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This paper considers the newly introduced fountain codes for fixed-rate error control coding, with emphasis on Raptor codes. The performance of Raptor codes of low-to-moderate rates with iterative decoding is evaluated over memoryless, as well as correlated, fading channels. A global decoding algorithm, incorporating feedback between the component codes of the Raptor code, is introduced. Results show that fixed-rate Raptor codes closely approach the capacity limits of memoryless channels. It is also shown that Raptor codes incur a performance degradation over slow-fading channels relative to memoryless fading. Comparison with other state-of-the-art codes reveals that fixed-rate Raptor codes deliver performance that is comparable with, or better than, several high-performance schemes over both memoryless and correlated fading channels.