Space-Time Coding Design for RIS-Assisted Integrated Sensing and Communication System

This letter designs a reconfigurable intelligent surface (RIS) assisted integrated sensing and communication (ISAC) system, where time division multiplexing cooperated with the space-time coding for the RIS is employed. In the communication subframe, the RIS is utilized to realize quadrature phase shift keying (QPSK) modulation. During the sensing, the angle information corresponding to the location of the user is extracted by controlling the space-time code of the RIS. Addressing the instability and low sensing accuracy of the traditional random coding strategy, this letter proposes a spatial codebook design scheme, which improves the sensing performance greatly. Besides, the transmitter performs beamforming based on the sensing information, achieving the synergistic enhancement of the communication quality and sensing accuracy.