Design Development And Verification Of OTA Module For 5G Test

With the application of Massive Multiple-input multiple-output and millimeter wave technology in 5G,the limitations of the conduction test are becoming more and more obvious.Over the air(OTA)testing which can provide realistic conditions for the Device under test without cable connection in the lab has attracted extensive attention.Multiple-probe anechoic chamber(MPAC)OTA testing is the main solution of the OTA testing method for its advantage that can controllably and repeatably reconstruct any channel models in theory.The Reconstruction of the Channel model by the Channel Model Emulator is the core of MPAC OTA testing.This dissertation completed the design,development,and verification of the OTA module of the channel emulator based on the Pre-faded Signals Synthesis(PFS)method for the demand of the 5G test,and the problem of probe selection in the test is studied to improve the efficiency and accuracy of channel model reconstructed by the OTA module.The main works of this dissertation are as follows:1.The OTA module of the channel simulator is designed and developed.The channel model reconstruction methods of Multi-Probe Anechoic Chamber and Simple Sectored Multi-Probe Anechoic Chamber(SS-MPAC)used in 5G user equipment test are studied.Based on the channel simulation modeling technique and the theory of channel model reconstruction by PFS,the OTA module of the channel simulator is designed and developed.The statistical characteristics of the reconstructed channel model are compared with the target channel model including power delay spectrum,time correlation,and cross-polarization power ratio,and the correctness of the channel reconstruction function of the OTA module is verified.2.The probe selection problem of the SS-MPAC system is studied.To solve the problem that the computation time of probe selection is too long and the testing efficiency is lowered when the number of available probes is large,a dynamic step-size Multi-shot algorithm and a probe selection algorithm based on Orthogonal Matching Pursuit are proposed to improve the efficiency of probe selection exploiting the sparsity of the probe weight matrix.Simulation experiments show that the two algorithms given in this thesis can effectively improve the efficiency of probe selection.In order to improve the channel model reconstruction accuracy under the small number of probes,this thesis proposes a probe selection algorithm based on the differential evolution algorithm,which finds the global optimal solution through a heuristic random search,and the simulation analysis shows that when the number of valid probes is small,the probe selection algorithm based on the differential evolution can obtain a valid probe set with high channel model reconstruction accuracy,effectively improving the channel model reconstruction accuracy under the low number of probes condition.The simulation analysis shows that when the number of effective probes is small,the set of effective probes with high channel model reconstruction accuracy can be obtained.