Transcript QoS Guarantee in Wirless Network

IEEE 802.15.1 (a.k.a. Bluetooth)
Bluetooth:
• King Harold Blatand, or Bluetooth, a Viking and
King of Denmark 940-981, united Denmark &
Norway
• 1994 – Ericsson study on a wireless technology
to link mobile phones and accessories
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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
• July 1999: 1.0A spec (>1,500 pages) is published
• December 1999: ver. 1.0B is released
• December 1999: The promoter group increases to 9
– 3Com, Lucent, Microsoft, Motorola
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March 2001: ver. 1.1 is released
Aug 2001: There are 2,491+ adopter companies
Nov. 2003: ver. 1.2 is released
Nov. 2004: ver. 2.0 is released
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Bluetooth positioning
• Bluetooth:
– Wireless voice and data for mobile devices
• IrDA:
– Wirelss data cable replacement for devices in line of sight
• HomeRF:
– Networking mobile data and voice devices to a PC anywhere in the
home
• IEEE 802.11 and Hiperlan 2:
– Wireless enterprise networking in the office
• DECT:
– Wireless voice at home and in the office
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Bluetooth positioning
Bandwidth
Bluetooth
GSM
GPRS
UMTS
DECT
WLAN
IrDA
IR
Bluetooth
WLAN
UMTS
GPRS
Dect
GSM
Coverage
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Bluetooth positioning
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Usage Models
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Headset – hands free cell phone (road, office, car)
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3 in 1 Phone – intercom (no charge), portable phone (fixed line charge),
cellular
– Office-->LAN/PSTN
Home-->PSTN
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Internet Bridge – Network access point, for mobile internet browsing
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Automatic Synchronizer – Background syncs between PC & PDA,
Phone & PC, etc.
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Instant Postcard – digital camera send to cell phone
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Interactive Conference – Exchange business cards & data in meetings
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Wireless Workplace – Peripherals connect to your PC or LAN without
wires
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Core Bluetooth Products
• Notebook PCs & desktop
computers
• Printers
• PDAs
• Other handheld devices
• Cell phones
• Wireless periperals:
– Headsets
– Cameras
• Access Points
• CD Player
• TV/VCR/DVD
• Telephone Answering
Devices
• Cordless Phones
• Cars
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Other Products…
• 2004 Toyota Prius – hands free calls
• Toshiba Washer & Dryer – downloads the
washer/dryer software for new clothes!
• Nokia N-gage
• Digital Pulse Oximetry System
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Future Usage Scenarios
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Home Automation
Home Entertainment/Games
Electronic Commerce/M-Commerce
Industrial Control
Surveillance
Access Control
Location Based Services
Current Trials: Shopping Malls, Train Stations
……
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Key Success Factors
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Interoperability (assured by BQB)
Mass Production at Low Cost
Ease of Use
End User Experience
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Bluetooth Qualification Body (BQB)
• A person authorized to provide qualification services for
products
• Bluetooth Qualification Test Facility (BQTF)
• Preparation – Testing – Assessment & Listing – Qualified
Products List (QPL)
• Stats (as of 02/01/04):
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Qualified Products: 1368
BQBs Worldwide: 35
BQTFs Worldwide: 25
Only 4 of each in US
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Bluetooth Profiles
• Profiles implement usage models
• Profiles will use 1 or more protocols
• Qualification based on set of profiles provided
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Profiles & Services
• An application that provides a capability to
another device, e.g. printing, LAN Access,
synchronization, etc.
• Bluetooth profiles define core services
• Programmers can write new services
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Example...
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Baseband
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Bluetooth Technical Features
• 2.4 GHz ISM Open Band
– Globally free available frequency
– 79 MHz of spectrum = 79 channels
– Frequency Hopping & Time Division Duplex (1600 hops/second)
• 10-100 Meter Range
– Class I – 100 meter (300 feet)
– Class II – 20 meter (60 feet)
– Class III – 10 meter (30 feet)
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Frequency Hopping among Piconets
• Typically, FH scheme uses carriers spacing of 1
MHz with up to 79 different frequencies.
• f = 2402 + k ; k = 0…78
• So, with FH, there are 79 logical channels
(theoretically).
– When two piconets choose the same 1MHz-band, collision occurs.
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Frequency hopping
78
Frequency
0
Time
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Frequency Hopping Sequences
• Each time, the FH kernel selects a segment of 64
adjacent channels, and then hops to 32 of them
without repetition in a random order
• Next, a different 32-hop sequence is chosen from
another segment of 64 adjacent channels
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Interference
• Frequency hopping
• Short range
• Power control
• FEC and ARQN
• Short packets and fast acknowledgements
• Other equipment in ISM band e.g. WLAN, micro-wave
oven, etc.
• Adaptive Frequency Hopping (AFH) is proposed in
IEEE 802.15.1.
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Bluetooth Link types
• Synchronous Connection Oriented (SCO)
– Circuit switched typically used for voice
– Symmetric, synchronous service
– Slot reservation at fixed intervals
– Point-to-point
• Asynchronous Connectionless Link (ACL)
– Packet switched
– Symmetric or asymmetric, asynchronous service
– Polling mechanism between master and slave(s)
– Point-to-point and point-to-multipoint
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Packet Types
Data/voice
packets
Control
packets
ID*
Null
Poll
FHS
DM1
Voice
HV1
HV2
HV3
DV
data
DM1
DM3
DM5
DH1
DH3
DH5
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Packet Format
72 bits 54 bits
Access
code
Header
0 - 2744 bits
Payload
Voice
Data
No CRC
No retries
FEC (optional)
ARQ
CRC
FEC (optional)
625 µs
master
slave
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Packet Header
54 bits
Access
code
Header
m
Payload
s
s
s
Purpose
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•
•
•
•
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Addressing (3)
Packet type (4)
Flow control (1)
1-bit ARQ
(1)
Sequencing (1)
HEC
(8)
total
Max 7 active slaves
16 packet types (some unused)
Broadcast packets are not ACKed
For filtering retransmitted packets
Verify header integrity
18 bits
Encode with 1/3 FEC to get 54 bits
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Voice Packets (HV1, HV2, HV3)
240 bits
72 bits 54 bits
Access
Header
code
= 366 bits
30 bytes
Payload
HV1
HV2
10 bytes
20 bytes
HV3
2.5ms
1.25ms (HV1)
+ 1/3 FEC
+ 2/3 FEC
30 bytes
3.75ms
(HV2)
(HV3)
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Data rate calculation: DM1 and DH1
625 µs
72 bits 54 bits
Access
Header
code
240 bits
= 366 bits
30 bytes
Payload
DM1 1
DH1 1
17
2
27
Di
r
2/3
FEC
2
Size Freq
Rate

