Thinkpadepot

Bluetooth is easily the best in wireless handheld
technology. When it comes to learning, Bluetooth
can get quite complicated. To help you, you’ll find
the key learning points of Bluetooth below:

1. Bluetooth is an energy efficient, low
overhead communication protocol that’s ideal for
interdevice communications.
2. Unlike infrared, Bluetooth doesn’t require
a line of sight.
3. Depending on the implementation, Bluetooth
can have a range of up to 100 meters.
4. The specification of Bluetooth consists of
a Foundation Profile Document and a Foundation Core
Document.
5. The protocol stack for Bluetooth consists
of core protocols, cable protocols, and even adapted
protocols.
6. The transmitter operates around the 2.4
GHz frequency band.
7. The data channel will change frequency, or
hops, 1,600 times in a second, between the 79 allocated
channels in the ISM band.
8. Bluetooth utilizes a spread spectrum
frequency hopping RF characteristic to ensure that
independant networking operates when the other
devices are in range.
9. A piconet is formed when one or more
devices open up a channel of communication.
10. A piconet can have a master and up to
seven slaves.
11. Communication of the interdevice is
based on the concepts of channels.
12. All Bluetooth devices are capable of
transmitting voice.
13. The channel has a total capacity of
1 MB per second.
14. There are two types of channels with
Bluetooth – SCO (Synchronous Connection Oriented) and
ACL (Asynchronous Connectionless).
15. The SCO channels are time oriented, and
are therefore primarily used for transferring time
critical data such as voice.
16. ACL channels are normally used for
communicating data.
17. Data contained in a packet can be up to
2,745 bits in length.
18. In a single piconet, there can be up
to three SCO links containing 64,000 bits a second
each.
19. To avoid collision and timing problems,
SCO links are reserved slots that are set up by
the master.
20. The masters can support up to three
SCO links with either one, two, or three slaves.
21. The slots that aren’t reserved for SCO
links can be used as ACL links.
22. The LMP (Link Management Protocol)
will handle link level security, error corrections,
and the establishment of communications links.
23. The LMP packets will have priority
over user packets that originate and form the
L2CAP layer.
24. The L2CAP layer will ensure an
acceptable quality of service.
25. No more than one ACL link can exist
at the L2CAP layer.

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Below, you’ll find several specifications for the
well known Bluetooth:

1. Throughout the United States and even Europe,
the range of frequency is 2,400 – 2,483.5 MHZ, with
79 1-MHz RF (radio frequency) channels. The
frequency range in Japan is 2,472 to 2,497 MHz with
23 1-MHz RF channels.

2. A data channel of Bluetooth randomly hops 1,600
times per second between the 79 RF channels.

3. Each Bluetooth channel is divided into time
slots, with each one being 625 microseconds long.

4. A Bluetooth piconet has one master and up to
seven slaves. The master will transmit in even
time slots, while the slaves will transmit in odd
time slots.

5. The data in a single packet can be up to 2,745
bits in length.

6. Currently, there are two types of data transfer
between devices – SCO (synchronous connection
oriented) and ACL (asynchronous connectionless).

7. In a Bluetooth piconet, there can be up to
three SCO links containing 64,000 bits per second
with each one. To help avoid collision and timing
problems, the links of the SCO will use reserved
slots set up by the master.

8. A master can support up to three SCO links
with either one, two, or even three slaves.

9. The slots not reserved for the SCO links can
be used for ACL links.

10. A single master and slave can have one ACL
link.

11. ACL is either master to one slave (point to
point) or it broadcasts to all of the slaves.

12. The ACL slaves will only transmit when it has
been requested by the master. If the master doesn’t
make the request, the ACL slaves won’t transmit
anything at all.

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The profile found in Bluetooth will describe how
the technology is used. Profiles can be best
described as vertical slices through the protocol
stack. It will define options in each protocol
that are mandatory for the profile.

The profile will also define the parameter ranges
for each protocol. The concept of the profile is
used to decrease the risk of interoperability
problems between the different products. These
profiles won’t normally define any additions to
the Bluetooth specification, which is why you can
add new profiles where you need them. The
Bluetooth underlying technology is the same, only
the specific method that it’s used is defined.

