Probabilistic Shaping Encryption Scheme Based on Dual-Parameter Bit-Weighted Distribution Matching in MMW-RoF System

In order to face the challenges of reliable performance and physical layer security performance in millimeter-wave radio-over-fiber (MMW-RoF), a probabilistic shaping (PS) encryption scheme based on dual-parameter bit-weighted distribution matching is proposed. In the proposed scheme, the implementation of PS depends on changing the bit probability of 32-quadrature amplitude modulation symbol, and dual parameters are utilized to control PS in bit sequences. Meanwhile, two hyperchaotic systems are used to accomplish diffusion and PS encryption. The encryption scheme based on PS cannot affect the distribution of constellation mapping. Analysis results show that the proposed scheme has a key space of 10432, which can effectively prevent brute force attacks. Diffusion significantly reduces the correlation between the plaintext and the corresponding ciphertext, which can effectively resist the chosen-plaintext attacks. In the experiment, the orthogonal frequency division multiplexing signals with PS encryption are successfully transmitted over 50 km standard single-mode fiber (SSMF) and 3m wireless channel. Experimental results show that, compared with the uniformly distributed signal, the PS encryption signal can achieve ∼1.62 dB and ∼1.87 dB received optical power gain for back-to-back and 50 km SSMF transmission when the bit error rate is 10-3. The advantages of the proposed scheme in terms of reliable performance and physical layer security performance are verified, showing that the scheme has good application potential in MMW-RoF.