For the benefit of improved intermediate performance, recently online fountain codes attract much research attention. However, there is a trade-off between the intermediate performance and the full recovery overhead for online fountain codes, which prevents them to be improved simultaneously. We analyze this trade-off, and propose to improve both of these two performance. We first propose a method called Online Fountain Codes without Build-up phase (OFCNB) where the degree-1 coded symbols are transmitted at first and the build-up phase is removed to improve the intermediate performance. Then we analyze the performance of OFCNB theoretically. Motivated by the analysis results, we propose Systematic Online Fountain Codes (SOFC) to further reduce the full recovery overhead. Theoretical analysis shows that SOFC has better intermediate performance, and it also requires lower full recovery overhead when the channel erasure rate is lower than a constant. Simulation results verify the analysis and demonstrate the superior performance of OFCNB and SOFC in comparison to other online fountain codes.

中文翻译：

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中级演出在线喷泉代码的设计与分析

为了提高中间性能，最近在线喷泉代码引起了很多研究的关注。然而，在线喷泉代码的中间性能和完全恢复开销之间存在权衡，这阻碍了它们同时改进。我们分析了这种权衡，并建议提高这两个性能。我们首先提出了一种称为无构建阶段的在线喷泉代码（OFCNB）的方法，其中首先传输度 1 编码符号，然后移除构建阶段以提高中间性能。然后我们从理论上分析了 OFCNB 的性能。受分析结果的启发，我们提出了系统在线喷泉代码（SOFC）以进一步减少完全恢复开销。理论分析表明，SOFC具有较好的中间性能，当信道擦除率低于一个常数时，它也需要较低的完全恢复开销。仿真结果验证了分析并证明了 OFCNB 和 SOFC 与其他在线喷泉代码相比的优越性能。