In a typical cellular radio system, wireless terminals communicate via a radio access network, RAN, with one or more core networks. The wireless terminals can be mobile stations or other types of user equipment, UE, such as portable, pocket, hand-held, computer-included, or car-mounted mobile devices which communicate voice and/or data with radio access network, e.g., mobile telephones and laptops with wireless capability.
The RAN covers a geographical area which is divided into cell areas. Within the cell area, radio coverage is provided by equipment at the radio access node including a base station, also known as a NodeB, and a radio network controller, RNC. Each cell is identified by an identity within the local radio area. The radio access nodes communicate over the air interface with the UE within the cells served by the node. A multitude of base stations including the radio transceiver equipment are controlled by a single radio network controller, RNC. The RNC handles the allocation of radio channels, signaling to UE and controls handovers from base station to base station among other tasks.
The radio network controller, RNC, controls a set of base stations connected to the RNC. The RNC carries out radio resource management and some of the mobility management functions. The RNC connects to the core network. The signaling protocol responsible for communication over the Iu interface between the RNC and the core network is the RANAP, radio access network application part.
The Universal Mobile Telecommunications System, UMTS, is a third generation mobile communication system, which evolved from the Global System for Mobile Communications, GSM, and is intended to provide improved mobile communication services based on Wideband Code Division Multiple Access, WCDMA, access technology. UTRAN is essentially a radio access network using wideband code division multiple access for user equipment units, UEs.
Paging is used for network-initiated connection setup. Each time a UE attaches to the network, it also performs an update and registers to a routing area or location area. The location update procedure allows a mobile device to inform the cellular network, whenever it moves from one location area to the next. Mobiles are responsible for detecting location area codes. When a mobile finds that the location area code is different from its last update, it performs another update by sending to the network, a location update request.
A “location area” is a set of base stations that are grouped together to optimize signaling. Typically, tens or even hundreds of base stations may share a single radio network controller, RNC, in UMTS. If the location areas are very large, there will be many mobiles operating simultaneously, resulting in very high paging traffic, as every paging message has to be broadcast to every cell in the location area. This wastes radio resources in the radio link, which is a scarce resource within the radio access network. If on the other hand, there are many small location areas, the mobile must contact the network very often for changes of location. A balance must therefore be sought when defining the extent of a location area.
In the packet switched domain a routing area is equivalent of the location area. A “routing area” may be a subdivision of a “location area”. With the increasing amount of packet data being delivered to smart phones or other types of user equipment signing up for automatic updates of information, more paging messages are being sent per mobile. Present functionality in UMTS for paging requires paging on the air interface to all cells in a routing area. Paging constitutes a large part of the signaling load for packet data. An increasing amount of data packets to be delivered to user equipment increases the signaling load in the radio interface and consumes air interface resources.
What is needed therefore, and an object of the technology described herein, is to provide solutions that reduces paging load in a 3G network, e.g. an UMTS network.