Walsh-coded orthogonal chaotic shift keying for key distribution in visible light communication systems

In contemporary society, secure communications employing chaotic communication schemes have opened new challenges. Chaotic communication schemes in which signals are spectrally spread, with low power spectral density, become useful to improve resilience against multipath fading, making them increasingly important for indoor applications in the framework of visible light communication (VLC). Here, we will explore the 16-QAM orthogonal shift key in combination with Walsh coded chaotic basis for application of a secure VLC link, used simultaneously for illumination and security-enhanced data transmission. The experimental results are carried out for a 12 Baud symbol rate, indicating a symbol error rate below the FEC hard threshold limit for an optical irradiance higher than 25 mW/cm(2), covering a 1.4 m(2) operating area.