An Efficient Feedback Coding Scheme With Low Error Probability for Discrete Memoryless Channels

Cheuk Ting Li, Abbas El Gamal

Abstract: Existing fixed-length feedback communication schemes are either specialized to particular channels (Schalkwijk-Kailath, Horstein), or apply to general channels but either have high coding complexity (block feedback schemes) or are difficult to analyze (posterior matching). This paper introduces a new fixed-length feedback coding scheme which achieves the capacity for all discrete memoryless channels, has an error exponent that approaches the sphere packing bound as the rate approaches the capacity, and has O(n log n) coding complexity. These benefits are achieved by judiciously combining features from previous schemes with new randomization technique and encoding/decoding rule. These new features make the analysis of the error probability for the new scheme easier than for posterior matching.