Enabling VNA Based Channel Sounder for 6G Research: Challenges and Solutions

To support research and development for sixth-generation (6G) communication, it is imperative to understand the application needs and develop accurate and realistic channel models to meet the application needs. Several key radio technologies are identified for 6G research, including utilization of frequency bands ranging from sub-6 GHz to THz, antenna configuration covering simple single antenna to complicated gigantic multiple-input and multiple-output (MIMO) systems, and diverse deployment scenarios requiring various measurement ranges. This paper summarizes latest strategies to significantly extend the capabilities of current vector network analyzer (VNA)-based channel sounder, mainly radio-over-fiber (RoF) to enable long-range channel measurements, phase compensation to achieve accurate and coherent phase measurement, frequency extension to extend the carrier frequency and frequency bandwidth, and virtual antenna array (VAA) schemes to enable multi-antenna/link channel measurements.