What Gives Bluetooth Its Bite?

The Bluetooth technology has specific features and functionality that
gives it the ability to encompass a divergent set of varied technologies.
These features include:


Bluetooth segments the frequency band into hops. Spread spectrum is
used to hop from one channel to another. The result is the addition of
a stronger security layer.


Up to eight devices can be networked in a personal area network
(PAN), a conglomerate of devices connected in an ad hoc way using
Bluetooth. A piconet or PAN is formed when at least two devices
(i.e., a portable PC and a cellular phone) connect. A PAN can support
as many as eight devices. When a PAN is formed, one device
acts as the master while the others act as slaves for the duration of
the connection.


Signals can be transmitted through walls and containers, eliminating
the need for line of sight.


Devices do not need to be pointed at each other, as signals are omnidirectional.


Both synchronous and asynchronous applications are supported; this
simplifies the process of implementing Bluetooth on a variety of
devices and for a variety of services including both voice and Internet.


Regulation by governmental agencies makes it easy to implement a
wide array of implementations globally.

Bluetooth defined Since the terminology for this technology can be
quite intensive, it is important first to learn the definitions for the most
common Bluetooth terms:


Piconet or personal area network (PAN)—Devices connected in
an ad hoc manner that don’t need to be predefined or planned in
advance (as opposed to a wired Ethernet). As few as two or as many
as eight devices can be networked into a piconet. This represents a
peer network, meaning that when it is connected, each device has
equal access to the others. Note: One device in the chain is the master,
while the others are slaves.


Scatternet—Several piconets or PANs can form a larger scatternet,
where each piconet is completely independent.


Master unit—The master in a piconet or PAN whose clock and hopping
sequence synchronizes all the other devices.


Slave unit—Devices in a piconet or PAN that are not the masters.


MAC address—Three-bit address that uniquely identifies each unit
in a piconet or PAN.


Parked units—Piconet devices that are synchronized, though they
don’t have MAC addresses.


Sniff and hold mode—Power-saving mode of a piconet device.
Bluetooth topology The typical Bluetooth network topology is either
point to point (P2P) or multipoint.


A PAN can establish a connection to another PAN to form a “scatternet.”
The typical scatternet has four units connected to a PAN that has
two units. It is important to note that the “master unit” in this scheme
is not the actual connection link between the two PANs.
Transmission speed Both circuit and packet switching combine
within the baseband protocol, which involves one single channel per
line. One major concern is that packets do not arrive out of sequence. To
avoid these problems, as many as five slots can be reserved for synchronous
packets. Note that a different hop signal is used for each individual
packet.
Using a baseband protocol, circuit switching can be either synchronous
or asynchronous.
You can have as many as three synchronous voice or data channels,
such that one synchronous and one asynchronous data channel can be
supported on any given channel. This means that each synchronous
channel can support as much as 64-Kbps transfer speeds (sufficient for
voice transmissions).
In contrast, asynchronous channels can send as much as 721 Kbps in
one direction with as much as 57.6 Kbps in the opposing direction. Furthermore,
you can also have an asynchronous connection supporting
432.6 Kbps in both directions when you have symmetric link.