Editing Mobility management (section)

===Location area===
A "location area" is a set of base stations that are grouped together to [[Engineering optimization|optimize]] signaling. Typically, tens or even hundreds of base stations share a single [[Base station subsystem#Base station controller|Base Station Controller]] (BSC) in GSM, or a [[Radio Network Controller]] (RNC) in UMTS. The BSC / RNC is the intelligence behind the base stations; it handles allocation of radio channels, receives measurements from the mobile phones, and controls handovers between base stations.

Each location area has an assigned unique identifier, made up of numbers, called a "location area code" (LAC). The LAC is broadcast by each base station at regular intervals. Within a location area, each base station is assigned a distinct "cell identifier" (CI) number, see also [[Cell Global Identity]].

If the location areas are large and moderately populated, there will likely be a high number of mobiles operating simultaneously, resulting in very high paging traffic. This is due to the fact that every paging request has to be broadcast to every base station in the location area. Ultimately, this wastes [[Bandwidth (signal processing)|bandwidth]] and power on mobile devices by requiring them to listen for broadcast messages too often. Similarly if on the other hand, there are too many small location areas, the mobile device must contact the network very often for changes of location, which will also drain the device’s battery. Therefore, it is important to strike a balance between the size of the location area and the number of mobile device users in the location area{{Citation needed|date=April 2009}}.