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GSM and UMTS (P11)

Before the specification of a protocol can be started, it is necessary first to determine the two entities that are exchanging the information. This in turn requires a description of the overall system in terms of entities, such as mobile stations, terminals attached to mobile stations, radio | GSM and UMTS The Creation of Global Mobile Communication Edited by Friedhelm Hillebrand Copyright 2001 John Wiley Sons Ltd ISBNs 0-470-84322-5 Hardback 0-470-845546 Electronic Chapter 11 System Architecture Michel Mouly1 11.1 Scope The decisions that were taken in GSM3 SMG3 were centred on the specification of signalling protocols. Signalling protocols can be understood as languages for exchanging control information between distant nodes such as network nodes or mobile stations. The exchanged information is quite variegated. It includes data such as identities called numbers nature of call description of allocated resources result of measures and so on. 11.2 Architecture Before the specification of a protocol can be started it is necessary first to determine the two entities that are exchanging the information. This in turn requires a description of the overall system in terms of entities such as mobile stations terminals attached to mobile stations radio base stations switches . The analysis and description of a system in terms of entities of interfaces between such entities and of dialogs flowing over these interfaces in short of the system architecture was originally a derived task of GSM3 this task was eventually given to a sub-group of SMG3 and to a spawn of SMG3 SMG12. The choices driving the specification of the architecture of a telecommunications system such as GSM are determined by a variety of factors. Some splits are derived naturally from fundamental requirements such as the split between the user equipment and the infrastructure with radio as the means for communication between the two sides. Roaming interfacing with non-GSM telecommunications networks interfacing with non-GSM user terminals are other requirements leading to natural splits. Some other splits have been introduced to answer particular requirements from the operators for example to centralise some functions and thus to reduce costs. For instance the separation between switches and radio