Bluetooth technology

Bluetooth is a short-range wireless communication standard designed to replace cables between nearby devices. It operates in the 2.4 GHz ISM band, the same unlicensed band used by many wireless LAN and consumer devices, and is intended for low-power links over distances of roughly a few metres to a few tens of metres depending on the device class. Common uses include connecting a phone to a wireless headset or speaker, a computer to a keyboard or mouse, and transferring data between portable devices.

To share the crowded 2.4 GHz band and resist interference, Bluetooth uses frequency-hopping spread spectrum. Rather than staying on one channel, the radio rapidly switches among many narrow channels in a pseudo-random sequence agreed between the connected devices, hopping many times per second. If one channel is briefly disturbed, only a small part of the transmission is affected and is retried on a different channel, which makes the link robust in the presence of other 2.4 GHz traffic. Devices that connect form a small network, with one acting as master to coordinate the timing of the others.

Bluetooth's strengths are low power consumption, modest cost and automatic pairing of devices, which made it ubiquitous in phones, audio accessories and computer peripherals. It is not designed for the high data rates of a full wireless LAN; where larger throughput is needed, WiFi based on the IEEE 802.11 standards is used instead. The two technologies coexist in the same band, each suited to different tasks: Bluetooth for low-power personal-area links and WiFi for higher-speed local networking.

Frequently asked questions

What frequency band does Bluetooth use?

Bluetooth operates in the unlicensed 2.4 GHz ISM band, shared with WiFi and many other consumer wireless devices.

Why does Bluetooth use frequency hopping?

Hopping rapidly among many channels spreads the signal and limits the effect of interference, so a disturbance on one channel affects only a small part of the data.

How does Bluetooth differ from WiFi?

Bluetooth is built for low-power, short-range links between personal devices, while WiFi provides higher data rates for local networking, though both share the 2.4 GHz band.