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Introduction to Sensor Networks


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Title: Introduction to Sensor Networks

Introduction to Sensor Networks
  • Rabie A. Ramadan, PhD
  • Cairo University
  • http//
  • 1

  • Website
  • http//

Class Format
  • Presentations by myself
  • Assignments

  • Some other materials will be provided

  • Introduction and Basic Concepts

Wireless Networks
  • Most of the traditional wireless networks occur
    over fixed infrastructure
  • Access points
  • Many wireless protocols (heterogeneity problem)
  • Bluetooth, WiFi, WiMax
  • We need Seamless network
  • Connects everyone from their home to work,..
  • Disasters may be a drive force for such networks

Katrina hurricane, 2006
General Types of Networks
  • Wireless Cellular Networks
  • First , Second, 2.5 , third, and 4th generations
  • Wireless Ad Hoc Networks
  • Nodes function as host and router
  • Dynamic topology
  • Nodes may departure
  • Requires efficient routing protocols
  • Mobile Ad Hoc Networks (MANET)
  • Wireless Sensor Networks (WSN)

Wireless Sensor Networks
Definitions and Background
  • Sensing
  • Is a technique used to gather information about
    a physical object or process, including the
    occurrence of events (i.e., changes in state such
    as a drop in temperature or pressure).
  • Sensor
  • An object performing such a sensing task
  • Converts energy of the physical worlds into
    electrical signal.
  • Sometimes named Transducer ? converts energy
    from one form to another.
  • Examples on remote sensors
  • Nose, ears, and eyes ? They do not need to touch
    the monitored objects to gather information

Sensing Task
e.g. amplification, filtering, ..etc
An example of a sensor Passive infrared
  • PIR is a differential sensor detects target as
    it crosses the beams produced by the optic

PIR signal Amplitude
Car 20-25 mph _at_ 25m
Human 3 mph _at_ 10m
What is a Smart Sensor Node?
Nodes Responsibilities
  • Data Collection
  • In-Network Analysis
  • Data Fusion
  • Decision Making

Sensors Classification
  • Types of Measured Phenomena

What is a sensor Network?
(No Transcript)
History of WSN
Academic Effort
  • Defense Advanced Research Projects Agency (DARPA)
    organized the Distributed Sensor Nets Workshop
    (DAR 1978).
  • DARPA also operated the Distributed Sensor
    Networks (DSN) program in the early 1980s,

Academic Effort
  • Rockwell Science Center, the University of
    California at Los Angeles proposed the concept of
    Wireless Integrated Network Sensors or WINS.
  • One outcome of the WINS project was the Low Power
    Wireless Integrated Microsensor (LWIM), produced
    in 1996

Academic Effort
  • The Smart Dust project at the University of
    California at Berkeley focused on the design of
    extremely small sensor nodes called motes. (year
    of 2000).
  • The goal of this project was to demonstrate that
    a complete sensor system can be integrated into
    tiny devices, possibly the size of a grain of
    sand or even a dust particle.

Academic Effort
Sample Sensor Hardware Berkeley motes
(No Transcript)
Commercial Effort
  • Crossbow (,
  • Sensoria (,
  • Worldsens (http//,
  • Dust Networks (http// ),
  • Ember Corporation (http// ).

Challenges and Constraints
  • Energy
  • Sensors powered through batteries? sometimes
    impossible to do.
  • Mission time may depend on the type of
    application (e.g. battlefield monitoring hours
    or days)
  • Nodes layers must be designed carefully.

Wireless Range Controls the Network Topology
Routing in multihop network is a challenge Relay
node may aggregate the data
Medium Access Control layer (MAC)
  • Responsible for providing sensor nodes with
    access to the wireless channel.
  • Responsible of Contention free Transmission .
  • MAC protocols have to be contention free as well
    as energy efficient.
  • Contention free requires listening to the
    wireless channel all the time
  • Energy efficient requires turning off the radio

Network Layer
  • Responsible for finding routes from a sensor node
    to the base station
  • Route characteristics such as length (e.g., in
    terms of number of hops), required transmission
    power, and available energy on relay nodes
  • Determine the energy overheads of multi-hop
    communication and try to avoid it.

