Packet-Level Complex CIR Tracking for Communication-Native mmWave Sensing: An 802.11ad Testbed

Abstract

Commercial millimetre-wave (mmWave) Wi-Fi platforms based on IEEE 802.11ad/ay have demonstrated sensing capabilities, but they provide limited visibility into the packet-level measurements and synchronisation mechanisms that determine temporal coherence. We present a programmable 60~GHz IEEE 802.11ad testbed that exposes the complete complex 128-tap channel impulse response (CIR) for every detected packet. This access exposes packet-to-packet delay shifts and common phase drift that commercial-transceiver studies generally do not characterise. We develop a delay-profile alignment method and define a static-reference relative CIR phase that cancels common drift while preserving target-induced variation. We use 30~s respiration sensing to evaluate long-term phase stability for sub-wavelength motion tracking. Across 39 recordings, median absolute waveform correlation increases from 0.41 (timestamp regularised) to 0.52 (delay aligned) and 0.61 (relative-phase calibrated); breathing-rate mean absolute error decreases from 5.1 to 4.1 and 3.6~breaths/min. The results demonstrate controlled characterisation and stabilisation of communication-native WiGig CIR measurements on a fully programmable physical layer.