QoS-Aware Cooperative Multi-AP Wi-Fi Sensing for Coarse Indoor Awareness in OpenWrt-Based WLANs

Introduction: Wi-Fi sensing infers indoor changes from radio propagation, but single-link measurements are interference-sensitive. Multi-AP CSI fusion (Ding et al., 2023) and ReWiS combine CSI views for recognition; EfficientFi compresses CSI, whereas SenCom reuses communication packets. Unlike these systems and the published CSAN reliability/QoS workflow, this contribution is a design specification for a CSI-optional, QoS-aware OpenWrt controller; it is not an implemented or deployed system. Its distinction is one interface that normalizes native, companion-assisted, or absent CSI while exposing reliability and acquisition cost to admission, rather than a new fusion or recognition model.

Methods: The specification defines three routers, six telemetry classes (CSI, RSSI, packet counters, retry/loss, PHY-rate variation, and QoS/traffic load), and four output labels: stable/empty, presence/motion, static obstruction/environmental change, and uncertain. A deterministic fixture-based software check exercised all acquisition modes and CSI-loss fallback using no measured room or WLAN inputs.

Results: The deterministic fixture-based check validated use of all three router descriptors and retention of five conventional telemetry classes during complete CSI loss. This establishes interface and code-path consistency only, not sensing accuracy, WLAN performance, or OpenWrt integration. The provisional 10 s cycle trades response speed for a nominal 100-sample window per router at 10 samples/s and one decision per cycle, suiting coarse rather than real-time awareness. The provisional 5% ceiling is a single-digit admission bound chosen to leave 95% of modeled capacity outside sensing. Under the payload-only assumptions—three routers, 512-byte samples, 128 control bytes per router per cycle, and 6 Mb/s—the load is 2.05%, leaving 2.95 percentage points of headroom. These are design inputs, not measured latency, airtime, or QoS guarantees.

Conclusions: The contribution is a proposed controller method specified through an internally consistent contract that unifies CSI-present and CSI-free modes with explicit cost accounting. Hardware deployment, measured WLAN impact, and room-state accuracy remain future work.