Bluetooth and specifically BLE is way more capable and versatile than most people understand. We are using it for a connectionless time synchronisation protocol that also contains a rudimentary control plane.

The clients can receive synchronisation data every minute and listen for a year on a coin cell. It’s broadcast, so a single beacon node can service hundreds of clients simultaneously.

BLE also can manage data connections over a kilometer and a half with reasonable (not great) antennas.

It’s not terribly fast, but modern radio protocols are opening up the possibilities. Lora and BLE are bringing the environment alive with communication.