Near-optimum serial concatenation of single-parity codes with convolutional codes

Abstract

A class of concatenated codes using convolutional codes and low-density parity check codes as component codes is proposed, extending the author's previous work. A special case is considered serial concatenation of single parity check codes as the outer code, a convolutional code with recursive systematic encoder as the inner code, separated by a random interleaver. A way to design the interleaver ‘or the corresponding LDPC code’ is presented to minimise the correlation between the extrinsic information. The results show that this parity concatenated code can operate within 0.45 dB of the Shannon limit. Similar to the parity concatenated codes presented in earlier work, these codes are superior in approaching the sphere packing bound (SPB), achieve near-SPB decoding can be achieved for block sizes ranging from 200 (about 0.8 dB) to 10 000 (within 0.6 dB) information bits (for a block error rate of 10−4). The improvement over previous coding schemes is 0.3–0.4 dB for block lengths more than 300 bits, and over JPL turbo codes is 0.3 dB for block lengths less than 1000 bits. A reliable error-detection method is proposed that makes this coding scheme very attractive for communications using short packets.