Preemption changes optimal routing to favor slower delayed paths
Worse Routes, Fresher Information: Preemption Redefines Which Route is Best
Information Theory
Summary
This paper looks at how to best send updates through different network paths when balancing freshness of information with the cost of sending. The authors found that allowing new transmissions to interrupt ongoing ones can make it better to choose routes that are actually slower or more variable in delay. Surprisingly, this strategy can improve how quickly fresh information is received by up to 96%. This shows that when interruptions are allowed, the route that looks worse on average can actually be best for keeping information up to date.
What this means in practice
- •For network schedulers: Design routing policies that allow transmission preemption to minimize information age despite slower route delays.
- •For industrial control system engineers: Implement update mechanisms for sensor networks that optimize timing using preemption to improve data freshness under cost constraints.
Authors
Adem Utku Atasayar, Aimin Li, Elif Uysal
Abstract
This paper studies joint sampling, route activation, and preemption control over $N$ heterogeneous transmission routes under a long-run objective combining Age of Information (AoI) with sampling and transmission costs. We formulate the problem as an average-cost impulse-control model, derive a vector-form integral average-cost optimality equation over a hybrid state space, and establish structural reductions on the state. We consider a two-route case and compute optimized policies using discretized policy iteration. Surprisingly, the results show that preemption can reverse routing preferences: the optimized policy may exclusively use a route with both a larger mean delay and a larger delay variance while avoiding the seemingly superior route. Relative to baselines that do not allow preemption, the proposed policy reduces average AoI by up to $96\%$.