Minimum Achievable Peak Age of Information Under Service Preemptions and Request Delay

There is a growing interest in analysing freshness of data networked systems. Age Information (AoI) has emerged as relevant metric to quantify this at receiver, and minimizing for different system models received significant research attention. However, fundamental question remains: what the minimum achievable AoI any single-server-single-source queuing given service-time distribution? We address average peak (PAoI) statistic by considering generate-at-will source model, service preemptions, request delays. Our main result on characterization PAoI, we show that it achieved fixed-threshold policy among set all causal policies. use provide necessary sufficient condition preemptions be beneficial distribution. numerical results, obtained using well-known distributions, demonstrate heavier tail distribution higher performance gains preemptions.