Key Technology Design And Verification Of CCSDS Multi-code Channel Encoding And Decoding

Channel coding is one of the key technologies in deep space communications,and the LDPC code is one of the recommended code words in recent years.This paper designs a multi-rate LDPC codec that supports 1/2,2/3,and 4/5 code rates for deep space LDPC codes recommended by the US Consultative Committee for Space Data System(CCSDS).Under the premise of ensuring high throughput and decoding performance,the realized multi-rate codec is reduced by 50% with respect to the total resources of single-rate decoding.The main research content is as follows:First,introduce the code structure of deep space LDPC codes.Firstly,it summarizes the three representations of LDPC codes and the basic classification of LDPC codes.Secondly,it describes the deep-space LDPC code word constitution methods with different code rates and code lengths.Finally,it summarizes the development process of LDPC coding techniques and decoding techniques.Second,multi-rate LDPC encoder design.Analyze the respective implementation complexity of the generative matrix encoding method and the check matrix encoding method,and according to this codeword generation matrix has the characteristics of quasi-cyclicity,adopts a generative matrix encoding method to achieve the lowest complexity,and uses a feedback shift registering encoding method to give The design of a multi-rate LDPC encoder is given,and the overall structure and functional division of the solution are given.By sharing the same encoding structure and optimizing the storage of the generation matrix,the throughput rate of the multi-rate encoder relative to the single-rate encoder remains unchanged,while the register usage is reduced by 44%.Third,multi-rate LDPC decoder design.Through the simulation of the algorithm,the optimal minimum and decoding algorithm of selecting the appropriate correction factor outperforms the minimum sum algorithm 0.5dB,and less than 0.2dB after the log domain confidence propagation algorithm,while the logarithmic domain belief propagation algorithm has large computational complexity and implementation.Difficulties,so choose the minimum loss of performance and algorithm to achieve the minimum complexity of the algorithm;gives a multi-rate LDPC decoder design,and gives the overall structure of the program and functional division.A set of variable node processing and check node processing modules suitable for three code rates are designed,and an effective solution is provided on the matrix storage and node information cache problems,and the overall implementation of the decoder is achieved.About 50%.Fourth,multi-code rate encoder and decoder performance verification.Specific test plan,performance testing on the hardware platform,the test of multiple rate decoder and single rate decoder performance,and compared with the simulation performance,hardware implementation of the decoder performance loss within the range of 0.1 dB.The multi-rate codec designed and implemented in this thesis can realize the coding and decoding of three code rates in the CCSDS deep-space LDPC code,and has low implementation complexity and excellent decoding performance.The deep space codes in the CCSDS standard are implemented.Provide a certain reference value in practical application.