments. The measurements demonstrate the feasibility of 8-layer downlink single-user MIMO over a 100 MHz bandwidth, achieving more than 3 Gbps for a single user under urban outdoor propagation conditions. Channel analysis based on measured data further suggests how the large digital aperture of X-MIMO supports high-order spatial multiplexing even with limited dominant angular clusters. Finally, we identify key challenges and outline research directions toward practical deployment of 7 GHz X-MIMO systems for 6G.