Performance Analysis of Key Distribution System Based on Short-term Correlation of Fiber Channel

This paper proposes a key distribution system based on short-time correlation of optical fiber channels. The communicating parties adopt the odd-even interleaved data transmission method to send binary random number sequences to each other. Taking advantage of the close arrangement of data parity, the data obtained by the communicating parties has short-time correlation characteristics. By analyzing the bit error rate (BER) of the transmitted data, quantizing and encoding the BER, and executing the key negotiation protocol, the short-time correlation characteristics of the channel can be extracted, and the original key with good consistency can be obtained. The experimental results show that when the optical fiber length between Alice and Bob is 40 km, the signal is modulated by Quadrature Phase Shift Keying with Orthogonal Frequency Division Multiplexing (QPSK-OFDM), the signal transmission rate is 1 Gbit/s, and the channel BER is about 0.2, the change trend of the BER sampling values measured by Alice and Bob has good consistency. After the BER sampling value is quantized and encoded, the original key with a consistency rate of 95.93% is finally obtained. We further analyze the impact of the quantization threshold on the number of keys and key error rate under different BER. When L = 50, L×ασ = 2.5, and BER = 0.12, 146 keys can be obtained, and the key error rate is 0, which is the best key generation effect.