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25cm; line-height: 120%; }AIM:_______________________________________________ CaseStudy On GSMRQUIREMENTS:____________________________________ Internet,MS Word, Libre OfficeTHEORY:___________________________________________Introduction:GlobalSystem for Mobile Communications is a standard developed bythe European Telecommunications Standards Institute (ETSI) todescribe the protocols for second-generation digital cellularnetworks used by mobile devices such as tablets, first deployed inFinland in December 1991.As of 2014, it has become the globalstandard for mobile communications – with over 90% market share,operating in over 193 countries and territories.GSMuses a variation of time division multiple access (TDMA) and is themost widely used of the three digital wireless telephony technologies(TDMA, GSM, and CDMA). GSM digitizes and compresses data, then sendsit down a channel with two other streams of user data, each in itsown time slot. It operates at either the 900 MHz or 1800 MHzfrequency band.Featuresof GSM Module:Improved spectrum efficiency International roaming Compatibility with integrated services digital network (ISDN) SIM phonebook management Fixed dialing number (FDN) Real time clock with alarm management High-quality speech Uses encryption to make phone calls more secure Short message service (SMS)Block Diagram of GSM: GSMprovides recommendations, not requirements. The GSM specificationsdefinethe functions and interface requirements in detail but do not addressthe hardware. The reason for this is to limit the designers as littleas possible but still to make it possible for the operators to buyequipment from different suppliers.

TheGSM network is divided into three major systems: the switching system(SS), the base station system (BSS), and the operation and supportsystem (OSS). TheSwitching SystemTheswitching system (SS) is responsible for performing call processingand subscriber-related functions. The switching system includes thefollowing functional units:HomeLocation Register (HLR). The HLR is a database used for storage andmanagement of subscriptions. The HLR is considered the most importantdatabase, as it stores permanent data about subscribers, including asubscriber’s service profile, location information, and activitystatus.

When an individual buys a subscription from one of the PCSoperators, he or she is registered in the HLR of that operator.MobileServices Switching Center (MSC)TheMSC performs thetelephony switching functions of the system. Itcontrols calls to and from other telephone and data systems. It alsoperforms such functions as toll ticketing, network interfacing,common channel signaling, and others.VisitorLocation Register (VLR)TheVLR is a database that contains temporary information aboutsubscribers that is needed by the MSC in order to service visitingsubscribers. The VLR is always integrated with the MSC. When a mobilestation moves to a new MSC area, the VLR connected to that MSC willrequest data about the mobile station from the HLR. Later, if themobile station makes a call, the VLR will have the information neededfor call setup without having to interrogate the HLR each time.

AuthenticationCenter (AUC)Aunit called the AUC providesauthentication and encryption parametersthat verify the user’s identity and ensure the confidentiality ofeach call. The AUC protects network operators from different types offraud found in today’s cellular world.EquipmentIdentity Register (EIR)TheEIR is a database that contains information about the identity ofmobile equipment that prevents calls from stolen, unauthorized, ordefective mobile stations. The AUC and EIR are implemented asstand-alone nodes or as a combined AUC/EIR node.

TheBase Station System (BSS) Allradio-related functions are performed in the BSS, which consists ofbase station controllers (BSCs) and the base transceiver stations(BTSs).BSCTheBSC provides all the control functions and physical links between theMSC and BTS. It is a high-capacity switch that provides functionssuch as handover, cell configuration data, and control of radiofrequency (RF) power levels in base transceiver stations. A number ofBSCs are served by an MSC.

BTSTheBTS handles the radio interface to the mobile station. TheBTS is theradio equipment (transceivers and antennas) needed to service eachcell in the network. A group of BTSs are controlled by aTheOperation and Support SystemTheoperations and maintenance center (OMC) is connected to all equipmentintheswitching system and to the BSC. The implementation of OMC is calledtheoperationand support system (OSS). The OSS is the functional entity from whichthenetwork operator monitors and controls the system. The purpose of OSSis toofferthe customer cost-effective support for centralized, regional, andlocaloperationaland maintenance activities that are required for a GSM network.

