Efficient Symbol Sorting for High Intermediate Recovery Rate of LT Codes

Abstract

LT codes are modern and efficient rateless forward error correction (FEC) codes with close to channel capacity performance. Nevertheless, in intermediate range where the number of received encoded symbols is less than the number of source symbols, LT codes have very low recovery rates. In this paper, we propose a novel algorithm which significantly increases the intermediate recovery rate of LT codes, while it preserves the codes' close to channel capacity performance. To increase the intermediate recovery rate, our proposed algorithm rearranges the transmission order of the encoded symbols exploiting their structure, their transmission history, and an estimate of the channel's erasure rate. We implement our algorithm for conventional LT codes, and numerically evaluate its performance.