Bluetooth Ari

8/13/2019 Bluetooth Ari

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Characteristics

Operates in the 2.4 GHz range, using

Short range

Up to 10 m

Asynchronous (data) and synchronous (voice)service available

Bluetooth 1.2

Up to 721 kbit/s (with signaling 1 Mbit/s)

Bluetooth 2.0 + EDR (Enhanced Data Rate), 2004 Up to 2.1 Mbit/s (with signaling 3 Mbit/s)

Bluetooth 2.1 + EDR (Enhanced Data Rate), 2007


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Bluetooth Radio

FHSS (2.402 GHz - 2.480 GHz; 79

channels)

Fast FHSS (1600 hops/s)

GFSK modulation, 1M Symbol/s 2 FSK modulation yields 432 kbit/s bidirectional /

721 kbit/s asymmetrical EDR, QPSK or 8PSK modulations


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Piconets

Nodes can assume the role of master or slave

One or more slaves can connect to a master, forming apiconet

The master sets the hopping pattern for the piconet, andall slaves must synchronize to that pattern

Maximum of 7 slaves controlled by a master (3-bitaddresses used)

Other operational states Parked: device does not participate in the piconet, but is

known to the master and can be quickly reactivated

Standby: device does not participate in the piconet


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Piconet

active slave

master parked slave

standby

Star Toplogy 1 Master, up to 7 active slaves

Unlimited number of parked

slaves

Master:

determines hopping scheme

and timing

Administers piconet (polling)

Logical Channels

Asynchronous, packet oriented

Synchronous, connection-

oriented (voice, slot

reservation)


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Operational States

Master

P

SB

SB

SB

Operational States

Slave

Parked*

Standby*

* Low power states

A piconet

M

S

S

S

S


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Forming a Piconet (1)

Initially, devices know only about themselves

No synchronization

Everyone monitors in standby mode

All devices have the capability of serving as master or

slave

D

AE

B

C

F

K

J

H

G

I

M

N

L

PO

Q


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Forming a Piconet (2)

Unit establishing the piconet automaticallybecomes the master

It sends an inquiry to discover what other devices areout there

Addressing

Active devices are assigned a 3-bit active memberaddress (AMA)

Parked devices are assigned an 8-bit parked memberaddress (PMA)

Standby devices do not need an address


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INQUIRY PAGE CONNECTION

Connection Establishment


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Inquiry

D

A

10 meters

HM

N

L

P

O

Q

B

C

F

K

J

G

I

E

H

Note that a device canbe Undiscoverable


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States

disconnected

connecting

active

detach

standby

inquiry page

Transmit

AMA

Connected

AMA

Park

PMA

Hold

AMA

Sniff

AMAlow power

Typical = 2s

Typical = 0.6s

AMA = Active Member Address

PMA = Parked Member Address

Typical = 2ms


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Connecting to a Piconet

Device in standby listensperiodically

If a device wants to establish apiconet, it sends an inquiry,broadcast over all wake-up carriers

It will become the master of thepiconet

If inquiry was successful,device enters page mode

Devices in standby may respond tothe inquiry with its device address

It will become a slave to thatmaster

standby

inquiry page

Transmit

AMA

Connected

AMA

Park

PMA

Hold

AMA

Sniff

AMA


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Page and Connect States

After receiving a response fromdevices, the master can connect to

each device individually

An AMA is assigned

Slaves synchronize to thehopping sequence established by

the master

In active state, master and slaves

listen, transmit and receive A disconnect procedure allows

devices to return to standby

mode

standby

inquiry page

Transmit

AMA

Connected

AMA

Park

PMA

Hold

AMA

Sniff

AMA


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Low Power States

Sniff state Slaves listen to the piconet at a

reduced rate

Master designates certain slots totransmit to slaves in sniff state

Hold state

Slave stops ACL transmission,but can exchange SCO packets

Park state

Slave releases its AMA

Still FH synchronized and wakesup periodically to listen to

beacon

standby

inquiry page

Transmit

AMA

Connected

AMA

ParkPMA

HoldAMA

SniffAMA


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Scatternets (1)

Piconets with overlapping coverage use differenthopping sequences

Collisions may occur when multiple piconets use thesame carrier frequency at the same time

Devices can participate in multiple piconetssimultaneously, creating a scatternet

A device can only be the master of one piconet at a time

A device may serve as master in one piconet and slavein another

A device may serve as slave in multiple piconets


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J

F

I

E

A

G

Scatternets (2)

D

M

OB

L

H

K

C

N

P

Q

M l i Sl P k R d d


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Multi-Slot PacketsReduced

Overhead

f(k)

625 s

f(k+1) f(k+2) f(k+3) f(k+4)

f(k+3) f(k+4)f(k)

f(k)

f(k+5)

f(k+5)

f(k+5) f(k+6)

f(k+6)

f(k+6)


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Data Rates (kbit/s)

single slot

packets

triple slot

packets

five slot packets

DM1

DH1

DM3

DH3

DM5

DH5

108.8

172.8

256.0

384.0

286.7

432.6

108.8

172.8

384.0

576.0

477.8

721.0

108.8

172.8

54.4

86.4

36.3

57.6

Packet Type symmetric asymmetric

DM1, DM3, DM5 use rate 2/3 coding


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ACLMASTER

SLAVE 1

ACL

SLAVE 2

SLAVE 3

ACLSCO SCO SCO SCO ACL

Mixed Link Example


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Protocol stack

Source: Bluetooth Protocol Architecture v.1, white paper available at

www.bluetooth.org


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Baseband

Responsible for channel coding/decoding, timing

and managing a Bluetooth link.

Master/slave Devices in a connection are either master or slave.

Communication is only possible between a master and

its slaves.

A master and the slaves are named piconets.

Scatternet; multiple piconets connected together.


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The Link Manager

Responsible for establishing, supervising and teardown connections and logical links.

Link controller states introduced to carry out thesetasks.

States:

Standby

Inquiry / Inquiry Scan Page / Page Scan

Connection


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The Link Manager (cont.)

Inquiry

Used to detect all devcies in an unknown environment.

Page / Page Scan Describes how connection is established.

Have to know the address of the other devices. Is

usually achieved through inquiry.

Connection

Master and slaves are synchronized.

Connection is established.


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Bluetooth Packet format

LSB

ACCESSCODE

HEADER

MSB

PAYLOAD

68/72b 54b 0-2745b

LSB

ACCESS

CODE

HEADER

MSB

PAYLOAD

72b 54b 16-8200b

GUARD SYNC

5 s 11 s

2FSK PSK

General basic rate packet format

General enhanced data rate packet format

Documents

Bluetooth Ari