A RIS-Aided OFDM-Based Integrated Sensing and Communication System for Communication, Detection, and Tracking

In integrated sensing and communication (ISAC) systems, multi-antennas are commonly used for spatial processing, resulting in high cost and extra complexity. To tackle this issue, we propose an efficient ISAC system by combining reconfigurable intelligent surface (RIS) and orthogonal frequency-division multiplexing (OFDM) technologies, which can process signals in the time-frequency-space domains. In particular, an integrated waveform is designed by adding a time slot in each frame of the OFDM signals. In this time slot, the ISAC system transmits a single-tone signal and the RIS generates a set of random patterns to sense the spatial information of the cooperative user and noncooperative target. The perceived spatial information retrieved in the previous OFDM frame is used in the current OFDM frame to form an adaptive mechanism of beam tracking. Range and velocity detections are implemented by processing the transmitted and received OFDM symbols. Finally, a prototype of the RIS-aided ISAC system is established and is experimentally verified in terms of wireless communication, detection, and tracking.