Transcript Mobile Communications

Bluetooth
ad-hoc piconets
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.1
Bluetooth - original
 A cable replacement technology
 1 Mb/s symbol rate
 Range 10+ meters
 Single chip radio + baseband
– at low power & low price point
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
Why not use Wireless LANs?
- power
- cost
MC SS02
7.2
What does Bluetooth do for you?
Landline
Cable
Replacement
Data/Voice
Access
Points
“Usage
Models” Class
Personal Adhoc Networks
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.3
Bluetooth
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.4
Who is Bluetooth?
Harald Blaatand “Bluetooth” II
King 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
7.5
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 WPANs
WPAN: Wireless Personal Area Networks
July 2009: There are 10000+ adopters
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.6
Bluetooth Protocol Stack
Applications
IP
SDP
RFCOMM
Data
Audio
L2CAP
Link Manager
Baseband
RF
Single chip with RS-232,
USB, or PC card interface
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.7
Bluetooth Radio Specification
Applications
IP
SDP
RFCOMM
Data
Audio
L2CAP
Link Manager
Baseband
RF
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.8
Radio Spectrum
l
12cm
5cm
83.5 Mhz
125 Mhz
2.4 Ghz
5.725 Ghz
2.4835 Ghz
5.785 Ghz
802.11a
HiperLan2
802.11b/g
Bluetooth
Microwave oven
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.9
Bluetooth Radio Link
1Mhz
. . .
79
12 3
83.5 Mhz
 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)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.10
Reliability
The hostile ISM band is managed by:
1. Frequency hopping
2. Adaptive power control
3. Short data packets
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.11
Bluetooth Baseband
Applications
IP
SDP
RFCOMM
Data
Audio
L2CAP
Link Manager
Baseband
RF
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.12
Bluetooth Physical Link
 Point to point link
– master - slave relationship
– radios can function as masters or slaves
m
m
 Piconet
– Master can connect to 7 slaves
– Each piconet has max capacity (1 Mbps)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
s
MC SS02
s
s
7.13
s
Piconet
Collection of devices connected in an ad hoc
fashion
P
One unit acts as master and the others as slaves
for the lifetime of the piconet
S
S
M
Master determines hopping pattern, slaves have
to synchronize
SB
S
P
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)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
P
SB
M=Master
S=Slave
P=Parked (can be reactivated
within some milliseconds)
SB=Standby (not active at all)
MC SS02
7.14
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
S
SB
SB 
SB
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
P 
S
M
P
S
P 
SB
7.15
Link types
ACL – Asynchronous Connection Less
Used for all data communication and signalling.
A device may keep multiple ACL connections.
SCO – Synchrounous Connection Oriented
Used for synchrounous voice transmission (Point to Point).
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.16
Bluetooth Packet Format
72 bits 54 bits
Access
code
Header
0 - 2744 bits
Payload
Access code:
– Synchronization.
– Identification.
Header:
–
–
–
–
–
AM-ADDR: MAC-address
Type: payload type
Flow: flow control
ARQ: fast retransmit
HEC
header
Voice
No CRC
No retries
FEC (optional)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
Data
CRC
ARQ
FEC (optional)
7.17
Bluetooth Channel
FH/TDD
f1
Hopping pattern is decided by the master
f2
f3
f4
f5
f6
m
s1
s2
625 µsec
1600 hops/sec
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.18
Multislot Packets
Data rate depends on type of packet
FH/TDD
f1
f4
f5
f6
m
s1
s2
625 µsec
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.19
Data Packet Types for ACL
Symmetric
2/3 FEC
DM1
108.8 108.8 108.8
DM3
258.1 387.2
54.4
DM5
286.7 477.8
36.3
Symmetric
No FEC
Asymmetric
DH1
DH3
DH5
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
kbps
Asymmetric
172.8 172.8 172.8
390.4 585.6 86.4
433.9 723.2 57.6
MC SS02
7.20
kbps
Link types
SCO – Synchrounous Connection Oriented
Used 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)
HV1
HV2
HV3
audio (10)
FEC (20)
audio (20)
FEC (10)
audio (30)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.21
Physical Link Types
 Synchronous Connection Oriented (SCO) Link
– slot reservation at fixed intervals
 Asynchronous Connection-less (ACL) Link
– Polling access method
m
SCO ACL
ACL
SCO
ACL
ACL
SCO ACL
ACL
s1
s2
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.22
Robustness
Slow frequency hopping with hopping patterns determined by a master

