# Research on Performance Metrics and Environmental Conditions for 5G MIMO OTA
)1 State Key Laboratory of Media Convergence and Communication, School of Information and Communication Engineering, Communication University of China, Beijing 100024, China; [EMAIL_ADDRESS] (M.Q. );[EMAIL_ADDRESS] (Z.C. )1 State Key Laboratory of Media Convergence and Communication, School of Information and Communication Engineering, Communication University of China, Beijing 100024, China; [EMAIL_ADDRESS] (M.Q. );[EMAIL_ADDRESS] (Z.C. )1 State Key Laboratory of Media Convergence and Communication, School of Information and Communication Engineering, Communication University of China, Beijing 100024, China; [EMAIL_ADDRESS] (M.Q. );[EMAIL_ADDRESS] (Z.C. )1 State Key Laboratory of Media Convergence and Communication, School of Information and Communication Engineering, Communication University of China, Beijing 100024, China; [EMAIL_ADDRESS] (M.Q. );[EMAIL_ADDRESS] (Z.C. )1 State Key Laboratory of Media Convergence and Communication, School of Information and Communication Engineering, Communication University of China, Beijing 100024, China; [EMAIL_ADDRESS] (M.Q. );[EMAIL_ADDRESS] (Z.C. )1 State Key Laboratory of Media Convergence and Communication, School of Information and Communication Engineering, Communication University of China, Beijing 100024, China; [EMAIL_ADDRESS] (M.Q. );[EMAIL_ADDRESS] (Z.C. )1 State Key Laboratory of Media Convergence and Communication, School of Information and Communication Engineering, Communication University of China, Beijing 100024, China; [EMAIL_ADDRESS] (M.Q. );[EMAIL_ADDRESS] (Z.C. required in 4G user equipment (UEs), and more MIMO antennas will be installed in 5G smartphones and beyond [13; 14; 15; 16; 17; 18]. For MIMO UE, OTA testing of radiated multi-antenna reception performance is crucial to guarantee actual network performance and has been mandated by the Cellular Telecommunication and Internet Association (CTIA) and the 3 rd Generation Partnership Project (3 GPP) as the standard method to evaluate the transceiver performance of MIMO wireless devices [19; 20; 21]. For LTE MIMO OTA, 3 GPP and CTIA use different figures of merits (FoMs) and environmental conditions to evaluate MIMO performance of smartphones under Spatial Channel Model Extended (SCME) UMa and UMi channel models. In 3 GPP, Total Radiated Multi-antenna Sensitivity (TRMS) under noise-limited environmental condition is selected as the FoM with both UMa and UMi channel models. In CTIA, MIMO Average Radiated SIR Sensitivity (MARSS) under interference-limited environmental condition is defined as the FoM with only UMi channel model. Under noise-limited environmental condition, UE MIMO throughput performance is evaluated in terms of the minimum downlink power at a low downlink signal level. Under interference-limited environmental condition, UE MIMO throughput performance is evaluated in terms of the minimum signal to interference ratio (SIR) at a relatively high downlink signal power from the emulator while the level of an additive white gaussian noise (AWGN) power is varied. A comparison of MIMO OTA methods in 3 GPP and CTIA is listed in Table 1. For 5G MIMO OTA, 3 GPP has specified the clustered delay line (CDL) channel models as the reference channel models. Compared with LTE (2 \(\times\) 2), higher order (4 \(\times\) 4) is required in 5G channel models. In addition, the channel environment in 5G presents higher directivity due to higher operating frequency, which requires new FoMs characterizing variance per spatial orientation. So far, environmental conditions and FoMs for 5G MIMO OTA have not been determined yet. Therefore, analysis and performance comparison of environmental conditions and related FoMs aforementioned are of great importance to determine which ones should be adopted in 5G MIMO OTA. The objective of this paper is to compare and define the performance metrics and environmental conditions for the verification of the radiated multi-antenna reception performance of 5G MIMO DUTs.