Effects of degree distribution in rateless coding

In this thesis rateless codes which are adopted by a variety of applications such as, wireless transmission, 3GPP, data storage, multicasting, video streaming are inspected in details. The performance of two important types of rateless codes which are Luby Transform and Raptor codes are measured via computer simulations. Both hard decision and soft decision methods are used while measuring the performance of these codes. For the soft decision decoding Belief Propagation algorithm was used in an iterative manner. Degree distribution is an important criteria for the performance of Luby Transform codes. A new degree distribution called random degree (or exponential random) distribution is proposed for Luby Transform codes. And simulation results support that the proposed distribution shows better performance than the classical degree distributions such as all-at-once, ideal soliton, robust soliton, and sparse.