Raptor codes

LT-codes are a new class of codes introduced by Luby for the purpose of scalable and fault-tolerant distribution of data over computer networks. In this paper, we introduce Raptor codes, an extension of LT-codes with linear time encoding and decoding. We will exhibit a class of universal Raptor codes: for a given integer k and any real epsiv>0, Raptor codes in this class produce a potentially infinite stream of symbols such that any subset of symbols of size k(1+epsiv) is sufficient to recover the original k symbols with high probability. Each output symbol is generated using O(log(1/epsiv)) operations, and the original symbols are recovered from the collected ones with O(klog(1/epsiv)) operations. We will…