This paper proposes a novel coding scheme for Visible Light Communications (VLC) systems using symbol mapping permutations on the color domain. The permutation is done through symbol-hopping over the points of an optimized 4-CSK constellation. This scheme provides diversity gains, promises robustness against monochromatic channel degradation, and increases the information security of the communication link. It can also be used in conjunction with Single-Input and Single-Output (SISO) systems, as well as in Multiple-Input and Multiple-Output (MIMO) systems. Monte Carlo computational simulations evaluate the performance of the proposed scheme over the conventional QuadLED (QLED) CSK system and other codes, showing superior coding and diversity gains over two direct competitors, under a Rician flat-fading channel.

The Optical Camera Communication (OCC) technology allows Visible Light Communications (VLC), one of the key technologies for the Sixth Generation (6G) of mobile communications, to be used with image sensors on the receiver side. For Screen-to-Camera (S2C) applications, in which Light Emitting Diode (LED) screens are used to send information symbols, increasing either (transmitted) image resolution or video frame rate may negatively impact the bit error performance and the visual quality of the OCC-encoded videos. This work proposes a completely new OCC/S2C transmission and reception system, in which it is possible to recover both the transmitted symbols and to restore the video quality at the same time. For this dual-task, a Parallel Factor Analysis (PARAFAC) decomposition is applied to model an OCC system for the first time in the literature. Computational simulations corroborate the correct formulation of the proposed models, propositions and algorithms, in addition to demonstrating that increasing the number of frames of the OCC-encoded video can generate diversity gains. This work also includes discussion on the practical aspects of data rate, data volume, and computational complexity of the receiver, accordingly to the system’s parameters.