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Gsm architecture pdf

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GSM Architecture. Numbering and Routing. GSM Services. GSM Network Architecture. Engr. Mian Shahzad Iqbal. Lecturer. Department of Telecommunication. GSM uses Digital Communication System or DCS and GSM Architecture and Subsystems. Open architecture according to the Open Systems. Base Station Subsystem (BBS),. Network and Switching Subsystem (NSS),. Operation Management Subsystem (OMS). BSS. NSS. OMS. GSM. MS. External.

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Global system for mobile communication (GSM) is a globally accepted standard This tutorial provides an introduction to basic GSM concepts, specifications. GSM Architecture and Interfaces. INTRODUCTION. In this chapter we present an overview of the GSM as described in ETSI's rec- ommendations. GSM - ARCHITECTURE. A GSM network comprises of many functional units. These functions and interfaces are explained in this chapter. The GSM network can.

Skip to main content. Log In Sign Up. GSM Architecture. Maria Mimy. This document is intended for the use of Nokia Networks' customers only for the purposes of the agreement under which the document is submitted, and no part of it may be reproduced or transmitted in any form or means without the prior written permission of Nokia Networks. The document has been prepared to be used by professional and properly trained personnel, and the customer assumes full responsibility when using it. Nokia Networks welcomes customer comments as part of the process of continuous development and improvement of the documentation.

If the synchronisation chain is not working correctly, calls may be cut or the call quality may not be the best possible. Ultimately, it may even be impossible to establish a call. The MS must have a connection through these two interfaces before a call can be established.

Architecture pdf gsm

Generally speaking, this connection may be either a signalling connection or a traffic speech, data connection. Mobility management and speech transcoding BSS mobility management mainly covers the different cases of handovers. These handovers and speech transcoding are explained in later sections.

It has several important tasks, some of which are presented in the following: Mobility management The BSC is responsible for initiating the vast majority of all handovers, and it makes the handover decision based on, among others, measurement reports sent by the MS during a call.

This task is accomplished with the help of some parameters. The BTS parameters handle the following major items: The BTS has several very important tasks, some of which are presented in the following. Figure 6. Nokia MetroSite Base Transceiver Station Air interface signalling A lot of both call and non-call related signalling must be performed in order for the system to work. One example is that when the MS is switched on for the very first time, it needs to send and receive a lot of information with the network more precisely with the VLR before we can start to receive and make phone calls.

Another example is the signalling required to set up both mobile originated and mobile terminated calls. A third very important signalling in mobile networks is the need to inform the MS when a handover is to be performed and later when the MS sends a message in the uplink direction telling the network that the handover is completed.

Later in this chapter, we will have a closer look at all of these different cases. The base station can contain several TRXs Transceivers , each supporting one pair of frequencies for transmitting and receiving information.

The antennas are either omnidirectional or sectorised. To enable an efficient transmission of digital speech information over the air interface, the digital speech signal is compressed. We must however also be able to communicate with and through the fixed network, where the speech compression format is different.

Somewhere between the BTS and the fixed network, we therefore have to convert from one speech compression format to another, and this is where the Transcoder comes in. Location of Transcoder and Submultiplexer The Transcoder TC thus takes care of the change from one bit rate to another. This increases the efficiency of the PCM lines, and thus lowers the costs for the operator.

When we connect to the MSC, the multiplexed lines have to be de-multiplexed. Another task for the TC is to enable DTX Discontinuous transmission , which is used during a call when there is nothing to transmit no conversation.

GSM Network Architecture

It is activated in order to reduce interference and to save MS battery. The purpose of the NMS is to monitor various functions and elements of the network. The database server stores the management information about the network.

The DCN is normally implemented using an X. 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. Fault management provides the network operator with information about the current status of alarm events and maintains a history database of alarms.

The alarms are stored in the NMS database and this database can be searched according to criteria specified by the network operator. Figure 9. Fault management Configuration management The purpose of configuration management is to maintain up-to-date information about the operation and configuration status of network elements.

Specific configuration functions include the management of the radio network, software and hardware management of the network elements, time synchronisation, and security operations. There are a number of elements to the cell phone, although the two main elements are the main hardware and the SIM.

