This paper investigates two distinct types of block errors - undetected errors (confusions) and erasures - in additive white Gaussian noise (AWGN) channels with error-bounded block decoders operating in the finite blocklength (FBL) regime. While block error rate (BLER) is a common metric, it does not distinguish between confusions and erasures, which can have significantly different impacts in cross-layer protocol design, despite upper-layer protocols universally assuming physical (PHY) errors manifest as packet erasures rather than undetected corruptions - an assumption lacking rigorous PHY-layer validation. We present a systematic analysis of confusions and erasures under BLER-constrained maximum likelihood (ML) decoding. Through sphere-packing analysis, we provide analytical bounds for both block confusion and erasure probabilities, and derive the sensitivities of these bounds to blocklength and signal-to-noise ratio (SNR). To the best of our knowledge, this is the first study on this topic in the FBL regime. Our findings provide theoretical validation for the block erasure channel abstraction commonly assumed in medium access control (MAC) and network layer protocols, confirming that, for practical FBL codes, block confusions are negligible compared to block erasures, especially at large blocklengths and high SNR.

翻译：本文研究了加性高斯白噪声（AWGN）信道中，在有限块长（FBL）体制下运行的误差有界块解码器所面临的两种不同类型的块错误：未检测错误（混淆）与删除错误。虽然块错误率（BLER）是常用度量指标，但它无法区分混淆与删除错误，而这两者在跨层协议设计中可能产生显著不同的影响。尽管上层协议普遍假设物理层（PHY）错误表现为数据包删除而非未检测的损坏——这一假设缺乏严格的物理层验证。我们在BLER约束的最大似然（ML）解码框架下，对混淆与删除错误进行了系统性分析。通过球堆积分析，我们给出了块混淆概率与块删除概率的解析界，并推导了这些界对块长度和信噪比（SNR）的敏感度。据我们所知，这是该主题在FBL体制下的首次研究。我们的研究结果为媒体接入控制（MAC）和网络层协议中普遍采用的块删除信道抽象提供了理论验证，证实对于实际FBL编码，块混淆相较于块删除可忽略不计，尤其是在大块长和高SNR条件下。