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
What does the Future hold for Wireless Sensor Networks?
2
Why Wireless Sensors Now?
 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 Art
in Wireless Sensors
What does the Future hold for Wireless Sensor Networks?
Typical Sensor Node Features
 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
4
5
What does the Future hold for Wireless Sensor Networks?
Advances in Wireless Sensor Nodes
Consider Multiple Generations of Berkeley Motes
Model
Rene
Mica
Mica-2
Mica-Z
Date
1999
2002
2003
2004
CPU
4 MHz
4 MHz
4 MHz
4 MHz
Flash
Memory
8 KB
128 KB 128 KB
128 KB
RAM
512 B
Radio
4 KB
4 KB
4 KB
10 Kbps 40 Kbps 76 Kbps 250 Kbps
6
What does the Future hold for Wireless Sensor Networks?
Historical Comparison
Consider a 40 Year Old Computer
Model
Honeywell H-300
Mica 2
Date
6/1964
7/2003
CPU
2 MHz
4 MHz
Flash
Memory
None
128 KB
RAM
32 KB
4 KB
What does the Future hold for Wireless Sensor Networks?
7
A Rosy Future for Wireless Sensors?
 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
What does the Future hold for Wireless Sensor Networks?
9
Smart Home / Smart Office
 Sensors controlling
appliances and
electrical devices in
the house.
 Better lighting and
heating in office
buildings.
 The Pentagon
building has used
sensors extensively.
What does the Future hold for Wireless Sensor Networks?
Biomedical / Medical
 Health Monitors
– Glucose
– Heart rate
– Cancer detection
 Chronic Diseases
– Artificial retina
– Cochlear implants
 Hospital Sensors
– Monitor vital signs
– Record anomalies
10
What does the Future hold for Wireless Sensor Networks?
11
Military
Remote deployment of
sensors for tactical monitoring
of enemy troop movements.
What does the Future hold for Wireless Sensor Networks?
Industrial & Commercial
 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
12
What does the Future hold for Wireless Sensor Networks?
13
Traffic Management & 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 Adopting
New Technology
What does the Future hold for Wireless Sensor Networks?
15
Economic Factors
 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
What does the Future hold for Wireless Sensor Networks?
16
Novelty
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?
What does the Future hold for Wireless Sensor Networks?
17
Legal / Liability
 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??
What does the Future hold for Wireless Sensor Networks?
Entertainment
 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?
18
What does the Future hold for Wireless Sensor Networks?
19
Not Technical Superiority
 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
What does the Future hold for Wireless Sensor Networks?
21
Unexpected Killer Applications
 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
What does the Future hold for Wireless Sensor Networks?
22
Unanticipated Uses Arise
 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
What does the Future hold for Wireless Sensor Networks?
24
Noisy Sensors
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
What does the Future hold for Wireless Sensor Networks?
Wireless Channel Conditions
 Limitations of wireless channels
– Noisy
– Interference
– Link Contention
– Unidirectional Links
 But inherently a broadcast medium
25
What does the Future hold for Wireless Sensor Networks?
26
Environmental Factors
 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?
28
What does the Future hold for Wireless Sensor Networks?
Large-Scale Deployments
 Sensor networks
will grow in size
because of:
– Lower cost
– Better protocols
– Advantages of
dense networks
Sensing Zone with sensor-coordinator,
sensing-collaborators, and backbone nod
What does the Future hold for Wireless Sensor Networks?
29
Heterogeneous Sensors
 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
What does the Future hold for Wireless Sensor Networks?
Mobile Sensors
Sensors with Micromachines
Low-Power Motors that Support Mobility
30
What does the Future hold for Wireless Sensor Networks?
General Purpose Sensors
 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
31
What does the Future hold for Wireless Sensor Networks?
Overlapping Coverage Areas
 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
32
What does the Future hold for Wireless Sensor Networks?
Mixture of Wired and Wireless
 Wireless sensors will become a
seamless part of larger networks!
– Combining wired 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
33
Some Impediments to
Creating Future
Applications
What does the Future hold for Wireless Sensor Networks?
Need a Standardized Interface
 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
35
36
What does the Future hold for Wireless Sensor Networks?
Service Discovery Protocol
Anyone need
a printer?
What does the Future hold for Wireless Sensor Networks?
37
Service Discovery Protocol (cont.)
 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
What does the Future hold for Wireless Sensor Networks?
Security Issues
 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!
38
What does the Future hold for Wireless Sensor Networks?
39
Liability and Safety Concerns
 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
What does the Future hold for Wireless Sensor Networks?
40
Software Engineering
 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.
What does the Future hold for Wireless Sensor Networks?
41
Summary and Conclusions
 Wireless sensor networks have a bright 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
What does the Future hold for Wireless Sensor Networks?
Acknowledgments
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
42