There is a growing interest in analysing the freshness of data in networked systems. Age of Information (AoI) has emerged as a popular metric to quantify this freshness at a given destination. There has been a significant research effort in optimizing this metric in communication and networking systems under different settings. In contrast to previous works, we are interested in a fundamental question, what is the minimum achievable AoI in any single-server-single-source queuing system for a given service-time distribution? To address this question, we study a problem of optimizing AoI under service preemptions. Our main result is on the characterization of the minimum achievable average peak AoI (PAoI). We obtain this result by showing that a fixed-threshold policy is optimal in the set of all randomized-threshold causal policies. We use the characterization to provide necessary and sufficient conditions for the service-time distributions under which preemptions are beneficial.

中文翻译：

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一般服务时间分配信息的最低可达到年龄

人们对分析网络系统中数据的新鲜度越来越感兴趣。信息时代 (AoI) 已成为量化特定目的地新鲜度的流行指标。在不同设置下的通信和网络系统中优化该指标方面进行了大量的研究工作。与之前的工作相比，我们对一个基本问题感兴趣，即对于给定的服务时间分布，任何单服务器单源排队系统中可实现的最小 AoI 是多少？为了解决这个问题，我们研究了在服务抢占下优化 AoI 的问题。我们的主要结果是关于可实现的最小平均峰值 AoI (PAoI) 的表征。我们通过证明固定阈值策略在所有随机阈值因果策略集中是最优的来获得这个结果。