Age of Information Analysis for Queueing Systems With Proactive Obsolete Packet Management: Multi-Hop, Multi-Source, and Priority Mechanisms

This paper investigates the Age of Information (AoI) in single-hop First-Come-First-Serve (FCFS) queueing systems, multi-hop Last-Come-First-Serve (LCFS) systems, and single-hop, multi-source priority-based LCFS systems, all featuring parallel servers at each node pair. AoI analysis in such systems remains largely unexplored, and our goal is to evaluate AoI performance under these models. A key challenge in parallel server systems is out-of-order packet reception. To address this, we utilize the Proactive Obsolete Packet Management (POPMAN) strategy, which proactively identifies and discards outdated packets. The single-hop FCFS system is a benchmark for comparing more efficient queueing disciplines such as LCFS. We use the stochastic hybrid systems (SHS) framework for the AoI analysis. We analyze single-hop FCFS systems using work-conservative and probabilistic routing policies. Our results show that at high arrival rates, the average AoI in a two-server system reduces by 37.5% with the conventional approach and 43.75% with POPMAN, compared to a single-server FCFS system. For multi-hop LCFS networks, a node's packet departure rate is inversely proportional to its average AoI, given by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda \approx c*\frac{1}{AoI}$</tex-math></inline-formula>, where c ranges from 1 to 1.05.