RIS-Aided Radar for Target Detection: Clutter Region Analysis and Joint Active-Passive Design

• Published in: IEEE transactions on signal processing Vol. 72; pp. 1706 - 1723
• Main Authors: Xie, Zhuang, Wu, Linlong, Zhu, Jiahua, Lops, Marco, Huang, Xiaotao, Shankar, M. R. Bhavani
• Format: Journal Article
• Language: English
• Published: New York IEEE 2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Clutter; Design analysis; Design optimization; Electromagnetic radiation; Iterative algorithms; Line of sight; Logic gates; majorization-minimization; Non-Line of Sight (N-LoS); Radar; Radar clutter; Radar cross-sections; Radar detection; Radar equipment; Reconfigurable Intelligent Surface (RIS); Reconfigurable intelligent surfaces; Signal to noise ratio; Target detection; waveform design; Waveforms
• ISSN: 1053-587X; 1941-0476
• DOI: 10.1109/TSP.2024.3371292

Reconfigurable Intelligent Surface (RIS) brings a transformative potential to radar systems by providing a new dimension to control electromagnetic waves. This paper focuses on enhancing target detectability through the design and analysis of RIS-aided radar. A comprehensive signal model is established, recognizing both Line of Sight (LoS) and Non-Line of Sight (N-LoS) returns, factoring in RIS location and range gate shifts. This modeling enables an examination of the RIS-dependent effect of enlarged clutter region, underscoring the essential need for precise RIS phase optimization. A joint design problem encompassing transmit waveform, receive filter, and RIS phase is then formulated with the aim to optimize Signal-to-Interference-plus-Noise-Ratio (SINR), complying with practical waveform constraints and discrete RIS phase alphabet. For this nonconvex problem, an iterative algorithm is developed to monotonically enhance SINR, ensuring convergence by alternately updating the radar waveform and RIS phases. Through the majorization-minimization framework, radar waveform updates are achieved using the feasible point pursuit technique, while a quasi-closed form solution is employed for the RIS phases. Simulation results demonstrate the efficacy of the proposed design, revealing the crucial role of RIS in the system.