Tick 9 — 2026-05-22 05:34 UTC

Thread: R1 (ToA multistatic CRLB) Verdict: Quantitative precision floor for WiFi multistatic localisation. Phase ranging beats ToA ranging by 238× at WiFi bandwidths — but only after solving the integer-ambiguity (cycle-slip) problem.

What shipped

• examples/research-sota/r1_toa_crlb.py — pure-numpy CRLB grid over bandwidth/SNR + phase-noise-vs-precision grid + 4-anchor multistatic geometric dilution.
• examples/research-sota/r1_toa_crlb_results.json — machine-readable predictions.
• docs/research/sota-2026-05-22/R1-toa-crlb.md — research note with the math, the headline numbers, the integer-ambiguity catch, ADR-029 architectural implication.

Headline numbers

20 MHz HT20 channel, 20 dB SNR (ESP32-S3 typical):

Method	Single-shot	100x averaged
ToA CRLB	0.413 m	0.041 m
Phase (single-subcarrier, 5° noise)	1.73 mm	0.17 mm
Phase advantage	238×	240×

4-anchor multistatic 5×5 m room, GDOP 1.5:

Method	Position precision
ToA	25.3 cm
Phase (ambiguity-resolved)	1.06 mm

Why this matters for the loop

1. Bounds what's physically possible for any WiFi-localisation feature. 25 cm position precision via ToA-only is the room-pose-quality floor; 1 mm via phase is RTK-quality but ambiguity-resolution-bound.
2. Strongest architectural lever for ADR-029: explicit ToA-then-phase pipeline (≤2× from CRLB by Kay's theory) probably outperforms the current learning-based attention. Provable optimality vs flexibility tradeoff.
3. Composes cleanly with R6: spatial envelope (R6) × ranging precision (R1) = full multistatic geometry budget. They are independent and additive.
4. Closes a gap R10 created: foliage drops SNR, which directly worsens ToA CRLB. A 50 m foliage link at 5 dB SNR → ~1 m ToA precision. The 100 m sparse-foliage number from R10 is not the same as 100 m localisable.

Honest scope landed

• CRLB is a lower bound; real estimators sit 1-2× above it
• 5° phase noise assumes phase_align.rs is applied; raw ESP32 is 60-180°
• Multipath degrades CRLB by 2-5× even with MUSIC super-resolution
• Cycle-slip is unsolved at the WiFi bandwidth level without multi-subcarrier wide-lane unwrap

Coordination

ticks/tick-9.md. No PROGRESS.md edit. Branch research/sota-r1-toa-crlb.

Remaining threads

R2 (subsumed by R6+R12), R3 (cross-room re-ID), R4 (federated learning), R11 (through-bulkhead maritime), R13 (contactless BP), R15 (RF biometric).

~6.4h to cron stop. 9 threads landed.