Research on Performance Metrics and Environmental Conditions for 5G MIMO OTA

Meijun Qu,Xianhui Liu,Siyang Sun,Zihan Chen

doi:10.3390/electronics11050747

Abstract

For Multiple-input, multiple-output (MIMO) user equipment (UE), over-the-air (OTA) testing of radiated multi-antenna reception performance is crucial to guarantee actual network performance and is mandatory in North America, Europe and China. For 5G MIMO OTA, 3GPP has specified the clustered delay line (CDL) channel models as the reference channel models, which present higher order and directivity than those of 4G. Therefore, which kinds of performance metrics and environmental conditions are feasible and necessary to better characterize the MIMO performance should be studied. In this paper, MIMO OTA measurement results of different figures of merits (FoMs) under both UE noise-limited and interference-limited environmental conditions have been compared and discussed, respectively. In addition, the impact of different channel models on MIMO OTA throughput performance as well as the variance per azimuth are compared. Based on the analysis, Peak-Null can better reflect the difference between the 12 azimuth positions than Variance. Total Radiated Multi-antenna Sensitivity (TRMS) under both channel models presents nearly the same performance trends at different thresholds. On the contrary, MIMO Average Radiated SIR Sensitivity (MARSS) exhibits a high dependence on channel models. The MARSS under UMi channel model shows a much smaller performance variation between UEs than UMa channel model. TRMS under 3GPP UE noise-limited environmental condition exhibits a stronger ability to distinguish between good and bad performing devices than that of MARSS under CTIA interference-limited environmental condition. The discrepancy can reach 4 dB at most. This discrepancy does not come from different average manners between TRMS and MARSS, but originates from environmental condition itself. Therefore, it is proposed to adopt TRMS under UE noise-limited environmental condition as the unique or baseline test condition in 5G FR1 MIMO OTA. Peak-Null can be considered as a secondary FoM to characterize the variance per azimuth.

Highlights

A multiple-input, multiple-output (MIMO) system is adopted in 4G and 5G mobile communications to achieve higher channel capacity and data throughput [1–5]
It can be concluded that Total Radiated Multi-antenna Sensitivity (TRMS) under user equipment (UE) noise-limited environmental condition has a stronger ability to distinguish between good and bad performing UE devices than that of MIMO Average Radiated signal to interference ratio (SIR) Sensitivity (MARSS) under Cellular Telecommunication and Internet Association (CTIA)
In our experiments, limited by the testing time, only 7 of 10 DUTs were tested with alternative channel models (i.e., Uma for TRMS under 3GPP UE noise-limited environmental condition and UMi for MARSS under CTIA interference-limited environmental condition)

Summary

Introduction

A multiple-input, multiple-output (MIMO) system is adopted in 4G and 5G mobile communications to achieve higher channel capacity and data throughput [1–5]. The requirements for high rates of wireless communication networks grow exponentially with the applications of smart terminals and the development of MIMO and antenna arrays [6–12]. It is reported in [2] that with 8 MIMO antennas for 8 × 8 MIMO operation in one smartphone, the channel capacity can reach 37 bps/Hz at a 20 dB signal-to-noise ratio (SNR), which is much larger than that of a single antenna for single-input, single-output (SISO) operation. 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 3rd Generation Partnership Project (3GPP) as the standard method to evaluate the transceiver performance of MIMO wireless devices [19–21]

Objectives

Methods

Results

Conclusion