Bluetooth Terminology

A glossary of terms to enable you to understand the various definitions used on this website.

 Connection Type

There exist three main types of connection used by Bluetooth masterslave.gif

  1. Single-slave enabling communication between two devices.
  2. Multi-slave allows for 7 slaves to be connected to one master - the multi-slave connection is the basis for piconets.
  3. Scatternet, connecting multiple piconets the scatternet allows for the creation of large ad-hoc networks.


A collection of devices connected via Bluetooth technology in an ad hoc fashion. A piconet is initialised with two Bluetooth enabled devices, such as a PDA and mobile phone. A 3-bit address space limits the number of devices in any piconet to eight. All devices in a piconet are peer units and have identical implementations. When establishing a piconet, however, one device must act as a master for synchronisation purposes - the master is dynamically elected when a link is created. The other piconet units will act as slaves for the duration of the network.


A scatternet is comprised of two or more independent piconets which communicate with one another. The scatternet is created by either a master or slave in one piconet electing to become a slave in a neighbouring piconet. The device connected to both piconets may then relay communications. This setup enables communication between many and possibly remote piconets. Bandwidth is reduced proportionally if more than 10 piconets are operating in the same 10m radius.

scatternet diagram

 Master Unit

The master unit is responsible for synchronising all other devices in the piconet. Its clock and hopping sequence are used to perform synchronisation. The master also assigns numbers to the communication channels.

 Slave Unit

All devices in a piconet that are not the master are classed as slave units. They synchronise with the rest of the piconet by way of clock and hopping sequence instructions sent from the master unit.

 MAC Address

The 3-bit Media Access Control address is used to distinguish between the maximum of eight units participating in a piconet.


An interoperable Bluetooth device is able to establish a link and communicate with another Bluetooth unit regardless of vendor or implementation. An Ericsson mobile should thus be just as happy talking to a Toyota sat-nav system or Sony camcorder as it should to another Ericsson mobile. Only devices which have been comprehensively tested for interoperability may carry the Bluetooth logo.

 Bluetooth Connection Protocol

The set of rules used by Bluetooth devices which enables them to establish links and communicate with one another. Please click here for a full description of the connection protocol.

 Bluetooth SIG

The Bluetooth Special Interest Group, founded in 1998 by IBM, Ericsson, Nokia, Intel and Toshiba is responsible for the design and implementation of all Bluetooth technologies.

 Data Synchronisation

Keeping files in all locations up to date, regardless of whether the file is located on a home PC, PDA or laptop.


Institute of Electrical and Electronics Engineers . The IEEE is responsible for defining standards. IEEE 802.11 is the standard for a wireless LAN.


Wireless Application Protocol. WAP is a communications protocol for mobile phones, meant as an extension of available, Internet-based services.

 Bluetooth Device Address

An address unique to every Bluetooth device, it is also used to determine the frequency hopping sequence in a piconet.

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