Animportantfunction of OSS is to provide a network overview and support themaintenanceactivities of different operation and maintenance organizations.Serivces offered byGSM:GSM offers much more thanjust voice telephony. Contact your local GSM network operator to thespecific services that you can avail.

GSM offers three basictypes of services:Telephony services or teleservices Data services or bearer services Supplementary services TeleservicesThe abilities of a BearerService are used by a Teleservice to transport data. These servicesare further transited in the following ways:VoiceCallsThe most basic Teleservicesupported by GSM is telephony. This includes full-rate speech at 13kbps and emergency calls, where the nearest emergency-serviceprovider is notified by dialing three digits.

Videotextand FacsmileAnother group ofteleservices includes Videotext access, Teletex transmission,Facsmile alternate speech and Facsmile Group 3, Automatic FacsmileGroup, 3 etc.Short TextMessagesShort Messaging Service(SMS) service is a text messaging service that allows sending andreceiving text messages on your GSM mobile phone. In addition tosimple text messages, other text data including news, sports,financial, language, and location-based data can also be transmitted.BearerServicesData services or BearerServices are used through a GSM phone.

to receive and send data isthe essential building block leading to widespread mobile Internetaccess and mobile data transfer. GSM currently has a data transferrate of 9.6k. New developments that will push up data transfer ratesfor GSM users are HSCSD and GPRS now available.SupplementaryServicesSupplementary services areadditional services that are provided in addition to teleservices andbearer services.

These services include caller identification, callforwarding, call waiting, multi-party conversations, and barring ofoutgoing (international) calls, among others. A brief description ofsupplementary services is given here:Conferencing : It allows a mobile subscriber to establish a multiparty conversation, i.e., a simultaneous conversation between three or more subscribers to setup a conference call. This service is only applicable to normal telephony. Call Waiting : This service notifies a mobile subscriber of an incoming call during a conversation.

The subscriber can answer, reject, or ignore the incoming call. Call Hold : This service allows a subscriber to put an incoming call on hold and resume after a while. The call hold service is applicable to normal telephony.

Call Forwarding : Call Forwarding is used to divert calls from the original recipient to another number. It is normally set up by the subscriber himself. It can be used by the subscriber to divert calls from the Mobile Station when the subscriber is not available, and so to ensure that calls are not lost. Call Barring : Call Barring is useful to restrict certain types of outgoing calls such as ISD or stop incoming calls from undesired numbers. Call barring is a flexible service that enables the subscriber to conditionally bar calls. Number Identification : There are following supplementary services related to number identification: Calling Line Identification Presentation : This service displays the telephone number of the calling party on your screen. Connected Line Identification Presentation : This service is provided to give the calling party the telephone number of the person to whom they are connected.

This service is useful in situations such as forwarding’s where the number connected is not the number dialled. Connected Line Identification Restriction : There are times when the person called does not wish to have their number presented and so they would subscribe to this person. Normally, this overrides the presentation service.

Malicious Call Identification : The malicious call identification service was provided to combat the spread of obscene or annoying calls. The victim should subscribe to this service, and then they could cause known malicious calls to be identified in the GSM network, using a simple command. Advice of Charge (AoC) : This service was designed to give the subscriber an indication of the cost of the services as they are used. Furthermore, those service providers who wish to offer rental services to subscribers without their own SIM can also utilize this service in a slightly different form.

AoC for data calls is provided on the basis of time measurements. Closed User Groups (CUGs) : This service is meant for groups of subscribers who wish to call only each other and no one else. Unstructured supplementary services data (USSD) : This allows operator-defined individual services.CONCLUSION___________________________ Thus we have studied theFeatures, Block Diagram and different Services offered by GSM.

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