How Does Bluetooth Work?

Bluetooth technology, standardised by the IEEE as 802.15.1, was developed by Ericsson in 1994 and named after 10th-century Viking king Harald "Bluetooth" Gormsson. It operates in the globally unlicensed 2.4 GHz ISM (Industrial, Scientific, Medical) band, the same as Wi-Fi and microwave ovens. To coexist with other devices, Bluetooth uses adaptive frequency-hopping spread spectrum (AFH-SS): the transmitter and receiver synchronise and hop between up to 79 frequency channels 1,600 times per second in a pseudo-random pattern, spending less than 1 millisecond on each channel. If interference is detected on a channel, it is removed from the hopping pattern. Classic Bluetooth supports data rates of 1-3 Mbps over distances of about 10 metres. Bluetooth Low Energy (BLE), introduced in Bluetooth 4.0 (2010), drastically reduces power consumption for IoT devices. Bluetooth 5.0+ offers ranges up to 240 metres and data rates of 2 Mbps.