发表机构
University of Massachusetts Boston; University of Nebraska Omaha（马萨诸塞大学波士顿分校; 内布拉斯加大学奥马哈分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文针对能量受限Wi-Fi状态更新问题，设计了可证明性能的Harmonic-Greedy TWT调度器，可最小化加权平均AoI，在关键场景中性能优于能量优先基线，接近松弛下界。
AI 中文摘要
目标唤醒时间（Target Wake Time, TWT）是IEEE 802.11ax标准中引入的机制，允许接入点精确调度每个站点的唤醒、传输和休眠时刻。现有TWT调度器主要优化能量或吞吐量，最多将信息新鲜度作为约束，不提供性能保证。本文针对新鲜度设计唤醒调度方案：在满足每个站点能量预算的前提下，最小化站点的加权平均信息年龄（Age of Information, AoI），决策变量为TWT三元组（唤醒间隔、偏移量、服务时段持续时间）。我们推导了每服务时段（SP）块衰落下TWT的更新精确AoI模型，并通过分组级802.11ax仿真验证，平均误差约为1%。研究发现，与可抢占调度不同，非抢占式TWT打包在调度密度为1时可能不可行，且确定了粒度条件，使小优先最佳适配打包器可证明成功。基于此，我们构建了Harmonic-Greedy调度器，该调度器结合凸松弛、锚点优化的二取整以及均匀最佳保障，证明其为常数因子近似：在温和粒度假设下为4/ln2≈5.77，无条件下为6/ln2≈8.66。我们在ns-3中实现了完整系统，包括集成节能架构的TWT唤醒/休眠机制及调度器，结果显示其是唯一在所有场景中接近松弛下界的调度器：与强能量优先基线相比，当每个站点能量下限已固定时段时性能相当，在调度密度需通过AoI权重或信道质量而非能量预算重新分配的场景中，性能提升4%-36%，这正是本文分析确定的场景。
英文摘要
Target Wake Time (TWT), introduced in IEEE 802.11ax, lets an access point schedule exactly when each station wakes, transmits, and dozes. Existing TWT schedulers optimize energy or throughput, treating information freshness at best as a constraint and offering no performance guarantees. We design the wake schedule itself for freshness: minimize the weighted average Age of Information (AoI) over stations subject to per-station energy budgets, where the decision variables are the TWT triples (wake interval, offset, service period duration). We derive a renewal-exact AoI model for TWT under per-SP block fading and validate it against packet-level 802.11ax simulation with ~1% mean error. We show that, unlike preemptive scheduling, non-preemptive TWT packing can be infeasible at schedule density 1, and identify the granularity condition under which a small-first best-fit packer provably succeeds. Around this we build Harmonic-Greedy, a scheduler combining a convex relaxation, anchor-optimized power-of-two rounding, and a best-of-uniform safeguard, and prove it is a constant-factor approximation: 4/ln 2 ~= 5.77 under a mild granularity assumption and 6/ln 2 ~= 8.66 unconditionally. We implement the complete system in ns-3 -- a TWT wake/doze mechanism integrated with the power-save architecture, plus the scheduler -- and show that it is the only scheduler that stays near a relaxation lower bound across all regimes: against a strong energy-greedy baseline it ties when per-station energy floors already pin the periods, and wins by 4-36% exactly where the schedule density is binding and must be redistributed by AoI weight or channel quality rather than by energy budget -- the regime our analysis identifies.
Comments11 pages, IEEE conference format; extended version (full proofs in the appendix) of a paper accepted at MSWiM 2026, Paris. This version adds the IEEE copyright notice and the funding acknowledgment. Code and data: https://github.com/Haoyu2/age-optimal-twt
