Design of Non-punctured Protograph LDPC Codes for JSCC Systems over Partial Response Channels

Traditional protograph low-density parity-check (PLDPC) codes with punctured nodes perform poorly over partial response (PR) channels. Therefore, several good PLDPC codes without punctured nodes have been designed so far over PR channels. However, these codes are based on the separate coding structure and neglect the residual redundancy left by source coding. So in this paper, based on the joint source-channel coding (JSCC) system, three new types of rate-1/2 non-punctured PLDPC codes are designed for PR channels. Higher rate channel codes are further designed by code lengthening from one of the proposed codes. The joint protograph extrinsic information transfer (JPEXIT) algorithm is also used to calculate the decoding threshold of the system. Both the JPEXIT analysis and the bit-error-rate (BER) simulation results show that in the JSCC system over PR channels, three new codes all possess performance improvement in the water-fall region compared to existing non-punctured PLDPC codes, especially one of them can also obtain a very low error floor. Also for the higher rate channel codes, no error floors are observed down to BER=10
⁻⁶
.