Eight-Planar-Monopole MIMO Circular Array Generating Eight Uncorrelated Waves for 6G Upper Mid-Band 8 × 8 MIMO Access Points

For next-generation or six-generation (6G) mobile communications, the 8 x 8 MIMO operation is envisioned for the user. In this case, as compared to the fifth-generation (5G) mid-band 4 x 4 MIMO operation, a much larger spectral efficiency can be expected for the user, which in turn will effectively increase the user-experienced data throughput with a fixed carrier bandwidth. For such applications, to transmit eight MIMO streams for the 6G 8 x 8 MIMO access point, a simple yet compact MIMO array formed by eight planar monopoles arranged in a circular array with radial metal walls to generate eight uncorrelated waves is presented in this study. The MIMO array operates in a wide band of 5.9-8.4 GHz, which covers the possible new 6G mobile bands in 5.925-7.125 GHz and 7.125-8.4 GHz. The targeted new 6G mobile bands are in the upper mid-band’s lower frequency region, close to the 5G mid-band, and are expected to show similar rich multipath scattering as the 5G 4 x 4 MIMO operation. To verify it, we apply the proposed MIMO array to transmit eight MIMO streams for the 8 x 8 MIMO operation in a practical on-campus scenario and obtain a spectral efficiency of about 34 bps/Hz, which is about two times that of the 5G 4 x 4 MIMO operation. The results indicate that the proposed MIMO array is promising for applications in the 6G 8 x 8 MIMO system.