Operating System
  • Energy affects the O.S. design
  • Small memory footprint,
  • Efficient switching between tasks
  • security mechanisms

Challenges and Constraints
  • Self-Management
  • Sensors usually deployed in harsh environment.
  • There is no pre-infrastructure setup.
  • Once deployed, must operate without human
  • Sensor nodes must be self-managing in that
  • They configure themselves,
  • Operate and collaborate with other nodes,
  • Adapt to failures, changes in the environment,

A self-managing Network
  • Self-organization
  • A networks ability to adapt configuration
    parameters based on system and Environmental
  • Self-optimization
  • A devices ability to monitor and optimize the
    use of its own system resources
  • Self-protection
  • Allows a device to recognize and protect itself
    from intrusions and attacks
  • Self-healing
  • Allows sensor nodes to discover, identify, and
    react to network disruptions.

Ad Hoc Deployment
  • Deterministic Vs. Ad Hoc Deployment

Challenges and Constraints
  • Wireless Networking
  • Transmission Media
  • Sensors use wireless medium
  • Suffer from the same problems that wireless
    networks suffer from
  • Fading
  • High error rate

Challenges and Constraints
  • Wireless Networking
  • Communication range
  • Communication ranges are always short
  • It is required for the network to be highly
  • Routing paths will be long
  • What about critical applications where delay is
    not acceptable
  • QoS will be an issue

Challenges and Constraints
  • Wireless Networking
  • Sensing Range
  • Very small
  • Nodes might be close to each other
  • Data Redundancy

Challenges and Constraints
  • Decentralized Management
  • Requires Distributed Algorithms
  • Overhead might be imposed
  • Security
  • Exposed to malicious intrusions and attacks due
    to unattendance characteristics.
  • denial-of-service
  • jamming attack

In Network Processing
Enable Data Base Like Operations
Network Characteristics
  • Dense Node Deployment
  • Battery-Powered Sensors
  • Sever Energy , Computation , and Storage
  • Self Configurable
  • Application Specific
  • Unreliable Sensor Nodes
  • Frequent Topology Change
  • No Global Identifications
  • Many-to-One Traffic pattern ( multiple sources
    to a single Sink node)
  • Data Redundancy

Design Issues
  • Fault Tolerance
  • Large number of nodes already deployed or
  • Nodes do the same job. If one fails , the network
    still working because its neighbor monitors the
    same phenomenon .
  • Mobility
  • Helps nodes to reorganize themselves in case of a
    failure of any of the nodes
  • Attribute-Based Addressing
  • Addresses are composed of group of
    attribute-value pairs
  • Ex. lt temp gt 35, location area Agt

Design issues
  • Location Awareness
  • Nodes data reporting is associated with location
  • Priority Based Reporting
  • Nodes should adapt to the drastic changes in the
  • Query Handling
  • The sink node / user should be able to query the
  • The response should be routed to the originator
  • We might have multiple sinks in the network

Traditional networks Vs. wireless sensor networks
Technological Background MEMS Technology
  • Micro-Electro-Mechanical Systems
  • (MEMS) is a core technology that
  • Leverages IC fabrication technology
  • Builds ultra-miniaturized components
  • Enables radical new system applications

Advantages of MEMS
Pressure Sensor Belt on Jet Planes
Hardware Platforms
  • Augmented General Purpose PCs
  • Embedded PCs (PC104), PDAs, etc..
  • Usually have O.S like Linux and wireless device
    such as Bluetooth.
  • Dedicated Sensor Nodes
  • Commercially off the shelf components (e.g.
    Berkeley Motes)
  • System-on-chip Sensor
  • Platform like Smart dust, BWRC PicoNode

Software Platforms
  • Operating Systems and Language Platforms
  • Typical Platforms are
  • TinyOS, nesC, TinyGALS, and Mote
  • TinyOS
  • Event Driven O.S.
  • Requires 178 bytes of memory
  • Supports Multitasking and code Modularity
  • Has no file system only static memory
  • Simple task scheduler
  • nesC extension of C language for TinyOS- set of
    language constructs
  • TinyGALS - language for TinyOS for event
    triggered concurrent execution .
  • Mote - Virtual machine for Berkeley Mote

Wireless Sensor Network Standards
  • IEEE 802.15.4 Standard
  • Specifies the physical and MAC Layers for
    low-rate WPANs
  • Data rates of 250 kbps, 40 kbps, and 20 kbps.
  • Two addressing modes 16 - bit short and 64 -
    bit IEEE addressing.
  • Support for critical latency devices, for
    example, joysticks.
  • The CSMA - CA channel access.
  • Automatic network establishment by the
  • Fully handshaking protocol for transfer
  • Power management to ensure low - power
  • Some 16 channels in the 2.4 - GHz ISM band, 10
    channels in the 915 MHz band, and 1 channel in
    the 868 - MHz band.

