LBS for application developers

This document gives a brief description of some LBS concepts for application developers.

Location Based Services (LBS) enables client applications and remote parties to determine the location of a mobile device. A client application is one installed on the mobile device. A remote party may be a part of the network infrastructure, such as a network-originating request to acquire mobile device location when an emergency services call is made. A remote party may also be another mobile device user, or a web-based service.

LBS provides the infrastructure for application developers to create location-aware applications. Such applications include location stamping of photographs, finding nearby services and facilities, navigation and the ability for remote parties (for example emergency services) to discover the location of the mobile device.

Client applications installed on the mobile device use the Location Acquisition API to obtain the device location. One of the key features of this API is that it allows applications to discover the location of the mobile device without the need to know details of the positioning technology (see below) which is used to obtain the location fix.

A positioning technology is the means by which a mobile device discovers its location. Some positioning technologies are terminal based, such as the Global Positioning System (GPS) and some are based on the network infrastructure, such as enhanced Cell-ID. Some techniques combine device capabilities with information obtained from the network such as Assisted GPS (A-GPS). The accuracy of a location fix, the cost of obtaining it and the ability to obtain it indoors all depend on the positioning technology used to obtain the fix.

LBS can obtain location information from a set of positioning technologies. These technologies have different capabilities but generally provide location information (latitude, longitude and altitude) together with location accuracy information and the time at which the fix was obtained. LBS allows applications to select the criteria of their location request and the required accuracy of information that must be satisfied. LBS can also provide additional location information, such as the mobile device speed and the positioning satellite details when these are available from the positioning technology.

The ability of a client application or remote party to discover the location of a mobile device raises privacy and security issues. LBS addresses these issues in two ways. Firstly, the Symbian OS capability security model is used to ensure that only applications granted permission to use LBS can discover the device location. Secondly, a process of user privacy verification or notification is followed when a remote party makes a request over the network for the position of the mobile device.

The Location Acquisition API