Exploiting NOMA and RIS in Integrated Sensing and Communication

A novel integrated sensing and communication (ISAC) system is proposed, where a dual-functional base station utilized to transmit the superimposed non-orthogonal multiple access (NOMA) signal for serving users targets simultaneously. Furthermore, new reconfigurable intelligent surface (RIS)-aided-sensing structure, dedicated RIS deployed provide virtual line-of-sight (LoS) links radar targets, also proposed address significant path loss or blockage of LoS task. Based on this setup, beampattern gain at target derived adopted as metric. The objective paper maximize minimum by jointly optimizing active beamforming (BS), power allocation coefficients among NOMA passive RIS. To tackle non-convexity formulated optimization problem, constraints are first transformed into more tractable forms. Then, an iterative block coordinate descent (IBCD) algorithm employing successive convex approximation (SCA), Schur complement, semidefinite relaxation (SDR) sequential rank-one constraint (SRCR) methods. reduce complexity IBCD algorithm, low-complexity alternating (IAO) proposed. Particularly, optimized solving programming (SDP) problem closed-form solutions derived. Numerical results show that: i) RIS-NOMA-ISAC always outperforms RIS-ISAC without in illumination power; ii) IAO achieves comparable performance that achieved algorithm. iii) high can be joint algorithms underloaded overloaded scenarios.