Secrecy Analysis of Generalized Space-Shift Keying Aided Visible Light Communication

This paper investigates the physical layer security (PLS) problem of visible light communication (VLC) systems relying on generalized space-shift keying (GSSK) termed as GSSK-VLC. The GSSK-VLC system considered is assumed to be comprised of three nodes: a transmitter equipped with multiple light-emitting diodes (LEDs), a legitimate receiver as well as a passive eavesdropper. Each of them is equipped with a single photo-detector (PD). Specifically, the average mutual information (AMI) of a GSSK-VLC system is derived. We also obtain both a lower bound and an accurate closed-form expression of the approximate AMI, which can be employed for efficiently estimating the achievable secrecy rate of GSSK-VLC systems. Furthermore, the pairwise error probability (PEP) and bit error rate (BER) of GSSK-VLC systems are analyzed, and again some closed-form expressions are obtained. Additionally, in order to enhance the secrecy performance of the GSSK-VLC system, an optimal LED pattern selection algorithm is proposed under the minimax criterion. We show that the proposed LED pattern selection algorithm is capable of enhancing both the AMI between the transmitter and legitimate user as well as the achievable secrecy rate of the GSSK-VLC system.