“On Multi-Channel Huffman Codes for Asymmetric-Alphabet Channels” Accepted to ISIT 2021

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The paper “On Multi-Channel Huffman Codes for Asymmetric-Alphabet Channels” has been accepted to the 2021 IEEE International Symposium on Information Theory. This is a joint work of Russell W. F. Lai with Hoover H. F. Yin, Xishi Wang, Ka Hei Ng, Lucien K. L. Ng, and Jack P. K. Ma.

Below you will find the abstract of the paper.

Zero-error single-channel source coding has been studied extensively over the past decades. Its natural multi-channel generalization is however not well investigated. While the special case with multiple symmetric-alphabet channels was studied a decade ago, codes in such setting have no advantage over single-channel codes in data compression, making them worthless in most applications. With essentially no development since the last decade, in this paper, we break the stalemate by showing that it is possible to beat single-channel source codes in terms of compression assuming asymmetric-alphabet channels. We present the multi-channel analog of several classical results in single-channel source coding, such as that a multi-channel Huffman code is an optimal tree-decodable code. We also show some evidences that finding an efficient construction of multi-channel Huffman codes may be hard. Nevertheless, we propose a suboptimal code construction whose redundancy is guaranteed to be no larger than that of an optimal single-channel source code.