Biblio

Visible light communications (VLC) have been the focus of many recent investigations due to its potential for transmitting data at a higher bitrate than conventional communication systems. Alongside the advantages of being energy efficient through the use of LEDs (Light Emitting Diodes), it is imperative that these systems also take in consideration privacy and security measures available. This work highlights the technical aspects of a typical 16-QAM (Quadrature Amplitude Modulation) VLC system incorporating an enhanced privacy feature using an hyperchaotic map to scramble the symbols. The results obtained in this study showed a low dispersion symbol constellation while communicating at 100 Baud and with a 1 m link. Using the measured EVM (Error Vector Magnitude) of the constellation, the BER (Bit Error Rate) of this system was estimated to be bellow 10−12 which is lower than the threshold limit of 3.8.10−3 that corresponds to the 7% hard-decision forward error correction (HD- FEC) for optimal transmission, showing that this technique can be implemented with higher bitrates and with a higher modulation index.

In this paper a new physical layer security method is proposed against eavesdropping attacks. Our purpose is to demonstrate that performance of the legitimate receiver can be increased and performance of the eavesdropper can be decreased by matching between the roll of factors of root raised cosine filters in the transmitter and receiver. Through the matching between the roll of factors (a), a performance difference is generated between the legitimate receiver and the eavesdropper. By using three software defined radio nodes error vector magnitude of the legitimate receiver and the eavesdropper is measured according to roll of factors. Performance differences the receiver are demonstrated when the roll off factor is matched and mismatched.