prof. dr.-ing. jochen schiller, ss027.1 bluetooth ad-hoc piconets

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.1

Bluetooth

ad-hoc piconets


Bluetooth - original

A cable replacement technology 1 Mb/s symbol rate Range 10+ meters

Single chip radio + baseband – at low power & low price point

Why not use Wireless LANs?- power- cost


What does Bluetooth do for you?

Personal Ad-Personal Ad-hoc Networkshoc Networks

Cable Cable ReplacementReplacement

Landline

Data/Voice Data/Voice Access Access PointsPoints

“Usage Models” Class


Bluetooth


Who is Bluetooth?

Harald Blaatand “Bluetooth” IIKing of Denmark 940-981

Son of Gorm the Old (King of Denmark) and Thyra Danebod (daughter of King Ethelred of England)

This is one of two Runic stones erected in his capital city of Jelling (central Jutland) This is the front of the stone depicting the chivalry of Harald Harald controlled Denmark and Norway Harald thinks mobile PCs and cellular phones should seamlessly

communicate


Bluetooth Working Group History

February 1998: The Bluetooth SIG is formed promoter company group: Ericsson, IBM, Intel, Nokia, Toshiba

May 1998: Public announcement of the Bluetooth SIG

December 1999: The promoter group increases to 9 3Com, Lucent, Microsoft, Motorola

November 1999: IEEE802.15 was formed to promote WPANsWPAN: Wireless Personal Area Networks

July 2009: There are 10000+ adopters


Bluetooth Protocol Stack

RF

Baseband

AudioLink Manager

L2CAP

Data

SDP RFCOMM

IP

Single chip with RS-232,USB, or PC card interface

Con

trol

Applications


Bluetooth Radio Specification

RF

Baseband

AudioLink Manager

L2CAP

Data Con

trolSDP RFCOMM

IP

Applications


Radio Spectrum

125 Mhz

5.725 Ghz5.785 Ghz

802.11aHiperLan2

83.5 Mhz

2.4 Ghz

2.4835 Ghz

802.11b/gBluetoothMicrowave oven

12cm 5cm


Bluetooth Radio Link

frequency hopping spread spectrum– 2.402 GHz + k MHz, k=0, …, 78– 1,600 hops per second

GFSK modulation– 1 Mb/s symbol rate

transmit power– 0 dbm (up to 20dbm with power control)

. . .

1Mhz

1 2 3 79

83.5 Mhz


Reliability

The hostile ISM band is managed by:

1. Frequency hopping2. Adaptive power control 3. Short data packets


Bluetooth Baseband

RF

Baseband

AudioLink Manager

L2CAP

Data Con

trolSDP RFCOMM

IP

Applications


Bluetooth Physical Link

Point to point link– master - slave relationship– radios can function as masters or slaves m s

ss

m

s

Piconet– Master can connect to 7 slaves

– Each piconet has max capacity (1 Mbps)


Piconet

Collection of devices connected in an ad hoc fashion

One unit acts as master and the others as slaves for the lifetime of the piconet

Master determines hopping pattern, slaves have to synchronize

Each piconet has a unique hopping pattern

Participation in a piconet = synchronization to hopping sequence

Each piconet has one master and up to 7 simultaneous slaves (> 200 could be parked)

M=MasterS=Slave

P=Parked (can be reactivated within some milliseconds)SB=Standby (not active at all)

M

S

P

SB

S

S

P

P

SB


Forming a piconet

All devices in a piconet hop together Master gives slaves its clock and device ID

Hopping pattern: determined by device ID (48 bit, unique worldwide) Phase in hopping pattern determined by clock

Addressing Active Member Address (AMA, 3 bit) Parked Member Address (PMA, 8 bit)

SB

SB

SB

SB

SB

SB

SB

SB

SB

M

S

P

SB

S

S

P

P

SB


Link types

ACL – Asynchronous Connection LessUsed for all data communication and signalling. A device may keep multiple ACL connections.

SCO – Synchrounous Connection OrientedUsed for synchrounous voice transmission (Point to Point).


Access code:– Synchronization.

– Identification.

Header:– AM-ADDR: MAC-address

– Type: payload type

– Flow: flow control

– ARQ: fast retransmit

– HEC

Bluetooth Packet Format

72 bits 54 bits 0 - 2744 bitsAccess code

Header Payload

DataVoice CRC

No CRCNo retries

header

ARQ

FEC (optional) FEC (optional)


Bluetooth Channel

m

s1

s2

625 µsec

f1 f2 f3 f4

1600 hops/sec

f5 f6

FH/TDD Hopping pattern is decided by the master


Multislot Packets

m

s1

s2

625 µsec

f1 f4 f5 f6FH/TDD

Data rate depends on type of packet


Data Packet Types for ACL

DM1

DM3

DM5

DH1

DH3

DH5

2/3 FEC

No FEC

Symmetric Asymmetric

36.3477.8 286.7

54.4387.2258.1

108.8108.8108.8

Symmetric Asymmetric

57.6723.2 433.9

86.4585.6390.4

172.8172.8172.8

kbps

kbps


Link types

SCO – Synchrounous Connection OrientedUsed for synchrounous voice transmission (Classic telephone (voice)).

