Denser-CSI + higher-occupancy floor-lift — does CSI quality rise with more links/crowd?
The staleness-switch's sparse-regime floor is set by CSI->count quality (~weak). This session tests the
lever directly: a NEW 10-Rx dense experiment on resplan-12439 (csi-link-resplan-12439-dense10,
combining the multiroom + topo placements), high occupancy, vs a 5-Rx multiroom control, 3 seeds each,
with a per-link CSI feature (full per-link CV vector → ridge) vs the old scalar mean-CV. Reported as
R^2 (count variance explained — scale-free), nMAE, MAE.
First run (seated-STAY, occ ~constant at 17): 10-link per-link R^2=0.16, nMAE 0.15 — looked promising, but occupancy was near-constant (seated agents stayed), so the low variance flattered both R^2 and nMAE.
Corrected run (seated arrive AND depart, occ varies 0->18): the result deflates honestly —
- 10-link per-link-ridge: R^2=0.09, nMAE 0.23
- 10-link scalar-CV: R^2=0.00
- 5-link per-link / scalar: R^2 ~ -0.02 / -0.01
Verdict: the floor was NOT meaningfully lifted. Both levers help directionally — more links (10 > 5: R^2 0.00→0.09 per-link) and a richer feature (per-link > scalar: 0.00→0.09) each move it up, and they are the only configs above R^2=0 — but the absolute signal stays very weak: even 10 links + crowds to 18 + proper variance, the CSI temporal-CV explains <10% of count variance (~23% relative error). The synthetic, quasi-static ray-traced amplitude-CV is a fundamentally poor count predictor on these floors; adding receivers does not fix that.
What this means. The CSI floor cannot be raised by link count / occupancy alone — the bottleneck is the feature/signal, not the geometry. The real remaining levers are (1) richer temporal CSI structure — doppler micro-fading (deliberately off here for frame-axis alignment; flagged as the count-relevant carrier in c-csi-band-calibration), or a learned spectro-temporal feature instead of a single CV scalar/vector; and (2) real CSI (hardware temporal richness the quasi-static sim lacks, IP-106). This reinforces the whole arc's conclusion: BLE device-counting is the load-bearing modality; CSI is a weak coarse fallback, and the staleness-switch is the right way to use it — but its sparse-regime ceiling is set by a CSI signal that more anchors won't rescue.
Caveats: in-silico; quasi-static RT (no doppler); amplitude-CV feature only (not learned); 3 seeds; one floor. The doppler-on + learned-feature rerun is the clean next probe before concluding CSI is irredeemably weak.