Real-time decision making relies on the availability of accurate data and, therefore, delivering status updates in a timely fashion is of paramount importance. The topic of real-time status updates has received much attention in recent years. This article contributes new results to this research area by studying the interplay between average timeliness and design decisions made at the physical layer, for unreliable communication channels. Specifically, this study explores the tension between the fact that more reliable transmissions with lower probabilities of decoding failure tend to improve timely delivery, unless these improvements come at the expense of significantly longer codewords. The average timeliness is adopted as an evaluation criterion, and a framework to efficiently compute the performance of various transmission schemes for the binary erasure channel is developed. We show that the average timeliness decreases as we increase the feedback rate in a hybrid ARQ scheme for a range of codeword lengths. This article also provides design guidelines for the codeword length selection for an hybrid ARQ scheme to improve the average information timeliness. Numerical examples are included to further illustrate the applicability of our findings.

中文翻译：

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通过擦除通道的完美反馈实时状态更新

实时决策依赖于准确数据的可用性，因此，及时提供状态更新至关重要。近年来，实时状态更新的话题备受关注。本文通过研究平均时效性与物理层设计决策之间的相互作用，为该研究领域贡献了新的成果，以应对不可靠的通信渠道。具体而言，这项研究探讨了以下事实之间的紧张关系：解码失败概率较低的更可靠的传输往往会改善及时交付，除非这些改进是以明显更长的码字为代价的。采用平均时效作为评价标准，并且开发了一个框架来有效地计算二进制擦除信道的各种传输方案的性能。我们表明，随着我们在一定范围的码字长度的混合 ARQ 方案中增加反馈率，平均及时性会降低。本文还为混合ARQ方案的码字长度选择提供了设计指南，以提高平均信息时效。包括数值示例以进一步说明我们发现的适用性。