Friday, June 22, 2007

Universal Mobile Telecommunications Service (UMTS) architecture


UMTS is the third generation system promoted by ETSI and provides vital link between today's multiple GSM systems and the ultimate single worldwide system for all mobile telecommunications, IMT-2000. It is one of the most significant advances to the evolution of telecommunications into 3G networks. It will address the the growing demands of the mobile and Internet applications in the overcrowded mobile communications sky. It will increase the network speeds to 2Mbps per mobile user and establishes a global roaming standard.

A UMTS network consist of three interacting domains; Core Network (CN), UMTS Terrestrial Radio Access Network (UTRAN) and User Equipment (UE). The main function of the core network is to provide switching, routing and transit for user traffic. Core network also contains the databases and network management functions. The basic Core Network architecture for UMTS is based on GSM network with GPRS. All equipment has to be modified for UMTS operation and services.

The UTRAN provides the air interface access method for User Equipment. Base Station is referred as Node-B and control equipment for Node-B is called Radio Network Controller (RNC).

It is necessary for a network to know the approximate location in order to be able to page user equipment. Here is the list of system areas from largest to smallest.

  • UMTS systems (including satellite)
  • Public Land Mobile Network (PLMN)
  • MSC/VLR or SGSN
  • Location Area
  • Routing Area (PS domain)
  • UTRAN Registration Area (PS domain)
  • Cell
  • Sub cell


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