BLUETOOTH TECHNOLOGY - PowerPoint PPT Presentation

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BLUETOOTH TECHNOLOGY

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BLUETOOTH TECHNOLOGY A revolution in wireless communication – PowerPoint PPT presentation

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Title: BLUETOOTH TECHNOLOGY

1
BLUETOOTH TECHNOLOGY

A revolution in wireless communication

2
ROAD MAP

Introduction
Basic Definitions
Topology
Protocols
Link Management Security
Applications and Future

3
Introduction

Aim - To replace cables between mobiles, PC
cards, headsets, desktops and other devices.
Developed by Special Interest Group (SIG)
Association of I.T majors like Intel, IBM, Nokia
and Toshiba

4
Bluetooth Verses Infrared

Slower than IR as time taken to discover the
intended recipient
Penetration of solid objects
Omni directional

Advantage of proximity so less time requirement
No such feature
Unidirectional with 30 degrees range

5
BT Verses IR

Data transfer rate 721 Kbps
30 feet range
Mobility during data transfer
Internet compatible
(emulating EIA\ TIA 232)

Rate is 4 Mbps
Range very less
Relatively stationary

6
Bluetooth Definitions

Piconet Collection of devices connected via
Bluetooth in ad hoc fashion. Limited to 8 units
in a Piconet
Scatternet Two or more independent
unsynchronized Piconet.

7
Definitions

Master A device in Piconet whose clock and
hopping sequence are used to synchronize all the
devices. It also numbers the communication
channels

8
Definitions

Slave All other devices in the Piconet except
master
MAC 3-bit media access control address used to
differentiate between participating units

9
Bluetooth technology

Implemented using short range transreceivers
Specifications comprises a system solution
consisting of a hardware, a software
interoperability requirements
Uses globally available unlicensed ISM radio band
of 2.4 GHz.
Frequency range 2.4 2.484 GHz

10
BT technology

Advantage of using an unlicensed frequency band
is that it is globally acceptable

11
Types of Links

Asynchronous Connection Links (ACL)
Supports symmetrical, asymmetrical,
packet-switched point to multipoint links
Data Transfer Rate 433.9 Kbps(sym.)
732.2 Kbps in one, 57.6 Kbps in
reverse(asymmetric)

12
Types of Links

Synchronous Connection Oriented Links (SCO)
Provide symmetrical, circuit-switched point to
point connections

13
Audio and Video

For voice coding 64 Kbps channels are required
Channels are derived through use of PCM or CVSDM
Video encoding decoding using MPEG 4 format
Radio links use freq. hopping spread spectrum
techniques

14
Spread Spectrum

Method of wireless communication that takes a
narrow band signal and spreads it over a broader
portion of the available frequency band.
CDMA applies the same concept

15
Advantages of Spread Spectrum Technique

Prevents Interference where transmission
disruption by external source such as noise from
electromagnetic devices.
Prevents Jamming where stronger signal
overwhelms the weaker one.
No reflection off solids.
No interception where unauthorized users
capture signal to determine the content.

16
Performance Characteristics
Features\Functions Performance
1.Connection Type 2.Spectrum 3.Transmission Power 4.Aggregate Data Rate 5.Range 6.Supported stations Spread spectrum 2.4GHz. ISM band 1 milliwatt 1 Mbps using frequency hopping Up to 30 feet Up to 8 devices per piconet
17
Features\Functions Performance
Voice Channels Up to 3
Data Security For authentication a 128 bit key for encryption key size configurable (8-128 bits)
Addressing Each bit has 48 bit MAC address
18
Bluetooth Topology

Ad-hoc connection where each Piconet is
identified by a different hopping sequence
Synchronization in unlicensed ISM band not
permitted but BT devices do it using TDM
Service discovery protocol allows wider
applications ex create LAN
Clustering avoided using technical safeguards.

19
Bluetooth Protocols

Bluetooth Protocol Layers
Bluetooth Core Protocols (Baseband, LMP, L2CAP,
SDP)
Cable Replacement Protocols (Radio Freq.
Communication)
Telephony Control Protocols (TCSBIN, AT-Commands)
Adopted Protocols (PPP, TCP, OBEX, WAP, vCard,
vCalender)

20
LMP and SDP

LMP responsible for link setup control
between Bluetooth devices, including the control
and negotiations of baseband packet sizes
SDP device information, services and
characteristics of services can be queried.

