Ergodic Secrecy Capacity of RIS-Assisted Communication Systems in the Presence of Discrete Phase Shifts and Multiple Eavesdroppers

09/01/2020

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by   Peng Xu, et al.

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This letter investigates the ergodic secrecy capacity (ESC) of a reconfigurable intelligent surface (RIS)-assisted communication system in the presence of discrete phase shifts and multiple eavesdroppers (Eves). In particular, a closed-form approximation of the ESC is derived for both non-colluding and colluding Eves. The analytical results are shown to be accurate when the number of reflecting elements of the RIS N is large. Asymptotic analysis is provided to investigate the impact of N on the ESC, and it is proved that the ESC scales with log_2 N for both non-colluding and colluding Eves. Numerical results are provided to verify the analytical results and the obtained scaling laws.