Abstract:

A novel superposing degree distribution (SPDD) is designed for systematic Luby transform (LT) codes. Compared with precoding systematic Raptor codes and interleaving encoding Quasi systematic doped LT codes (QS DLT), SPDD is designed based on weaken robust degree distribution superposing with a doping degree (DD) distribution, and the systematic form output symbols are generated by the intermediate symbols with LT encoding. By optimizing of the superposing proportion of DD, the asymptotic performance of systematic LT codes is analyzed, and the coding complexity is O(k·ln(1/ε)), where k is the code length and ε is the overhead. Simulation results show that, the proposed systematic LT codes solve the error floor problem in the systematic Raptor codes when the channel erasure rate is larger than 0.01, and can achieve decoding failure rate of 10e-4 with a 12%~20% reduction in overhead when compared to the QS DLT codes.