A Directly Connected OTA Measurement for Performance Evaluation of 5G Adaptive Beamforming Terminals

Abstract

Spatially beamformed communication, which is achieved by antenna array and multiple-input and multiple-output (MIMO) technologies, has become the most critical technology to drastically increase spectrum utilization rate of 5G. To guarantee the successful deployment of 5G, different aspects of device design, particularly those related to radio-frequency front end and antenna array for enabling beamformed communication, have to be accurately verified. It is more cost effective to identify design imperfections through lab testing rather than using field testing-based trial and error approaches, especially for the explosive growth of 5G-enabled Internet of Things devices. In this article, a directly connected over-the-air (OTA) test solution for 5G MIMO OTA evaluations with the focus on dynamic beamforming devices is proposed. The proposed solution can mathematically achieve constructions among the S ports of base station (BS) and U ports of the receiving antenna array, which makes it possible for measuring the throughput of terminal with an adaptive beamforming array in an OTA way. All system parameters are emulated, including S elements BS antenna gain, U elements of receiving terminal performance, and 3-D <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S{\times }U$ </tex-math></inline-formula> propagation channel characteristics. To further validate the theoretical analysis and test procedure, a newly developed 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\times }$ </tex-math></inline-formula> 4 5G MIMO device is measured in terms of its throughput. The results exactly reflect the true performance of the proposed solution under realistic operational conditions.