Bluetooth is a wireless technology standard that allows short-range wireless connections between electronic devices like mobile phones, headphones, printers, etc. It was developed by the Bluetooth Special Interest Group to replace wired connections like cables. Bluetooth uses radio waves in the 2.4 GHz spectrum to connect devices within a 10 meter range through ad-hoc networks called piconets. Each piconet can have one master device and up to seven active slave devices connected at once.

1. BlueBluetoothtooth
TechBluetooth gy

2. Bluetooth
 What is Bluetooth?
 Goals
 Requirements
 Usage Models
 Bluetooth Architecture
 Security

3. What Is Bluetooth?
• Designed to be used to connect both mobile
devices and peripherals that currently require a wire
• Short range wireless radio technology
- operate range of 10 meters
• Simplifying communications
between:
- devices and the internet
- data synchronization
• “USB without wires”

4. Bluetooth
 Bluetooth is a new standard developed by a
group of electronics manufacturers that will
allow any sort of electronic equipment -- from
computers and cell phones to keyboards and
headphones -- to make its own connections,
without wires, cables or any direct action from
a user.
 A key difference with other existing wireless
technologies is that bluetooth enables
combined usability models based on functions
provided by different devices.

5. What’s With the Name?
• King Harald Bluetooth (A.D. 940 to 985)
• 10th century Viking king in Denmark
• Credited for uniting the country and
established Christianity
• Viking states included Norway & Sweden,
which is the connection to Ericsson (creator
of bluetooth)

6. Who Started Bluetooth?
• Bluetooth Special Interest Group (SIG)
-5 founding members
-Ericsson, Nokia, IBM, Intel & Toshiba
• Promoter’s Group
- 3COM, Lucent, Microsoft, Motorola
• Now over 1900 members
Ericsson Mobile Communication

7. Bluetooth Special Interest
Group
 The Bluetooth Special Interest Group
comprises more than 1000 companies.The
major companies who created the technology
include
 Intel
 3 com
 Ericcson
 IBM
 Motorola
 Nokia
 Toshiba

8. Nine Promoters
Founders Y2K Additions
And over 2000additional SIG members
The Bluetooth Special Interest Group (SIG)

9. No Wires!
In the home
On the move
Personal Area Networking (PAN)
Enabling a collection of YOUR personal devices to
cooperatively work together
Locality sensitive services
Visibility and access to additional resources, but only
when they are within range and useful to you
What is Bluetooth
Good For?

10. PDA
Cell Phone
Cordless Phone
Base Station
xDSL
Access Point
Inkjet
Printer
Scanner
Home Audio System
Computer
Digital Camera
MP3
Player
Bluetooth @ Home
NO WIRES

11. Car Audio System
Pay Phone
& Access Point
Hotel Phone
& Access Point
Headset
MP3
Player
PDA
Cell Phone
Laptop
On the Move

12. Bluetooth in Computer
Products
Computer devices
 Laptop computers
 PDAs/HPCs
 Desktop PCs
 Broadband access
points
 Ethernet/xDSL/cable
 Printers
 Scanners
 Video projectors
Computer applications
 Peripheral connectivity
 Printers
 Scanners
 Video projectors
 Network access
 Broadband access points
 Packet radio cellular
phones
 File synchronization
 Calendars
 Contact management
 File transfer
 VCards
 MP3
 Digital pictures

13. Bluetooth in Telephone
and Consumer Products
Telephone devices
 Cellular handsets
 Wireless headsets
 PSTN access points
 Payphones
 Hotel/home phones
Consumer devices
 Digital cameras
 MP3 audio players
 Home audio systems
Telephone applications
 Hands free use
 File synchronization
 Calendars
 Contact management
Consumer applications
 File transfer
 MP3
 Digital pictures
 Peripheral connectivity
 Keyboard/mouse/remote
 Printer

14. Strength of Bluetooth
1- Cheap Initial costs $ 20 Future target $ 5
2- Tiny It is only 10.2 *14* 1.6 mm. Easy implementation.
3- low-power consumption
Bluetooth radio consumes less than 3% of
the power compared to that of modern mobile phone .
4- It works all over the world
Operates on ISM radio band.
-Unlicensed band.
5- Supports point-to-point & point-to-multi-point
communication.
6- High Security - It allows authentication & encryption.
- Protection against interference.
7- High speed .
- Current speed up to 1 Mbps (723.2 Kbps)

15. Ad hoc client/server
topology, 8 active & up to 256
parked devices per piconet.
1 master per piconet
“speaking” to slaves via TDM.
Multiple piconets up to 13
per scatternet.

