MSA - Mobile Student Assistant

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  • Letizia Tanca (Full Professor) [1]
  • Giorgio Orsi (Ph.D Student) [2]
  • Dang Nhon Tuan (Author,Student)[3]

In this project, I focus on locationing using GPS


Geographic Coordinate System:

Geographic coordinates are given using the World Geodetic System (WGS 84) datum. Geographic coordinate system is also currently used as a reference system by the Global Positioning System (GPS). The coordinates are constructed from latitude, longitude, and altitude values. (In this case, altitude is the elevation above the sea level.) In Figure 1, the horizontal lines measure latitude. These lines represent the north-south position between the poles. The North Pole is 90 degrees North (+90 degrees) and the South Pole is 90 degrees South (-90 degrees). The largest circle is called the Equator and is defined as 0 degrees. Locations above the Equator have positive latitudes (0 to +90 degrees) and locations below the Equator have negative ones (0 to -90 degrees).


Figure 1: Geographic coordinate system

The lines drawn from north to south in Figure 2.3 are meridians, which are constant longitudinal values. There is no natural starting position for longitude, which is why a reference meridian had to be chosen. Traditionally the Prime Meridian is the meridian that passes through the Greenwich Observatory (located in Greenwich, England). The value of the Prime Meridian (Greenwich Meridian) is 0 degrees. WGS84, which the Location API uses, defines its zero meridian about 100 meters east of the traditional one. Locations east of the prime meridian have positive longitudinal values (0 to +180 degrees). Locations west of the prime meridian have negative longitudinal values (0 to -180 degrees).

      From Location API Developer's Guide in Nokia Forum

The positioning of a device:

Devices may not necessarily need a built-in location-providing method. For example, devices implementing the Location API may require an accessory that implements a location method. Such an accessory may be a GPS receiver with a Bluetooth connection or a GPS receiver in a functional cover. The accuracy of the location information depends on the location-providing method. Some devices may support a hybrid approach called assisted-GPS (A-GPS), in which GPS and the network are used to provide the location. In general, location data from GPS receivers is more accurate than network-based data. Figure 2 demonstrates Location API MIDlet model that uses satellites for positioning of a device.


Figure 2: Location API MIDlet model

GPS information:

By using JSR-179 Location API, I am able to receive data:


Figure 3: Location data received by GPS antenna on mobile phone

Intergrate Locationing to MSA:

Dimension Tree is used for mainly two activities: giving access to the nodes (both random access via getByName and root access via getRoot) and providing a convinient way to connect to the server via the ServerConnector object since it exports a low level description of the query to the server.

To identify if student is in a Politecnico di Milano or not, I need to measure:

1) GPS information of that campus


Figure 4: GPS information of Leonardo campus

2) GPS information of student's mobile devices

Locationing on campus:

Besides Intergrate Locationing to MSA, I independently developed another application called LocationMSA, which is provided in the same package. With this application, new student can know where he is on the campus. This application is useful to new student who is not familiar to campus map.


Figure 5: The Star "*" in green shows Student location in Leonardo campus