High-security UFMC optical transmission system of seven-core fiber based on updating the 3D discrete chaotic model

In this paper, we propose a high-security universal filtered multicarrier (UFMC) transmission system based on a novel, to the best of our knowledge, three-dimensional (3D) discrete chaotic model. The cascade of counters and the 3D discrete chaotic system is used to generate three masking factors and update these factors to encrypt the bitstream, constellation, and the information of the subcarriers. Using this structure, the key space is 10²⁷⁰ and the key is updated in a timely manner. In this work, the encryption scheme solves the dynamic degradation of chaotic cryptography. Experimental results show that there is no significant difference in error performance in comparison with before encryption. Compared with the orthogonal frequency division multiplexing (OFDM) system, the spectrum efficiency of the UFMC system is higher, which reduces out-of-band leakage and interference between services. Considering the complexity constraints of the receiver, the inter-symbol interference caused by fiber dispersion is alleviated by optimizing the distribution of data subbands, and the bit error rate (BER) performance is improved. It is shown that the UFMC system obtains 1.9 dB gain compared with the OFDM system in terms of receiver sensitivity when the BER is 10^-3. This encryption scheme has a promising application prospect in short-distance optical access systems in the future.