The Encoder And Decoder Design Of LDPC Codes According To CCSDS Standards

Human activities will extend to the deep-space in the 21st century. Space activities have further affect on human civilization and social progress. Due to long distance and great signal loss of deep space communication, it is necessary to adopt high-gain channel codes and other techniques to protect the information transmission effectively. As a high-gain channel coding technology, LDPC(low density parity check) codes have been received more and more attention for their outstanding performance in deep-space communication. It is a hot spot to be researched how to design suitable ldpc codes for deep space communication.LDPC code was originally discovered by Gallager.It is a kind of linear bloke code that defined by very sparse parity matrix or tanner graph. Because of the limitation at that time, it has been ignored for more than 30 years. Ever since the rediscovery the design, construction, decoding, efficient encoding, performance analysis and applications of these codes in digital communication and storage systems have become the focal points of research.Firstly, the paper introduces the fundamental principles of LDPC code, including the basic concept and representation and classification of LDPC code. Then, the paper highlights the construction methods of check matrix of deep-space LDPC codes based on CCSDS standard and studies the AR4A LDPC code construction methods and analyses the construction principles of deep-space LDPC codes based on CCSDS standard. After that, the paper devises a suitable encoder structure according to the characteristics of the codes and completes encoder hardware design using VHDL language in the Xilinx ISE and simulates the algorithm in matlab. The results of the two design methods are perfectly fit. Finally, under analyzing several decoding algorithms, decoding method that is suitable for deep-space condition is selected. LDPC decoder hardware design is completed using VHDL language.The result shows that the encoder has low complexity coding structure and the decoder has excellent performance. The design is correct and suitable for deep-space communication.