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Standardization efforts to define radiated metrics and test methods for verifying millimeter-wave (mmWave) new radio (NR) devices are currently ongoing. Multiprobe 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 communication, 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 2-D and 3-D testing setup), applicable for both near-field and far-field conditions and robust (i.e., insensitive to measurement distance errors). [ABSTRACT FROM AUTHOR]

Hybrid beamforming antenna arrays are a prominent component in communications at millimeter-wave frequencies. Multiple analog beamforming arrays will be used for spatial multiplexing of signals also in hand-held devices. In this letter, we derive the correlation coefficient for signals received by two ideal arrays in simple power angular distribution schemes. The purpose is to develop tools for evaluating over-the-air (OTA) setups for testing of hybrid beamforming devices. We show a few exemplary correlation error evaluations that compare near-field multiprobe OTA setups with a perfect target channel model. Results indicate that the correlation error increases with decreasing range length and channel angular spread. Moreover, larger interarray spacing and subarray sizes increase the correlation error. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 (UE) 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 UE. 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 $16 \times 16$ planar arrays can be tested with a range length of 1 m and with at minimum eight active dual polarized probes. [ABSTRACT FROM AUTHOR]

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 $2\times 2$ 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 $4\times 4$ MIMO terminals. [ABSTRACT FROM AUTHOR]

A simple throughput model for multiple-input–multiple-output (MIMO) systems has been proposed in the literature. The model takes the MIMO antenna effects into account and shows good agreement with measured throughputs in a reverberation chamber (RC). The RC emulates a multipath environment with isotropic incoming angular distribution and Rayleigh (or Rician) fading channel. In this work, we extend the throughput model to arbitrary multipath environments and verify it using (synthesized) multiprobe anechoic chamber method and two-stage method with various channel models. The throughput model can well predict the measured throughputs of all the cases. [ABSTRACT FROM AUTHOR]

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., $\rho > 0.5$). [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

This paper discusses virtual drive testing (VDT) for multiple-input multiple-output (MIMO)-capable terminals in multiprobe anechoic chamber (MPAC) setups. We propose to perform VDT, via reproducing ray-tracing (RT)-simulated channels with the field synthesis technique. Simulation results demonstrate that realistic RT channels can be accurately reproduced within the test zone with a limited number of probes in MPAC setups. The feasibility of performing VDT via reproducing RT-simulated channels is supported by measurement results in a practical three-dimensional (3-D) MPAC setup. The amplitude and phase of the electric field have been measured throughout the test zone with a calibration dipole, and excellent match between simulation and measurement was achieved. [ABSTRACT FROM PUBLISHER]