prof. dr.-ing. jochen schiller, ss027.1 bluetooth ad-hoc piconets
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Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.1
Bluetooth
ad-hoc piconets
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.2
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.3
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.4
Bluetooth
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.5
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.6
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.7
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.8
Bluetooth Radio Specification
RF
Baseband
AudioLink Manager
L2CAP
Data Con
trolSDP RFCOMM
IP
Applications
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.9
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.10
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.11
Reliability
The hostile ISM band is managed by:
1. Frequency hopping2. Adaptive power control 3. Short data packets
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.12
Bluetooth Baseband
RF
Baseband
AudioLink Manager
L2CAP
Data Con
trolSDP RFCOMM
IP
Applications
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.13
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)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.14
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.15
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.16
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).
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.17
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)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.18
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.19
Multislot Packets
m
s1
s2
625 µsec
f1 f4 f5 f6FH/TDD
Data rate depends on type of packet
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.20
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.21
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)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.22
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.23
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!)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.24
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.25
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.26
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.27
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.28
Scatternet Example
PDACell phone
Cordless
headset
Cell phone
PDA
Cell phone
mouse
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.29
End
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.30
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 )
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.31
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)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.32
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 (0-121) 2/3 FEC
header (2) payload (0-183)
header (2) payload (0-224) 2/3 FEC
header (2) payload (0-339)DH5
DM5
DH3
DM3
DH1
DM1 CRC (2)
CRC (2)
CRC (2)
CRC (2)
CRC (2)
CRC (2)
(bytes)
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