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Fifth Generation (5G) technology is about to set its global footprint. Its success relies heavily on the standardization process, which is rapidly progressing to specify verification metrics and test methodologies for 5G New Radio (NR) device certifications. For this purpose, three-dimensional (3D) multiprobe anechoic chamber (MPAC) has been selected as a reliable reference solution for creating an accurate test environment. This paper reports first ever FR2 MIMO over-the-air (OTA) channel models validation measurements according to 3GPP specified verification procedure. The evaluated validation metrics include power-delay profile (PDP) and power-angular spectrum (PAS) similarity percentage (PSP). The measurement results closely follow the simulated and theoretical references, thereby demonstrating the feasibility of FR2 MIMO OTA channel models validation procedure adopted by 3rd Generation Partnership Project (3GPP).

Standardization efforts to define radiated metrics and test methods for verifying millimeter-wave (mmWave) new radio (NR) devices are currently ongoing. Multi-probe anechoic chamber (MPAC) method, which is capable of reproducing spatial fading channels in the test zone, is selected as the reference solution for NR device testing. It is of importance to ensure that the defined testing propagation environment in the test zone is correctly implemented. In this paper, a novel algorithm is proposed to determine the wideband power-angle-delay profile of the reconstructed channels in the test zone for mmWave NR. The proposed algorithm is shown to be generic (applicable for both 2D and 3D testing setup), applicable for both near-field and far-field conditions and robust (i.e. insensitive to measurement distance errors).

Conducted cable testing has been dominantly utilized in the industry to evaluate multiple-input multiple-output (MIMO) capable mobile terminals. However, direct RF cable connection introduces many practical problems. Therefore, radiated testing, where built-in antennas on the mobile terminal is utilized as RF interface to receive desired testing signals, is highly desirable. Wireless cable method is a radiated testing method, where signals can be guided over-the-air to respective antenna ports, just like in the conducted cable case but without RF cable connection. In this paper, several different ways to achieve wireless cable connection for mobile terminal performance testing in the radiated setup is discussed. Validation of the wireless cable method is done both in simulation and active throughput measurements. Future directions and applicability of the wireless cable method are also discussed.

This paper discusses a multi-probe anechoic chamber setup, capable of reconstructing non-stationary radio propagation environments for testing of millimetre wave and massive Multiple-Input-Multiple-Output devices. The test setup is aimed for evaluation of end to end performance of devices, including hybrid beamforming operations of antenna arrays and base band processing, in highly time variant channel conditions. In this work we present simulated comparison of an ideal reference radio channel model and corresponding model implemented with limited resources of multi-probe anechoic chamber components. We give a qualitative analysis of the results with non-line of sight channel models, without quantitative evaluation. The example device under test is a 8 × 8 planar array with half wavelength inter-element spacing.

A millimeter-wave (mm-wave) channel emulator (CE) is an essential tool for air-interface testing of the upcoming mm-wave communication systems. A flexible CE, which is capable of frequency setting from sub-6 GHz to mm-wave bands and flexible system bandwidth setting, is highly desirable. This is due to the fact that potential frequency bands and system bandwidths are undecided for mm-wave systems and it is likely that multibands with scalable system bandwidths will be supported. In this communication, a frequency-extension scheme based on frequency up-and-down conversion and a novel bandwidth enhancement scheme based on the band-combining principle are proposed to upgrade the existing sub-6 GHz CE to meet the requirements in the mm-wave CE design. The designed mm-wave CE is experimentally validated, where the measured Doppler and delay profiles agree well with the target ones. Moreover, the beamforming validation measurements showed that excellent gain and phase control of the mm-wave CE output ports can be realized.

