Code construction algorithm for architecture aware LDPC codes with low-error-floor

Abstract

The common approach for the design of an error correction system is first to construct a code and then to define the hardware structure of the encoder and decoder. However, in the case of LDPC codes (low-density parity-check) such a constructed code is generally not well suited for a hardware implementation. It has been recognized that the code construction and hardware design must be considered jointly to facilitate LDPC decoder and encoder implementation. In this paper, an efficient decoder structure for regular and irregular LDPC codes, based on TDMP (turbo-decoding message passing) scheme is designed first. The decoder has been implemented and verified in an FPGA device. Constraints for the parity check matrix of a code to be suitable for the decoder architecture are defined. Then an algorithm for LDPC parity check matrix construction subject to these constraints is presented. The algorithm aims at improving performance of the code in the low SNR region by employing irregular codes as well as in high SNR region by reducing the number of small Stopping Sets and Trapping Sets in the Tanner graph of the code making use of a computer search technique.