Research On Key Technologies Of High-security Multi-carrier Modulation Based On Chaos Improvemen

The exponential growth of global data traffic is driving the demand for high-capacity optical transmission systems and networks.New multi-carrier modulation technology is constantly proposed and improved by domestic and foreign researchers.Chaos encryption algorithm provides a reliable idea for physical layer security,and has the advantages of high randomness,anti-interference,anti-interception and so on.The PAPR（Peak-to-Average Power Rate）of multi-carrier system is also an important issue.Aiming at improving the security and capacity of multi-carrier optical fiber transmission system,this paper studies the improved high-security multi-carrier modulation technology based on chaos,breaks through the chaos of the traditional chaotic mapping model,reduces the high PAPR of multi-carrier system,and uses joint modulation to improve the transmission capacity of multi-carrier.The specific research contents are as follows:（1）An Orthogonal Frequency Division Multiplexing（OFDM）passive optical network（PON）transmission scheme based on improved chaotic model is proposed.The Lyapunov index of Lorenz chaos model improved by 295%based on the feedback factor.The chaotic model generates three masking matrices that encrypt the constellation,subcarrier frequency and symbol of OFDM.Using the idle frequency band of OFDM,a method to reduce signal PAPR is proposed according to the characteristics of signal itself,which achieves the reduction of 1.6d B PAPR with low computational complexity.A transmission experiment of 25 km single-mode fiber（SMF）with 14.7 Gb/s was established,and the key space was up to 10⁹⁰.（2）In order to improve the transmission capacity,performance and safety of the system,a kind of multi-carrier co-modulation transmission system based on modified Selective Mapping（SLM）algorithm is proposed,which can increase the transmission capacity by 50%within the same transmission time.The SLM algorithm is creatively combined with the chaotic model,and the pseudo-random sequence is generated by the chaotic model.The transmission side band problem is solved,and the PAPR performance of 3.8 d B is improved under low computational complexity,and the key sensitivity is high,and the key space resistant to brute force cracking reaches 10¹³⁶.In order to verify the feasibility of this scheme,a 2 km seven-core SMF optical transmission system was built and 97.4 Gb/s transmission experiment was achieved.