IRWIN AND JOAN JACOBS CENTER FOR COMMUNICATION AND INFORMATION TECHNOLOGIES On-Line Fountain Codes with Low Overhead

An on-line fountain code is defined as a fountain code for which an optimal encoding strategy can be found efficiently given any instantaneous decoding state. This property is important for data distribution in practical networks. In this paper we formalize the problem of on-line fountain code construction, and propose new on-line fountain codes that outperform known ones in having factor 3-5 lower redundancy overhead. The bounding of the code overhead is carried out using analysis of the dynamics of random-graph processes. Index Terms Fountain codes, rateless codes, on-line codes, codes with feedback, random graphs.