(UAV) trajectory and reconfigurable intelligent surface (RIS) reflection coefficients in UAV-
RIS-assisted cognitive non-terrestrial networks (NTNs) to enhance the secrecy performance.
The practical RIS phase shift model, outdated channel state information (CSI) and
interference from neighboring satellites are considered. We introduce a deep reinforcement
learning (DRL) algorithm to solve the UAV trajectory optimization problem to enhance the …