16. Bluetooth - overview
 Goals of the Bluetooth SIG
• Wireless standard (unification) for the
interconnection of computing and
communication devices.
• Inexpensive
• Short range
• Wireless radios

17. Bluetooth - overview
 Differences between V 1.0 and 802.15
 V 1.0 is a complete specification from application
layer to physical layer
 802.15 is only standardizing (modifying) the
physical and data link layers.
 The Bluetooth 802.15 specification not only
creates competition for other wireless
technologies, namely 802.11, but the two
occupy most of the same 2.4 GHz spectrum
and thus interfere with each other.
(More on this later)

18. Bluetooth Devices
• Telephones
• Headsets
• Computers
• Cameras
• PDAs
• Cars
• Etc …
Bluetooth will soon be enabled in
everything from:

19. Motivation
 Present wireless technology like infra red
data communication has two problems –
1)Line of Sight 2) One to One
 Using data synchronizing– e.g. hot syn on
a PDA --- problem of using the right cradle
and cable.
 BLUETOOTH OVERCOMES THESE
PROBLEMS

20. Bluetooth Products 1
 Bluetooth-
enabled PC Card

21. Bluetooth Products 4
 Bluetooth-
enabled Head
Set

22. Advantages (+)
• Wireless (No Cables)
• No Setup Needed
• Low Power Consumption (1 Milliwat)
• Industry Wide Support
•Fairly inExpensive

23. Disadvantages (-)
• Short range (10 meters)
• Small throughput rates
- Data Rate 1.0 Mbps
• Mostly for personal use (PANs)

24. The Basic Idea
 Bluetooth is a standard for a small , cheap
radio chip to be plugged into computers,
printers, mobile phones, etc
 Bluetooth chip is designed to replace
cables.Information normally carried by
the cable, is transmitted at a special
frequency to a receiver Bluetooth chip.
 These devices can form a quick ad-hoc
secure “piconet” and start communication.
 Connections in the “piconets” can occur even
when mobile.

25. The Basic Idea
 It provides agreement at the physical level --
Bluetooth is a radio-frequency standard.
 Provides agreement at the data link level
where products have to agree on
 when bits are sent
 how many will be sent at a time
 how the parties in a conversation can be
sure that the message received is the same
as the message sent

26. Bluetooth - architecture
 Piconet – the basic unit of a Bluetooth
system.
 1 Master node
 1 to 7 active slave nodes
 0 to 255 parked nodes

27. Bluetooth - architecture
 Parked node
 a slave device in a low power state to
conserve the drain on the devices batteries
 In this state the device can only respond to
the beacon from the master node

28. Bluetooth - architecture
 Node range
 Slave nodes need to be within 10 meters of
the master node.
 Why design such a short range?

29. Bluetooth - architecture
 Answer : Money,
Money Money !!!
 The designers
wanted this
technology to be
used widely (i.e. to
sell product).
 Bluetooth chips
under $5.00

30. Bluetooth - architecture
 Communication
 Only possible between master and slave
nodes
 Piconet uses centralized Time Division
Multiplexing.
 The master node controls the clock and
determines which devices occupy which
time slot.

31. Bluetooth - architecture
 How can such a limited range
architecture really provide competition
for 802.11 (WiFi)?

32. Bluetooth - architecture
 How can such a limited range
architecture really provide competition
for 802.11 (WiFi)?
 Answer : Scatternets

33. Bluetooth – architecture
Tanenbaum, Andrew S., Computer Networks 4th Ed. figure 4-35

34. “Piconet”
 A collection of devices connected via
Bluetooth technology in an ad hoc fashion.
 A piconet starts with two connected
devices, and may grow to eight connected
devices.
 All Bluetooth devices are peer units and
have identical implementations. However,
when establishing a piconet, one unit will
act as a Master and the other(s) as
slave(s) for the duration of the piconet
connection.

