An Introduction to An Introduction to

BLUETOOTH TECHNOLOGYBLUETOOTH TECHNOLOGY

BY Vikas Jagtap

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CONTENT

• Overview of Bluetooth History

• The Bluetooth Specifications

• Typical Bluetooth Scenario

• Protocols

• Profiles

• Security

• Comparison with other technologies

• Future of Bluetooth

• Summary

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Example : The Networked Home

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What is Bluetooth?

• “Bluetooth wireless technology is an open specification for a low-cost, low-power, short-range radio technology for ad-hoc wireless communication of voice and data anywhere in the world.”

One of the first modules (Ericsson) A recent module

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Ultimate Headset

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Cordless Computer

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Bluetooth Goals & Vision

• Originally conceived as a cable replacement technology

• Short-Range Wireless Solutions

• Open Specification

• Voice and Data Capability

• Worldwide Usability

• Other usage models began to develop:— Personal Area Network (PAN)

— Ad-hoc networks

— Data/voice access points

— Wireless telematics

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Overview of Bluetooth History

• What is Bluetooth?— Bluetooth is a short-range wireless communications technology.

• Why this name?— It was taken from the 10th century Danish King Harald Blatand who

unified Denmark and Norway.

• When does it appear?— 1994 – Ericsson study on a wireless technology to link mobile phones &

accessories.

— 5 companies joined to form the Bluetooth Special Interest Group (SIG) in 1998.

— First specification released in July 1999.

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Timeline

• 1994 : Ericsson study complete / vision

• 1995 : Engineering work begins

• 1997 : Intel agrees to collaborate

• 1998 : Bluetooth SIG formed: Ericsson, Intel, IBM, Nokia & Toshiba

• 1999 : Bluetooth Specification 1.0A

SIG promoter group expanded: 3Com, Lucent, Microsoft & Motorola

• 2000 : Bluetooth Specification 1.0B, 2000+ adopters

• 2001 : First retail products released, Specification 1.1

• 2003 : Bluetooth Specification 1.2

• 2005 : Bluetooth Specification 2.0 (?)

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Special Interest Group

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Technical features

Connection Type Spread Spectrum (Frequency Hopping) & Time Division Duplex (1600 hops/sec)

Spectrum 2.4 GHz ISM Open Band (79 MHz of spectrum = 79 channels)

Modulation Gaussian Frequency Shift Keying

Transmission Power 1 mw – 100 mw

Data Rate 1 Mbps

Range 30 ft

Supported Stations 8 devices

Data Security –Authentication Key 128 bit key

Data Security –Encryption Key 8-128 bits (configurable)

Module size 9 x 9 mm

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Bluetooth FHSS

• Employs frequency hopping spread spectrum

• Reduce interference with other devices

• Pseudorandom hopping

• 1600 hops/sec- time slot is defined as 625 microseconds

• Packet 1-5 time slots long

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Time-Division Duplex Scheme

• Channel is divided into consecutive slots (each 625 µs)

• One packet can be transmitted per slot

• Subsequent slots are alternatively used for transmitting and receiving

— Strict alternation of slots between the master and the slaves

— Master can send packets to a slave only in EVEN slots

— Slave can send packets to the master only in the ODD slots

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Classification

POWER RANGE

CLASS I 20 dBm 100 m

CLASS II 0-4 dBm 10 m

CLASS III 0 dBm 1 m

• Classification of devices on the basis of Power dissipated & corresponding maximum Range.

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Typical Bluetooth Scenario

• Bluetooth will support wireless point-to-point and point-to-multipoint (broadcast) between devices in a piconet.

• Point to Point Link— Master - slave relationship

— Bluetooth devices can function as masters or slaves

• Piconet— It is the network formed by a Master and one or more slaves

(max 7)

— Each piconet is defined by a different hopping channel to which users synchronize to

— Each piconet has max capacity (1 Mbps)

m s

s s s

m

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Piconet Structure

Master

Active Slave

Parked Slave

Standby

• All devices in piconet hop together.• Master’s ID and master’s clock determines frequency hopping

sequence & phase.

