the brief
A European IoT platform provider builds safety-critical monitoring networks for remote environments: battery-powered sensors spread across difficult terrain, far from mains power and usually far from any mobile coverage. A sensor that detects a critical event is only useful if its alert gets out, so the provider needed a way to carry messages from sensor to sensor until they reached a gateway with a cellular connection.
No existing protocol could do that reliably under these conditions, so we designed one. The project ran for two years, from research on paper to field deployment, and the protocol is in production today.
power, range and airtime limits
Almost every constraint a radio network can face shows up at once. Sensors run on batteries and have to last for years, and the distances between them are long, with terrain and obstacles eating into range. LoRa itself carries very little data at a time, and in Europe the 868 MHz band limits each device to a small share of airtime, typically 1%. And none of this can come at the cost of reliability, because the one message that must never be lost is the alert.
from star topology to multi-hop mesh
The usual way to build networks on LoRa is a star, in which every sensor talks directly to a gateway. At these sites that would mean a gateway, with its own power and cellular connection, within radio range of every sensor, which is exactly what they can’t offer. The sensors had to relay for each other instead, so that a single gateway at the edge of coverage could serve a whole area.
protocol design requirements
Routing protocols for low-power networks exist, but they were designed for radios far faster than LoRa, and the traffic they spend just keeping routes up to date can use up a device’s entire airtime budget before any real data is sent.
The protocol we designed had to do the opposite: spend almost nothing on its own upkeep, in airtime or in battery, find its way around nodes that fail or lose contact, and keep working for years without anyone on site to intervene.
research, simulation, field deployment
The work followed the order this kind of problem demands. We studied how existing routing approaches behave on radios like LoRa, designed the new protocol on paper, and validated it in simulation before a single device was flashed. Only then did we implement it on the provider’s devices and test it in real deployments, refining it until it was ready for production.
results
In production. The protocol carries alerts in the provider’s monitoring networks today.
Built for the constraints. A single cellular gateway can serve sensors spread across terrain that a star network couldn’t cover, within the airtime and battery limits the deployments impose.
what it took
Designing a routing protocol is a different discipline from implementing one: it takes theory, simulation and field testing, and a clear sense of what a network can afford when every transmission costs battery and airtime. We’ve worked on mesh routing for many years, including as long-time contributors to batman-adv, and this project took that experience from Wi-Fi mesh networks down to radios with a tiny fraction of the bandwidth.
if this sounds familiar
If your devices have to talk across distances, terrain or power budgets that standard protocols weren’t designed for, we can design the protocol that gets the message through.
Just book a call and let’s discuss.
More about our wireless and mesh work · Our open-source contributions