Architecture pdf gsm

The hardware itself contains the main elements of the mobile phone including the display, case, battery, and the electronics used to generate the signal, and process the data receiver and to be transmitted. This is installed in the phone at manufacture and "cannot" be changed.

It is accessed by the network during registration to check whether the equipment has been reported as stolen. It must be noted that as the number of BS increases with the scaling of the subscriber population some of the maintenance tasks are transferred to the BTS, allowing savings in the cost of ownership of the system.

Architecture pdf gsm

The 2G GSM network architecture follows a logical method of operation. It is far simpler than current mobile phone network architectures which use software defined entities to enable very flexible operation. However the 2G GSM architecture does show the voice and operational basic functions that are needed and how they fit together. A basic diagram of the overall system architecture for 2G GSM with these four major elements is shown below: The major elements within the core network include: These include registration, authentication, call location, inter-MSC handovers and call routing to a mobile subscriber.

It also provides an interface to the PSTN so that calls can be routed from the mobile network to a phone connected to a landline. Interfaces to other MSCs are provided to enable calls to be made to mobiles on different networks.

This database contains all the administrative information about each subscriber along with their last known location. When a user switches on their phone, the phone registers with the network and from this it is possible to determine which BTS it communicates with so that incoming calls can be routed appropriately.

Even when the phone is not active but switched on it re-registers periodically to ensure that the network HLR is aware of its latest position. Call control MSC identifies the type of call, the destination, and the origin of a call. It also sets up, supervises, and clears connections.

Initiation of paging Paging is the process of locating a particular mobile station in case of a mobile terminated call a call to a mobile station. Charging data collection Charging will be covered later in this material. Please note that a mobile subscriber must always be registered in a VLR in order to use the services of the network. Also the mobile stations located in the own network is always registered in a VLR. The VLR database is temporary, in the sense that the data is held as long as the subscriber is within its service area.

It also contains the address to every subscriber's Home Location Register, which is the next network element to be discussed. In addition to the fixed data, the HLR also keeps track of the current location of its customers. As you will see later, the MSC asks for routing information from the HLR if a call is to be set up to a mobile station mobile terminated call. The Authentication Centre supports the VLR's work by issuing so-called authentication triplets upon request.

Later we will discuss more about the Authentication Centre's role, and how the authentication triplets are used. This number consists of type approval code, final assembly code and serial number of the mobile station. It is then placed in the grey list. Some operators do not even implement the EIR at all. A BSS itself may cover a considerably large geographical area consisting of many cells a cell refers to an area covered by one or more frequency resources.

The BSS consists of the following elements: Radio path control In the GSM network, the Base Station Subsystem BSS is the part of the network taking care of radio resources, that is, radio channel allocation and quality of the radio connection. Synchronisation is a critical issue in the GSM network due to the nature of the information transferred. If the synchronisation chain is not working correctly, calls may be cut or the call quality may not be the best possible.

Ultimately, it may even be impossible to establish a call.

GSM Network Architecture | GSM System Architecture | Electronics Notes

The MS must have a connection through these two interfaces before a call can be established. Generally speaking, this connection may be either a signalling connection or a traffic speech, data connection.

Pdf gsm architecture

Mobility management and speech transcoding BSS mobility management mainly covers the different cases of handovers. These handovers and speech transcoding are explained in later sections. It has several important tasks, some of which are presented in the following: Mobility management The BSC is responsible for initiating the vast majority of all handovers, and it makes the handover decision based on, among others, measurement reports sent by the MS during a call.

This task is accomplished with the help of some parameters.

The BTS parameters handle the following major items: The BTS has several very important tasks, some of which are presented in the following. Figure 6. Nokia MetroSite Base Transceiver Station Air interface signalling A lot of both call and non-call related signalling must be performed in order for the system to work.

One example is that when the MS is switched on for the very first time, it needs to send and receive a lot of information with the network more precisely with the VLR before we can start to receive and make phone calls. Another example is the signalling required to set up both mobile originated and mobile terminated calls.

A third very important signalling in mobile networks is the need to inform the MS when a handover is to be performed and later when the MS sends a message in the uplink direction telling the network that the handover is completed.

Later in this chapter, we will have a closer look at all of these different cases.

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