Timing for power grids, financial networks and cellular backhaul arrives from
satellites transmitting at a power level that reaches the ground weaker than
the thermal noise around it. Ports, mines, farms, hospitals and factories now
run private LTE and 5G. Industrial telemetry, building automation, medical
telemetry and uncrewed aircraft all share unlicensed spectrum with every
consumer device in range. The radio environment has quietly become a
dependency of physical operations — and, unlike the network stack above
it, it is almost never instrumented.
When something goes wrong there, the response is still a specialist with a
spectrum analyzer, a truck, and a day. That is a drive-test answer to a
continuous problem: it tells you what the environment looked like on Tuesday
afternoon at one location, which is exactly the wrong shape of information for
interference that is intermittent, mobile, or deliberate.
Two mature toolkits exist and neither closes the gap. Deterministic
propagation modeling — Longley-Rice, ITU-R recommendations, ray
tracing — encodes real physics, but describes a static, cooperative world you
have to specify by hand, and it does not learn from what actually happened.
Modern spectrum machine learning learns readily from data, but
is typically terrain-blind: trained on captures divorced from the geography
that shaped them, so a classifier that works beautifully at the site it was
trained on degrades at the next valley over, and nobody can say why.
The useful system is the fusion of the two. A model should be free to learn
what an emitter looks like, while being told what the ridge line, the tree
cover, the building mass and the antenna geometry make physically possible.
That constraint is not a limitation — it is most of the signal.