Exact Error and Erasure Exponents for the Asymmetric Broadcast Channel

TL;DR

This paper derives exact error and erasure exponents for the asymmetric broadcast channel using optimal decoding strategies, providing a detailed analysis of trade-offs and efficient evaluation methods.

Contribution

It introduces ensemble-tight error and erasure exponents for the asymmetric broadcast channel with superposition coding, and proposes convex optimization methods for their evaluation.

Findings

Optimal decoder for message pairs achieves best trade-off between total and undetected exponents.

Convex optimization procedures enable efficient evaluation of exponents.

Numerical examples illustrate the theoretical results.

Abstract

Consider the asymmetric broadcast channel with a random superposition codebook, which may be comprised of constant composition or \iid codewords. By applying Forney's optimal decoder for individual messages and the message pair for the receiver that decodes both messages, exact (ensemble-tight) error and erasure exponents are derived. It is shown that the optimal decoder designed to decode the pair of messages achieves the optimal trade-off between the total and undetected exponents associated with the optimal decoder for the private message. Convex optimization-based procedures to evaluate the exponents efficiently are proposed. Finally, numerical examples are presented to illustrate the results.