Analysis of Test Volume Size in 3D MIMO OTA for 5G

Abstract

The method based on the multiprobe anechoic chamber (MPAC) has become the mainstream solution for multiple input multiple output (MIMO) over the air (OTA) testing in recent years. In the MPAC method, the device under test should be located within the entire test volume to ensure the accuracy of the MIMO OTA testing results. As the size of wireless terminals increasing, how to determine the maximum of test volume size (MTVS) becomes crucial. In this paper, we present a new method to calculate the MTVS of the ellipsoid-shaped test volume (horizontal plane is round) for any selected channel model and probe configuration. Compared with the sphere-shaped test volume, the ellipsoid-shaped test volume can support the testing of larger wireless terminals without extra expenditure. The MTVS in two different shapes is compared by proposed indicators. By changing the probe positions, the effect of the probe positions on MTVS of the ellipsoid-shaped test volume is studied to obtain a larger MTVS. Based on the simulation results, it is concluded that using the ellipsoid-shaped test volume can obtain a larger test volume size, which is more in line with the needs of MIMO OTA testing.