Pioneering 6G Spectrum with Extreme-MIMO Outdoor Field Test in the 7GHz Band

The 7GHz band has been proposed as a candidate frequency higher than 5G that can still be expected to balance ultra-high-speed capacity with coverage. Samsung Research verified the viability of this band for 6G through outdoor field trials, confirming performance in real propagation environments using a PoC platform based on Extreme-MIMO (X-MIMO).

At the heart of the base station side is the X-MMU (eXtremely large Massive MIMO Unit). This device is equipped with 256 digital ports and 1024 antenna elements, and supports a 100 MHz channel in the 7.125 - 7.325 GHz range. It also secures high output power and beamforming performance of about 85 dBm EIRP, and was combined with the X-DU emulator to verify not only RF performance but also 6G air interface design.

On the UE side, a dedicated emulator developed together with Keysight Technologies was used. This platform maps 8 receive antennas 1:1 to 8 digital ports to support 8-layer downlink reception, and includes transport block processing for 7GHz, reference signal structure, and dynamic beam tracking functionality, enabling precise measurement of real channel conditions.

The field test was conducted at the Samsung Seoul R&D campus. The base station was installed on a building rooftop at a height of about 50m, and outdoor measurement points were configured across various LOS/NLOS environments at distances of 50-300m, including indoor points such as concrete buildings and offices with glass exteriors. A commercial 5G C-band (about 3.8GHz) MMU was also deployed for comparison to measure coverage differences.

The results were clear.

• On the downlink, combining 8-layer MIMO with 256QAM achieved 3.06Gbps.
• This result was achieved on a single 100MHz channel, realized even in NLOS environments at a distance of about 100m.
• It demonstrated that beamforming and precoding can effectively operate massive MIMO at 7GHz.

Coverage measurements also confirmed the potential. Based on SSB RSRP, the median gap between 7GHz and C-band was about 5.72 dB, and it was found that with appropriate beamforming and high-power design, 7GHz could also be expected to achieve outdoor reach close to that of 5G C-band. However, indoor coverage and signal penetration remain challenges, and plans call for addressing these through AI-based network optimization and advanced antenna technologies going forward.

In conclusion, 7GHz has emerged as a key spectrum candidate serving as a capacity layer for 6G, suited for urban and ultra-dense environments as well as fixed wireless access. This outdoor demonstration provided a concrete example of the bandwidth, capacity, and beamforming design direction required for 6G.