What does the Future hold for Wireless Sensor Networks? - PowerPoint PPT Presentation

What does the Future hold for Wireless Sensor Networks?

Loren Schwiebert

Wayne State University

Department of Computer Science

loren@wayne.edu

http://www.cs.wayne.edu/~loren

• Moore’s Law is making sufficient CPU performance available with low power requirements in a small size.
• Research in Materials Science has resulted in novel sensing materials for many Chemical, Biological, and Physical sensing tasks.
• Transceivers for wireless devices are becoming smaller, less expensive, and less power hungry.
• Power source improvements in batteries, as well as passive power sources such as solar or vibration energy, are expanding application options.

Current State of the Artin Wireless Sensors

• A sensor node has:
• Sensing Material
• Physical – Magnetic, Light, Sound
• Chemical – CO, Chemical Weapons
• Biological – Bacteria, Viruses, Proteins
• Integrated Circuitry (VLSI)
• A-to-D converter from sensor to circuitry
• Packaging for environmental safety
• Power Supply
• Passive – Solar, Vibration
• Active – Battery power, RF Inductance

Consider Multiple Generations of Berkeley Motes

Consider a 40 Year Old Computer

• Is the effort on wireless sensor protocols a waste of time??
• Can we just wait 10-15 years until we have sensors that are very powerful??

• NO!! Will still face:
• Very limited storage
• Modest power supplies

Proposed Applications of Wireless Sensors

• Sensors controlling appliances and electrical devices in the house.
• Better lighting and heating in office buildings.
• The Pentagon building has used sensors extensively.

• Health Monitors
• Glucose
• Heart rate
• Cancer detection
• Chronic Diseases
• Artificial retina
• Cochlear implants
• Hospital Sensors
• Monitor vital signs
• Record anomalies

Remote deployment of sensors for tactical monitoring of enemy troop movements.

• Numerous industrial and commercial applications:
• Agricultural Crop Conditions
• Inventory Tracking
• In-Process Parts Tracking
• Automated Problem Reporting
• RFID – Theft Deterrent and Customer Tracing
• Plant Equipment Maintenance Monitoring

• Future cars could use wireless sensors to:
• Handle Accidents
• Handle Thefts

• Sensors embedded in the roads to:
• Monitor traffic flows
• Provide real-time route updates

Driving Forces for AdoptingNew Technology

• New technologies replace existing technologies or fill new niches when there are economic advantages.
• Wireless sensors will replace wired sensors
• No wiring – lower costs
• More flexible deployments
• Wireless sensors will provide new services
• Provide cost advantages or lower overhead
• Improve product quality or product features

• Some early adopters use new technology simply for novelty or the fun of it. Examples include:
• Java rings and internet watches.
• Maybe wireless sensors for dating or meeting new people?
• Personal wireless sensors for fun – a temperature monitor you carry around?

• New technologies are adopted because of government mandates:
• Air bags in automobiles
• Child safety seats
• Companies employ new technologies to avoid being sued!!
• Temperature sensors to detect coffee that is too hot??

• New technology is adopted for entertainment.
• Playing games is major use of home PCs.
• So is Internet browsing.
• Games on cellular phones.
• 3D visualization for … games.
• Games of tag using wireless sensors?
• Interactive role-playing games with sensors?

• Useful technologies may not dominate the marketplace for several reasons.
• Delay in getting to market.
• Lack of standardization.
• Limited applications.
• Consumer preference – VHS vs. Betamax.
• Weaker marketing or capitalization.
• Unusual that there are no alternative technologies that can be used.

Uses of New Technology

• Useful applications often follow available technology. For example,
• PCs were available and people looked for a killer app – Visicalc.
• The Internet was not created with these current applications in mind:
• World Wide Web
• E-Commerce
• Peer-to-Peer Digital Music Sharing

• Once technology is available, creativity leads to new applications:
• Sims Internet world
• E-Bay auctions
• Mirror for the Palm Pilot
• Digital cameras with PC interface
• What surprising applications for wireless sensor networks?
• Depends on sensor technology/form factor

Some Technical Challenges

Sensor readings can be inaccurate. Protocols need to recognize this.

