Location-Based Services Using CellID
Past papers have discussed how to interface with GPS receivers to obtain the geographical position of a device and then transmit the information over to a server for mapping purposes. However, not all mobile devices today have built-in GPS receivers. Moreover, GPS does not work in-doors. This seriously limits the usefulness of applications built around GPS technologies. If one doesn't have GPS, or it's unavailable, a good alternative is to obtain the ID (often known as the CellID) of the base station to which the device is currently connected. As the mobile device moves from one position to another, it generally connects to a base station that offers the best signal (though this decision can be based on a number of criteria).