Wireless Sensornetworks
Concepts, Protocolls and Applications
Chapter 1
Introduction, Applications and Challenges
Hon.-Prof. Dr. rer. nat. Peter Langendrfer
leader of the research group of sensor nets
telefon: 0335 5625 350
fax: 0335 5625 671
e-mail: langendoerfer [ at ] ihp-microelectronics.com
web: www.tu-cottbus.de/systeme
general information
lecture dates
exercise each time after lecture (starts on demand)
exam at the beginning of the vacations by exam or orally
certificate by proof of their participation in lecture
(list of participants: at least 5 participated)
documents for lecture and exercise on chair website
for rescheduling information or other announcements
will be publish on chair website and/or by email
(please register in LEHVIS system)
www.tu-cottbus.de/systeme
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Literatur und Quellen
Protocols and Architectures for Wireless Sensor Networks
Prof. Holger Karl; Andreas Willig, Wiley, ISBN 0-470-09510-5
Distributed Sensor Networks
S. Sitharama Iyengar and Richard. R. Brooks, Chapman &
Hall/CRC, ISBN 1-58488-383-9
Wireless Sensor Networks, Architectures and Protocols
Edgar H. Callaway, Jr, Auerbach Publications ISBN 0-8493-1823-8
Sensor Technology Handbook
John S. Wilson, Newnes ISBN 0-7506-7729-5
Ad Hoc Wireless Networks
Mohamed Ilyas, CRC Press, ISBN 0-8493-1332-5
Prsentationen aus dem WWRF
Folien des Kollegen Karl aus Paderborn
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lecture overview
Introduction, Applications and Challenges
Single Node Architectures
Physical Layer
MAC Protocols
LLC Protocols
Routing Protocols
Network Architectures
DSN Architectures
Power Management
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infrastructure-based wireless networks
Typical wireless network: Based on infrastructure
e.g., GSM, UMTS,
base stations connected to a wired backbone network
mobile entities communicate wirelessly to these base stations
traffic between different mobile entities is relayed by base stations and
wired backbone
mobility is supported by switching from one base station to another
backbone infrastructure required for administrative tasks
Gateways
Server
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IP backbone
Router
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infrastructure-based wireless networks (2)
Which are the limits ?
What if
no infrastructure is available ?
e.g., in disaster areas
it is too expensive/inconvenient to set up ?
e.g., in remote, large construction sites
there is no time to set it up ?
e.g., in military operations
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possible applications for
infrastructure-free networks
factory floor automation
disaster recovery
car-to-car communication
ad
c
ho
military networking: tanks, soldiers,
finding out empty parking lots in a city, without asking a
server
search-and-rescue in an avalanche
personal area networking (watch, glasses, PDA, medical
appliance, )
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sensor equipment
tiny 1cm Particle
includes sensors, battery,
CPU, communication
source: www.teco.edu
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sensor nodes
UC Berkeley: COTS Dust
UC Berkeley: COTS Dust
UC Berkeley: Smart Dust
Rockwell: WINS
UCLA: WINS
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JPL: Sensor Webs
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Sensor Node
Antenna
Processor
Radio Frontend
Sensor Interface
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Sensorknoten
Antenne
Processor
Radio Frontend
Sensor Internface
Power
Mgmt.
Power
Supply
Microcontroller
I/O
HardwareAccelerator
Memory
Baseband
Base
band
Analogue
Frontend
Sensor
Communication Interface
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IHP Sensor nodes
Tandem Node
Power
Mgmt.
Power
Supply
Microcontroller
Speicher
Memory
250KB
Ein-/Ausgabe
Basisband
Baseband
IPMS430
SPI
HardwareHW
Acc
Beschleuniger
ECC, AES
Baseband
Analoges
868MHz
Frontend
Sensor
Kommunikationsschnittstelle
On board comm.
