On the achievable secrecy rate of the MIMO VLC Gaussian wiretap channel

We investigate in this paper the achievable secrecy rate of the multiple-input multiple-output (MIMO) visible light communication (VLC) Gaussian wiretap channel. We consider a system model comprising three nodes: one transmitter (Alice) equipped with multiple fixtures of LEDs, one legitimate receiver (Bob) and one eavesdropper (Eve), each equipped with multiple photo-diodes (PDs). We study at first the problem of optimal signaling scheme that maximizes the achievable secrecy rate of the MIMO VLC wiretap channel. We consider the cases where the location of Eve is known (i.e. perfect channel state information (CSI)) or unknown (i.e. imperfect CSI). Finally, we derive an upper bound on the secrecy capacity that we used to assess the closeness of the achievable secrecy rate to the derived bound.