Research On MIMO OTA Channel Emulation Method Based On Multi-Probe Anechoic Chamber

With the advent of next-generation mobile communication technology,data transmission rates are getting faster and faster.Millimeter wave technology and MIMO(Multiple Input Multiple Output)technology have been widely applied,which leads to the high integration of MIMO device and brings difficulties to the assessment of MIMO device.The MIMO OTA(Over The Air)testing method based on multi-probe anechoic chamber reduces the difficulty of testing MIMO device greatly.In addition,it can assess the radio performance of MIMO device.Channel emulation method is the core problem of MIMO OTA testing.That is how to map the ideal channel model onto a limited number of probes through a certain algorithm,and then they are transmitted from the probes to synthesize an accurate channel model in the test area,so as to assess the performance of MIMO device accurately.The specific content of this thesis is divided into the following three aspects:1.A novel channel emulation method is proposed,which is based on the doppler characteristics of multipath channel.In this thesis,it allocates the subpaths with different doppler frequencies onto the probes with appropriate angles.Compared with prefaded synthesis method and spatial fading emulator method,the novel channel emulation method can reproduce more accurate channel model than spatial fading emulator under the same number of subpaths.Apart from this,it complements the drawback that doppler spectrum for all the probes are identical for prefaded synthesis method.2.The accuracy of 3D channel model reproduced in multi-probe anechoic chamber is investigated.In this thesis,the emulated channel transmission functions for plane wave synthesis and prefaded synthesis method in the case of 3D channel model are deduced,and the corresponding spatial correlation functions of the two methods are further derived.Finally,taking the root mean square of the deviation between target spatial correlation and emulated spatial correlation as the criterion,the accuracy of the channel model reproduced by two methods in test area is compared.3.The effect of 2D and 3D multi-probe setups on the accuracy of the reproduced channel model in test area is investigated.In this thesis,taking the dimension of multi-probe setup as the main variable,the influence of target channel model and multi-probe configuration on the accuracy of the reproduced channel model are investigated when different channel emulation methods are applied.