FeuerWhere Node designed by IHP
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First Tandem node, security
flavour for BSI
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sensors and local infrastructure
location aware mall Metro FutureStore
location aware shopping system
finds location of products
ubiquitous mall
mobile communication + sensors/RFID
tags
Sensor node
tiny 1cm
sensors,
battery,
CPU,
communication
Source: www.teco.edu
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telecom and internet world
most modern cell phones combine
features of former PDAs plus:
internet access
NFC
payment functionality
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sensors and internet
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applications
bird observation on Great Duck Island
interest: breeding behavior: usage of burrows,
environment, breeding sites
nodes located in burrows and on surface
measurement: humidity, pressure, temperature,
ambient light (every minute)
infrared sensors detect presence of birds
ad-hoc clusters with dedicated node for long-range
communication
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applications (2)
ZebraNet
interest: behavior of individual animals, interactions,
human impact
hundreds of square kilometers, years of observation,
every 3 minutes
animals carry nodes with GPS and sensors (now
light, more coming)
data transferred whenever nodes come close
together
mobile base station (car or plane) collects data from
time to time
related: cattle herding using virtual fences
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applications (3)
disaster relief operations
drop sensor nodes from an aircraft over a
wildfire
each node measures temperature
derive a temperature map
biodiversity mapping
use sensor nodes to observe wildlife
intelligent buildings (or bridges)
reduce energy wastage by proper humidity,
ventilation, air conditioning (HVAC) control
needs measurements about room
occupancy, temperature, air flow,
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sensors and local infrastructure
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Tunnel Monitoring
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application (3)
glacier monitoring
interest: monitor glacier dynamics to understand climate
nodes in drill holes measure pressure, temperature, tilt
base station on glacier uses differential GPS, transmits data via
GSM
major problem: radio communication through ice and water
ocean water monitoring
interest: global, long-term coverage of ocean and climate
measure temperature, salinity, ocean profile continuously
nodes cycle to 2000m depth every ten days
data transmitted to satellite when on surface
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application (4)
vital sign monitoring
Interest: monitor vital signs of patients in hospital using WSN
Better accuracy and patient comfort compared to conventional
approaches
Components: patient identifier, medical sensors, display device,
setup pen
Staff uses setup pen to set up associations between body area
nodes
parts assembly
Interest: assist assembly of do-it-yourself furniture
Parts and tools equipped with sensor nodes
Use force sensors (joints), gyroscope (screwdriver),
accelerometer (hammer)
Ad-hoc network detects activities, feedback via LEDs in furniture
parts
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application (5)
power monitoring
interest: save power in large office building
sensor node connected to each power outlet
transceiver nodes form multihop network to central unit, gateway
to internet
other applications
grape monitoring: conditions which influence plant growth
cold chain management: monitor food temperature compliance
avalanche rescue: assist rescue of avalanche victims
military vehicle tracking: find and track e.g. tanks
self-healing mine field: Intact mines hop into a breach
sniper localization: locate snipers and bullet trajectories
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application scenarios
facility management
intrusion detection into industrial sites
control of leakages in chemical plants,
machine surveillance and preventive maintenance
embed sensing/control functions into places no cable has gone
before
e.g., tire pressure monitoring
precision agriculture
bring out fertilizer/pesticides/irrigation only where needed
medicine and health care
post-operative or intensive care
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application scenarios (2)
logistics
equip goods (parcels, containers) with a sensor node
track their whereabouts total asset management
note: passive readout might suffice compare RFIDs
telematics
provide better traffic control by obtaining finer-grained
information about traffic conditions
intelligent roadside
cars as the sensor nodes
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Application Areas
Homeland Security
Industrial Automation
Telemedicine
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Context aware systems
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Geographical setting and system req.
