Abstract
This paper proposes an over-the-air (OTA) testing setup for millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) equipment using cascaded amplitude and phase modulation (APM) network and channel emulator. Compared with the existing test setup with mechanical switch, the proposed testing setup enables more accurate reconstruction of the radio channel environment under the multiprobe anechoic chamber (MPAC) setup without increasing the number of channel emulators (CEs) to control the system cost. The constructed MPAC testing setup for mmWave and massive MIMO equipment is composed of an anechoic chamber, a sectored probe wall containing a number of probes, an APM network, a fading channel emulator, and a user emulator (UE). In this paper, the structural model and the performance advantages of the proposed radiated testing setup are described, and a fully connected APM network for radiated testing is more prominent than the existing switch. Moreover, the angular spectrum is selected as the performance metric for the reconstructed channel. The ability of the proposed system to reconstruct the power angular spectrum (PAS) of the target channel is studied under both static and dynamic channel models, which can reflect the performance of beamforming procedures of the massive MIMO antenna arrays, e.g., beam acquisition, tracking, and refinement. The simulation results for angular spectrum support the superiority of the proposed OTA testing setup. Furthermore, the simulations for average channel capacity also show that radiated testing setup using cascaded APM network and channel emulator is valid.
Highlights
Due to the large amount of available spectrum in the millimeter-wave band, mmWave communication has become an important technology in 5G cellular communication systems
For the mmWave massive multiple-input multiple-output (MIMO) antenna testing, a three-dimensional (3D) sectored multiprobe anechoic chamber (MPAC) setup is proposed [4]. e MPAC OTA testing setup for the massive MIMO equipment is composed of an anechoic chamber which can shield external interference signals and absorb reflected waves, a sectored probe wall which can place a large number of probes, a switch system, a channel emulator, and an user emulator. e procedure of the massive MIMO OTA testing and the configuration of the sectored OTA setup are detailed in [5]
We have proposed a MPAC testing setup for mmWave massive MIMO devices using cascaded APM network and channel emulators (CEs). e internal structure of the APM network and the drawbacks of mechanical switch for the mmWave devices testing are introduced in detail. e paper uses spherical angular spectrum to determine probe weights instead of using the spatial correlation
Summary
Due to the large amount of available spectrum in the millimeter-wave (mmWave) band, mmWave communication has become an important technology in 5G cellular communication systems. E MPAC OTA testing setup for the massive MIMO equipment is composed of an anechoic chamber which can shield external interference signals and absorb reflected waves, a sectored probe wall which can place a large number of probes, a switch system (mechanical relay switch: the key parameters, e.g., switching speed, insertion loss, isolation, cost, crosstalk, and lifetime, are dependent on the manufacturing technology of the switch), a channel emulator, and an user emulator. Given the shortcomings of the mechanical relay switch, a new system structure is required and applied to the mmWave massive MIMO OTA testing system. In view of the above drawbacks of the current mmWave OTA testing system with switches, this paper proposes the amplitude and phase modulation (APM) network, which is fully connected and digital, to replace the mechanical switch in the MPAC setup. Erefore, the MPAC testing setup with a cascaded APM network and channel emulator (CE) model is presented in this paper.
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