Wireless Sensor Network Standards
  • IEEE 802.15.4 Standard
  • The physical layer is compatible with current
    wireless standards such as Bluetooth
  • MAC layer implements synchronization , time slot
    management , and basic security mechanisms.

Wireless Sensor Network Standards IEEE 802.15.4
ZigBee In Context
  • the software
  • Network, Security Application layers
  • Brand management
  • IEEE 802.15.4
  • the hardware
  • Physical Media Access Control layers

Security 32- / 64- / 128-bit encryption
ZigBee Alliance
Network Star / Mesh / Cluster-Tree
IEEE 802.15.4
PHY 868MHz / 915MHz / 2.4GHz
ZigBee Utilization
Applications Example
Project ExScal Concept of operation
Put tripwires anywherein deserts, other areas
where physical terrain does not constrain troop
or vehicle movementto detect, classify track
intruders Computer Networks 2004,
ALineInTheSand webpage, ExScal webpage
ExScal scenarios
  • Border Monitoring
  • Detect movement where none should exist ,
  • Decide target classes, e.g., foot traffic to
  • Ideal when combined with towers, tethered
    balloons, or UAVs

WSN Research Fields
  • Sensors HW and Software
  • Deployment
  • Physical , MAC, Routing, Applications
  • Data Aggregation and Data Mining
  • Artificial Intelligence and data handling
  • Self Healing
  • Web Integration
  • Heterogeneity
  • Security
  • Software Engineering (Simulators )
  • Cloud Computing and Sensor Networks
  • Mobility Issues and Localization

Assignment 1 (adopted from Ted Herman)
  • Your assignment is to read one sensor network
    application, as reported in a published paper.
    Surf the web to find material complementary to my
  • Prepare a presentation for only 15 minutes use
    the model of this power point presentation
  • Before next class, you'll need to email me your
  • Your presentation will let other students know
    about some sensor network application, so they
    have an overview without having to read the paper
    in as much detail as you did.
  • To prepare the presentation, you likely neednt
    master all the details of the paper. Often,
    though, it can help to find backup technical
    reports and presentations by the researchers, to
    help you prepare. Overall, you should spend about
    four to six hours on this task.
  • Your presentation will be posted on the website
    to be read by others and it is part of our class
    . Be ready for some questions from your
    classmates or from the instructor

References for Applications Assignment
  1. Hospital Epidemiology Wireless Applications for
    Hospital Epidemiology ref
  2. Nericell Rich Monitoring of Road and Traffic
    Conditions using Mobile Smartphones ref
  3. Participatory sensing in commerce Using mobile
    camera phones to rack market price dispersion
  4. The BikeNet Mobile Sensing System for Cyclist
    Experience Mapping ref
  5. Model-Based Monitoring for Early Warning Flood
    Detection ref
  6. NAWMS Nonintrusive Autonomous Water Monitoring
    System ref
  7. Luster Wireless Sensor Network for Environmental
    Research ref
  8. Hybrid sensor network for cane-toad monitoring
  9. SensorFlock An Airborne Wireless Sensor Network
    of Micro-Air Vehicles ref
  10. Identification of Low-Level Point Radiation
    Sources Using a Sensor Network ref