17
1600/2 108.8

17
108.8

27
172.8

27
172.8
625 µs
1
2
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Data rate calculation: DM3 and DH3
1875 µs
54
72
bits bits
= 1626 bits
1500 bits
Access Header
code
187 bytes
Payload
DM3 2
121
DH3 2
2
183
Di
r
2/3
FEC
2
Size Freq
Rate

121
1600/4 387.2

17
54.4

183
585.6

27
86.4
1875 µs
1
2
3
4
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Data rate calculation: DM5 and DH5
3125 µs
54
72
bits bits
= 2870 bits
2744 bits
Access
Header
Code
343 bytes
Payload
DM5 2
224
DH5 2
339
2
3
2/3
FEC
2
Size Freq
Rate

224
1600/6 477.8

17
36.3

339
723.2

27
57.6
625 µs
3125 µs
1
2
Di
r
4
5
6
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Summary of Bluetooth Packet Types
SCO
Packet
Timeslots
CRC
FEC
Symmetric
(kbps)
HV1
1
-
1/3 rate
 64
HV2
1
-
2/3 rate
 64
HV3
1
-
-
 64
DV
1
Data only
Voice no FEC,
Data 2/3 FEC
 64
Packet
ACL
Timeslots
CRC
FEC
Symmetric
(kbps)
Asymmetric (kbps)
Forward
Reverse
DM1
1
Yes
Yes
108
108
108
DH1
1
Yes
-
172
172
172
DM3
3
Yes
Yes
258
387
54
DH3
3
Yes
-
390
585
86
DM5
5
Yes
Yes
286
477
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DH5
5
Yes
-
433
723
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AUX
1
-
-
185
185
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Bluetooth v2.0 Enhanced Data Rate (EDR)
• EDR achieves higher data throughput by using
Phase Shift Keying (PSK) modulation, instead of
Gaussian Frequency Shift Keying (GFSK)
modulation.
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Bluetooth Physical link
• Point to point link
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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
– hopping pattern is determined by the master
s
s
s
s
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Piconet capacity
One ACL link (432 kbps symmetric or 721/56 kbps asymetric)
or
Three simultaneous SCO links (64 kbps)
or
S4
S1
M1
A combination of voice/data
S3
S2
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Piconet Management
Attach and detach slaves
Master-slave switch
Establishing SCO links
Handling of low power modes ( Sniff, Hold, Park)
Paging
s
s
s
req
response
Slave
m
Master
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Connection Setup
• Inquiry - scan protocol
– to learn about the clock offset and
device address of other nodes in
proximity
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Baseband: Connection state
• Active mode:
– Bluetooth unit listens for each master transmission.
– Slaves not addressed can sleep through a transmission.
– Periodic master transmissions used for sync.
• Sniff mode
– Unit does not listen to every master transmission.
– Master polls such slaves in specified sniff slots.
– For ACL mode only.
• Hold mode
– Master and slave agree on a time duration for which the slave is not polled.
– The physical link is only active during slots that are reserved for the
operation of the synchronous link types SCO.
• Park mode
– Slave gives up AM_ADDR.
– Listens periodically for a beacon transmission to synchronize and uses
PM_ADDR/AR_ADDR for unparking.
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Low power mode (Sniff)
Sniff offset
Sniff duration
Slave
Sniff period
Master
• Traffic reduced to periodic sniff slots
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Low power mode (hold)
Hold offset
Slave
Hold duration
Master
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Low power mode (Park)
Slave
Beacon instant
Master
Beacon interval
• Power saving + keep more than 7 slaves in a piconet
• Give up active member address, yet maintain
synchronization
• Communication via broadcast LMP messages
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Piconet formation
• Page - scan protocol
– to establish links with nodes
in proximity
Master
Active Slave
Parked Slave
Standby
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Intra-piconet communication
The master controls all traffic on the piconet
SCO link - reservation
The master allocates capacity for SCO links by reserving slots
in pairs.
ACL link – polling scheme
The slave transmits in the slave-to-master slot only when it has
been addressed by its MAC address in the previous master-toslave slot. Therefore no collisions.
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Piconet MAC protocol : Polling
FH/TDD
f1
f2
f3
f4
f5
f6
m
s1
s2
625 sec
1600 hops/sec
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Multi slot packets
FH/TDD
f1
f4
f5
f6
m
s1
s2
625 µsec
Data rate depends on type of packet
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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
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Piconet capacity