21
BLUETOOTH

LINK MANAGEMENT

22
Link Management

Peer to Peer communication using LMP
Link Manager
Messages Exchanged (PDUs)
Within 30 seconds
PDU
55 different types of PDUs
7 bit op code

23
AUTHENTICATION

General Response Messages
LMP_accepted
LMP_not_accepted
Challenge- Response Scheme
Verifier sends(LMP_au_rand)
Response is a function of challenge ,Claimant s
(BD_ADDR)Secret Key
Common Secret key is required for proper
calculation

24
PAIRING

When no Common Link Key
128 bit Initialization Key based on PIN and
random no.
Calculation of Response on key
Verifier Approves the Link Key
Response not correct then Error
Code authentication failure (LMP_detach)

Link Key is Created after authentication
Link Key Created may be either combination of
Keys or one of the units unit key(LMP_unit _key
LMP_comb_key)
Waiting Interval
Increased exponentially

26
ENCRYPTION

Is an Option.
Masters Will in piconet
Master Slave must Agree
Point to Point or also broadcast packets

27
ENCRYPTIONStart Stop

Master is configured to Transmit unencrypted
packets and receive encrypted .
Slave is configured To Transmit and Receive
encrypted packets
Master is configured to Transmit and Receive
encrypted packets

Master is configured to Transmit encrypted and
receive unencrypted .
Slave is configured To Transmit and Receive
unencrypted .
Master is configured to Transmit and Receive
unencrypted .

28
Clock Offset Request

Every Device has an Internal System Clock
Timing and frequncy determined by the master in
Piconet.
Difference between slaves and masters.
Clock offset is updated on each time a packet is
received.

29
BLUETOOTH SECURITY

Built in Security
Frequency Hopping
Pseudorandom code sequence
Lasts 0.4 seconds
75 channels in 2.4GHZ
Authentication preventing spoofing unwanted
access
Encryption makes data unintelligible.
Inhibiting user-friendly hence 3 levels of
security.

30
Security Modes

Mode 1
Absence of security (Bypassing Link Level
security functions)
Exchange of vCard and vCalenders
Mode 2
Service Level Security for parallel applications
Mode 3
Link Level Security
LM enforces security at connection set up.
Link Keys

Key Length(8 and 128 bits)
128 bit challenge and 32 bit response .
Depends on Level of Security
Maximum length limited by Hardware

32
LAYOUT

FIELDS OF APPLICATION.
BLUETOOTH ADVANTAGE
SHORTCOMINGS OF THE TECHNOLOGY.
COMPARISON WITH IR WLAN.
MISNOMERS.
RESEARCHES ON THE TECHNOLOGY.
FUTURE ASPECTS.

33
APPLICATIONS

WAP enabled smart phones.
Electronic trading via handheld devices.
ad hoc Home/personal area network.
3G Telephony.

34
BLUETOOTH ADVANTAGE

Increased mobility in office by connecting
various peripherals with BT.
Voice and data transmission possible
721 kbps suffices most of the common uses.
Built in sufficient encryption and
authentication.
Cheaper insatllation maintainence.

35
ERROR CORRECTION

1/3 rate FEC (Forward Error Correction)
2/3 rate FEC
ARQ unnumbered scheme (Automatic Repeat Request).
This reduces the available bandwidth.

36
RADIATION THREATS

Penetration depth of RF is about 1.5 cm at 2450
MHz and about 2.5 cm at 900 MHz
It cannot generate enough heat to produce fire
hazards.
Radiation not beamed but dispersed in all
direction.
But in long run EM radiation can cause ill
effects in some persons.

37
LOOPHOLES IN SECURITY

Key initialization is not reliable.
Unit key can leak the information in traffic.
BT device address can be used to generate logs of
transaction.
Battery draining denial of service scheme.

38
BLUETOOTH v/s INFRAREDBT
IrDA
Range-10 to 100 m 20 cm to 2 m
Omnidirectional comm. Bidirectional comm.
Peak data rate- 1mbps 16 mbps
Can support 8 devices in piconet 2 devices can interact at time
39
BLUETOOTH v\s WLAN WLAN
BT
Vendors Proxim, 3COM, Symbol, Cisco Most chip vendors
SPEED 11-54 Mbps 1-2 Mbps
No. of access pts required Every 200 feet Every 30 feet
Distance coverage Upto 300 feet Upto 30 feet
interference 2.4 GHz band is significant here polluted interference
Cost expensive Cheaper (Rs1200-300)
40
IrDa Response