06-04-2013, 04:10 PM
A TRAINING REPORT ON GSM Or GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS At BHARAT SANCHAR NIGAM LIMITED(BSNL) BHILWARA
GLOBAL SYSTEM FOR MOBILE.doc (Size: 1.76 MB / Downloads: 33)
INTRODUCTION
Global System for Mobile communications (GSM – originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. Its promoter, the GSM Association, estimates that 82% of the global mobile market uses the standard. GSM is used by over 3 billion people across more than 212 countries and territories. Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs from its predecessors in that both signaling and speech channels are digital, and thus is considered a second generation (2G) mobile phone system. This has also meant that data communication was easy to build into the system.
HISTORY
In 1982, the European Conference of Postal and Telecommunications Administrations (ECPT) created the Groupe Spécial Mobile (GSM) to develop a standard for a mobile telephone system that could be used across Europe. In 1987, a Memorandum of Understanding (MoU) was signed by 13 countries to develop a common cellular telephone system across Europe.
In 1989, GSM responsibility was transferred to the European Telecommunications
Standards Institute (ETSI) and phase I of the GSM specifications were published in
1990. The first GSM network was launched in 1991 by Radiolinja in Finland with joint technical infrastructure maintenance from Ericsson.
GSM Specifications
GSM was designed to be platform-independent. The GSM specifications do not specify the actual hardware requirements, but instead specify the network functions and interfaces in detail. This allows hardware designers to be creative in how they provide the actual functionality, but at the same time makes it possible for operators to buy equipment from different suppliers.
The GSM recommendations consist of twelve series, which are listed, in the table below. Different working parties and a number of expert groups wrote these series. A permanent nucleus was established in order to coordinate the working parties and to manage the editing of the recommendations. All these groups were organized by ETSI.
GSM Phase
In the late 1980s, the groups involved in developing the GSM standard realized that within the given time frame they could not complete the specifications for the entire range of GSM services and features as originally planned. Because of this, it was decided that GSM would be released in phases with phase 1 consisting of a limited set of services and features. Each new phase builds on the services offered by existing phases.
Gateway Functionality (GMSC)
Gateway functionality enables an MSC to interrogate a network's HLR in order to route a call to a Mobile Station (MS). A Gateway MSC is the MSC that determines which visited MSC the subscriber who is being called is currently located. It also interfaces with the Public Switched Telephone Network. All mobile to mobile calls and PSTN to mobile calls are routed through a GMSC. The term is only valid in the context of one call since any MSC may provide both the gateway function and the Visited MSC function; however, some manufacturers design dedicated high capacity MSCs which do not have any BSSes connected to them. These MSCs will then be the Gateway MSC for many of the calls they handle.
Roaming
Roaming is a general term in wireless telecommunication that refers to the extending connectivity service in a location that is different from the home location where the service was registered. Roaming occurs when a subscriber of one wireless service provider uses the facilities of another wirelesss service provider. A device will usually indicate when it is roaming. In some cases roaming occurs in a phone’s designated home area when it transmits via a different providers tower (sometimes at a higher price). This is likely to occur when the service provider’s signal is too weak or if the volume of callers is too high. In order for a mobile device to use a different carrier’s service, the phone’s service provider must have a roaming agreement with that carrier.