eladio martin - presentation at emerging communications conference & awards (ecomm 2011)
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eComm 2011, San Francisco
Alternatives to GPS for Localization Leveraging
Smart Phones.
June 29th 2011 Slide 2 of 16
Location Applications
Monitoring
Tracking
Assisted Living
Targeted advertising
Social Networking
10% of all the iPhone applications employ location information
A quarter of all USA wireless phone users have utilized LBS
Slide 3 of 16
Satellite Navigation Systems
USA: GPS European Union: Galileo (2014)
– € 5.3 billion Russia: GLONNAS (2011)
– Most expensive project in Russian Federal Space Agency China: Compass (2020)
Other regional satellite-based systems:
France: Doris
India: IRNSS (2014)
Japan: QZSS (2013)
Slide 4 of 16
GPS Accuracy ~ 6 meters
GPS errors’ sources:
• Ionospheric effects (±5meters),
• Shifts in the satellite orbits (±2.5 meters),
• Satellite clock errors (±2 meters),
• Multipath effects (±1 meters),
• Tropospheric effects (±0.5 meters),
• Calculation and rounding errors (±1 meters)
Slide 5 of 16
Main Drawbacks of Satellite Systems
Power
Coverage
Slide 6 of 16
Satellite Navigation Systems
USA: GPS European Union: Galileo (2014)
– € 5.3 billion Russia: GLONNAS (2011)
– Most expensive project in Russian Federal Space Agency China: Compass (2020)
Other regional satellite-based systems:
France: Doris
India: IRNSS (2014)
Japan: QZSS (2013)
Slide 7 of 16
Alternatives to GPS
High Sensitivity GPS
• Advanced signal processing techniques.
- Low accuracy
Inertial Navigation Units (acc + gyro)
- Very expensive.
Radio Fingerprinting
Slide 8 of 16
WiFi Fingerprinting in the iPhone
Slide 9 of 40
Outdoor WiFi Fingerprinting in Smart Phones
Accuracy depends on density of Access Points
• Typical error: 50 meters.
Example: WiFi-based Localization by Google
Slide 10 of 16
Radio Fingerprinting
Slide 11 of 40
Cellular Fingerprinting
- Existing systems need Dedicated Hardware
- Smart Phones:
- Granularity is poor and Hardware dependent
- Slow refreshing rate
- Only RSSI information from the same SIM card operator
Slide 12 of 16
Fingerprinting with other Technologies
- Bluetooth
• Accuracy of up to 1.2 meters
- Dedicated Hardware
- Conventional Radio
- Dedicated Hardware
- Low accuracy (urban suburb)
- Digital TV
- Dedicated Hardware
- Zigbee
- Dedicated HardwareSlide 13 of 16
State-of-Art in WiFi Fingerprinting
- Radar, by Microsoft
• Accuracy 2 – 3 meters
- Dedicated Hardware
- Ekahau
• Accuracy 1 – 3 meters
- Dedicated Hardware
Slide 14 of 16
Improvements that Smart Phones can bring to Fingerprinting
Integrate both the online and offline phases in
fingerprinting
• Avoid errors due to differences in antenna characteristics and
measurement schemes between different equipments
• e.g. 10 dB between Dell Latitude laptop and Motorola Droid phone
Leverage accelerometer (gravity vector) and
magnetometer (orientation)
• Orientation of phone helps enhance the localization accuracy
Slide 15 of 16
WiFi Fingerprinting with Smart Phones
Slide 16 of 40
Stride Length Estimation with Wavelet
Slide 17 of 40
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