35. Bluetooth Specifications
• Each channel is divided into time slots 625
microseconds long
• Data in a packet can be up to 2,745 bits in length
• Packets can be up to five time slots wide

36. Requirements
 Low cost as cables – chip $5
 Secure as cables – must support authentication and
encryption
 Must support both data and voice.
 Must connect to a variety of devices.
 Must be able to function in a noisy environment.
 Data rates – 721kbps , using the 2.45Ghz radio
frequency band –I.S.M (Industrial, scientific and
medical)
 Must support many simultaneous and private
“piconets”.
 Must be low power, compact and global.

37. Bluetooth Frequency
Has been set aside by the ISM for exclusive use of
Bluetooth wireless products
• Communicates on the 2.45 GHz frequency

38. Usage Models- Voice/Data Access Points
 Connecting a computing
device to a communicating
device.
 Allows any device with a
bluetooth chip to connect to
the internet while located
within the range of the
access point.
 Example- a notebook could
link to the internet using a
mobile phone as an access
point.
 Envisions public data access
points

39. Avoiding Interference :Hopping
• Bluetooth uses a technique called spread-spectrum
frequency hopping.
• In this technique, a device will use 79 individual,
randomly chosen frequencies within a designated range
• Transmitters change frequency 1600 times a second

40. Usage models-Peripheral Interconnects
 Standard peripheral devices
like keyboard, mice, headsets
etc working over a wireless
link.
 The same device can be used
in multiple functions e.g a
headset can access phones
while in the office and can
interface with a cellular
phone when mobile.

41. Usage model- Personal Area Networking.(PAN)
 Allows dynamic
formation and
breakdown of
“PICONETS”--ad-hoc
personal networks.

42. spread-spectrum frequency
hopping
 In order to minimize interference the nominal
antenna power is 1 mW which can be
extended to 100mW.
 The low power limits the range to about 10
centimeters to 10 meters. With higher power
of 100mW range of 100meters can be
achieved.
 It uses a packet switching protocol based on
a technology called spread-spectrum
frequency hopping to spread the energy
across the ISM band.

43. Spread-Spectrum frequency hopping
 A device will use 79 individual randomly chosen
frequencies within a designated range, changing
from one to another on a regular basis.
 The designated range is from 2.402GHz to 2.480GHz,
in steps of 1MHz.
 The frequency hopping is done at a rate of 1600
times a second.
 This allows more devices to use the limited time slice
and secondly reduces the chance of two transmitters
being on the same frequency at the same time.

44. Bluetooth Addressing
The following device addresses are used in a
Bluetooth system:
BD_ADDR
AM_ADDR
PM_ADDR
AR_ADDR
The master uses AM_ADDR to address
each active slave in the piconet

45. Network Topology
 All units have a unique global ID(BD_Addr)
address( 48 bits)
 The unit that initializes the connection is
assigned as the master which controls the
traffic of the connection.
 A master can simultaneously connect upto
seven slaves.
 The master/slave roles can be swapped.
 A device can be a master in only one
“piconet” at a time.

46. Forming a piconet
 Needs two parameters --- a) Hopping pattern
of the radio it wishes to connect. b) Phase
within the pattern i.e. the clock offset of the
hops.
 The global ID defines the hopping pattern.
 The master shares its global ID and its clock
offset with the other radios which become
slaves.
 The global ID and the clock parameters are
exchanged using a FHS (Frequency Hoping
Synchronization) packet.

48. Forming a piconet
 Devices not connected to a piconet are in STANDBY
mode, using low power.
 A connection is made by either a PAGE command if
the address is known or by the INQUIRY command
followed by a PAGE
 When a radio sends an INQUIRE command, all the
listening radios respond with their FHS packets,
which tells the inquiring radio of all the radios in the
area.
 All listening radios perform a page scan and/or an
inquiry scan every 1.25 seconds.
 The master radio sends an FHS to the paged radio.

49. Forming a piconet
 Shows a bunch of
bluetooth devices
in proximity of
each other.
 Each device has
its own ID and its
clock offset

50. Forming a piconet
 Radio A has become
the master and has
formed a piconet
with B and C as the
slaves.
 Both B and C now
share A’s ID and
and clock offset.

