piconet

A piconet is the basic unit of Bluetooth networking. It is formed when one device acts as the master and one or more devices act as slaves, all sharing a common radio channel and coordination. The master provides the clock and the hopping sequence that guides communication across the frequency-hopping spread spectrum. In a piconet, devices communicate in a time-division manner, with the master controlling when each slave can transfer data. The Bluetooth radio operates in the 2.4 GHz ISM band, hopping among 79 1-MHz channels to reduce interference. Slaves can be kept in a parked state, allowing additional devices to remain linked without occupying active communication slots.

Structure and capacity. A piconet typically supports up to seven active slaves; more devices may be linked to the same master but in parked mode or idle states, not actively exchanging data. In total, a single piconet can include up to 255 devices, counting the master, active slaves, and parked devices. The master’s clock and hopping sequence provide the timing and channel access for all devices in the piconet, while each device maintains a link with the master.

Scatternets and range. Piconets can be interconnected to form scatternets, where devices participate in multiple piconets, potentially acting as a master in one and a slave in another. Scatternets expand the network’s reach but add coordination complexity and potential latency. Range varies by device class and environment; typical Bluetooth devices offer approximately 10 meters in standard class, with greater ranges possible for higher-power classes.