  Visible Light Communication (VLC) systems have relatively higher security
compared with traditional Radio Frequency (RF) channels due to line-of-sight
(LOS) propagation. However, they still are susceptible to eavesdropping. The
proposed solution of the papers have been built on existing work on
hyperchaos-based security measure to increase physical layer security from
eavesdroppers. A fourth-order Henon map is used to scramble the constellation
diagrams of the transmitted signals. The scramblers change the constellation
symbol of the system using a key. That key on the receiver side de-scrambles
the received data. The presented modulation scheme takes advantage of a higher
degree of the map to isolate the data transmission to a single dimension,
allowing for better scrambling and synchronization. A sliding mode controller
is used at the receiver in a master-slave configuration for projective
synchronization of the two Henon maps, which helps de-scramble the received
data. The data is only isolated for the users aware of the key for
synchronization, providing security against eavesdroppers. The proposed VLC
system is compared against various existing approaches based on various
metrics. An improved Bit Error Rate and a lower information leakage are
achieved for a variety of modulation schemes at an acceptable Signal-to-Noise
Ratio.
