Duty: defines how the basic hardware that controls the
radio transmissions functions
In this layer, data bits (0 and 1) are converted into radio signals
and transmitted
It is equivalent to OSI Physical layer
Radio Module at the heart of this layer
Is a single radio transmitter/receiver (transceiver) that
is built into tiny circuit boards and contain small
microprocessors
Could include an interface, such as USB.
the only hardware required for Bluetooth to function.