51. Forming a piconet
 When a radio joins a piconet it is assigned a 3
bit Active Member Address(AMA).
 Once the piconet has eight radios, the master
assigns puts a radio into the PARK mode.
 This is one of the low power states, in which
the radio releases its AMA for a 8 bit PMA
(Passive Member Address).
 The freed AMA can be assigned to another
radio wishing to join the piconet.
 Though upto 256 radios can actively reside
on a piconet, only 8 of them with AMA’s can
transfer data.

52. Inquiry Scan
 One radio performs a page function on a
special Inquiry ID global address.
 Listening radios perform an inquiry scan on a
unique sequence of 32 channels.
 The radio will listen every 1.25 seconds on
each of these 32 channels for 10ms and will
then repeat the same for the next channel.
 The inquiring radio issues a number of pages
on the inquire channels and then listens for a
response for 1.25 seconds for 16 of the 32
channels.

53.  If a listening radio was doing a page scan on
one of these inquire channels it will respond
with its FHS packet.
 The sequence is repeated for the second set
of 16 channels.
 After an inquire scan is performed the
inquiring radio will have a list of all the FHS
packets of all the radios within its range.

54. Page Scan
 A page scan is done by a radio in the Standby mode
if the address of the device to connect is known.
 Each radio has a unique sequence of 32 paging
frequencies and 32 response frequencies based on its
Global ID.
 The radio will listen for a page of its global ID on
each of the 32 paging frequency for 10ms, changing
frequency every 1.25 seconds.
 The paging radio will continuously page using the
paged radio’s Global ID on one of the set of 16
paging frequency for 1.25seconds.

55.  The paging radio estimates the 16 frequencies on
which to start paging based on the last known clock
offset.
 If the paging radio receives no response then it will
page on the remaining 16 frequencies for the next
1.25 seconds.
 Connecting time  Clock offset
 Clock offset  how recently were they were
connected.

56.  Once a radio joins the piconet and has an
AMA it can direct data to other devices on the
piconet.
 In order to remain in the connected state
within a piconet, the radio needs to maintain
the frequency hopping pattern and offset
while consuming low power.
 To achieve this the connected radios can be
placed in either PARK, HOLD or SNIFF modes.

57. HOLD MODE
 When data needs to be transmitted very infrequently,
thus conserving power.
 In this mode only an internal timer is running.
 No data is transferred when in HOLD mode.
 The master can put slaves on HOLD mode.
SNIFF MODE
 A slave device listens to the piconet at a reduced
rate.
 The SNIFF interval is programmable.
 In both the HOLD and SNIFF states the device
retains its AMA.

58. PARK MODE
 The device has given up the AMA and
has become passive.
 The parked device will occasionally
listen to see if the master has sent any
broadcast data asking it to become
active.

59. Master
Active Slave
Parked Slave*
Standby*
N
J
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D
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Operational States
* Low power state
How Bluetooth Works

60. D
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B
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F
K
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P
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In the beginning

61. Inquiry
Discovering Who’s Out
There
D
A
10 meters
H
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P
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Q
B
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K
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G
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Note that a device can
be “Undiscoverable”

62. D
E
F
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G
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K
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Paging
Creating a Piconet
C
M
N
L
P
O
Q
B
B
A
A
10 meters

63. D
E
F
H
G
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K
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Paging
A Simplistic Illustration
C
M
N
L
P
O
Q
B
B
A
A
A
10 meters

64. D
Expanding a Piconet (1)
H
B
C
M
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P
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Q
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F
G
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F
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K
K
A
10 meters

65. B
B
J
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D
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K
F
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Parking
C
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P
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A
10 meters

66. D
K
F
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Expanding a Piconet (2)
B
J
M
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P
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Q
H
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H
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A
10 meters

67. J
F
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G
Scatternets
D
M
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B
L
H
K
C
N
P
Q

68. N
H
K
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Advanced Scatternets
D
M
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B
L

69. Types of Links and Packets
Synchronous Connection Oriented(SCO)
 Point to point full duplex link.
 Typically used for voice data.
 These packets do not use CRC and are
not retransmitted.
 Needs an asynchronous connectionless
(ACL) type link to be first established.

70. Asynchronous Connectionless Link
 This is a packet switched link between a
master and slave.
 Supports both isochronous and
asynchronous data.
Error Correction Schemes
 Forward error correction(1/3 and 2/3)
 Automatic Repeat Request scheme.

71. References
 Bluetooth Architecture Overview
James Kardach
 www.bluetooth.com
 www.palowireless.com