Global System for Mobile Communications – Railway (GSM-R) is a radio communication system offering a wide range of voice and data services needed for. This group was named “Groupe Spéciale Mobile” and the system name GSM arose. This abbreviation has since been interpreted in other ways. This group was named “Groupe Spéciale Mobile” and the system name GSM arose. This abbreviation has since been interpreted in other ways, but the most.

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How can we maintain the connection in such cases? In addition to a standard fee, subscribers have to pay for the calls they make and the services they use. There is a limited number of frequencies available to each Base Station Subsystem. The Billing Centre with information from the transcoder. Since each carrier supports eight channels, we can make a rough estimation that this cell must be equipped with three carriers, that is, three transceivers or TRXs.

It was not possible to have many different signalling messages. When either the base transceiver station or mobile station transmits user information, the information contained in the burst is not all user data.

This is called the TransCoder TC. No matter how often or how quickly he moves, the network must be able to locate him continuously in case somebody wants to call him. Let us sum up the entire process: As shown in the table, this service is not currently supported by Nokia. Exchange Signalling Signalling towards towards subscribers other exchanges Computer units Message bus Collecting Collecting dialled statistical data numbers Collecting Supervising the charging processes data running Making speech Hunting for a path free circuit connections Figure Services and Facilities SMG2: Short message T21 For the reception of short messages.

It is used by the mobile station in order to initiate a transaction, or as a response to a PCH. Person about to use a mobile phone On the other hand, a connection through the mobile network is possible only if there is a point to point connection between the caller and the person who is called.


Factors to consider when, for instance, making a BTS site survey are the surroundings, possible structural and geographical obstacles and existing radio equipment. Whether the subscriber has access to the service or not? Where is the Called Party? Locating the subscriber This locates a subscriber before establishing a call. There are fixed databases that maintain basic information about their customers, including data on their current location, and temporary databases storing information about the users who are currently located in their service area.

These events can be the defined call cases or other possible chargeable events, such as location updates. When these services are provided as a basic or supplementary service, it is not only important to know what is transmitted.

In the example of the army, the soldiers are one type of logical channel and the officers are other types of logical channels, and they exercise some kind of control depending on their responsibilities. Now it is time to investigate another case: He would then hear his phone ringing.

It identifies the called subscriber on the basis of the MSISDN and then checks its database to determine the subscriber’s location. Its main functions are: This may cause situations where the order of messages that are received, are different from the original sequence. The modulation scheme used in GSM is predominantly based on: Moreover, the roaming number and the handover number have a similar purpose, that is, connecting two MSCs.

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However, in the VLR, the subscriber data is stored temporarily. First of all, the current status of the mobile station is stored in the VLR database and we need to know the status to avoid setting up a call to a subscriber whose phone is switched off.

Fault management The purpose of fault management is to ensure the smooth operation of the network and rapid correction of any kind of problems that are detected. Things will be easier to grasp if we go back for a moment and follow the famous professor in the hotel.

When a user subscribes for gsj than one basic service, he will have a different MSISDN for every basic service to which he subscribes.

The 2 sectorised BTS is suitable for, for instance, providing coverage for a highway. There are three types of broadcast channels: A speech connection is a network service and it can be handled only by an MSC.


It supports the GSMand frequency bands. The VLR receives the request and confirms the registration of the mobile in the same location area.

A small logistical problem Obviously, the only solution is to divide the army into groups of eight people. As an example, the following table shows the distribution of frequencies in GSM If we go back to the analogy of the army, the road is the radio carrier frequency, the vehicle is the TDMA frame and the seats in each vehicle are the Gwm timeslots.


In order to succeed, detailed information about the network is needed, such as growth estimates, protection, available and needed infrastructure, plus goals for quality and performance. A teleservice or a bearer service is also a basic service that has an enhanced performance by the use of a number of supplementary services. One factor that limits the cell size is the wavelength of the frequency. The serving operator controls the entire charging process.

Collect call is the third case in which the called subscriber pays for the vsm. This is enabled by a location update of which there are three types: The only thing we know is that he is in the hotel, because he has not checked out. The document has been prepared to be used by professional and properly trained personnel, and the customer assumes full responsibility when using it. Hopping can be cyclic or pseudo-random as defined in the GSM specifications.

These algorithms are A3, A5 and A8. An essential part of the planning of microwave links is to make sure that it is possible to get free line of sight between different elements for instance between BTS and BSC sites.