Conducted cable setups have been dominantly utilized in the industry for performance testing of multiple-input multiple-output (MIMO) terminals. The wireless cable method, which can achieve cable connection functionality without actual radio frequency cable connections, is a promising alternative. To date, the wireless method has been only discussed for 2 × 2 MIMO terminals in the literature. However, the algorithm is not directly applicable for high-order MIMO terminals, due to the high computation complexity to determine the calibration matrix and high system cost to implement the calibration matrix. In this paper, an efficient particle swarm optimization (PSO) algorithm is proposed to determine the calibration matrix for high-order MIMO systems. Furthermore, a novel implementation of the calibration matrix in the radio channel emulator is proposed, which can significantly reduce the system cost. To validate the proposed algorithm, two MIMO mockups, each equipped with four antennas, were measured in an anechoic chamber. The measured results demonstrated the effectiveness of the PSO algorithm to establish wireless cable connections for 4×4 MIMO terminals.

Radiated testing of massive multiple-input-multiple-output devices in fading radio-channel conditions is expected to be essential in the development of the fifth-generation (5G) base stations and user equipment (TIE) operating at or close to the millimeter-wave (mm-wave) frequencies. In this paper, we present a setup upgrading the multiprobe anechoic chamber-based system designed originally for 4G TIE. We describe methods for mapping radio-channel models onto the probe configuration and discuss the differences to the former 4G case. We also propose metrics to assess the accuracy of the test setup and find key design parameters by simulations. The results with the utilized channel models indicate that at 28 GHz, up to 16 × 16 planar arrays can be tested with a range length of 1 m and with at minimum eight active dual polarized probes.

This correspondence discusses over-the-air (OTA) testing for multiple-input multiple-output (MIMO) capable terminals, with an emphasis on test zone size characterization for multi-probe anechoic chamber (MPAC) OTA configurations. For an MPAC setup, it is important to understand the test zone size that can be supported by its design. Further, it is desirable that the test zone size should be determined in terms of measured throughput deviation. However, such works have not been reported in the literature yet, due to challenges in practical MPAC setups. In this correspondence, we propose to simulate the MPAC OTA configuration and MS design in a channel emulator and perform MIMO throughput measurements in a conductive setup. With the proposed scheme, we can investigate how large a test zone can be supported for the synthetic MPAC configuration in terms of throughput deviation. This scheme is attractive, since various MS antenna designs and MPAC configurations can be flexibly selected and test zone size in terms of measured MIMO throughput deviation can be achieved. Measurement results show that with a high antenna correlation at the base station (BS) side, measured throughput results would be low, irrelevant to MPAC OTA designs and antenna designs at the MS side. Therefore, the antenna correlation at BS side should be set uncorrelated to ensure that true MS performance can be measured. Further, spatial correlation accuracy at the MS side becomes critical for throughput accuracy only when correlation values are in the high region (e.g., ρ > 0.5).

Conventional conductive method, where antennas on the device under test (DUT) are disconnected from antenna ports and replaced with radio frequency (RF) coaxial cables, has been dominantly utilized in industry to evaluate multiple-input multiple-output capable terminals. However, direct RF cable connection introduces many practical problems and a radiated method to replace cable connection is highly desirable. Existing wireless cable method relies on the knowledge of a transfer matrix between the channel emulator (CE) output ports and DUT antenna ports, and also requires an anechoic chamber, which might be impractical and expensive. In this paper, a novel wireless cable method is proposed and experimentally validated. By recording the average power (i.e., reference signal received power in the long-term evolution) per DUT antenna port and selecting optimal complex weights at the CE output ports, a wireless cable connection can be achieved. The proposed method can be executed in a small RF shielded anechoic box and offers low system cost, high measurement reliability, and repeatability.

User influence, together with propagation environments and antenna designs, determines how well multiple-input–multiple-output (MIMO) terminals operate in true usage conditions. In this letter, we investigate to what extent the user influence affects the performance of a realistic MIMO terminal under various reproduced spatial channel models in a practical 3-D multi-probe anechoic chamber setup. A terminal mock-up, operating at 2.55 GHz, together with a realistic user phantom was used, and channel models with different spatial and polarization profiles, device under test with different operation modes and orientation angles were tested.