- In GSM network, all cells in the world have a
global uniqueID made up of four numbers. Cell Id, LAC, MNC and MCC
- Database are being created that map cell IDs
into locations(with post code level accuracy)
- Cells can be manually mapped to semantic
locations (e.g. University, Home, Work etc.)
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| Usage of Cell ID |
- Determine when someone is/was at a given place (e.g. home)
- Distinguish between walking/driving/stationary
- Provide reasonably accurate positioning
- accurately determine a position within
163m 95% of the time
- Determine when people are moving between
locations
- Database such as ZoneTag and Place Lab
can map Cell to physical locations
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- 30 satellites in Earths orbit
- 6 satellites always in line of site of any place
on earth
- Receivers must find 4 or more satellites for a fix
- First fix usually in 1.5 minutes
- Typical phone battery can last about 4 hours
with GPS on
- Position is accurate within 10 metres with altitude
- On average, people are in GPS coverage 4.5% of the day
- Some Phones have built in GPS
- All Motorola phones on the iDEN (Nextel) network
- Some GSM phones (A780, V9)
- Many CDMA (USA) phones (e.g. RAZR on Verizon)
- Phones without GPS can use an external GPS unit and connect to it via Bluetooth (JSR 82)
- send a NMEA stream to the phone
- phone can listen through a BT serial connection
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