8x8 MU-MIMO
8x8 MIMO, often referred to as 8T8R, uses eight antennas to establish up to eight spatial data streams with a receiving device. Compared to traditional single-antenna systems (SISO), 8x8 MIMO can theoretically increase throughput by up to 800%, although in real-world deployments the actual gain is typically much lower.
When eight spatial streams are active, the data payload is distributed across all eight antennas and transmitted within the same frequency band. Unlike standard 2x2 MIMO configurations, 8x8 MIMO does not rely on eight independent polarizations. Instead, it combines dual-polarized antenna elements with spatial separation to achieve multiple data streams.
Designing 8x8 MIMO antenna systems requires extensive computer simulation and optimization to ensure low envelope correlation and sufficient isolation between antenna ports. These parameters are critical for maintaining independent spatial streams and achieving meaningful throughput gains.
Field measurements conducted by Ericsson in 2012 showed that 8x8 MIMO can effectively double the throughput of a 4x4 MIMO network, provided that the base station is well isolated from co-channel interference and that the propagation environment offers rich scattering conditions to support multiple signal paths.
In practical deployments, achieving the expected performance of 8x8 MIMO depends not only on the radio technology itself, but also on antenna design, installation quality and the surrounding RF environment. Without proper isolation and favorable propagation conditions, the performance gains may be significantly limited.
Despite its potential, 8x8 MIMO has not been widely deployed due to the relatively small ecosystem of user equipment (UE) supporting this configuration. As a result, many mobile network operators have chosen to move directly towards Massive MIMO, which provides throughput improvements for standard 2x2 and 4x4 devices, as well as significant gains for more advanced terminals supporting Transmission Mode 9 (TM9) and newer technologies.