Protection from interference on certain frequencies
 Separation from other piconets (FH-CDMA)
Retransmission

Error in payload
(not header!)
ACL only, very fast
Forward Error Correction

MASTER
SLAVE 1
NAK
SCO and ACL
A
C
B
C
D
F
ACK
H
E
SLAVE 2
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
G
MC SS02
G
7.23
Link Manager Protocol (LMP)
Applications
IP
SDP
RFCOMM
Data
Audio
L2CAP
Link Manager
Baseband
RF
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
Setup and management
of Baseband connections
• Piconet Management
• Link Configuration
• Security
MC SS02
7.24
L2CAP
Applications
IP
SDP
Logical Link Control and
Adaptation Protocol
RFCOMM
Data
Audio
L2CAP
Link Manager
Baseband
RF
L2CAP provides
• Protocol multiplexing
• Segmentation and Re-assembly
• Quality of service negotiation
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.25
Profiles
Represent default solutions for a certain usage model
Applications
Vertical slice through the protocol stack
 Basis for interoperability
Protocols

Generic Access Profile
Service Discovery Application Profile
Cordless Telephony Profile
Intercom Profile
Serial Port Profile
Additional Profiles
Headset Profile
Advanced Audio Distribution
Dial-up Networking Profile
PAN
Fax Profile
Audio Video Remote Control
LAN Access Profile
Basic Printing
Generic Object Exchange Profile
Basic Imaging
Object Push Profile
Extended Service Discovery
File Transfer Profile
Generic Audio Video Distribution
Synchronization Profile
Hands Free
Hardcopy Cable Replacement
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.26
Profiles
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
•
Master
Slave 3
A Bridging node may only participate
in one piconet at a time
–
–
–
•
Slave 2
Slave 1
Bluetooth unit only has one transceiver
Different frequency hop sequences used for
each piconet
Has to switch between piconets on a time
division basis
Master 2
Slave 4/
Master 3
Scatternet scheduling
–
The task of controlling the presence of
Bridging nodes in different piconets
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
Slave 5
MC SS02
7.27
Scatternet Example
PDA
mouse
Cordles
s
headset
Cell phone
Cell phone
PDA
Cell phone
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.28
End
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.29
Example: Power consumption/CSR BlueCore2
Typical Average Current Consumption (1)
VDD=1.8V Temperature = 20°C
Mode
SCO connection HV3 (1s interval Sniff Mode) (Slave)
SCO connection HV3 (1s interval Sniff Mode) (Master)
SCO connection HV1 (Slave)
SCO connection HV1 (Master)
ACL data transfer 115.2kbps UART (Master)
ACL data transfer 720kbps USB (Slave)
ACL data transfer 720kbps USB (Master)
ACL connection, Sniff Mode 40ms interval, 38.4kbps UART
ACL connection, Sniff Mode 1.28s interval, 38.4kbps UART
Parked Slave, 1.28s beacon interval, 38.4kbps UART
Standby Mode (Connected to host, no RF activity)
Deep Sleep Mode(2)
Notes:
(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
26.0 mA
26.0 mA
53.0 mA
53.0 mA
15.5 mA
53.0 mA
53.0 mA
4.0 mA
0.5 mA
0.6 mA
47.0 µA
20.0 µA
7.30
Baseband


Piconet/channel definition
Low-level packet definition
 Access

Channel, device access, e.g., derived from master
 Packet

code
header
1/3-FEC, active member address (broadcast + 7 slaves), link type, alternating
bit ARQ/SEQ, checksum
68(72)
54
0-2745
access code packet header
4
preamble
64
sync.
(4)
3
(trailer) AM address
bits
payload
4
1
1
1
8
type
flow
ARQN
SEQN
HEC
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS02
7.31
bits
ACL Payload types
payload (0-343)
header (1/2)
DM1 header (1)
DH1 header (1)
DM3
header (2)
DH3
header (2)
DM5
header (2)
DH5
header (2)
payload (0-339)
payload (0-17)
2/3 FEC
payload (0-27)
payload (0-121)
CRC (2)
CRC (2)
2/3 FEC
CRC (2)
payload (0-183)
CRC (2)
payload (0-224)
2/3 FEC
payload (0-339)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
(bytes)
CRC (2)
MC SS02
CRC (2)
CRC (2)
7.32