Pair Scheduling and Beamforming in STAR-RIS Empowered ISAC Networks

A novel simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) empowered integrated sensing and communication (ISAC) framework with non-orthogonal multiple access (NOMA) scheme is proposed, referred to as STAR-NOMA-ISAC. The average weighted sum-rate problem is formulated by jointly optimizing user pair scheduling, active beamforming, and passive beamforming, subject to the sensing intensity and communication quality requirements. A dual-layer penalty-based algorithm is proposed, which greatly enlarges the objective values from the initial points, with guaranteeing the rank-1 and 0-1 integer constraints. Numerical results demonstrate that the proposed STAR-NOMA-ISAC framework has the following superiorities: 1) the STAR-RIS outperforms the reflecting-only or transmitting-only RIS for improving the transmission rate; and 2) the adopted NOMA achieves significant advantages in terms of enhancing the spectrum efficiency than the time division multiple access (TDMA) scheme.