A mmWave MIMO Joint Radar-Communication Testbed with Radar-assisted Precoding

As the demand for vehicle-to-everything communication (V2X) band in the 5.9 GHz increases, the millimeter-wave spectrum offers alternative options in unlicensed or radar-dedicated bands with wider bandwidth. Joint radar-communication (JRC) systems emerge as a comprehensive solution to effectively utilize these bands by integrating both functions within the same waveform and hardware. In this work, we present a multiple-input and multiple-output (MIMO) JRC testbed, operating in the 24 GHz mmWave band, utilizing orthogonal frequency division multiplexing (OFDM) waveform that simultaneously carries data across all subcarriers. In particular, we develop a real-time operating, full-duplex JRC prototype with a fully-digital front-end and software-defined radios, providing enhanced flexibility and capability. Additionally, for systems with high computational power, we introduce a high-resolution range-angle processing method based on the MUSIC algorithm. Through mobile experiments with multiple targets, we showcase simultaneous data transmission and high-resolution radar processing capabilities enabled by the fully-digital MIMO architecture. By leveraging radar's tracking capability, we propose a radar-assisted precoding approach, offering a low-complexity beamforming solution with reduced feedback overhead. Our experimental results demonstrate that the proposed precoding method achieves comparable performance compared to the conventional precoding method.