Time-frequency domain encryption with SLM scheme for physical-layer security in an OFDM-PON system

The security of orthogonal-frequency-division-multiplexing-based passive optical network (OFDM-PON) systems has been an important problem recently. In this paper, a time-frequency domain encryption technique based on multi-chaotics for physical layer security and selected mapping (SLM) for peak-to-average-power ratio (PAPR) reduction is proposed and experimentally demonstrated in an OFDM-PON system. The proposed scheme is based on Lozi and Logistic maps and can generate chaotic sequences to scramble the subcarrier in both the time and frequency domains for enhancing physical layer security. Meanwhile, a SLM method can be applied in the scheme to improve the PAPR performance of the system. In the experiment, an 8.9 Gb/s encrypted OFDM signal has been securely transmitted over 100 km standard single-mode fiber. The results show that the proposed method can effectively enhance the physical layer security and simultaneously improve the bit-error-rate performance of the system.