Location-based service

Location-based services (LBS) use real-time geo-data from a mobile device or smartphone to provide information, entertainment or security. Some services allow consumers to "check in" at restaurants, coffee shops, stores, concerts, and other places or events. Often, businesses offer a reward — prizes, coupons or discounts — to people who check in. Google Maps, Foursquare, GetGlue, Yelp and Facebook Places are among the more popular services.

Definition
Location-based services are a general class of computer program-level services that use location data to control features. As such LBS is an information service and has a number of uses in social networking today as an entertainment service, which is accessible with mobile devices through the mobile network and which uses information on the geographical position of the mobile device. This has become more and more important with the expansion of the smartphone and tablet markets as well.

Control plane locating
Sometimes referred to as positioning, with control plane locating the service provider gets the location based on the radio signal delay of the closest cell-phone towers (for phones without GPS features) which can be quite slow as it uses the 'voice control' channel. In the UK, networks do not use trilateration; LBS services use a single base station, with a "radius" of inaccuracy, to determine a phone's location. This technique was the basis of the E-911 mandate and is still used to locate cellphones as a safety measure. Newer phones and PDAs typically have an integrated A-GPS chip.

GSM Location
GSM localization is the second option. Finding the location of a mobile device in relation to its cell site is another way to find out the location of an object or a person. It relies on various means of multilateration of the signal from cell sites serving a mobile phone. The geographical position of the device is found out through various techniques like time difference of arrival (TDOA) or Enhanced Observed Time Difference (E-OTD).

LBS applications
LBS are used in a variety of contexts, such as health, indoor object search, entertainment, work, personal life, etc. Some examples of location-based services are:
 * Requesting the nearest business or service, such as an ATM, restaurant or a retail store
 * Turn by turn navigation to any address
 * Assistive Healthcare Systems
 * Locating people on a map displayed on the mobile phone
 * Location-based mobile advertising
 * Contextualizing learning and research
 * Real-time Q&A revolving around restaurants, services, and other venues