Beamforming Design for Hybrid Active-Passive RIS Assisted Integrated Sensing and Communications

• Published in: IEEE communications letters Vol. 27; no. 11; pp. 2938 - 2942
• Main Authors: Liao, Chikun, Wang, Feng, Han, Guojun, Huang, Yongwei, Lau, Vincent K. N.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Array signal processing; Beamforming; Convexity; Copper; Design optimization; hybrid active-passive RIS; Integrated sensing and communication (ISAC); Interference; Optimization; Radio frequency; robust beamforming design; Sensors; Signal to noise ratio
• ISSN: 1089-7798; 1558-2558
• DOI: 10.1109/LCOMM.2023.3314609

In this letter, we investigate the robust beamforming design for a hybrid active-passive reconfigurable intelligent surface (RIS) assisted integrated sensing and communication (ISAC) system, where the RIS consists of both active and passive reflecting elements. Different from the existing works, we consider the target location estimation error. We aim to maximize the minimum sensing beampattern gain among multiple targets, subject to the signal-to-interference-plus-noise ratio (SINR) constraint for each communication user (CU), the transmit power constraints for the BS and the active elements. To address the non-convexity of the max-min RIS-assisted ISAC design problem, we propose an alternating-optimization based design solution to alternately optimize the BS's transmit beamforming design and the hybrid RIS's coefficient matrix in a low-complexity manner. Simulation results demonstrate the benefit of the proposed design scheme over the existing baseline schemes.