Generally speaking, all profiles of Bluetooth are
based on the GAP (Generic Access Profile). There
are 9 profiles that fall in the GAP category, and
they are below:
1. AVRCP – Audio/Video Remote Control
Profile
2. ESDP – Extended Service Discovery Profile
3. CIP – Common ISDN Access Profile
4. PAN – Public Area Network Profile
5. HCRP – Hardcopy Cable Replacement
Profile
6. GAVDP – Generic Audio/Visual Distribution
Profile
7. A2DP – Advanced Audio Distribution Profile
8. VDP – Video Distribution Profile
9. HID – Human Interface Device Profile

To put it another way, usage models will describe
Bluetooth device applications and the associated
profiles that are used. The usage model focuses
mainly on three categories – voice/data access points,
peripheral interconnects, and PAN (Personal Area
Networking).

The voice and data access points involve connecting
computing devices to communicating devices through
a wireless link. This way, data can be transferred
in a wireless manor, without the need of cables or
other types of connectivity.

PAN is another very important usage model with
strong appeal to business customers. Bluetooth
networks are easy to set up in virtually any type
of environment. An example would be meeting
others at a trade show.

Instead of having contact information beamed via
infrared, business cards can quickly and easily be
transferred via Bluetooth wireless. The fact is
that many documents can be exchanged this very
same way – making the uses and possibilities
virtually endless.

The Bluetooth profile is very important to the
specification, as it enables you to do so much
more. You can use peripherals and devices with
the profiles, and virtually anything else that you
decide.

As Bluetooth expands and gets bigger and better,
you can count on the profiles to expand and get
even more functions. If you have experience with
Bluetooth profiles, you should know exactly what
they are and what you can do with them. If not,
all you need is a Bluetooth device – and a vivid
imagination.

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Constantly evolving, the technology of Bluetooth
started off as a basic wireless connection standard
but has since then been adapted and proven with many
different uses and functions.

A good example is Bluetooth for cell phones. It
enables mobile users to connect to their hands free
headset without using wires. Bluetooth technology
will also allow mobile phone users to connect
with their hands free kit as well.

Another handy use of Bluetooth is file sharing. It
allows the sharing of files between two cell phones,
between a cell phone and computer, which makes the
sharing of files a snap. If you have a cell phone
and computer, you can easily transfer data between
the two.

Say for example you wanted to put an MP3 on your
phone from your computer you could do it easily
with Bluetooth. All you would need is a Bluetooth
adapter for your computer. It doesn’t stop with the
swapping of files either,as you can use your computer
and phone to synchronise phone books, send SMS messages,
and much more.

Although Bluetooth may be dandy for cell phones,
it also comes in handy for the home office as well.
Utilizing Bluetooth is a great way to set up a
home office – two computers, a printer, and even a
scanner. They all can be connected using Bluetooth
technology with effective ranges of up to 10 meters.

The technology and devices of Bluetooth will be
around for years and years to come. As years go
by, Bluetooth will provide even better wireless
solutions for different applications. Even though
Bluetooth has a short range, it has that short
range for a reason. Bluetooth is easily the best
in wireless technology – which it continues to
prove time and time again.

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The technology of Bluetooth wireless is a short
range communications method intended to replace
the cables that connect portable or fixed devices
while maintaining the highest levels of security.

The key features offered by Bluetooth include
low power and low cost. The specification in
Bluetooth defines a uniform structure for a wide
range of devices to communicate and connect with
one another.

The technology behind Bluetooth has achieved
global satisfaction such as enabled devices, almost
everywhere in the world. Bluetooth devices will
connect and communicate without wires through
short range and networks known as piconets.

Each device will simultaneously communicate with
up to seven other devices within a single piconet,
meaning that each device can also belong to
several piconets simultaneously. The piconets
are dynamically established as Bluetooth enabled
devices enter and leave the proximity of radio.

A fundamental to Bluetooth strength is the
ability to handle both data and voice transmissions
simultaneously. This will enable users to enjoy
varieties of innovative solutions such as hands
free talking, printing and fax capabilities,
and other applications.

Specifications
Unlike other standards of wireless, the Bluetooth
specification gives product developers both a
link layer and application layer definitions,
which will help support data and voice applications.

Spectrum
The Bluetooth technology operates in the industrial
and scientific band at 2.4 to 2.485 GHz, using a
spread spectrum, frequency hopping signal.

Interference
The adaptive frequency hopping of Bluetooth
technology was designed to reduce interference
between wireless technologies that share the 2.4
GHz spectrum. Adaptive frequency hopping (AFH)
works well within the spectrum to take full
advantage of the frequency available.

AFH hopping allows for more efficient transmission
within the spectrum, which provides users with
greater performance even if they are using other
technologies along with Bluetooth.

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