Research On Encryption Algorithm For Secure OFDM-PON System Based On Hyperchaotic Sequences

OFDM technology which can transmit multiple signals within a channel has been widely used in optical fiber communication and other fields of communication,due to its high spectrum efficiency and strong dispersion tolerance,and it can effectively resist selective fading of frequency.With the transmission information capacity increasing brought about by the development of society,combining OFDM technology with PON system to construct OFDM-PON system to realize a more efficient,high-speed and flexible optical access network is the current research hotspot.As the participants of information transmission on the optical network are increasing,how to ensure the security of information becomes a very important task.Applying chaos technology to the secure communication area can solve this problem partly,because of high unpredictability and pseudo-random nature of the chaos.This essay makes a key research on encryption performance of OFDM-PON system based on hyperchaotic sequences.This thesis introduces hyperchaotic system and OFDM-PON system,then hybrid TWDM-PON,TDM-OFDM-PON and WDM-OFDM-PON systems are mentioned.And the simulation experiments are completed in the Optisystem communication simulation software and Matlab software.The main works in this study are as follow:(1)Combining WDM technology and TDM-PON to construct hybrid TWDM-PON system meets the growing bandwidth demand.Comprehensive analysis of the system under different conditions(such as optical branching ratio,optical power,dispersion and rate)laid a good commercial foundation.(2)A four level encryption TDM-OFDM-PON scheme with hyperchaotic sequences,subcarrier mask,FRFT and SLM algorithm is proposed and experimentally demonstrated due to the shortage of security performance of optical transmission network.The key which controls the encryption process is generated by hyperchaotic system and the receiver must use the same hyperchaotic sequence to decrypt information.Unpredictability of dynamic behavior of hyperchaotic system guarantees the secure transmission of information.This scheme has a well performance in encryption performance through simulation experiment and data analysis.(3)Proposing a five level encryption WDM-OFDM-PON scheme with timing synchronization,channel estimation,subcarrier mask,Packet FRFT and SLM algorithm.Hyperchaotic sequences control every step of the encryption system.Hyperchaotic system further improves the security of the system because of more initial values and greater key space.Simulation results show that the scheme simultaneously improve the physical security and the transmission performance,verifying the feasibility of hyperchaotic encryption system in the optical fiber communication network.