Wireless Home Networking - Index of

Figure 3-1:
Piconets
have one
master and
at least one
slave.
application — like a headset profile for attaching a wireless headset to a
phone, or an audio profile for playing music over a wireless Bluetooth connection.)
Piconets get their name from merging the prefix pico (probably from
the Italian word piccolo [small]) and network. A capability called unconscious
connectivity enables these devices to connect and disconnect almost without
any user intervention.
A particular Bluetooth device can be a member of any number of piconets at
any moment in time (see Figure 3-1). Each piconet has one master, the device
that first initiates the connection. Other participants in a piconet are slaves.
The three types of Bluetooth connections are
� Data only: When communicating data, a master can manage connections
with as many as seven slaves.
� Voice only: When the Bluetooth piconet is used for voice communication
(for example, a wireless phone connection), the master can handle no
more than three slaves.
� Data and voice: A piconet transmitting both data and voice can exist
between only two Bluetooth devices at a time.
Each Bluetooth device can join more than one piconet at a time. A group of
more than one piconet with one or more devices in common is a scatternet.
Figure 3-2 depicts a scatternet made up of several piconets.
The amount of information sent in each packet over a Bluetooth connection,
and the type of error correction that is used, determine the data rate a connection
can deliver. Bluetooth devices can send data over a piconet by using
16 types of packets. Sending more information in each packet (that is, sending
longer packets) causes a faster data rate. Conversely, more robust error
correction causes a slower data rate. Any application that uses a Bluetooth
connection determines the type of packet used and, therefore, the data rate.
Master
Slave
Chapter 3: Bluetooth and Other Wireless Networks
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