Novel Scheme of Unequal Error Protection Based on Regularized Variable-node and Expanding Window Fountain Codes

A novel scheme named EWF-RLT codes, which produces Unequal Error Protection (UEP) for Luby Transform (LT) codes over Additive White Gaussian Noise (AWGN) channel by using a windowing technique before regularizing variable-node distribution, is proposed in this paper. Firstly, the idea of windowing the data sets according to their protection requirements is applied to allow coded symbols to make more edge connections with more important parts of the information bit stream with high probability. Then, variable-node degree distribution is exploited to improve the error floor and ensure the more important class of information bit stream have a higher minimum variable-node degree by modifying the traditional method of choosing neighbor nodes randomly in encoding. Compared with the conventional UEP scheme, what is confirmed both theoretically and experimentally is that the proposed approach can provide significant performance improvement in the most important bits class and improve network transmission performance. Furthermore, the proposed scheme introduces additional parameters in the UEP LT code design, making it more general and flexible in terms of the realization of UEP scheme.