Random Codebook-Based 3D-SCMA-OFDM High-Security Optical Communication

In this article, a three-dimensional sparse code division multiple access (SCMA) orthogonal frequency division multiplexing (OFDM) passive optical network (PON) high-security optical transmission system based on a random codebook is proposed. The system can achieve a 150% overload of access users and secure user information through chaotic encryption on the physical layer. The encryption method includes random codebooks, encrypted constellations, and encrypted frequency domain symbols. In addition, a 3D codebook design method is proposed in this article. The 3D-SCMA-OFDM signal transmission of 8.86 Gb/s is experimentally verified on a 2 km 7-core fiber. The receiver sensitivity gain of 3D-SCMA-OFDM is 3 dB compared to conventional 2D-SCMA-OFDM. This is achieved at a bit error rate of 3.8 x 10(-3) for hard decision forward error correction (HD-FEC). In addition, the complexity of the 3D-SCMA-OFDM receiver-side decoding algorithm is 86.36% lower than that of the conventional 2D-SCMA-OFDM. The reduction in complexity dramatically improves the responsiveness of the system. The key space of this encryption method is 10(165), which can strongly resist illegal reception. The results show that the 3D-SCMA-OFDM PON high-security optical transmission system proposed in this article has many points: extensive user access, good transmission performance, fast response speed, and high security. It has a broad application prospect in the future optical access network.