Demonstration side
65 Ground water measurement
points
12,6km area
250m to 2000m distance
Rural/forest area
No power supply
Requirements
Automatic measurement (min. once
a day)
Radio transmission
Local buffering of measurement
results
10 year maintenance free operation
Temperature range -30Cto +40C
Protection against vandalism and
animals
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IQlevel System
Centralised server
GPRS/GSM connection
node
Local Internet-Server
Solar module
Low Power Wireless Sensor Network
868MHz Long Distance Radio
Ultra Low Power Micro controller
Low Duty Cycle Protocol
Crypto-based security
10 years life time
Mesh-Network incl. adaptive
routing
Digital probe
Ultra Low Power Micro controller
Modular probe
Pressure-, ph-value-, sulphate- and
elect. conductivity measurements
Buffering of measurement results
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Protecting First Responders
Vital parameters:
Body core temperature
Pulse
Blood oxygen saturation
Environmental data:
Remaining air in the breathing apparatus
Temperature inside protective clothing
Temperature at surface of protective clothing
Environmental temperature appr. 2 m above the head of fire
fighters
Relative humidity inside protective clothing
Relative humidity around the fire fighters
Explosive gas and/or explosive pyrolysis products
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Data handling
Buffering of all measurement data in the BAN
In network processing (local evaluation)
Timely transmission according a red-yellow-green model
Red: acute life threatening situation, immediate data transmission
(continuously)
Yellow: situation might become life threatening in a short time scale, data
transmission latest 10 sec. after measurement
Green: no threat at all, transmission of data every 60 seconds as self-test
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Harsh Environmental Conditions
Temperature up to 1000C
Saturated steam atmosphere
No sight due to smoke
Extremely noisy
Aggressive liquids and gas
Ionizing radiation
Blast e.g. after explosion
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Protecting Critical Infrastructure (Drinking
Water Pipeline)
Flow rate, pressure, quantity
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Measurement parameters
Measurements are done every 30 seconds
Location
Waterworks Briesen
Distance to next
substation
~1800 m
Briesen
<~5800m
(protection on pipe bursts)
Jacobsdorf
(protection on pipe bursts)
~4800m
Pilgram/Pagram
(protection on pipe bursts)
~2500m
Reservoir
0m
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Parameter
flow rate
pressure, outlet
position of butterfly valve
pressure pipe A(1)
pressure pipe N(2)
position of butterfly valve
flow rate
quantity
pressure pipe A(1)
pressure pipe N(2)
position of butterfly valve
pressure pipe A(1)
pressure pipe N(2)
position of butterfly valve
flow rate
quantity intake from
waterworks with negativ
back flow
quantity intake from
waterworks
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Unit
(m/h)
(bar)
indication
(bar)
(bar)
indication
(m/h)
(m)
(bar)
(bar)
indication
(bar)
(bar)
indication
(m/h)
(m)
(m)
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Pipe access points
Spot to place additional
hardware
No power supply
Distance up to 3 km (usually
less)
Power supply
Distance up to 6 km
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SCADA Integration
WSAN
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Intended System /software architecture
MSP430 uC
Standard 868MHz radio (e.g. cc1100)
+ power amplifier + good antenna
Tailored MAC & network stack
tinyOS
Software Architecture
Sensor
control
Node Control
Transport
Routing
Forwarding
MAC
Update
service
Ciphers
Data storage
radio
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tinyOS
HW
IDS
Attestation
watchdog
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Sensor
Network Services DCU PROT
MIB/Identity
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What we would like to have
Lego like sensor node construction kit
Secure Sensor Node for CIP
Sensor Node for Protection of First
Responders/Environmental Monitoring
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Construction Kit: Existing Components
C/Processors
Leon 2-3; MIPS; MSP430 derivate; 8051
Radio Front Ends
UWB (802.15.4a), 868MHz (802.15.4 V2006); EN13757-3-4
Hardware Accelerators/Power management
AES, ECC, TCP Checksum ; PowerSwitches
Operating systems
tinyOS, Contiki, Reflex (BTU Cottbus); eCos
Protocols
TCP, 802.15.4 Software (hardware under development); IHP-beaconing
Middleware
tinyDSM (Event Definition; SQL like query language)
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roles of participants in WSN
sources of data: Measure data, report them somewhere
Typically equip with different kinds of actual sensors
sinks of data: Interested in receiving data from WSN
