GPS Auto-Sleep for Energy-Efficient Location Tracking

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GPS Auto-Sleep for Energy-Efficient Location
Tracking

• Sean Barbeau, Phil Winters, Nevine Georggi
• Center for Urban Transportation Research
• Rafael Perez, Miguel Labrador
• Department of Computer Science Engineering

Portions of work funded by the Florida Department
of Transportation and the National Center for
Transit Research
Protected under US Patent 8,036,679
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Problem

• Past vehicle-based GPS tracking give
  low-resolution view of daily travel behavior
• Are these GPS fixes
• Points-of-interest?
• Stops in traffic?
• Difficult to extract info
• Distance traveled
• Origin-Destination pairs
• Misses non-vehicle trips

Protected under US Patent 8,036,679
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Innovation

• Our research team created TRAC-IT, a GPS-enabled
  mobile phone app
• TRAC-IT can capture high-definition view of
  travel behavior
• Much easier to determine
• Path, distance traveled
• Origin-Destination pairs
• Avg. speeds
• Can capture transit/bike/walk trips

Protected under US Patent 8,036,679
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New Problem

• We can record GPS fixes as frequently as once per
  second and send to our server
• However, frequent GPS fixes come at great cost
  to
• battery energy
• data transfer over network
• Both battery life and cell network data transfer
  are very limited resources

Protected under US Patent 8,036,679
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One-day Requirement
Sprint CDMA EV-DO Rev. A network
Sprint CDMA EV-DO Rev. A network
Protected under US Patent 8,036,679
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New Idea

• What if we could dynamically change the GPS
  sampling interval on the phone?
• Use four second sampling interval when moving
• Use five minute interval when stopped
• Challenges
• Can we create mobile apps that do this?
• Would this be enough to make a difference in
  battery life?
• How do we handle GPS noise when trying to detect
  movement?

Protected under US Patent 8,036,679
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GPS Data Noise Causes Uncertainty in Movement
HTC Hero Sprint EV-DO Rev A network
29.7 meters
Protected under US Patent 8,036,679
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Detecting User Movement
4 second GPS sampling
5 minute GPS sampling

• GPS noise causes uncertainty in states
• Many false transitions waste battery energy

Protected under US Patent 8,036,679
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Detecting User Movement
4 second GPS sampling
5 minute GPS sampling

• What if we represent this binary, or two-state,
  problem more like a continuum?

Protected under US Patent 8,036,679
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New invention GPS Auto-Sleep
ASLEEP
AWAKE

• Gradually change GPS interval from awake to
  asleep based on certainty in users movement
• With some data (e.g., very high speeds) snap back
  to awake

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Protected under US Patent 8,036,679
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Sanyo Pro 200
Sprint CDMA EV-DO Rev. A network
Protected under US Patent 8,036,679
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Asleep
Sanyo Pro 200
Sprint CDMA EV-DO Rev. A network
Awake
Protected under US Patent 8,036,679
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Evaluation Summary of 30 tests

• n 30

Protected under US Patent 8,036,679
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Evaluation Daily Tracking
Impact of GPS Auto-Sleep on Battery Life
Sanyo Pro 200
Sprint CDMA EV-DO Rev. A network
Protected under US Patent 8,036,679
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Potential Data Savings GPS Auto-Sleep
  With GPS Auto-Sleep Without GPS Auto-Sleep
Assisted GPS Fixes Over 13 hrs 1,035 (0.1 MB) 11,700 (1.4 MB)

• Assuming each GPS fix is transmitted to server,
  GPS Auto-Sleep saves 1.3MB in data transfer PER
  PHONE in 13 hours
• Sleep time of 120 seconds between GPS fixes
  while user is not moving,
• and 4 seconds between GPS fixes while user is
  moving

Protected under US Patent 8,036,679
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Patent issued on Oct. 11, 2011

• US Patent 8,036,679
• Optimizing Performance of Location-Aware
  Applications using State Machines

Protected under US Patent 8,036,679
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Utility Commercialization

• We have been tracking high-def travel behavior of
  over 30 participants over 9 months
• Using TRAC-IT mobile app w/ GPS Auto-Sleep
• USDOT-funded Value Pricing project
• DAJUTA, a Florida-based company, has
  non-exclusively licensed the technology from USF
• Other companies are also expressing interest
• GPS Auto-Sleep is one module in Location-Aware
  Information Systems Client (LAISYC) framework
• 15 patents pending on other modules

Protected under US Patent 8,036,679
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Thank you

• Questions?
• Sean Barbeau, M.S.
• Research Associate
• barbeau_at_cutr.usf.edu
• [phone]
• locationaware.usf.edu

Protected under US Patent 8,036,679