Location Based Services
By definition a mobile user may be in a variety of different locations while accessing applications and data from a mobile device. In a number of situations knowing that location may add additional value to the application being used. It may also be useful for someone else to know the current position of the mobile device. Two main technologies have evolved to meet these requirements and supply information on the location of a mobile device. This information can then be integrated within applications on the mobile device, or used by applications monitoring the position of the mobile device. These capabilities and the applications using them are termed Location Based Services or LBS.
GPS
GPS, or Global Positioning Service, is a capability provided by a series of geo-stationary satellites in orbit around the Earth. Each Satellite emits a radio signal which can be detected by an electronic receiver which has line of site to the satellite. Typically a receiver may be in line of site of a number of satellites and it only requires 3 separate signals to be detected in order to determine the location of the receiver to approximately 10cm anywhere on the globe. Therefore by combining a GPS receiver with a mobile application device it is possible to provide location based information as part of the application. Currently, the major consumer application utilising this technology is in car-navigation which provides turn by turn directions as you drive along a chosen route.
A-GPS
A-GPS or assisted GPS uses a GPS device within a mobile phone combined with additional information provided by the mobile network to allow position to be calculated more quickly and accurately than with GPS alone. Typically it involves the network providing details of the satellite positions which are retrieved from a central database and transmitted to the phone over the network. This has the result that the phone can 'lock' onto available GPS positions faster than it could otherwise. This speeds up the time it takes to calculate a position and gives some improvements in the accuracy of the position.
Cell ID
The cellular technology used by the mobile operator to provide the GSM communication network used by mobile phones also allows the mobile operator to determine the location of the mobile phone. This is accomplished through the detection of signal strengths at the radio masts which make up each radio cell. Through evolving technology which analyses these signal strengths using triangulation at approximate position can be determined. This varies depending on the size of the cell. In a rural environment it could typically be to around one km in accuracy. In urban areas it could typically be to within a few metres. This technology is termed Cell ID.
Although not as accurate as GPS, mobile operators have been particularly keen to exploit this capability of their network. It requires no extra equipment other than the mobile phone and it presents an additional revenue opportunity for the operator. In fact most operators now provide access to this information so 3rd parties can deliver applications based on the location of particular mobile users.
Some Examples of Location Based Services Applications
Tracking
Local Search
Mapping
Navigation
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