The Research And Implementation Of Non-binary LDPC Codes

Low Density Parity Check Codes(LDPC codes) is one of high efficient err-correcting codes, it gets wide attention for its excellent performance. Most research of LDPC codes focus on binary LDPC codes at the present time, little research has been done in the field of non-binary LDPC codes for its complexity, we do not find any published paper or production about the implementation of non-binary LDPC codes either.Our team compared the performance of a non-binary LDPC code, a serial concatenation of a non-binary LDPC code with a convolutional code, and a serial concatenation of a RS code with a convolutional code in deep space communication system. The early research results show that with the same code length and code rat, 4-ary LDPC code can gain about 5.1 dB SNR performance improved. With this conclusion, we begin the research and study of implementation of non-binary LDPC codes.Based on deep understanding of encode and decode algorithm of LDPC codes, we first make some improvement of non-binary LDPC codes decode algorithm to make it possible to implement on hardware, second, through analyze and compare the advantage and disadvantage of structure used in binary LDPC codes decoder, then we create a new structure which is suitable for non-binary LDPC codes. Finally we successfully implement a 4-ary LDPC encoder and decoder with code length 2040 symbol, code rate 0.437255 irregular 4-ary LDPC code on Xilinx FPGA for the first time in the world which can be used in satellite communication. Compared with other encoder and decoder of binary LDPC codes, we control the resource very well and the speed of encoder and decoder basically meet the need of satellite communication, this work will do great contribution to the application of non-binary LDPC codes in real communication system.