Which CSI receiver impairments can the empty-room sample identify?
Current assessment (2026-09-15)
Session 01M14KGBE9NBQB89AMRZ4N272W estimated CFO 62,258 Hz [60,970, 63,545], timing offset 6.74 samples [6.35, 7.21], and effective SNR 8.57 dB [7.43, 9.61] from ten host segments. The reported intervals are bootstrap intervals over hosts, not independent nights. Sixteen simulations over eight paired seeds gave an attenuation contrast of −4.066 dB/person, 95% CI [−4.860, −3.359], fitted minus shipped profile.
The broad hypothesis that every impairment parameter is identifiable failed its own scope test: three terms remain channel-confounded. The fit samples one roughly 2,000-record segment per host, not a month of empty-room evolution. Effective SNR may include AGC variation. This is a measured-profile sensitivity analysis, not full identification of the receiver or proof of real transfer.
Next evidence needed: Preserve raw-channel lineage and acquisition class. Validate fitted terms with independent sessions or a reference instrument, and carry confounded terms as uncertainty. The result motivates the reopened csi-sim2real-transfer comparison without deciding its outcome.
Basis: Thesis Narrative, the September 10 synthesis, and the September 15 register review. See the review record for evidence sources and outstanding checks.
Earlier protocol and dated results
The methods and observations below retain their original scope. Read their readiness statements and proposed next steps as historical. The current assessment above records what has changed; frozen thresholds have not been retrospectively revised.
Original hypothesis (before this review): Every parameter of ImpairmentProfile is estimable from first-party empty-room capture, and the fitted values differ materially from the commodity-NIC literature prior the simulator currently ships. The consequential claim is the second-order one: because the IP-101 impairment grid found that mild NIC impairments halve the occupancy attenuation signature and sign-flip the Rician-K slope, the fitted operating point decides whether the project's in-silico occupancy results were computed at an impairment level the real hardware has.
What each parameter is read from
| Parameter | Estimated from the empty-room corpus |
|---|---|
snr_db |
per-link amplitude variance against RSSI |
cfo_hz |
packet-to-packet common phase rotation across tones |
sto_samples |
linear phase-ramp slope across subcarriers, per packet |
iq_amp_imbalance_db, iq_phase_imbalance_deg |
mirror-tone conjugate correlation |
phase_noise_deg_rms |
residual per-tone phase RMS after CFO and STO removal |
n_bits |
read from the csiq container. Known, not fitted. |
symbol_duration_s is a constant of the standard and is not a free parameter.
The trap in the data path
The measurement lake cannot answer this. packets carries chain_amp_rms,
ratio_amp_db and ratio_phase_rad. The last two are inter-chain ratios taken
within one NIC, so a common carrier-frequency offset cancels exactly — the column
that looks like a phase measurement is the one column in which CFO is invisible.
The fit reads per-tone complex CSI from the csiq containers through the csi
package.
What a null means
If the fitted values land inside the shipped prior's neighbourhood, the simulator's measurement model was right by luck or by good reading, and every prior in-silico result keeps its current standing. That is a clean, quotable outcome.
If they land far outside — and the impairment grid says the region where the attenuation signature halves and the K-slope sign-flips is close by — then the project's published in-silico occupancy figures were computed at an impairment level the AX210 does not have, and each needs a stated correction rather than a footnote.
Secondary, if the primary lands
OccupancyDiffuse.from_real_anchor fits {k0_db, k_slope_db_per_person} from a real
anchor's (count, Rician-K) pairs. It is currently fitted against WiMANS and OPERAnet.
A first-party anchor is strictly better, but it needs labelled occupancy, which the
fleet does not yet have. Named here so it is not forgotten, and explicitly out of
scope for this session.