Connections require symmetrical, circuit switched, point-to-point connections

The master reserves two consecutive slots (forward and return slots) at fixed intervals.

Using an SCO link, three different types of single-slot packets can be used

payload (30)

audio (30)

audio (10)

HV3

HV2

HV1 FEC (20)

audio (20) FEC (10)


Physical Link Types

m

s1

s2

SCO SCO SCO

Synchronous Connection Oriented (SCO) Link – slot reservation at fixed intervals

Asynchronous Connection-less (ACL) Link– Polling access method

SCO SCO SCOACL ACL ACLACL ACL ACL


Robustness

Slow frequency hopping with hopping patterns determined by a master Protection from interference on certain frequencies Separation from other piconets (FH-CDMA)

Retransmission ACL only, very fast

Forward Error Correction SCO and ACL

MASTER

SLAVE 1

SLAVE 2

A C C HF

G G

B D E

NAK ACK

Error in payload(not header!)


Link Manager Protocol (LMP)

RF

Baseband

AudioLink Manager

L2CAP

Data Con

trolSDP RFCOMM

IP

Applications

Setup and management of Baseband connections

• Piconet Management• Link Configuration• Security


L2CAP

Logical Link Control andAdaptation Protocol

L2CAP provides• Protocol multiplexing• Segmentation and Re-assembly• Quality of service negotiation

RF

Baseband

AudioLink Manager

L2CAP

Data

SDP RFCOMM

IP

Applications


Profiles

Represent default solutions for a certain usage model Vertical slice through the protocol stack Basis for interoperability

Generic Access ProfileService Discovery Application ProfileCordless Telephony ProfileIntercom ProfileSerial Port ProfileHeadset ProfileDial-up Networking ProfileFax ProfileLAN Access ProfileGeneric Object Exchange ProfileObject Push ProfileFile Transfer ProfileSynchronization Profile

Additional ProfilesAdvanced Audio DistributionPANAudio Video Remote ControlBasic PrintingBasic ImagingExtended Service DiscoveryGeneric Audio Video DistributionHands FreeHardcopy Cable Replacement

Profiles

Pro

toco

ls

Applications


Scatternet

• Scatternet– A set of inter-connected piconets– Some devices participate in more than

one piconet– Called Bridging node.– A Bridging node may be slave in

several piconets but only master in one of its piconets

• A Bridging node may only participate in one piconet at a time

– Bluetooth unit only has one transceiver– Different frequency hop sequences used for

each piconet– Has to switch between piconets on a time

division basis

• Scatternet scheduling– The task of controlling the presence of

Bridging nodes in different piconets

Master

Slave 1Slave 2

Slave 3

Master 2

Slave 4/Master 3

Slave 5


Scatternet Example

PDACell phone

Cordless

headset

Cell phone

PDA

Cell phone

mouse


End


Example: Power consumption/CSR BlueCore2

Typical Average Current Consumption (1)VDD=1.8V Temperature = 20°CMode SCO connection HV3 (1s interval Sniff Mode) (Slave) 26.0 mASCO connection HV3 (1s interval Sniff Mode) (Master) 26.0 mASCO connection HV1 (Slave) 53.0 mASCO connection HV1 (Master) 53.0 mAACL data transfer 115.2kbps UART (Master) 15.5 mAACL data transfer 720kbps USB (Slave) 53.0 mAACL data transfer 720kbps USB (Master) 53.0 mAACL connection, Sniff Mode 40ms interval, 38.4kbps UART 4.0 mAACL connection, Sniff Mode 1.28s interval, 38.4kbps UART 0.5 mAParked Slave, 1.28s beacon interval, 38.4kbps UART 0.6 mAStandby Mode (Connected to host, no RF activity) 47.0 µADeep Sleep Mode(2) 20.0 µANotes:(1) Current consumption is the sum of both BC212015A and the flash.(2) Current consumption is for the BC212015A device only.(More: www.csr.com )


Baseband

Piconet/channel definition Low-level packet definition

Access code Channel, device access, e.g., derived from master

Packet header 1/3-FEC, active member address (broadcast + 7 slaves), link type, alternating

bit ARQ/SEQ, checksum

access code packet header payload

68(72) 54 0-2745 bits

AM address type flow ARQN SEQN HEC

3 4 1 1 1 8 bits

preamble sync. (trailer)

4 64 (4)


ACL Payload types

payload (0-343)

header (1/2) payload (0-339) CRC (2)

header (1) payload (0-17) 2/3 FEC

header (1) payload (0-27)


header (2) payload (0-183)


header (2) payload (0-339)DH5

DM5

DH3

DM3

DH1

DM1 CRC (2)

CRC (2)

CRC (2)

CRC (2)

CRC (2)

CRC (2)

(bytes)

prof. dr.-ing. jochen schiller, ss027.1 bluetooth ad-hoc piconets

Documents

bluetooth slide

jochen schiller

bluetooth sig

bluetooth ad

bluetooth original

mbps slide

piconets slide

bluetooth radio link