Horizontal Layering

Today’s modern telecommunications and data communications environment consists of a variety of networks. Most of these networks are highly specialized and optimized to serve a specific purpose such as PLMN, ISDN/PSDT and Data/IP Network. To a larger extent these networks are all vertically integrated in a sense they combine functionality in one and the same network element.
Due to the fact that most networks are vertical in structure, they have evolved separately and therefore differ in many respects. However, this has the effect of limiting the network operators ability to create synergies among their networks.

The architecture of the core network for UMTS is shown is Figure 35, this illustrates the way to evolve this multi-network situation in order to overcome some of the existing defects. In short the UMTS solution is based on a horizontalisation of the core network into a number of independent networks.

Basically UMTS is a “Network of Networks” (Personal Comment). Special Media Gateways (MGW), controlled by specific network servers, adapt and connect different access types to a common backbone network. End user applications are provided by a specific service layer, common to different access types.