Lecture 8: Wireless Sensor Networks

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Lecture 8 Wireless Sensor Networks
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Announcement

• Midterm EXAM 500 615 pm March 28
  (Thursday)
• Midterm project report due 4/4 (Email submission)
• No class on 4/4 due to Chancellor's Inauguration
• we ask that all classes be cancelled beginning
  at 1230 for the remainder of the day. Classes
  will resume on Friday morning, April 5, 2013
  Provost
• Project Presentation on April 9

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Sensor Node Hardware

• Two main components
• Sensor Board
• Base (Processor Transceiver)
• Base Sensor Board(s) Sensor Node

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Sensor Board

• Light
• Ultraviolet
• IR
• Visible Light
• Color sensors
• Magnetic
• Sound
• Ultrasound
• Accelerometer
• Temperature
• Pressure
• Humidity
• Touch sensors

Sounder
Temperature
Light
Accelerometer
1.25 in
Magnetometer
2.25 in
Microphone
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Sensor Node Hardware
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Properties of wireless sensor networks

• Sensor nodes (SN) monitor and control the
  environment
• Nodes process data and forward data via radio
• Integration into the environment, typically
  attached to other networks over a gateway (GW)
• Network is self-organizing and energy efficient
• Potentially high number of nodes at very low cost
  per node

GW
Bluetooth, TETRA,
SN
SN
SN
SN
SN
SN
GW
SN
SN
SN
SN
GW
SN
SN
GW
Ethernet
GPRS
WLAN
ALARM!
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Wireless Sensor Networks (WSN)

• Commonalities with MANETs
• Self-organization, multi-hop
• Typically wireless, should be energy efficient
• Differences to MANETs
• Applications MANET more powerful, moregeneral ?
  WSN more specific
• Devices MANET more powerful, higher data rates,
  more resources? WSN rather limited, embedded,
  interacting with environment
• Scale MANET rather small (some dozen devices)?
  WSN can be large (thousands)
• Basic paradigms MANET individual node important,
  ID centric? WSN network important, individual
  node may be dispensable, data centric

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Sensor Motes Timeline
Mica Open Experimental Platform
Rene Experimentation
Telos Integrated Platform
IMote
Stargate 2.0 IMote2
WeC Smart Rock
MicaZ
Mica2Dot
2005
2004
2003
2002
2001
2000
1999
1998
2006
2007
Spec Mote on a chip
Dot Scale
Mica2
Stargate
SunSpot
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Promising applications for WSNs

• Machine and vehicle monitoring
• Sensor nodes in moveable parts
• Monitoring of hub temperatures, fluid levels
• Health medicine
• Long-term monitoring of patients with minimal
  restrictions
• Intensive care with relative great freedom of
  movement
• Intelligent buildings, building monitoring
• Intrusion detection, mechanical stress detection
• Environmental monitoring, person tracking
• Monitoring of wildlife and national parks
• Cheap and (almost) invisible person monitoring
• Monitoring waste dumps, demilitarized zones
• and many more logistics (total asset
  management, RFID), telematics

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CodeBlue WSNs for Medical Care

• NSF, NIH, U.S. Army, Sun Microsystems and
  Microsoft Corporation
• Motivation - Vital sign data poorly integrated
  with pre-hospital and hospital-based patient care
  records

Reference http//www.eecs.harvard.edu/mdw/proj/c
odeblue/
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Wearable Patient Monitoring Application (ECG)
Through Wireless Networks

• Wearable Resilient Electrocardiogram (ECG)
  networked sensor device used for patient
  monitoring

Software GUI interface
Wireless ECG medical sensor
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Sensor Networks Research Areas

• Real-World Integration
• Gaming, Tourism
• Emergency, Rescue
• Monitoring, Surveillance
• Self-configuring networks
• Robust routing
• Low-power data aggregation
• Simple indoor localization
• Managing wireless sensor networks
• Tools for access and programming
• Update distribution
• Long-lived, autonomous networks
• Use environmental energy sources

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Routing in WSNs is different

• No IP addressing, but simple, locally valid IDs
• Example directed diffusion
• Interest Messages
• Interest in sensor data Attribute/Value pair
• Gradient remember direction of interested node
• Data Messages
• Send back data using gradients
• Hop count guarantees shortest path

Sink
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TTDD A Two-tier Data Dissemination Model for
Large-scale Wireless Sensor Networks
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A Sensor Network Example
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Assumptions

• Fixed source and sensor nodes, mobile or
  stationary sinks
• Nodes densely applied in large field
• Position-aware nodes, sinks not necessarily
• Once a stimulus appears, sensors surrounding it
  collectively process signal, one becomes the
  source to generate the data report

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Sensor Network Model
Stimulus
Source
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Mobile Sink
Excessive Power Consumption
Increased Wireless Transmission Collisions
State Maintenance Overhead
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Goal, Idea

• Efficient and scalable data dissemination from
  multiple sources to multiple, mobile sinks
• Two-tier forwarding model
• Source proactively builds a grid structure
• Localize impact of sink mobility on data
  forwarding
• A small set of sensor node maintains forwarding
  state

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Grid setup

• Source proactively divide the plane into aXa
  square cells, with itself at one of the crossing
  point of the grid.
• The source calculates the locations of its four
  neighboring dissemination points
• The source sends a data-announcement message to
  reach these neighbors using greedy geographical
  forwarding
• The node serving the point called dissemination
  node
• This continues

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TTDD Basics
Dissemination Node
Data Announcement
Data
Query
Immediate Dissemination Node
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TTDD Mobile Sinks
Dissemination Node
Trajectory Forwarding
Data Announcement
Immediate Dissemination Node
Data
Immediate Dissemination Node
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TTDD Multiple Mobile Sinks
Dissemination Node
Trajectory Forwarding
Data Announcement
Immediate Dissemination Node
Data
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Trajectory Forwarding
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Conclusion

• TTDD two-tier data dissemination Model
• Exploit sensor nodes being stationary and
  location-aware
• Construct maintain a grid structure with low
  overhead
• Proactive sources
• Localize sink mobility impact
• Infrastructure-approach in stationary sensor
  networks
• Efficiency effectiveness in supporting mobile
  sinks

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The Future of WSNs

• Fundamental requirements today onlypartially
  fulfilled
• Long life-time with/without batteries
• Self-configuring, self-healing networks
• Robust routing, robust data transmission
• Management and integration
• Think of new applications
• Intelligent environments for gaming
• ltyour idea heregt
• Still a lot to do
• Integration of new/future radio technologies
• Cheap indoor localization (/- 10cm)
• More system aspects (security, middleware, )
• Prove scalability, robustness
• Make it cheaper, simpler to use
• Already today Flexible add-on for
  existingenvironmental monitoring networks

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Major References

• TTDD http//portal.acm.org/citation.cfm?id116011
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• A survey on sensor networks
• http//www-net.cs.umass.edu/cs791_sensornets/paper
  s/akyildiz2.pdf
• Routing techniques in wireless sensor networks
  A Survey
• http//ieeexplore.ieee.org/stamp/stamp.jsp?tparn
  umber1368893userTypeinst