On OTA throughput evaluation of 8×8 MIMO handset antennas using 3D channel models

Multiple input multiple output (MIMO) throughput evaluation in over-the-air (OTA) testing labs is currently using standardized 2D geometry-based radio channel models, like SCME and WINNER II channels especially for 2×2 MIMO case. With fifth generation (5G) development, high order MIMO capable devices, supporting 4×4 and 8×8 MIMO are coming which rise the need for more accurate MIMO OTA testing framework. In this paper we mainly demonstrate, using idealistic and realistic MIMO antenna designs for portable devices, that conventional MIMO throughput OTA evaluation framework with 2D-channel model can underestimate the actual MIMO throughput, mainly in 8×8 MIMO case. To illustrate this we first started with an idealistic and generic 2×2, 4×4 and 8×8 MIMO designs where we evaluated the corresponding MIMO throughput for both 3D and 2D channel cases in free space scenario. Secondly we introduced a more realistic 8×8 MIMO antenna solution for portable device operating at three 3GPP TDD bands (41, 42 & 43). Resulting efficiency, correlation, multiplexing efficiency, and channel capacity measures for 8×8 operation are presented in freespace and PDA-hand use cases. Similarly as in the idealistic design case, we conducted extensive MIMO throughput evaluation corresponding to the 8×8 realistic design and confirmed the inaccuracy of the conventional 2D channel model in MIMO OTA throughput evaluation of high order MIMO.