Class-Based Expurgation Attains Csisz\'ar's Expurgated Source-Channel Exponent

Abstract

This paper studies expurgated error exponents for joint source-channel coding for discrete memoryless sources and channels. We consider a partition of the source messages into classes, where the codeword distributions depend on the class. We show that two carefully chosen classes suffice to achieve Csisz\'ar's expurgated exponent.