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Ad-hoc Network – the Scatternet

• Inter-piconet communication

• Up to 10 piconets in a scatternet

• Multiple piconets can operate within same physical space

• This is an ad-hoc, peer to peer (P2P) network

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Bluetooth Protocol Stack

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Baseband

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Baseband

• Addressing— Bluetooth device address (BD_ADDR)

– 48 bit IEEE MAC address

— Active Member address (AM_ADDR)– 3 bits active slave address– all zero broadcast address

— Parked Member address (PM_ADDR)– 8 bit parked slave address

• This MAC address is split into three parts— The Non-significant Address Part (NAP)

– Used for encryption seed

— The Upper Address part (UAP)– Used for error correction seed initialization & FH sequence generation

— The Lower Address Part (LAP)– Used for FH sequence generation

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Packet Structure

Voice

No CRC

Data CRCheader

ARQFEC (optional) FEC (optional)

72 bits 54 bits 0 - 2744 bits

Access Code

Header Payload

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Connection State Machine

Standby

Inquiry Page

Connected

Transmit data

Park Hold Sniff

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Channel Establishment

• There are two managed situations

— A device knows the parameters of the other– It follows paging process

— No knowledge about the other– Then it follows inquiring &

paging process

• Two main states and sub-states

— Standby (no interaction)

— Connection (working)

— Seven more sub-states for attaching slaves & connection establishment

Connection State Machine

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Channel Establishment (contd.)

• Seven sub-states— Inquiry

— Inquiry scan

— Inquiry response

— Page

— Page scan

— Master response

— Slave response

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Link Manager Protocol

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Link Manager Protocol

• The Link Manager carries out link setup, authentication & link

configuration.

• Channel Control

— All the work related to the channel control is managed by the master

– The master uses polling process for this

— The master is the first device which starts the connection

– This roles can change (master-slave role switch)

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• Service provided to the higher layer:

— L2CAP provides connection-oriented and connectionless data

services to upper layer protocols

— Protocol multiplexing and demultiplexing capabilities

— Segmentation & reassembly of large packets

— L2CAP permits higher level protocols and applications to transmit

and receive L2CAP data packets up to 64 kilobytes in length.

L2CAP

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Middleware Protocol Group

RF

Baseband

AudioLink Manager

L2CAP

Data

SDP RFCOMM

IP

Control

Applications

Middleware Protocol Group

•Additional transport protocols to

allow existing and new applications to

operate over Bluetooth.

•Packet based telephony control

signaling protocol also present.

•Also includes Service Discovery

Protocol.

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Middleware Protocol Group (contd.)

• Service Discovery Protocol (SDP)

— Means for applications to discover device info, services and its

characteristics.

• TCP/IP

— Network Protocols for packet data communication, routing.

• RFCOMM

— Cable replacement protocol, emulation of serial ports over wireless network.

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IP Over Bluetooth

• IP over Bluetooth v 1.0

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IP Over Bluetooth

• IP over Bluetooth v 1.1

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File Transfer Profile

• Profile provides:• Enhanced client-server interactions:

- browse, create, transfer folders- browse, pull, push, delete files

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Headset Profile

• Profile provides:• Both devices must provide capability to initiate connection &

accept/terminate calls.

• Volume can be controlled from either device.

• Audio gateway can notify headset of an incoming call.

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Core Bluetooth Products

• Notebook PCs & Desktop computers

• Printers

• PDAs

• Other handheld devices

• Cell phones

• Wireless peripherals:

• Headsets

• Cameras

• CD Player

• TV/VCR/DVD

• Access Points

• Telephone Answering Devices

• Cordless Phones

• Cars

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Other Products…

• 2004 Toyota Prius & Lexus LS 430 — hands free calls

• Digital Pulse Oximetry System

• Toshiba Washer & Dryer

• Nokia N-gage

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Security

• Security Measures

— Link Level Encryption & Authentication.

— Personal Identification Numbers (PIN) for device access.

— Long encryption keys are used (128 bit keys).

— These keys are not transmitted over wireless. Other parameters are

transmitted over wireless which in combination with certain

information known to the device, can generate the keys.

— Further encryption can be done at the application layer.

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A Comparison

WLAN

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Bluetooth vs. IrD

• Bluetooth

— Point to Multipoint

— Data & Voice

— Easier Synchronization due

to omni-directional and no

LOS requirement

— Devices can be mobile

— Range 10 m

•IrD

—Point to point

—Intended for Data Communication

—Infrared, LOS communication

—Can not penetrate solid objects

—Both devices must be stationary, for synchronization

—Range 1 m

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Bluetooth: Today & Tomorrow

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Will Bluetooth become a household name?

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Future of Bluetooth

• Success of Bluetooth depends on how well it is integrated into consumer products

— Consumers are more interested in applications than the technology

— Bluetooth must be successfully integrated into consumer products

— Must provide benefits for consumer

— Must not destroy current product benefits

• Key Success Factors— Interoperability

— Mass Production at Low Cost

— Ease of Use

— End User Experience

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Summary

• A new global standard for data and voice

• Eliminate Cables

• Low Power, Low range, Low Cost network devices

• Future Improvements

— Master-Slave relationship can be adjusted dynamically for optimal

resource allocation and utilization.

— Adaptive, closed loop transmit power control can be implemented

to further reduce unnecessary power usage.

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“Things that think…

don’t make sense unless they

link.”

- Vikas jagtap