GSM - Reviewed - Tutorialspoint
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 contact@tutorialspoint.com2
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 (MS) The Base Station Subsystem (BSS) The Network Switching Subsystem (NSS) The Operation Support Subsystem (OSS)GSM - The Mobile StationThe MS consists of the physical equipment, such as the radio transceiver, display anddigital signal processors, and the SIM card. It provides the air interface to the user in GSMnetworks. As such, other services are also provided, which include: Voice teleservices Data bearer services The features' supplementary servicesThe MS Functions9
GSMThe MS also provides the receptor for SMS messages, enabling the user to toggle betweenthe voice and data use. Moreover, the mobile facilitates access to voice messagingsystems. The MS also provides access to the various data services available in a GSMnetwork. These data services include: X.25 packet switching through a synchronous or asynchronous dial-up connectionto the PAD at speeds typically at 9.6 Kbps. General Packet Radio Services (GPRSs) using either an X.25 or IP based datatransfer method at the speed up to 115 Kbps. High speed, circuit switched data at speeds up to 64 Kbps.We will discuss more about GMS services in GSM - User Services.What is SIM?The SIM provides personal mobility so that the user can have access to all subscribedservices irrespective of both the location of the terminal and the use of a specific terminal.You need to insert the SIM card into another GSM cellular phone to receive calls at thatphone, make calls from that phone, or receive other subscribed services.GSM - The Base Station Subsystem (BSS)The BSS is composed of two parts: The Base Transceiver Station (BTS) The Base Station Controller (BSC)The BTS and the BSC communicate across the specified Abis interface, enabling operationsbetween components that are made by different suppliers. The radio components of a BSSmay consist of four to seven or nine cells. A BSS may have one or more base stations. TheBSS uses the Abis interface between the BTS and the BSC. A separate high-speed line (T1or E1) is then connected from the BSS to the Mobile MSC.10
GSMThe Base Transceiver Station (BTS)The BTS houses the radio transceivers that define a cell and handles the radio linkprotocols with the MS. In a large urban area, a large number of BTSs may be deployed.The BTS corresponds to the transceivers and antennas used in each cell of the network. ABTS is usually placed in the center of a cell. Its transmitting power defines the size of acell. Each BTS has between 1 and 16 transceivers, depending on the density of users inthe cell. Each BTS serves as a single cell. It also includes the following functions:11
GSM Encoding, encrypting, multiplexing, modulating, and feeding the RF signals to theantenna Transcoding and rate adaptation Time and frequency synchronizing Voice through full- or half-rate services Decoding, decrypting, and equalizing received signals Random access detection Timing advances Uplink channel measurementsThe Base Station Controller (BSC)The BSC manages the radio resources for one or more BTSs. It handles radio channelsetup, frequency hopping, and handovers. The BSC is the connection between the mobileand the MSC. The BSC also translates the 13 Kbps voice channel used over the radio linkto the standard 64 Kbps channel used by the Public Switched Telephone Network (PSDN)or ISDN.It assigns and releases frequencies and time slots for the MS. The BSC also handlesintercell handover. It controls the power transmission of the BSS and MS in its area. Thefunction of the BSC is to allocate the necessary time slots between the BTS and the MSC.It is a switching device that handles the radio resources.The additional functions include: Control of frequency hopping Performing traffic concentration to reduce the number of lines from the MSC Providing an interface to the Operations and Maintenance Center for the BSS Reallocation of frequencies among BTSs Time and frequency synchronization Power management Time-delay measurements of received signals from the MSGSM - The Network Switching Subsystem (NSS)The Network switching system (NSS), the main part of which is the Mobile SwitchingCenter (MSC), performs the switching of calls between the mobile and other fixed or mobilenetwork users, as well as the management of mobile services such as authentication.12
GSMThe switching system includes the following functional elements:Home Location Register (HLR)The HLR is a database used for storage and management of subscriptions. The HLR isconsidered the most important database, as it stores permanent data about subscribers,including a subscriber's service profile, location information, and activity status. When anindividual buys a subscription in the form of SIM, then all the information about thissubscription is registered in the HLR of that operator.Mobile Services Switching Center (MSC)The central component of the Network Subsystem is the MSC. The MSC performs theswitching of calls between the mobile and other fixed or mobile network users, as well asthe management of mobile services such as registration, authentication, location updating,handovers, and call routing to a roaming subscriber. It also performs such functions as tollticketing, network interfacing, common channel signaling, and others. Every MSC isidentified by a unique ID.Visitor Location Register (VLR)The VLR is a database that contains temporary information about subscribers that isneeded by the MSC in order to service visiting subscribers. The VLR is always integratedwith the MSC. When a mobile station roams into a new MSC area, the VLR connected tothat MSC will request data about the mobile station from the HLR. Later, if the mobilestation makes a call, the VLR will have the information needed for call setup without havingto interrogate the HLR each time.13
GSMAuthentication Center (AUC)The Authentication Center is a protected database that stores a copy of the secret keystored in each subscriber's SIM card, which is used for authentication and ciphering of theradio c
GSM 2 About the Tutorial GSM is a globally accepted standard for digital cellular communications. GSM uses narrowband Time Division Multiple Access (TDMA) for providing voice and text based services over mobile phone networks. So, this tutorial is divided into different chapters and descr
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2.2 The Global System for Mobile Communications (GSM) 56 2.3 The GSM Network Architecture 57 2.4 The GSM Radio Interface 58 2.5 Logical Channels in GSM 58 2.5. 1 Burst Structure for GSM 61 2.5.2 Mapping of Logical Channels in GSM 62 2.5.3 Mapping of Traffic Channels and Associaled Control Channels 65 2.5.4 Mapping of the BCCl-VCCCH 65
would usually be the source for mains failure back up). 5. The Auto dialer will automatically start to search for the SIM card GSM network. The words "GSM Start" will appear in the display and a counting sequence from 1 to 5. If the GSM network is found, the display will change to "On GSM Ready".
A novel mechanism for anonymizing GSM calls 5 GSM Carrier: This role ff the GSM mobile phone service. We assume the entities GSM carrier A, C and B, for Alice, Carol and Bob respectively. GSM Carrier A is assumed to be malicious and all other entities are assumed to be honest but curious. De nition 1.
GSM/GPRS/GNSS HAT User Manual 1 / 32 GSM/GPRS/GNSS HAT User Manual OVERVIEW This is a handy, low power Raspberry Pi HAT which features multi communication functionalities: GSM, GPRS, GNSS and Blueto
Sources: 1. Compatibility Study for UMTS Operating within the GSM 900 and GSM 1800 bands - ECC/CEPT . 2. Paper titled "Frequency coordination between UMTS and GSM systems at 900 MHz" submitted by Qualcomm and Huawei to 8. th. Annual IEEE International Symposium (PIMRC '07) 2 additional carriers for GSM. WCDMA/HSPA . GSM. 2.6 MHz. 2.2 .
Motorola T720 GSM R2.0 Motorola T720i GSM R2.0.5 Mobile Phone User Guide Preliminary Draft August 5, 2002 The T720 GSM product includes two user documents: A user guide (approximately 100 pages for the English version) that will be packaged in the box with the phone. This guide provides basic information for consumers.
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