References for Applications Assignment
  1. Mobile Sensor/Actuator Network for Autonomous
    Animal Control ref
  2. Detecting Walking Gait Impairment with an
    Ear-worn Sensor ref
  3. Textiles Digital Sensors for Detecting Breathing
    Frequency ref
  4. Recognizing Soldier Activities in the Field ref
  5. Physical Activity Monitoring for Assisted Living
    at Home ref
  6. PipeNet Wireless sensor network for pipeline
    monitoring ref
  7. Turtles At Risk ref
  8. Cyclists' cellphones help monitor air pollution
  9. Clinical monitoring using sensor network
    technology ref
  10. CargoNet low-cost micropower sensor node
    exploiting quasi-passive wakeup for adaptive
    asychronous monitoring of exceptional events
  11. Monitoring persons with parkinson's disease with
    application to a wireless wearable sensor system

References for Applications Assignment
  1. Expressive footwear, shoe-integrated wireless
    sensor network ref
  2. BriMon a sensor network system for railway
    bridge monitoring ref
  3. Monitoring Heritage Buildings ref
  4. PermaDAQ gathering real-time environmental data
    for high-mountain permafrost ref
  5. Firewxnet a multi-tiered portable wireless for
    monitoring weather conditions in wildland fire
    environments ref
  6. Development of an in-vivo active pressure
    monitoring system ref
  7. Personal assistive system for neuropathy ref
  8. Smart jacket design for neonatal monitoring with
    wearable sensors ref

References for Applications Assignment
  • Condition Monitoring in Intel Hillsboro
    Fabrication Plant
  • or BPs Loch Rannoch Oil Tanker ref
  • Other BP applications (safety, corrosion
    detection, empty propane tanks)
  • Volcano Monitoring
  • Seismic Monitoring
  • Landslide Detection
  • Water Distribution Monitoring and Control
    (agricultural and sewer)
  • Water Quality
  • Water Sense
  • Lake (Aquatic organism) Monitoring
  • Cane Toad Monitoring
  • Neptune Ocean Observatory ref
  • Atmospheric Observatory ref
  • Neon (scope and canonical experiments)

References for Applications Assignment
  1. SensorScope
  2. SenseWeb
  3. CarTel ref
  4. Odor Source Localization
  5. CodeBlue (Health care)
  6. Activity Recognition ref
  7. Assisted Living ref
  8. Wearable wireless body area networks (Health
  9. Adaptive house
  10. PlaceLab and House_n projects
  11. Participatory Sensing
  12. Responsive Environments (Uberbadge)
  13. Lovers cup context aware

References for Applications Assignment
  • SensorWebs in the Wild
  • Dynamic Virtual Fences for Controlling Cows
  • Hardware design experiences in ZebraNet
  • Energy-Efficient Computing for Wildlife Tracking
    Design Tradeoffs and Early Experiences
    with ZebraNet (see also additional background
    Zebranet Web Site)
  • Sensor/actuator networks in an agricultural
    application (you'll need to search for more on
    this topic)
  • http//
  • Smart-Tag Based Data Dissemination
  • Sensor network-based countersniper system
  • A large scale habitat monitoring application
  • Wireless Sensor Networks for Habitat Monitoring.
  • Habitat Monitoring Application Driver for
    Wireless Communications Technology.
  • Preprocessing in a Tiered Sensor Network for
    Habitat Monitoring

References for Applications Assignment
  • Dynamic Networking and Smart Sensing Enable
    Next-Generation Landmines
  • Flock Control
  • Adaptive Sampling Algorithms for Multiple
    Autonomous Underwater Vehicles, Proceedings IEEE
    Autonomous Underwater Vehicles Workshop
    Proceedings, Sebasco, ME, June, 2004
  • Sensor Web for In Situ Exploration of Gaseous
  • Active visitor guidance system (follow the single
    reference, using Google, to find more)
  • Two-Tiered Wireless Sensor Network Architecture
    for Structural Health Monitoring
  • Sensor-actuator network for damage detection in
    civil structures
  • Meteorology and Hydrology in Yosemite National
    Park A Sensor Network Application.
  • A Survey of Research on Context-Aware Homes.
  • The Aware Home A Living Laboratory for
    Ubiquitous Computing Research
  • Using Pervasive Computing to Deliver Elder Care
  • Workplace Applications of Sensor Networks
  • Cougar Project at Cornell (student projects,
    which have some slides about a demo)
  • Contaminant Transport Monitoring
  • Marine Microorganisms   (Adaptive Sampling for
    Marine Microorganism Monitoring)
  • A Support Infrastructure for the Smart
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