Online Fountain Codes With Unequal Recovery Time

Recently, fountain codes have developed some online versions to cope with the increasingly complicated spectrum environment. The conventional online fountain code structures are still not sufficient to meet the unequal recovery time (URT) requirement when the data have a mass of different priorities. This letter adopts an expanding-window strategy to implement two structures, where the data with higher priority ensure less recovery time. Simulation results verify the superior performance of two structures that can achieve a significant increase in decoding speed of the data of high priorities, except that they are accompanied by negligible extra overhead in comparison with the conventional online fountain codes.