RIS-Assisted Simultaneous Transmission and Secret Key Generation: An ICAS Paradigm

We propose an integrated communications and security (ICAS) design paradigm that is RIS-assisted simultaneous transmission and secret key generation by sharing RIS for these two tasks. Specifically, the legitimate transceivers intend to jointly optimize the data transmission rate and the key generation rate by configuring the phase-shift of RIS in the presence of a smart attacker. We first derive the key generation rate of the RIS-assisted physical layer key generation (PLKG). Then, we model the problem as a finite Markov decision process and propose a model-free reinforcement learning approach to optimize the phase-shift of RIS. Particularly, due to the channel state information (CSI) of the attacker cannot obtain in real-world conditions, we develop a deep recurrent Q-network (DRQN) based dynamic ST strategy. Simulation results show that the proposed DRQN based dynamic ST strategy has a better performance than the benchmarks even with a partial observation information, and achieves “one time pad” communication by allocating a suitable weight factor for data transmission and PLKG.