Research On Over-the-Air Test Method For Massive MIMO Devices Based On Multiprobe Anechoic Chamber

Performance testing plays an important role at the stage of research and producing for communication device.On one hand,performance testing can test the performance of the product,on the other hand,it can effectively find problems and make targeted improvements.In the future 5th generation mobile communication system,the base stations using massive multiple input multiple output(MIMO)technology are widely deployed to improve system capacity and user experience.The process from research to mass producing can not do without performance testing and the test method applied to massive MIMO base stations is exactly the focus of this paper.By comparing the conductive method,reverberation chamber method,two-step method and multiple probe anechoic chamber(MPAC)method,the MPAC method is selected as basic test method for massive MIMO base stations and the problems faced in the actual test is pointed out and studied.The MPAC method is applied at first in the MIMO over-the-air(OTA)test so that the performance testing result for MIMO device is compared with other test solution provider to ensure the correct execution of this method.As for the problems that need to be faced during applying the MPAC method to massive MIMO device,two issues of probe allocation and far field implementation are studied in this paper.Firstly,the probes5 positions need to be determined according to the target channel conditions to synthesize target environment in the test area.The artificial bee colony algorithm is applied to the selection of the probe position in this paper,which achieves better results than the previous multishot algorithm.In addition,two allocation principles respectively based on single cluster and multiple clusters are proposed in this paper and it is found that using single cluster as the basic allocation unit can reconstruct channel better.Secondly,performance testing needs to be performed under far-field conditions while large anechoic chamber is need for massive MIMO test,which will increase the cost of testing.Therefore,a new test system structure is proposed,which utilizes the signal superposition theory to achieve approximate far field conditions in the test area.