A flexible millimeter-wave radio channel emulator design with experimental validations

A millimeter-wave (mm-wave) channel emulator (CE) is an essential tool for air-interface testing of the upcoming mm-wave communication systems. A flexible CE, which is capable of frequency setting from sub-6 GHz to mm-wave bands and flexible system bandwidth setting, is highly desirable. This is due to the fact that potential frequency bands and system bandwidths are undecided for mm-wave systems and it is likely that multibands with scalable system bandwidths will be supported. In this communication, a frequency-extension scheme based on frequency up-and-down conversion and a novel bandwidth enhancement scheme based on the band-combining principle are proposed to upgrade the existing sub-6 GHz CE to meet the requirements in the mm-wave CE design. The designed mm-wave CE is experimentally validated, where the measured Doppler and delay profiles agree well with the target ones. Moreover, the beamforming validation measurements showed that excellent gain and phase control of the mm-wave CE output ports can be realized.