Improving Availability and Confidentiality via Hyperchaotic Baseband Frequency Hopping Based on Optical OFDM in VLC Networks

The security in visible-light communication (VLC) networks has recently gained attention. This work presents a hyperchaotic baseband frequency hopping method based on optical orthogonal frequency-division multiplexing (Hyperchaos-BB-FH-OOFDM) that can enhance both confidentiality and availability in VLC networks. A four-dimensional hyperchaotic scheme is employed for chaotic mapping. The proposed method exploits the random feature of the input data and chaotic codes to improve the confidentiality against correlation and statistical attacks and to improve the availability against illumination, disguised, and noise jamming. Using the chaotic scheme, the bipolar real OFDM samples are exploited to create dynamic cypher keys and spreading codes that are updated at each frame throughout the entire session, leading to high security against malicious attacks. The proposed method employs a four-fold encryption approach that involves chaotic frequency/time-domain scrambling of OFDM subcarriers, chaotic phase scrambling of frequency-domain subcarriers, and chaotic spreading of the OFDM signals upon transmission. According to the results, in addition to enhancing the confidentiality and availability, the method supports multiplexing, reduces the peak-to-average-power ratio of the OFDM signal, and improves the bit error rate performance for OFDM-based VLC networks.