Research On Dynamic Encryption Technology Of OFDM-PON Jointed With Compressed Sensing

In the digital age,multimedia,as a common information medium,plays an increasingly important role in people's production and life.OFDM-PON is regarded as an important solution for optical access networks due to its advantages of flexible resource allocation,high spectral efficiency,and strong robustness to fiber dispersion.With the continuous growth of business scale and number of users,OFDM-PON has an increasing demand for the transmission of multimedia data such as images.Massive data put pressure on the bandwidth resources of OFDM-PON,and frequent malicious attacks and eavesdropping also threaten its security.This thesis aims to solve the problems of improving the compression rate of transmitted image data and enhancing system security in the OFDM-PON system.By studying the current mainstream processing methods of multimedia data and hotspot schemes for physical layer security and transmission performance improvement,a method on dynamic encryption technology of system jointed with compressed sensing is proposed.First,the method encrypts and encodes the image data transmitted by the system through joint compressed sensing,and achieves a high compression ratio and high-security transmission while maintaining a low sampling rate.Second,the method encrypts the traditional data stream transmitted by the system through dynamic encryption technology,which realizes the enhancement of system security and the improvement of transmission performance.Finally,the two aspects are combined to form a complete full-cycle processing and protection scheme for various types of data in the OFDM-PON.The main work and contributions of this thesis are as follows:(1)A joint compressed sensing encryption and coding technology scheme is proposed,which combines the advantages of compressed sensing and JPEG coding to compressed sample and encrypted encode the image data in OFDM-PON.Firstly,this scheme uses chaos to control the generation of circulant matrix to perform block compressive sensing and encryption on image data.Secondly,the sampled data is analyzed,and differentiated quantization is performed according to its characteristics,which greatly reduces redundancy compared to traditional quantization methods.Thirdly,the quantized coefficients are scrambled and encrypted within the group to further break the correlation of the images while ensuring the compression ratio.Finally,according to the quantized data distribution,the serpentine path is used for value acquisition and entropy coding.It has been verified that the scheme increases the compression ratio by 5-8 times while maintaining the high quality of image restoration and improves the bandwidth utilization efficiency and data storage security of OFDM-PON effectively.(2)An OFDM-PON dynamic encryption technology scheme is proposed,which is implemented based on dynamic DNA encryption and cellular automata layered symbol encryption.Firstly,this scheme uses chaos to control the encoding and decoding rules of traditional DNA encryption,and performs dynamic segmentation encryption on binary data streams,such a method adds dynamic position scrambling based on sequence encryption,which improves the system's randomness and resistance to brute force cracking.Then,for the QAM modulation symbols,IQ stratification and cell division are performed,and chaos is used to scramble the positions of the cells within or between the layers.Finally,for the interior of the cell,the scheme uses the chaos and parallelism of reversible cellular automata to perform IQ parallel encryption of QAM symbols to achieve higher security.Since the scrambling and encryption process changes the phase relationship among the constellation points,this scheme ameliorates the communication performance of the system while improving the security performance.