GPS Sensor

Accurate within

2.8 meters

Relative Humidity Sensor

Accuracy of ±5%

±8% at 90% Relative Humidity

±2% with calibration

• Limitations of wireless channels
• Noisy
• Interference
• Link Contention
• Unidirectional Links
• But inherently a broadcast medium

• Wireless sensors need to operate in conditions that are not encountered by typical computing devices:
• Rain, sleet, snow, hail, etc.
• Wide temperature variations
• May require separating sensor from electronics
• High humidity
• Saline or other corrosive substances
• High wind speeds

What will Wireless Sensor Networks Look Like in the Near Future?

• Sensor networks will grow in size because of:
• Lower cost
• Better protocols
• Advantages of dense networks

• Homogeneous network of sensors has been the typical assumption, but not the future!!
• Combining sensors with different functions
• Hierarchy of sensors – a few expensive powerful sensors with more cheap sensors
• Useful for special communication nodes
• A few sensor nodes with expensive sensors, such as GPS-equipped sensors

Sensors with Micromachines

Low-Power Motors that Support Mobility

• Single-purpose network is the typical assumption, but not the future!!
• Sensors for evolving applications
• Sensors that can adapt to changing objectives
• More memory and CPU will allow more complex applications
• Flexibility increases marketability

• Sensors will be deployed for specific applications, but
• These deployments will overlap physically
• Sensors will have different properties
• Users will want to combine these different sensors for new applications:
• Temperature sensors for HVAC control
• Location tracking of employees
• Combine these for fire rescue operations

• Wireless sensors will become a seamlesspart of larger networks!
• Combiningwired sensors with wireless sensors
• Wired sensors can have more power
• Wired sensors can run TCP/IP
• Accessing wireless sensors through the Internet
• Need a gateway to translate requests
• Uploading/downloading information remotely
• Modifying wireless sensor tasks remotely
• Increased direct user interaction

Some Impediments toCreating Future Applications

• Automated interaction between sensors implies some standard mechanism for communication!
• Requires compatible wireless technology
• Standardization a common theme
• TCP/IP for the Internet
• Java for Internet programming
• Jini, SLP, etc. for 802.11 wireless devices
• Need a service discovery protocol
• Enables standard interface among sensors above the physical layer

Anyone need

a printer?

"Dear Mom...I'm sitting..."

• For a wireless sensor network, service discovery provides:
• Automated calibration of new devices
• Highly dynamic system configurations
• Cooperation among resource poor devices
• Resource sharing device solutions
• Storage and long-range networking services can be obtained from a nearby server
• Less duplication of functionality
• Supports novel interactions in the future

• Concerns about misuse and privacy
• Privacy issues may slow consumer adoption of technology
• User tracking – RFID concerns
• Has not proved true on the Internet!
• Authentication and privacy are not always complementary objectives
• Do not want your medical sensor hacked!!
• Data tampering and computer viruses could be a nightmare!

• Companies may adopt wireless sensors to reduce liability, but wireless sensors could also increase liability:
• Use in critical applications could be limited
• Imagine a medical sensor fails!!
• Or an automotive theft deterrent system failure
• Companies will be slow to adopt technology that increases their legal exposure
• May delay adoption

• Imagine a heterogeneous wireless sensor network with complex tasks and high levels of interaction…
• End-user level products – easy to use
• Software design??
• Debugging??
• Remote software updates??
• Example: Send a request over the Internet to turn on lights when your car reaches home. The request fails.

• Wireless sensor networks have abright future
• Many applications have been proposed
• Potential to revolutionize human-computer interactions
• Availability of sensors will lead to new and exciting applications
• A lot of research remains to be done
• Wireless sensors will not evolve into traditional computers
• Many obstacles to overcome
• Allow realism to guide research efforts

THANK YOU

Research collaborators (and for slides):

• Professor Gregory Auner
• Professor Sandeep K. S. Gupta
• Professor Golden G. Richard III
• Manish Kochhal

Technical Assistance: Joel Schwiebert