Research On Key Technologies Of 5G OTA Performance Testing

The 5th generation mobile communication system(5G)has been commercialized on a large scale and developed to millimeter wave and other higher frequency bands.In recent years,the research of the 6th generation mobile communication system(6G)has also been carried out all over the world.The radio frequency(RF)interface and antenna of high-frequency radio equipment are usually designed as an integrated structure,so the traditional conducted test method is generally no longer applicable,and may have to be tested by the over-the-air(OTA)test method.The performance of wireless devices is a key factor in user experience,and OTA performance testing of multiple-input multiple-output(MIMO)devices can effectively verify the real performance of devices in a specific channel environment.Among the existing MIMO OTA performance testing methods,the multi-probe anechoic chamber(MPAC)method is considered to be the most potential OTA testing method in the 5G era because of its superior performance advantages and applicability.In this paper,with the support of the National Natural Science Foundation of China’s major scientific research instrument development project "5G Massive MIMO Digital Multibeam Array Measurement Principle and Instrument Development",an in-depth study of the MPAC test method is carried out.The main work includes the following aspects:(1)Theoretical research and simulation verification of the multi-probe anechoic chamber method for 5G low-frequency terminal equipment.Using the spatial correlation coefficient between the virtual antennas as the figure of merit of the channel reconstruction accuracy,and uses the convex optimization algorithm to simulate the channel reconstruction of the two-dimensional single-ring and three-dimensional multiring MPAC systems.A probe selection algorithm based on memetic algorithm is designed,which can effectively reduce the number of probes and greatly reduce the cost of multi-probe system on the basis of ensuring the accuracy of channel reconstruction.Part of the content has been published in IEEE Antennas and Wireless Propagation Letters and applied for related invention patents;(2)Theoretical research and simulation verification are carried out on the multiprobe performance test methods of two types of beamforming 5G equipment,5G base stations and millimeter wave terminals.Firstly,theoretically deduce the power angular spectrum similarity percentage,which is the evaluation metric of the channel reconstruction accuracy of the sector-MPAC method,and simulate and reconstruct various standard channels in the 26 GHz frequency.The relationship between the reconstruction accuracy of various standard channels and the number of probes selected,the test distance of the anechoic chamber and the probe angular spacing is studied.A multi-probe performance test system with separate transceiver antennas is proposed,and the system is simulated and verified,which proves that the system can effectively reduce the complexity of OTA probe design;(3)Theoretical research and simulation verification of the multi-probe anechoic chamber dynamic performance test method for 5G millimeter-wave terminal equipment.In this part,the time dimension is added to the existing three-dimensional MPAC system,and a brand new four-dimensional MPAC test system is proposed.It has the ability to reconstruct time-domain non-stationary channels.Part of the content has been published in IEEE Antennas and Wireless Propagation Letters and applied for related invention patents;(4)The device under test with an 8×8 hybrid beamforming array set to 26 GHz was tested and verified in a multi-probe anechoic chamber,and the evaluation index was the spatial reconstruction accuracy of the user-defined channel model.The experimental results show that the multi-probe anechoic chamber system can accurately and effectively reconstruct the spatial RF characteristics of user-defined channels.