A Virtual Over-the-Air Method for 5G Massive MIMO Base Station Testing With Flexible Virtual Probes

Huaqiang Gao,Yuanan Liu,Yongle Wu,Weimin Wang,Gert Frolund Pedersen

doi:10.1109/access.2019.2931435

Abstract

Massive multiple-input-multiple-output (MIMO) is known as a large-scale antenna technology and has been enabled for the fifth generation (5G) mobile communication systems. The over-the-air (OTA) testing of massive MIMO antenna system has attracted a lot of attention in terms of evaluating the radio performance of a 5G base station (BS). As a promising OTA test methodology, the sectored multi-probe anechoic chamber (MPAC) setup is employed for the performance testing of massive MIMO BS. However, the system cost and installation are still an issue to be considered in practice (e.g., the anechoic chamber and multiple probes), though it can accurately reconstruct the flexible propagation channels by channel emulation methods. This paper proposes a virtual OTA test framework for the performance testing of massive MIMO BS on the basis of MPAC setups. As an alternative, the proposed virtual OTA test system adopting the concept of virtual probes solves the inconveniences and limitations of the actual probe installation in MPAC setups. The BS array responses to the actual probes of MPAC setups are generated in a phase matrix for the virtual probes. First, in this paper, the system description of virtual OTA testing is given. Then, the emulation method of spatial clusters is presented for the virtual OTA testing. Finally, simulations are performed with good channel emulation accuracy.

Highlights

The fifth generation (5G) wireless telecommunication systems are currently in standardization phase [1]–[3]
The function of active OTA probes to emulate spatial cluster characteristics in sectored multi-probe anechoic chamber (MPAC) setups is equivalent to the far-field array responses, which can be realized by a phase matrix
The main contributions of this paper lies in following aspects: 1) Challenges for the existing 3D sectored MPAC setup is discussed for massive multiple-input multiple-output (MIMO) base station (BS) testing and a virtual OTA test framework using virtual probes is proposed based on an MPAC method

Summary

INTRODUCTION

The fifth generation (5G) wireless telecommunication systems are currently in standardization phase [1]–[3]. The general idea of 3D sectored MPAC OTA setups for massive MIMO BS testing is to select probe locations and determine probe weights in the context of prefaded signal synthesis (PFS) or plane wave synthesis (PWS) method. The function of active OTA probes to emulate spatial cluster characteristics in sectored MPAC setups is equivalent to the far-field array responses (phase rotation of signals received at DUT elements), which can be realized by a phase matrix. The limitations relative with chamber size does not exist in the virtual OTA testing because the far-field array response is carried out in the phase matrix. The main contributions of this paper lies in following aspects: 1) Challenges for the existing 3D sectored MPAC setup is discussed for massive MIMO BS testing and a virtual OTA test framework using virtual probes is proposed based on an MPAC method. Scalars are shown in regular font, while vectors and matrices are in bold font

VIRTUAL OTA TEST SYSTEM

SIMULATION SETTINGS AND RESULTS

VIRTUAL PROBES AND PHASE MATRIX

CONCLUSION