Vol. I · A field notebook
Notes on cooperative-ITS — written slowly, in plain text.
Everything here through the V2X lens: positioning, in-vehicle networks, the software-defined vehicle, sensor fusion, PKI, and how any of it gets deployed, funded and regulated. Only what matters once vehicles start talking to each other and to the roadside.
Recent entries
The BTP port registry: the real count of C-ITS messages Nine acronyms get all the coverage. The BTP port registry in ETSI TS 103 248 assigns 26 ports to 28 message types, and one changed hands since 2024.
ETSI C-ITS, Release 1 to Release 2: a standards map Which ETSI document is current for each C-ITS layer and message, and which one it replaced. A Release 1 to Release 2 map, with version numbers.
measurementDeltaTime: the age of every object in a CPM Every object in a CPM carries an age accumulated down a sensor and fusion pipeline. measurementDeltaTime declares it; ignore it and you draw the past.
The CPM confidence field that TS 103 324 never pins down Every object in a CPM is an offset from the sender's pose, and that pose is wrong twice over. TS 103 324 never settles whether the confidence covers it.
The message that tells your car where to park, and what comes next ETSI's POIM (TS 103 916) broadcasts live parking availability to passing vehicles, inside a point-of-interest envelope with room for far more.
C-ITS architecture: four layers and two planes The European C-ITS stack is one diagram everyone redraws. Four horizontal layers, two vertical entities for security and management, and why those two refuse to be layers at all.
The cyclist can be sold a radio; the pedestrian only has a phone A bike brand put V2X in an e-bike, but the real adoption vector for vulnerable-road-user safety is shared micromobility: a fleet the city already licenses.
V2X in mid-2026: where it's deployed, where it's stalled One country is fitting millions of cars while another just cut its programme by 97%. A region-by-region look at where connected-vehicle tech actually is.
The post-quantum deadline is set by the oldest car on the road For connected vehicles, post-quantum cryptography has a deployment date. The industry bodies already treat it as a roadmap item.
ETSI TS 103 324 (CPM): from study to standard TR 103 562 asked whether vehicles should share sensor detections; TS 103 324 fixed the answers. What changed between report and specification, and the five containers a CPM carries.