Enhanced Physical Layer Security and PAPR Performance Based on Disturbance of Data Cluster Under Chaotic Sequence Color Seeking Mechanism in CO- OFDM System

This study proposes a physical layer encryption scheme based on disturbance of data cluster under color seeking mechanism of chaotic sequence which is generated by Brownian motion determined by keys aiming to improve security of coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. Chaotic sequences with good randomness and unpredictability are endowed with a unique color composed of two primary colors and go through order transformation by sorting and seeking, which forms the chaotic sequence color seeking mechanism. The disturbance of transmitted data is realized according to chaotic sequence color seeking mechanism and PAPR performance is optimized simultaneously. The security of system is enhanced due to a key space of 10
⁹⁰
and PAPR can be reduced by 0.5 dB. An experiment conducted in a 40 GHz 16QAM CO-OFDM system over an 80 km standard single mode fiber (SSMF) shows that the authorized user can successfully decrypt the received signal, while the eavesdroppers cannot derive valid information with bit error rate (BER) at approximately 0.5. Analyses of peak to average power ratio (PAPR) performance and time complexity of the scheme are further carried out under different cluster forming methods to derive the optimized configuration which is critical in encryption.