One ACL link (432 kbps symmetric or 721/56 kbps
asymetric)
or
Three simultaneous SCO links (64 kbps)
S4
S1
or
A combination of voice/data
M1
S3
S2
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Baseband: Summary
Device 1
Device 2
L2CAP
L2CAP
LMP
Data link
LMP
Baseband
Baseband
Physical
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TDD, frequency hopping physical layer
Device inquiry and paging
Two types of links: SCO and ACL links
Multiple packet types (multiple data rates with
and without FEC)
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Networking
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Addressing
• Bluetooth device address (BD_ADDR)
– 48 bit IEEE MAC address
• Active Member address (AM_ADDR)
– 3 bits active slave address
– all zero broadcast address
• Parked Member address (PM_ADDR)
– 8 bit parked slave address
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Why Scatternets
A group of overlapping piconets is called a
scatternet
 Users in a piconet share a 1 Mbps channel – individual
throughput decreases drastically as more units are added
 The aggregate and individual throughput of users in a
scatternet is much greater than when each user participates on
the same piconet
 Collisions do occur when 2 piconets use the same 1 MHz hop
channel simultaneously. As the number of piconets increases,
the performance degrades gracefully
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Inter-piconet communication
 A unit may particpate in more
than one piconet on a TDM basis.
 To participate on a piconet it
needs the master’s identity and the
clock offset.
 While leaving the piconet it
informs the master
 The master can also multiplex as
slave on another piconet. But all
traffic in its piconet will suspended
in its absence.
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Inter piconet communication
Cordless
headset
mouse
Cordless
headset
Cell phone
Cell phone
Cell phone
Cordless
headset
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Scatternet
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Scatternet, scenario 2
How to schedule presence in
two piconets?
Forwarding delay ?
Missed traffic?
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Bluetooth Scatternets
• Scatternet Formation Problem
– Assignment of roles to devices
(Master / Slave / Bridge)
– Independent devices, no prior knowledge
→ distributed
– Formation time should be reasonable.
– Assumption: all devices within transmission
range of each other.
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Piconet interconnection
3
6
34
23
9
28
5
12
15
7
42
14
4
1
51
35
32
45
10
8
9
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Bluetooth Scatternets
• Properties desired
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Reachability (basic)
Number of piconets (minimize)
Network diameter (minimize)
Degree (minimize; bounded)
Number of bridge nodes (minimize)
Number of roles (minimize)
• Various Trade-offs
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Protocol Architecture
• Radio:
– interface, frequency hopping, modulation, transmit power
• Baseband:
– connection establishment in a piconet, addressing, packet format,
timing, power control
• Link Management Protocol (LMP):
– link setup, authentication, packet size
• Logical Link Control and Adaptation Protocol
(L2CAP):
– adapts upper-layer protocols to baseband, connectionless service,
connection-oriented service
• Service Discovery Protocol (SDP):
– device info (service, characteristic), service query
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How some companies view Bluetooth's future
Protocols and Usage Models
Usage Models
Sync
File
Transfer
Dial-up
net.
Fax
Headset
IrMC
OBEX
SDP
LAN
Access
Cordless
Phone
TCP/IP
AT-commands
PPP
RFCOMM
L2CAP
Audio
TCS-BIN
LMP
Baseband
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SONY / CASIO
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HP
• Print data from network:
– maps, emails, web pages, …
• Print phone book & other phone data
• Print directly from camera
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Siemens
• Cable replacement
• Home Access Point
• Home Control
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CASIO
• Intelligent home:
– Door lock, Light, Audio/Video, Electronic equipment, Automatic
synchronisation, ...
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Research on Bluetooth
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Coexistence with other wireless technologies
Opportunistic Bluetooth overlay networks
Cross layer integration
???
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