Abstract
Recently, packet loss has become a more and more serious problem in various Internet applications. In many real-time transmission or multicast, it is not suitable to request retransmission of the unreceived data since the delay is unacceptable. Furthermore, many standard error-correction codes, for example the Reed-Solomon code, are not suitable because the encoding and decoding complexity is not feasible for high bandwidth applications.In this thesis, we design a special irregular low-density parity check codes to overcome this problem. This code is designed to be a very fast linear-time error-correction code transmitted just below channel capacity. Like other irregularlow-density parity-check codes designed for Internet transmission proposed previously, the structure of this code contains many bipartite graphs with careful chosen degreesequences. But unlike other codes based on random graph, the construction of each bipartite graph is not purely random, and we introduce a method to connect the nodes on each side of the bipartite graph in order to make the cycle length as large as possible.We strongly believe that by increasing the cycle length of the graph especially for nodes with low degree, the performance will be very good. We also provide some evaluation methods and simulation results in different kinds of situations to show that our design outperforms the original ones.