BLE broadcast
Broadcasting small data packets to nearby devices over Bluetooth Low Energy, without pairing.
A BLE broadcast is a transmitter announcing small packets at intervals while nearby devices listen without connecting. It is one way to reach many devices at once without the internet.
In Superevent CrowdLight's BLE mode the controller sends the state to the transmitters over Ethernet and PoE, and the transmitters refresh the broadcast every 100 ms. The mobile app listens, and because the show package is downloaded beforehand no internet is needed. Packets are signed, so spoofed broadcasts are rejected. Browsers can't listen to BLE broadcasts, so web attendees join in socket mode.