Passive Channel Sounding, Modeling, and Emulation for Achieving Virtual Drive Testing of MIMO-Capable Radios

Virtual drive test (VDT) has emerged as a promising solution for evaluating performance of multiple-input multiple-output (MIMO)-capable radios under realistic conditions. However, acquiring radio channels in practical deployment scenarios and replaying recorded channels in the laboratory setup, which is the essence for the VDT framework, still present significant challenges. Passive channel sounding, which can capture radio channels in the live cellular network, becomes a promising strategy. However, channel modeling and emulation based on data collected in passive channel-sounding campaign have not been well addressed in the state-of-art. In this work, we propose a novel channel modeling and emulation framework for the recorded channel data by the passive channel sounder, to achieve the VDT purpose. To demonstrate our proposed framework, a channel measurement campaign was conducted in the fifth-generation (5G) commercial network based on the home-developed passive channel sounder. The estimated multipath components based on the recorded channel data demonstrate that the base station (BS) beamforming can significantly impact the radio channels. The performance of different commercial user equipment (UE) is then evaluated under the recorded and emulated radio channels in the laboratory setup, where different figures-of-metrics (FoMs), including reference signal receiving power (RSRP), modulation and coding scheme (MCS), and throughput, were thoroughly analyzed. The experimental results clearly demonstrate the feasibility of the proposed VDT framework in the laboratory setup.