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Experimental evaluations of multiuser MIMO with two-dimensional antenna configuration

This paper presents experimental results for multiuser-multiple input multiple output (MU-MIMO) with a two-dimensional antenna configuration. MU-MIMO can increase spectral efficiency significantly by employing many antennas at the base station (BS). However, the performance is upper-bounded when many antennas are arranged in a line because antenna spacing has to be small to maintain the required span for antenna arrangement. In order to overcome the problem, this paper evaluates a two-dimensional antenna configuration, where multiple antennas are set in both the horizontal and vertical directions using the testbed developed by the authors. The experimental results show that the spectral efficiency with a two-dimensional antenna configuration is 12.8 % higher than that with conventional linear array configuration when the span for the antenna arrangement in the horizontal direction is constrained to 7λ, where λ indicates the wavelength of carrier frequency.