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Location-based Services (Applications (Infotainment services (Driving…

- - - - Relative: St. Kilda is 3km south of Melbourne
      - Symbolic: home, work, bedroom
      - Absolute: exact position e.g. address or GPS coordinates
  - - - Device computes its own location
      - E.g. GPS
      - Preserves location privacy of the device
    - - Network infrastructure calculates position of device
      - Client does not need power, just an RFID card
    - - Both device + network infrastructure participate in computing location
      - A-GPS: device communciates with cell towers
- - - - Time of flight
        
        Time to ping a reference point / 2
        
        Requires clock synchronisation between reference points
      - Signal strength attenuation
        
        Subject to complex interactions with physical environment
        
        Strong = near; weak = far (signal-to-noise ratio)
  - - - Needs directional antenna / antenna array => routers have multiple antenna so that there are ANGLES
      - Typically measured at reference points, not the device
  - - - Temporal stability
      - Spatial variability
    - - Spatial resolution
      - Positioning accuracy
- - - - Provide mobile access to library DB
      - Assist library users in finding books by themselves