May be part of the WSN or external entity, PDA, gateway,
actuators: Control some device based on data, usually
also a sink
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design space
deployment
random or installed at chosen spots
one-time or continuous
classes: random/manual; one-time/iterative
mobility
motion by environment (e.g. wind, water)
motion because attached to mobile entities (e.g. zebras)
motion of automotive nodes
can be desired property or undesirable accident
motion has large impact on network algorithms
classes: immobile/partly/all; occasional/continuous;
active/passive
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design space (2)
cost, size, resources, energy
form factor depends on application (microscopic to shoebox)
cost from cents to hundreds of euro's
energy, computing, processing resources depend on size
classes: brick, matchbox, grain, dust
heterogeneity
first approach: identical or indistinguishable nodes only
in practice: a variety of nodes can be very useful
bundle computational or communication resources (cluster
heads)
special capabilities only for some (e.g. GPS)
gateways to external networks (GSM, satellite, Internet)
heterogeneity has large effect on complexity of software
classes: homogeneous/heterogeneous
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design space (3)
communication modality
How do nodes communicate ?
most common: radio waves, usually sub-gigahertz bands
light beams or laser: smaller, more energy efficient (cf. Smart Dust)
RFID coupling, sound, ultrasound also useful
classes: radio, light, inductive, capacative, sound
infrastructure
How to construct the communication network ?
infrastructure-based: sensors communicate via base stations only
ad-hoc: direct communication between nodes
infrastructure is costly to deploy, ad-hoc often preferred
ad-hoc allows routers, multihop, message forwarding
classes: infrastructure / ad-hoc
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design space (4)
network topology
important property:
diameter = max number of hops between any two nodes
single hop (d=1), infrastructure based (d=2), ad-hoc (d big)
topology affects QoS and software complexity
classes: single-hop / star / networked stars / tree / graph
coverage
depends on range of attached sensors
sensors could cover only part of area of interest, or all, or
multiply
coverage influences observational accuracy, redundancy,
processing
classes: sparse / dense / redundant
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design space (5)
connectivity
Nodes always connected or only sometimes ?
Network sometimes partitioned ?
connectivity influences communication protocols and data gathering
classes: connected / intermittent / sporadic
size
range: a few nodes to thousands of nodes
lifetime
How long does the sensor network exist ?
range: some hours to several years
other QoS requirements
real-time, robustness, tamper-resistance, eavesdropping resistance,
unobtrusiveness, stealth
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Node Capabilities & Requirements
Processing power :
Memory :
Energy resources :
Active Time:
Cost :
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8 or 16 bit C
16 to 256 kByte
typical small batteries
1000-5000 mAh
energy harvesting
1-15 years
1-100 $/node
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real life connectivity
figures show WSN deployed on
a flat parking lot
expected: simple, circular shape
of region of communication
not realistic
instead:
correlation between distance and
loss rate is weak; iso-loss-lines are
not circular but irregular
asymmetric links are relatively
frequent (up to 15%)
significant short-term PER
variations even for stationary nodes
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three regions of communication
effective region: PER consistently 10%
transitional region:
anything in between,
with large variation
for nodes at
same distance
poor region: PER well beyond 90%
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discussion and conclusions
single hardware platform will not be sufficient to cover applications
avoid application-specific hardware by small set of platforms
cover different parts of design space
modular approach (exchange components of node) could help
software situation is even more complex
cover design space with set of protocols, algorithms, basic services
system designer is still faced by complexity of design space
use middleware as in conventional systems ? No...
aspects of DS are hard to hide from developer (e.g. topology)
must expose characteristics to handle resource limitations
Middleware would introduce significant resource overheads
unconventional approaches towards general abstractions under
discussion, may be tis is even kind of middleware
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see you !
Thanks for your attention !
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