Graph-based LT and Raptor codes

This paper deals with LT and raptor codes used on a noiseless channel, as it is the case for the BEC or the AWGN channel with high SNR. The performance measure for such family of codes is the efficiency, i.e., the average amount of redundancy needed to decode the information bits. We consider the new class of graph-based LT and raptor codes, we analyze their efficiency and we show that the optimal degree distribution of the LT code depends on the rate of the precoder.