Accumulate rateless codes and their performances over additive white Gaussian noise channel

In this study, the authors propose a new class of rateless codes applicable to noisy channels, that is, the so-called accumulate rateless (AR) codes, which concatenate the low density generator matrix (LDGM) rateless code with a simple post-code, that is, a post-position accumulator. The new coding structure is not only effective in reducing the ‘error floor’ as observed in traditional LDGM rateless codes such as Luby transform (LT) codes, but also quite simple for realisation as compared with the rateless codes using a pre-coding structure such as Raptor codes. The extrinsic information transfer charts and the corresponding projection of intersectant curves for both the systematic and non-systematic AR codes are analysed. Based on these, their convergence performance and optimal degree distributions are investigated. Simulation results show that, the performance of AR codes over additive white Gaussian noise channel is comparable to that of Raptor codes.