Research On Multi-Probe Anechoic Chamber Method For 5G Antenna System OTA Testing

In the Fifth-Generation(5G)era,the number of wireless users has increased significantly,and the communication system has become more advanced.As the key technologies,the Multi-Input Multi-Output(MIMO)and millimeter-wave communication systems bring higher bandwidth and data rates to the 5G users.Meanwhile,the antenna arrays of the transmitting and receiving systems of the terminals and the base station applying the Multi-Input Multi-Output(MIMO)and millimeter-wave band have also become more complex and integrated.With these technologies adopted in the commercial 5G systems,there is an urgent need for standard test methods which are suitable to test the performance of an antenna system using such a technical device.Furthermore,the performance evaluation of the antenna system is an essential step in the antenna system design and research work.Poor performance may significantly increase the network load and affect network optimization.Over-the-air(OTA)test provides a similar environment to simulate the real transmission environment,so that all important parameters of the antenna design under test can be tested in a laboratory in a controllable,debuggable,and repeatable method.Therefore,it is considered to be a feasible method to solve the testing problem of such a complex device.Based on the above considerations,the presented thesis analyzes and compares the feasibility of applying Fourth-Generation(4G)Long Term Evolution(LTE)OTA test methods to 5G antenna system performance testing.The focus is on the system design and optimization of the multi-probe anechoic chamber method to achieve the low-cost 5G antenna system OTA testing.The main contents and innovations are summarized as follows:(1)Aiming at the problem of high system cost caused by a large number of probes in the three-dimensional multi-probe anechoic chamber system for sub-6GHz terminal OTA testing,an optimization research method for the combination of the number and position of probes based on the threshold of target channel emulation error are proposed.Firstly,by analyzing the cost characteristics of the hardware structure in the anechoic chamber,the objective function of the probe combination optimization is established based on the signal model of the anechoic chamber system and the target channel reconstruction technology.Secondly,the combined optimization method based on the decreasing algorithm and the alternate search algorithm based on the error threshold are conducted.Finally,the simulation results shown that the two methods can effectively reduce the number of probe antennas in the anechoic chamber and ensure the emulation accuracy of the target channel model.(2)Aiming at the problem of the wasteful system configuration of the simple-sectored multi-probe anechoic chamber for millimeter-wave adaptive terminal OTA testing with black-box mode,a white-box mode test method with prior knowledge of the antenna arrays is proposed.By summarizing and analyzing the antenna design types of millimeter-wave terminals,the antennas of millimeter-wave adaptive terminals are divided into the following four models:1)black box;2)the terminal with one adaptive sub-array;3)the terminal is equipped with multiple adaptive sub-arrays and operates in switch mode;4)the terminal is equipped with multiple adaptive sub-arrays and operates in spatial multiplexing mode.Furthermore,the beamforming power pattern similarity and the spatial correlation error between the sub-arrays are used as the evaluation metrics of the OTA system of the single sub-array antenna and the multiple sub-array antennae.Furthermore,the influence of system design parameters on each evaluation metric is studied by numerical analysis.Finally,the simulation results shown that the configuration parameters(including the measurement range length and the number of active probes)of the simple-sectored multi-probe anechoic chamber can be significantly reduced by utilizing the prior data of the antenna design,so as to reduce unnecessary system configuration in the black-box mode.(3)Aiming at the complex structure of the simple-sectored multi-probe anechoic chamber system for massive MIMO base station OTA testing,a heuristic algorithm-based probe combination optimization scheme is proposed,and the selection strategy of design parameters is clarified.Firstly,according to the test system configuration structure and target channel reconstruction technology,the probe subset selection strategy is optimized based on the flower pollination algorithm.Furthermore,the fixed beam power loss and beamforming power pattern similarity are used as the evaluation metrics of the OTA system.The influence of system design parameters on each evaluation metric is studied by numerical analysis.Finally,the simulation results shown that the system configuration parameters and the system structure complexity can be effectively reduced based on the optimization of the probe combination and its evaluation metrics.The results of the presented thesis are of great significance to the standardization of 5G MIMO OTA.It also has an important theoretical reference value for the actual construction of a multi-probe anechoic chamber system.