Chaotic Pilot and Synchronization Encryption of Optical OFDM System Based on Polar Code

In this paper, we propose a chaotic pilot and synchronization encryption scheme for optical orthogonal frequency division multiplexing (O-OFDM) system based on polar code. In the chaotic pilot encryption scheme, the pilot structure and the pilot interval are encrypted. In the proposed scheme, the chaotic sequences produced by the three-dimensional Lorenz chaotic system are used to generate the structure of the pilot and the interval of pilot insertion, which can improve the physical layer security (PLS) of the system. Meanwhile, the chaotic sequences are also used to complete the OFDM symbol time synchronization by encrypting the training sequence. In addition, polar code is adopted to reduce the bit error rate (BER) of the system and improve system performance. Compared with the traditional OFDM signal, simulation shows that the BER performance of the system has been improved, and ~8.2dB gain can be reached at BER of 10-3 after 60km standard single-mode fiber (SSMF) transmission.