Improving the Alphabet Size in Expander Based Code Constructions

Various code constructions use expander graphs to improve the error resilience. Often the use of expanding graphs comes at the expense of the alphabet size. This is the case, e.g., in [1], [8] and [7]. We show that by replacing the balanced expanding graphs used in the above constructions with unbalanced dispersers or extractors depending on the actual construction) the alphabet size can be dramatically improved. Contents