bluetooth_dgk.ppt

7/27/2019 Bluetooth_dgk.ppt

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Bluetooth

By Kanade D G


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About.

Harald Bluetooth : 10th century Danish King, managed tounite Denmark and Norway.

Developed in 1994 by the Swedish company Ericsson

to enable laptops make calls over mobile phones

Also known as 802.15, it employs the 2.4 GHz

unlicensed band, the same as 802.11b wireless, but

does not interfere with it

Provides data rates of up to 720 Kbps

Bluetooth SIG (Special Interest Group) :

Founded in 1998 by : Ericsson, Intel, IBM, Toshiba and Nokia

Released version 1.0 in July 1999 and version 1.1 was released in 2001.


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Applications PC

Laptop

Digital Camera

PDA

Mobile Phone

Pager

Mp3 Player

Headset

Keyboard

Mouse

LCD Projector


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Bluetooth System Specification

Frequency of operation:- ISM band

frequency range 2400 MHz to 2483.5MHz.

Total 79 channels. Each packet is sent in different channel.

Uses frequency hopping

Nominal frequency hope rate is 1600 per second.

Though radio design becomes complex, provides secure

communication.

Modulation:-

GFSK is used as modulation technique.


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Operating Range:-

Three classes of devices are defined in Bluetooth

specifications

Class 1:-Transmits 100 mW and range is 100 mtrs.

Class 2:-Transmits 10 mW and range is 50 mtrs. Class 3:-Transmits 1 mW and range is 10 mtrs.

Most of the commercially available devicestransmits 1 milliwatt and hence a range of 10

meters.

Bluetooth System Specification(Continued..)


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Services supported:-

Both voice and data services supported by Bluetoothdevices.

Voice:-Synchronous Connection Oriented (SCO)

Circuit switching operation

Data:-Asynchronous Connection Less (ACL) Packet switching operation

Two types of voice coding are defined in specifications

PCM based on G.711 std. at 64 Kbps

Continuous Variable Slope Delta Modulation (CVSD) at 64Kbps

There is no retransmission of voice packets if lost orreceived in error.



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Services supported(continued..):-

For data services

Receiving device acknowledges or reports

Packets received in error retransmitted.

No acknowledgement in Broadcast mode

Data rates:- Support three synchronous voice channels and

one asynchronous data channel.

For voice communication 64 Kbps data rates in both

directions For asynchronous links two types of channel

asymmetric and symmetric

Asymmetric:- 723.2 Kbps and 57.6 Kbps

Symmetric:- 433.9 Kbps



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Network Topology :-

Piconet:- A set of devices form a PAN called Piconet One master and one or more slave

Any device can be master or slave

Each Piconet has one master and up to 7 simultaneous

slaves Master : device that initiates a data exchange.

Slave : device that responds to the master

S=Slave M=Master

SB=Standby P=Parked


MS

S

SP

P

SB

SB


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Piconet:-

In addition to active slave devices, Piconet can

contain many slaves that are in parked mode.

are synchronized but they are not active on channel.

Master and Slave uses Time Division Duplex(TDD). Piconet with one Master and one Slave

uses point-to-point communication.

Piconet with one Master and multiple Slaves

uses point-to-multipoint communication.



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Communication Between Master and Slave:-

The Master and Slave communicate in the form ofPackets.

Each Packet is transmitted in the Time-slot.

Each Time-slot is of 625 microseconds duration.

These Time-slots are numbered 0-to-227-1.

Master:-Transmits in even slots

Slave :-sends packets in odd numbered slot.

A packet occupies one time slot, may extend up to five.

If the Master starts the transmission in slot 0 usingfrequency f1 , the slave transmits in slot 1 using frequencyf2.



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Connection Establishment States

Inquiry

Page

Inquiry

scan

Masterresponse

Inquiryresponse

Pagescan

Slaveresponse

Connection Connection

(1) ID packet (Broadcast)

(2) FHS packet

(4) ID packet

(6) ID packet

(7) ID packet

StandbyStandby

Master Slave


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The two major states are

STANDBY- not part of a Piconet and

CONNECTION device is part of a Piconet.

To form a Piconet the master transmits an ID packetover 32 of the 79 channels.

Devices in the STANDBY state periodically scan for thispacket.

If it hears it, the device sends its address and timinginfo to the master.

The device then waits for the master to page it.

When the master is satisfied that it has identified all

the devices in its range it starts to form the Piconet.

Connection Establishment States (Continued)


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It pages each device with its own device accesscode (DAC) using a frequency hopping sequencebased on the slaves address.

When the slave hears this it sends a confirmationpacket.

On the next slot the master sends the slave themaster DAC.

