This paper proposes the design of polar and convolutional coset codes for the unequal message protection (UMP) in the short blocklength regime, to overcome the rate loss introduced by preamble-based solutions. After providing conditions to ensure message class disjointness, a two-step decoding architecture is proposed: it first identifies the message class via a likelihood ratio test--computable exactly for convolutional codes and approximated for polar codes--and subsequently performs maximum (or near) likelihood decoding among the codewords of the chosen message class. Numerical results show that our construction closely tracks finite-length benchmarks. Specifically, the analyzed CRC-aided polar codes perform comparable to existing polar code approaches, without requiring specific code design, while offering a robust and spectrally efficient solution for UMP scenarios.

翻译：本文针对短分组长度场景下的不等消息保护（UMP）问题，提出极化码与卷积陪集码的设计方案，以克服基于前导序列的解决方案带来的速率损失。在给出确保消息类不交叠条件后，提出一种两步译码架构：首先通过似然比检验识别消息类（该检验对卷积码可精确计算，对极化码采用近似计算），随后在所选消息类的码字中执行最大似然（或近似最大似然）译码。数值结果表明，所构造方案紧密逼近有限长度基准性能。具体而言，分析中的CRC辅助极化码在无需特定编码设计的前提下，性能可与现有极化码方案相当，并为UMP场景提供了兼具鲁棒性与频谱效率的解决方案。