STAR-RIS-Assisted Multicast Communications in DFRC-UAV-Enabled ISAC Systems

In this letter, we study a dual-function radar-communication unmanned aerial vehicle (DFRC-UAV)- enabled integrated sensing and communications (ISAC) system, and propose a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) assisted DFRC-UAV-enabled ISAC scheme called SRaDUI, where a DFRC-UAV simultaneously senses ground targets and multicasts information to users assisted by a STAR-RIS. To improve the multicast capacity, we formulate an achievable rate maximization problem by jointly designing the scheduling of targets, the covariance matrices of the transmitted symbol vectors, the STAR-RIS coefficients, and the DFRC-UAV trajectory. To address this non-convex problem, we propose an alternating optimization (AO) based iterative algorithm, decomposing the original problem into a series of subproblems, which can be solved alternately to obtain suboptimal solutions based on the semidefinite relaxation (SDR) and successive convex approximation (SCA). Numerical results demonstrate the superiority of the proposed SRaDUI scheme and the effectiveness of the designed iterative algorithm.