Why Choose Bluetooth wireless technology?
Bluetooth wireless technology is the simple choice
for convenient, wire-free, short-range communication
between devices. It is a globally available standard
that wirelessly connects mobile phones, portable
computers, cars, stereo headsets, MP3 players,
and more. Thanks to the unique concept of “profiles,”
Bluetooth enabled products do not need to install
driver software. The technology is now available
in its fourth version of the specification and
continues to develop, building on its inherent
strengths — small-form factor radio, low
power, low cost, built-in security, robustness,
ease-of-use, and ad hoc networking abilities.
Bluetooth wireless technology is the leading and
only proven short-range wireless technology on
the market today shipping over five million units
every week with an installed base of over 500
million units at the end of 2005.
Globally Available
The Bluetooth wireless technology specification
is available free-of-charge to our member companies
around the globe. Manufacturers from many industries
are busy implementing the technology in their
products to reduce the clutter of wires, make
seamless connections, stream stereo audio, transfer
data or carry voice communications. Bluetooth
technology operates in the 2.4 GHz, one of the
unlicensed industrial, scientific, medical (ISM)
radio bands. As such, there is no cost for the
use of Bluetooth technology. While you must subscribe
to a cellular provider to use GSM or CDMA, with
Bluetooth technology there is no cost associated
with the use beyond the cost of your device.
Range of Devices
Bluetooth technology is available in an unprecedented
range of applications from mobile phones to automobiles
to medical devices for use by consumers, industrial
markets, enterprises, and more. The low power
consumption, small size and low cost of the chipset
solution enables Bluetooth technology to be used
in the tiniest of devices. Have a look at the
wide range products made available by our members
in the Bluetooth product directory and the component
product listing.
Ease of Use
Bluetooth technology is an ad hoc technology that
requires no fixed infrastructure and is simple
to install and set up. You don’t need wires
to get connected. The process for a new user is
easy – you get a Bluetooth branded product,
check the profiles available and connect it to
another Bluetooth device with the same profiles.
The subsequent PIN code process is as easy as
when you identify yourself at the ATM machine.
When out-and-about, you carry your personal area
network (PAN) with you and can even connect to
others.
Globally Accepted Specification
Bluetooth wireless technology is the most widely
supported, versatile, and secure wireless standard
on the market today. The globally available qualification
program tests member products as to their accordance
with the standard. Since the first release of
the Bluetooth specification in 1999, over 4000
companies have become members in the Bluetooth
Special Interest Group (SIG). Meanwhile, the number
of Bluetooth products on the market is multiplying
rapidly. Volumes have doubled for the fourth consecutive
year and are likely to reach an installed base
of 500 million units by the close of 2005.
Secure Connections
From the start, Bluetooth technology was designed
with security needs in mind. Since it is globally
available in the open 2.4 GHz ISM band, robustness
was built in from the beginning. With adaptive
frequency hopping (AFH), the signal “hops”
and thus limits interference from other signals.
Further, Bluetooth technology has built-in security
such as 128bit encryption and PIN code authentication.
When Bluetooth products identify themselves, they
use the PIN code the first time they connect.
Once connected, always securely connected.
Overview of Operation
The Bluetooth RF (physical layer) operates in
the unlicensed ISM band at 2.4GHz. The system
employs a frequency hop transceiver to combat
interference and fading, and provides many FHSS
carriers. RF operation uses a shaped, binary frequency
modulation to minimize transceiver complexity.
The symbol
rate is 1 Megasymbol per second (Msps) supporting
the bit rate of 1 Megabit per second (Mbps) or,
with Enhanced Data Rate, a gross air bit rate
of 2 or 3Mb/s. These modes are known as Basic
Rate and Enhanced Data Rate respectively.
During typical operation, a physical radio channel
is shared by a group of devices that are synchronized
to a common clock and frequency hopping pattern.
One device provides the synchronization reference
and is known as the master. All other devices
are known as slaves. A group of devices synchronized
in this fashion form a piconet. This is the fundamental
form of communication for Bluetooth wireless technology.
Devices in a piconet use a specific frequency
hopping pattern which is algorithmically determined
by certain fields in the Bluetooth specification
address and clock of the master. The basic hopping
pattern is a pseudo-random ordering of the 79
frequencies in the ISM band. The hopping pattern
may be adapted to exclude a portion of the frequencies
that are used by interfering devices. The adaptive
hopping technique improves Bluetooth technology
co-existence with static (non-hopping) ISM systems
when these are co-located.
The physical channel is sub-divided into time
units known as slots. Data is transmitted between
Bluetooth enabled devices in packets that are
positioned in these slots. When circumstances
permit, a number of consecutive slots may be allocated
to a single packet. Frequency hopping takes place
between the transmission or reception of packets.
Bluetooth technology provides the effect of full
duplex transmission through the use of a time-division
duplex (TDD) scheme.
Above the physical channel there is a layering
of links and channels and associated control protocols.
The hierarchy of channels and links from the physical
channel upwards is physical channel, physical
link, logical transport, logical link and L2CAP
channel.
Within a physical channel, a physical link is
formed between any two devices that transmit packets
in either direction between them. In a piconet
physical channel there are restrictions on which
devices may form a physical link. There is a physical
link between each slave and the master. Physical
links are not formed directly between the slaves
in a piconet.
The physical link is used as a transport for one
or more logical links that support unicast synchronous,
asynchronous and isochronous traffic, and broadcast
traffic. Traffic on logical links is multiplexed
onto the physical link by occupying slots assigned
by a scheduling function in the resource manager.
A control protocol for the baseband and physical
layers is carried over logical links in addition
to user data. This is the link manager protocol
(LMP). Devices that are active in a piconet have
a default asynchronous connection-oriented logical
transport that is used to transport the LMP protocol
signaling. For historical reasons this is known
as the ACL logical transport. The default ACL
logical transport is the one that is created whenever
a device joins a piconet. Additional logical transports
may be created to transport synchronous data streams
when this is required.
The link manager function uses LMP to control
the operation of devices in the piconet and provide
services to manage the lower architectural layers
(radio layer and baseband layer). The LMP protocol
is only carried on the default ACL logical transport
and the default broadcast logical transport.
Above the baseband layer the L2CAP layer provides
a channel-based abstraction to applications and
services. It carries out segmentation and reassembly
of application data and multiplexing and de-multiplexing
of multiple channels over a shared logical link.
L2CAP has a protocol control channel that is carried
over the default ACL logical transport. Application
data submitted to the L2CAP protocol may be carried
on any logical link that supports the L2CAP protocol.
