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GSM1

GSMAbout the TutorialGSM is a globally accepted standard for digital cellular communications.GSM uses narrowband Time Division Multiple Access (TDMA) for providing voice and textbased services over mobile phone networks.So, this tutorial is divided into different chapters and describes the fundamental conceptsand functionalities of GSM.AudienceThis tutorial has been designed for the readers who want to understand the basics of GSMin very simple language. This tutorial provides just about enough material to have a solidfoundation on GSM from where you can move on to higher levels of expertise.PrerequisitesA general awareness of some basics of telecommunications is sufficient to understand theconcepts explained in this tutorial.Copyright & Disclaimer Copyright 2020 by Tutorials Point (I) Pvt. Ltd.All the content and graphics published in this e-book are the property of Tutorials Point (I)Pvt. Ltd. The user of this e-book is prohibited to reuse, retain, copy, distribute or republishany contents or a part of contents of this e-book in any manner without written consentof the publisher.We strive to update the contents of our website and tutorials as timely and as precisely aspossible, however, the contents may contain inaccuracies or errors. Tutorials Point (I) Pvt.Ltd. provides no guarantee regarding the accuracy, timeliness or completeness of ourwebsite or its contents including this tutorial. If you discover any errors on our website orin this tutorial, please notify us at [email protected]

GSMTable of ContentsAbout the Tutorial . 2Audience . 2Prerequisites . 2Copyright & Disclaimer . 2Table of Contents . 31.GSM — Overview . 6What is GSM? . 6Why GSM? . 6GSM History . 72.GSM ― Architecture . 9GSM - The Mobile Station . 9GSM - The Base Station Subsystem (BSS) . 10GSM - The Network Switching Subsystem (NSS) . 12GSM - The Operation Support Subsystem (OSS) . 14GSM Network Areas . 163.GSM — Specification . 17Modulation . 17Access Methods . 17Transmission Rate . 17Frequency Band . 17Channel Spacing . 17Speech Coding . 17Duplex Distance . 18Misc . 184.GSM — Addresses and Identifiers . 19International Mobile Station Equipment Identity (IMEI) . 193

GSMInternational Mobile Subscriber Identity (IMSI) . 19Mobile Subscriber ISDN Number (MSISDN) . 20Mobile Station Roaming Number (MSRN) . 20Location Area Identity (LAI) . 21Temporary Mobile Subscriber Identity (TMSI) . 21Local Mobile Subscriber Identity (LMSI) . 21Cell Identifier (CI) . 215.GSM — Operations . 22Mobile Phone to Public Switched Telephone Network (PSTN) . 22PSTN to Mobile Phone . 226.GSM ― Protocol Stack . 24MS Protocols. 24MS to BTS Protocols . 25BSC Protocols . 25MSC Protocols . 257.GSM — User Services . 27Teleservices . 27Bearer Services . 28Supplementary Services . 288.GSM — Security and Encryption . 30Mobile Station Authentication . 30Signaling and Data Confidentiality . 30Subscriber Identity Confidentiality . 319.GSM — Billing . 32Telephony Service . 32SMS Service . 32GPRS Services . 32Supplementary Services . 334

GSM10. GSM — Mobile Phones . 345

1. GSM — OverviewGSMIf you are in Europe or Asia and using a mobile phone, then most probably you are usingGSM technology in your mobile phone. It is widely used mobile technology across theworld.What is GSM?GSM stands for Global System for Mobile Communication. It is a digital cellular technologyused for transmitting mobile voice and data services. Important facts about the GSM aregiven below: The concept of GSM emerged from a cell-based mobile radio system at BellLaboratories in the early 1970s.GSM is the name of a standardization group established in 1982 to create acommon European mobile telephone standard.GSM is the most widely accepted standard in telecommunications and it isimplemented globally.GSM is a circuit-switched system that divides each 200 kHz channel into eight 25kHz time-slots. GSM operates on the mobile communication bands 900 MHz and1800 MHz in most parts of the world. In the US, GSM operates in the bands 850MHz and 1900 MHz.GSM owns a market share of more than 70% of the world's digital cellularsubscribers.GSM makes use of narrowband Time Division Multiple Access (TDMA) technique fortransmitting signals.GSM was developed using digital technology. It has an ability to carry 64 kbps to120 Mbps of data rates.Presently GSM supports more than one billion mobile subscribers in more than 190countries throughout the world.GSM provides basic to advanced voice and data services including roaming service.Roaming is the ability to use your GSM phone number in another GSM network.GSM digitizes and compresses data, then sends it down through a channel with two otherstreams of user data, each in its own timeslot.Why GSM?Listed below are the features of GSM that account for its popularity and wide acceptance. Improved spectrum efficiency International roaming Low-cost mobile sets and base stations (BSs) High-quality speech Compatibility with Integrated Services Digital Network (ISDN) and other telephonecompany services6

GSM Support for new servicesGSM HistoryThe following table shows some of the important events in the rollout of the GSM system.YearsEvents1982Conference of European Posts and Telegraph (CEPT) establishes a GSM groupto widen the standards for a pan-European cellular mobile system.1985A list of recommendations to be generated by the group is accepted.1986Executed field tests to check the different radio techniques recommended forthe air interface.1987Time Division Multiple Access (TDMA) is chosen as the access method (withFrequency Division Multiple Access [FDMA]). The initial Memorandum ofUnderstanding (MoU) is signed by telecommunication operators representing12 countries.1988GSM system is validated.1989The European Telecommunications Standards Institute (ETSI) was given theresponsibility of the GSM specifications.1990Phase 1 of the GSM specifications is delivered.1991Commercial launch of the GSM service occurs. The DCS1800 specifications arefinalized.1992The addition of the countries that signed the GSM MoU takes place. Coveragespreads to larger cities and airports.1993Coverage of main roads GSM services starts outside Europe.1994Data transmission capabilities launched. The number of networks rises to 69 in43 countries by the end of 1994.1995Phase 2 of the GSM specifications occurs. Coverage is extended to rural areas.1996June: 133 network in 81 countries operational.1997July: 200 network in 109 countries operational, around 44 million subscribersworldwide.7

GSM1999Wireless Application Protocol (WAP) came into existence and becameoperational in 130 countries with 260 million subscribers.2000General Packet Radio Service (GPRS) came into existence.2001As of May 2001, over 550 million people were subscribers to mobiletelecommunications.8

2. GSM ― ArchitectureGSMA GSM network comprises of many functional units. These functions and interfaces areexplained in this chapter. The GSM network can be broadly divided into: The Mobile Station (M