Optimizing Information Freshness for Wireless Local Area Networks with Multiple APs
For network operators deploying dense WLANs with centralized coordination, this work provides the first constant-factor optimal scheduling policies for AoI under interference, addressing a critical bottleneck in latency-sensitive applications.
The paper tackles the problem of minimizing Age of Information (AoI) in dense WLANs with multiple access points (APs) under interference coupling. It proposes stationary randomized policies with constant-factor optimality guarantees and a Lyapunov drift-based online policy, achieving about 50% AoI reduction over single-AP baselines in simulations.
Dense indoor WLANs increasingly rely on multiple access points (APs) operating over partially overlapping spectrum to support latency-sensitive applications. In such deployments, simultaneous transmissions across APs create co-channel and adjacent-channel interference, making scheduling decisions interdependent and directly impacting information freshness. Motivated by emerging software-defined WLAN architectures that enable centralized coordination, we study the problem of minimizing network-wide Age of Information (AoI) in multi-AP WLANs. Unlike classical AoI scheduling that runs at a single AP, each scheduling decision is now coupled across APs due to interference. This leads to a new class of combinatorial AoI control problems with action-dependent time evolution. We first derive a lower bound on the achievable AoI under arbitrary scheduling policies. We then design stationary randomized policies that have constant-factor optimality guarantees relative to this bound. Building on these insights, we develop a Lyapunov drift-based online policy for systems with action-dependent frame lengths, and establish constant-factor guarantees using new ratio-based drift analysis. To enable scalable implementation, we further show that per-frame scheduling admits efficient polynomial-time local-search approximations under a submodularity assumption. Simulations using realistic WLAN layouts demonstrate about 50% AoI reduction over distributed single AP baselines.