Resources
Books
Creating Location Services for the Wireless Web - Johan Hjelm
Mobile Location Based Services: Professional Developer Guide - Andrew Jagoe
Location-Based Services - Jochen Schiller (Editor), Agnes Voisard
Internet
Location based services
Types of LBS
User requested services
Triggered
Proximity
Positioning technologies
Inrared
Sound
Active Floor
GPS (Global Positioning Sytem)
Operated by United States military. Opened for civilian use.
Is based on at least 24 satellites and 5 monitoring stations.
First satellite launched 1978 ,50 satellites launched since then.
The cost of maintaining the system is approximately US$400 million per year, including the replacement of aging satellites.
Satellites use Intermediate Circular Orbit (ICO)
Ground stations measure and relay adminitrative data to satellites
Cellular technologies based locating
Cell based locating
In cell
In several cells
Arrival on cell
Parting from cell
Signals based methods
Time of Arrival (TOA)
Enhanced observed time difference (E-OTD)
Time difference of arrival (TDOA)
Angle of Arrival (AoA)
Several new methods under research
Choosing positioning technology
Location based service has to know the user position, in order to provide service.
How accurate the position has to be?
Continent, Country, City?
Kilometers, 100 meters, 10 meters, meters, centimeters?
Level 2 Headline
Positioning data transmission
APIs to MPC
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Defined by Location Interoperability Forum (LIF)
Founded 2000
Mobile Location Protocol
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Independent of the underlying network technology
HTTP is used for transmission
1. Immediate Query Service
2. Deferred Query Service
3. Location Attachment Service
e.g. Parlay
API for GSM intelligent networks.
Geographic data
GIS (geographical information system)
“A geographic information system (GIS) is a specialized form of an information system. In
the strictest sense, it is a computer system capable of assembling, storing, manipulating,
and displaying geographically-referenced information in a relational database, i.e. data
identified according to their locations. Practitioners also regard the total GIS as including
operating personnel and the data that go into the system.” -wikipedia
Legal issues
The location data can intrude privacy
What does my location tell about my behaviour?
Can my movements be used for blackmailing?
The laws in different countries vary on the status of location data
User consent on the use of data
Providing user location to third party?
Other way around: Enhanced 911