The slave then enters the CONNECTION state.

The master does this for all the slaves in thePiconet then it enters the CONNECTION stateitself.

Connection Establishment States (Continued)


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The connection can be put in one of the state

Hold Mode In this mode the device will stop receiving the data traffic

for a specific amount of time so that other devices in thePiconet can use channel. After the expiry of the specifictime the will start listening again.

Sniff Mode

In the sniff mode slave is instructed to listens only S slotsevery T slots for a period of N slots and not all packets.

Park Mode When the device only listens to beacon signal from Master

occasionally and synchronizes with Master and does not doanything.

Connection Establishment States (Continued.)


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Bluetooth Addressing

Each Bluetooth module is given 48 bit addresscontaining three fields

LAP(Lower Addrs Part):-24 bits

UAP(Upper Addrs Part):-8 bits

Non-significance Addrs. Part:-16 bits

This Address is assigned by each manufacturer and

consists of company ID and company assigned number.

This address is unique to every Bluetooth device and

referred to as BD-ADDR.


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Each active member in the Piconet will have a 3 bit

address.

Parked members also need to have addresses so

that master can make them active and exchangepackets.

Parked member address is either BD_ADDR(48 Bits)

or PM_ADDR(8Bits).

Bluetooth Addressing( Continued)


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BD_ADDR 48 bit Bluetooth device address (IEEE802 standard). It is divided into LAP

(Lower Address Part of 24 bits), UAP (Upper Address Part of 8 bits) and

NAP (Non-significant Address Part of 16 bits).

AM_ADDR 3 bit active member address. The all zero AM_ADDR is for broadcast

messages

PM_ADDR 8-bit member address that is assigned to parked slaves.

AR_ADDR The access request address is used by the parked slave to determine the

slave-to-master half slot in the access window it is allowed to send

access messages.

Bluetooth Addressing( Continued)


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Bluetooth Profiles For interoperatibility between devices manufactured by

different vendors, Bluetooth SIG released Bluetooth Profiles which defines the precise

characteristics and protocols supported by these devices.

Advanced Audio Distribution Profile (A2DP)

Audio Video Remote Control Profile (AVRCP) Basic Imaging Profile (BIP)

Basic Printing Profile (BPP)

Cordless Telephony Profile (CTP)

Dial-up Networking Profile (DUNP)

Fax Profile (FAX) File Transfer Profile (FTP)

Generic Access Profile (GAP)

Generic Object Exchange Profile (GOEP)

Hardcopy Cable Replacement Profile (HCRP)

Bl t th P fil (C ti d )


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Hands-Free Profile (HFP)

Human Interface Device Profile (HID)

Headset Profile (HSP)

Intercom Profile (IP)

LAN Access Profile (LAP)

Object Push Profile (OPP)

Personal Area Networking Profile (PAN)

SIM Access Profile (SAP)

Service Discovery Application Profile (SDAP) Synchronization Profile (SP): used to synchronise the device

with a personal information manager (or PIM for short).

Serial Port Profile (SPP)

Bluetooth Profiles(Continued)


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Bluetooth Protocol Architecture

Baseband and RF

ACL SCO

LMP L2CAP Voice

AudioSDP RFCOMM TCS


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Baseband and RF

Establishes Links between devices

ACL for data

SCO for voice

Addressing and managing different states of

Bluetooth devices.

RF portion provides radio interface.


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Link Manager Protocol(LMP)

LMP is used to set up and control links

The three layersRF, Link controller, Linkmanager will be on Bluetooth module attached tothe device.

The link manager on one device exchangemessages with link manager on the other.

Link messages have higher priority compared to

data and not sent to higher layer. Link messages are sent in single slot packets with

header of one byte.

f


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Functions of LMP Authentication

Challenge -Response Scheme

Encryption Clock offset request

Used for synchronization

Timing accuracy information request

Used for synchronization by Master LMP version number

Ensures both devises use same LMP version.

Type of packet supported LMP feature request and response

Switching master/slave role Name request

248 bit max (ASCII)

Detach

Close connection


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Hold mode Power saving when there is no data to send

Park mode Synchronized with master but no data exchange

Power Control Request to increase or decrease power ,specially class 1 devices

Quality of service parameters exchange No. of repetition of broadcast packets, delay & B.W. allocation

Request SCO links To request SCO link after ACL link is established

Multi slot packet control To control the procedure when data is sent in consecutive packets

LMP_max_slot , LMP_max_slot_req

Link supervision Monitors link when device goes out of range

Connection Establishment

LMP_host_connection_req

LMP_accepted

LMP_not_accepted LMP_setup_complete

Functions of LMP(continued)

Logical Link Control and Adaption


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Logical Link Control and Adaption

Protocol (L2CAP)

Runs above baseband and carries out data link layerfunctionality.

