Understanding Wireless Communications in Public Safety

When Bluetooth-enabled devices come within range of each other, a wireless
communication automatically takes place during which it is determined if the
devices have data to share, and/or if one needs to control the other. Each
device has an address assigned from a group of addresses reserved for each
class of devices. When one Bluetooth device detects another, this address
range is searched to see if the new device is a companion device.

If there is a need to communicate, the devices form a personal area network
(PAN, or piconet) that could fill a room (for a computer or stereo system),
or simply link an MP3 player on the belt to a set of headphones being worn
by the user. Different piconets establish their own random frequency
hopping algorithm, limiting interference between devices within range of
each other. Communications speeds vary from 57 kbps in one direction and
721 kbps in the other, to a bi-directional speed of 432.6 kbps.

[The full report is at: http://www.nlectc.org/pdffiles/wireless2003.pdf]