Encoding And Decoding Research On Convolutional LDPC Codes

LDPC code is proposed in 1962 by Gallager, it is also known Gallager codes. The mid-90s of last century, MacKay, Luby, who rediscovered LDPC codes, and point out the approaching Shannon limit performance and the decoding operation is simple and easy to implement. In recent years LDPC codes demonstrated the excellent performance, making its acclaimed in the communications field, and to apply it to 4G, satellite communications and deep space communications has become a topical research focus.LDPC convolutional code is a kind of LDPC code, the sparse parity check matrix requires to have a convolution, because of its special structure allows it to transmit information of any length. This makes LDPC convolutional codes compared to other structures of the LDPC codes is more suitable for certain communication systems, eg, IEEE802.11 wireless standard, which requests the transmission frame length ranged between 64bit and 1518bit. This paper focuses on encoding and decoding algorithm for LDPC convolutional codes.I studied the concept of LDPC convolutional codes; The construction method of LDPC code check matrix, which focuses on the PEG construction method; LDPC decoding algorithm, introduces the LLR BP algorithm, BP-Based Decoding Algorithm and a number of BP-Based Algorithm derivative algorithm.Through a better understanding of the concept of LDPC convolutional codes, give LDPC convolutional code encoding method, and the corresponding simulation; focus on the decoding of LDPC convolutional codes, first give LDPC convolutional code's decoder structure, and the whole simulation process, and for the different methods of check node decoding process, are given the simulation process of check node processing of LLR BP algorithm and BP-Based Algorithm, and last analysis and comparison of different decoding algorithms complexity.Establish the BER performance of simulation system for LDPC convolutional codes, and the simulation process; analysis of decoding algorithms, code structure, the number of iterations for the BER performance of LDPC convolutional codes; Discuss LDPC convolutional codes error performance with the normalized BP-Based Decoding algorithm and the offset BP-Based Decoding Algorithm, and the choice of normalized parameters and offset parameters.