Environmental Perception via Propagation-Equivalent Reconstruction from Opportunistic Cellular Signals

Low-altitude unmanned aerial vehicles (UAVs) need environmental evidence for perception and navigation, yet dedicated onboard sensing and prior maps may be unavailable. Existing cellular infrastructure offers persistent signals of opportunity, but a passive UAV observes only scalar RSRP, which conflates transmit power, sector response, and environmental loss. We formulate UAV environmental perception as passive, protocol-assisted sensing using non-cooperative commercial cellular downlinks and propose a protocol-anchored reconstruction of a propagation-equivalent virtual radio environment map (vREM). Decodable nominal reference power and path-loss normalization set the power scale, coarse site bearings constrain antenna directions, and multi-altitude UAV trajectories excite height dependence. A hard height-class Beer–Lambert model recovers occupancy support and a height proxy without building geometry at inference. In a controlled multi-altitude simulation based on Xi’an Bell Tower geometry, the method achieved a held-out RMSERSRP of 5.24 dB, compared with 15.70 dB for NoProtocol; all metrics improved across 200 paired repetitions. A separate ground-based field collection yielded 1518 observations from 82 LTE/NR sources at 41 sites and reduced relative-power mapping RMSE from 7.27 to 3.41 dB. The receiver uses public broadcast fields locally, while the commercial transmitters remain outside the sensing and inversion loop.