Used only for ACL

Data packets can be up to 64 Kbytes long.

Runs on hosts

When L2CAP messages are exchanged between two

devices, it assumes that ACL is already established.

Does not do any checksum calculation.

Does not support SCO for voice communication

Does not support multicasting.


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Functions of L2CAP

Protocol multiplexing Passing packet received by L2CAP to higher layers

Segmentation and reassembly Larger baseband packets need to be segmented in to small

Quality of service

L2CAP sends connection request and QoS request messagefrom application programs thru higher layers.

Receives responses for these request from lower layers Connection indication

Connection confirmation

Connect confirmation negative Connect confirmation pending

Disconnection pending

Disconnect confirmation

Timeout indication

Quality of service violation indication

L2CAP(Continued)

l ( )


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Service Discovery Protocol (SDP)

Service Discovery protocol

It provides the Bluetooth environment -

The capability to create ad hoc networks.

Used for discovering the services offered by device.

SDP Services:- A device can search for the service needed by it in the Piconet

Can discover service based on a class of services

Browsing of services

Discovery of new services when device enters in the radio

range of other device.

Mechanism to find out when the service becomes unavailable

when it goes out of the range.


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SDP Services (Continued)

SDP Services:-

The details of services such as classes of services and the

attributes of services

To discover services on another device without consulting

third device.


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Procedure :-

SDP client and server exchange SDP messages. SDP client sends SDP request to server thru application

software.

Server and client can be any two devices

Server is the device which can provide the service being requested. Server maintains list of service records

Each record is identified by 32 bit number

Service record will have number of attributes

Service class Id

protocol description list

Provider name

ICON URL

Service name and service description

Each attribute will have two components:-ID and value

SDP Services (Continued)


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Procedure for Obtaining Service

Procedure for obtaining service:-

Laptop(Client) Printer(Server)

Print Service class ID

Asking for the details of service

Service Search

Request

Service search

response

Service attribute

Request ,

Protocol descriptor list

Response

Print

Command Print Desired Document


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RFCOMM

RFCOMM is transport protocol to emulate serialcommunication (RS 232 serial port) over L2CAP.

Through RFCOMM, two devices can communicate

using serial communication protocol overBluetooth.

Uses 9 signals of RS-232.

RFCOMM is derived from the GSM

Support two types of devices

Type1:-communication end points such as PC ,Printer

Type2:-part of communication segment such as Modem


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TCS

H t C t l I t f (HCI)


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Host Control Interface (HCI)

Used to Bluetooth enable a laptop or a PC

by connecting small device to USB port of laptop and run

protocol stack on laptop(called host).

The Host Control interface provides std. interfacebetween Bluetooth module and host software.

Then Bluetooth device will have two parts A module implementing the lower layers(LMP and below)

The software module runs on laptop

Baseband Packets


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Baseband Packets

The Bluetooth general packet format is comprised of

three parts: Access Code, Header, and Payload

LSB 72 bits 54 bits 0-2745 bits MSB

Access Code Can be 68 or 72 bits wide, depending on whether a packet

header follows or not

Used for synchronization, DC offset compensation, and

identification

Access Code Header Pay Load

Preamble Sync Word Trailer

LSB 4 bits 64 bits 4 bits MSB

B b d P k t


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There are three categories of Access Codes:

Channel Access Code (CAC): Defines a Piconet

Device Access Code (DAC): Used for paging

Inquiry Access Code (IAC): There are two variations

General (GIAC) and Dedicated (DIAC), the latter is used only in

identifying Bluetooth devices sharing a common characteristic

Payload data is dependent on the Bluetooth application

(voice, data, )

The Packet Header consists Link Control (LC) and iscomprised of 6 fields: LSB 3 4 1 1 1 8 MSB

Baseband Packets

AM_ADDR Type HECSEQNARQNFLOW

Baseband Packets


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The 6 fields are as follows:

AM_ADDR is a 3-bit active member address used to

distinguish between the active members of a Piconet

Type is a 4-bit type code used to distinguish between one

of 16 different packet types, such as ID Packet, POLLpacket, or NULL Packet.

Flow is a bit used for flow control over ACL. When thereceiver buffer is full, a STOP indication is returned by

means of FLOW = 0 to prevent further transmission

Baseband Packets


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ARQN is the acknowledgement bit for CRCed

packets

SEQN provided sequencing for multiple data

packets

HEC is the Header Error Check used to verify

header integrity

Baseband Packets


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Thank You

bluetooth_dgk.ppt

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