Bluetooth:Technology for Short-Range Wireless Apps

Author:Pravin Bhagwat

Presented by Chin-Yi Tsai

IEEE INTERNET COMPUTING MAY.JUNE 2001

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Outline Introduction to Bluetooth Bluetooth Specifications The Frequency Hopping technique Inquiry and Paging Piconets and Scatternets Bluetooth Applications Conclusions

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Introduction to Bluetooth Why Bluetooth? Bluetooth History Bluetooth Feature and motivation

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Why Bluetooth? 1010thth Century Denmark Century Denmark

KingKing King Harald united King Harald united

Denmark and Norway. Denmark and Norway. Bluetooth of today will Bluetooth of today will unite the world of unite the world of computers and telecomcomputers and telecom

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Bluetooth History The Bluetooth Special Interest

Group(SIG) Initially the group comprised five

companies-IBM,Intel,Ericsson,Nokia,Toshiba The end of 1999 this number had increased

to nine through the addition of 3Com, Motorola, Microsoft, Lucent

By December 2000 the Bluetooth SIG had over 2000 members

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Bluetooth feature and motivation Bluetooth feature

ISM 2.4 GHz Small Simple Low cost Low power Short range Voice and data Point-to-point and point-to-multipoint

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Bluetooth feature and motivation Bluetooth motivation

Started as cable replement technology

Connecting with different devices Mobile acces to LANs/Internet Personal Area Network(PAN) Automatic synchronization of data

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Bluetooth Specifications Core specification

The core specification defines all layers of the Bluetooth protocol stack

Profile specification Special protocol different device,OS, and application interoperability

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Bluetooth Specifications

Radio

Baseband/Link Controller

Link Manager

Host Controller Interface

L2CAP

TCS SDP

RFCOMM

Applications OBEX

WAP

AT Commands

The Bluetooth protocol stack

Bluetooth Module

Host

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Radio Frequncy

2.4000~2.4835 GHz(license-free) Power:there are three power class

1mW,2.5mW,100mW Modulation

GFSK

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Baseband Physical channel

Formed after connection Transmition type

SCO(cricuit switch):point-to-point,voice ACL(packet switch),point-to-multipoint, data

Error correction 1/3 FEC,2/3 FEC ,ARQ

Timer synchronization

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Baseband Link controller state

Standby Intermediate:inquiry,inquiry

scan,inquiry response,page,page scan,page response,master response

Connection:active,sniff,hold,park

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LMP Piconet management

Attach and detach slave SCO and ACL connection,management Switch role of master,slave Handling low power

Link configuration QoS

Security function Authication,encryption,link key

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Host Controller Interface Host control

Bluetooth module

Radio

Baseband

LMP

Host transport fireware

Transport Bus

Bluetooth HCI Transport Driver (USB,UART,RS232)

Bluetooth HCI Driver

Host dirver and applicaiton

HCI

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L2CAP Protocol multiplexing Segment and reassembly Negotiation

MTU(maximum transmission unit) Flush timeout QoS

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Others RFCOMM TCS WAP OBEX PPP

Radio

Baseband/Link Controller

Link ManagerHost Controller Interface

L2CAP

TCS SDP

RFCOMM

Applications OBEX

WAP

AT Commands

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Profile Specifications Generic access Service discovery Cordless telephone Intercom(Walkie-Talkie) Serial port Headset

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Profile Specifications Dial-up networking Fax LAN access Generic object exchange Object push File transfer Synchronization

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The Frequency Hopping technique

…1 79

1MHz

Divide Frequency band into 1 MHz hop channels Radio hops from one channel to another in a pseudo -random manner as dictated by a hop sequence Hopping sequence is different for each

piconet(master’s device address and clock) Hop rate:1600 time/second

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The Frequency Hopping technique

Master

Slave1

Slave2

Slave3

1 slot

f(2k)

f(2k+1)

f(2k+2)

f(2k+3)

f(2k+4)

f(2k+5)

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Inquiry and Paging

ConnectedPagingInquiry

The purpose of inquiry and paging Connection establishment

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Inquiry and PagingMaster Slave

Start inquiry

FHS PacketInquiry result

Inquiry complete

Inquiry scanID Packet with inquiry Access Code

Randome delaybefore response

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Inquiry and PagingMaster SlavePage Page Scan

Master PageResponse

Slave PageResponse

Connected Connected

Page packet

ID packet

FHS packet

ID packet

POLL

NULL

Uses FHS to getCAC and clk infoAssigns active

addr

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Piconets and Scatternets

Bluetooth unit can communicate with other units, by forming a piconet One unit of a piconet is

defined as the master (the unit that establishes the piconet), the others units are called slaves

One piconet consists of 1 master and up to 7 slaves

Master

Slave1

Slave1Slave1

Slave1

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Piconets and Scatternets A group of piconets in which

connections consists between different piconets is called a scatternet A unit cannot be the master in different

piconet, since the master determines the property of a piconet

A scatternet example

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Bluetooth Applications Three-in-one Phone Ultimate Headset Automatic Synchronizer Internet Bridge Interactive Conderence Indoor positioning

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Conclusions Bluetooth eliminates the need for numerous

and inconvenient cable attachments for devices

Bluetooth enables the design of low-power, small-sized, low-cost radios that can be embedded in existing (portable) devices

The Bluetooth technology will be built into hundreds of millions of electronic devices in 2005

Commpared with 802.11 and HomeRF

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Transmition type

Master

Slave1

Slave2

Slave3

SCO SCO SCOACL ACL