GSM Tutorial

Discuss GSM

Discuss GSM &-8211; this Article or News was published on this date:2019-05-13 20:46:00 kindly share it with friends if you find it helpful

Discuss GSM


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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.



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GSM &-8211; Home

GSM &-8211; Overview

GSM &-8211; Architecture

GSM &-8211; Specification

GSM &-8211; Addressing

GSM &-8211; Operations

GSM &-8211; Protocol Stack

GSM &-8211; User Services

GSM &-8211; Security

GSM &-8211; Billing

GSM &-8211; Mobile Phones

GSM &-8211; Quick Guide

GSM &-8211; Useful Resources

GSM &-8211; Acronyms

GSM &-8211; Discussion

UPSC IAS Exams Notes

Developer&-8217;s Best Practices

Questions and Answers

Effective Resume Writing

HR Interview Questions

Computer Glossary

Who is Who

GSM – Useful Acronyms

GSM &-8211; Useful Acronyms &-8211; this Article or News was published on this date:2019-05-13 20:45:59 kindly share it with friends if you find it helpful

GSM &-8211; Useful Acronyms


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The following is a compiled list of mobile terms and acronyms taken from a GSM Association supported publication.

K
Y
Z

1G

The first generation of analogue mobile phone technologies including AMPS, TACS and NMT

2G

The second generation of digital mobile phone technologies including GSM, CDMA IS-95 and D-AMPS IS-136

2.5G

The enhancement of GSM which includes technologies such as GPRS

3G

The third generation of mobile phone technologies covered by the ITU IMT-2000 family

3GPP

The 3rd Generation Partnership Project, a grouping of international standards bodies, operators and vendors with the responsibility of standardising the WCDMA based members of the IMT-2000 family

3GPP2

The counterpart of 3GPP with responsibility for standardising the CDMA2000-based members of the IMT-2000 family. 3GPP2 is spearheaded by ANSI

8PSK

Octantal Phase Shift Keying

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A5/1/2/3/8X

Encryption algorithms for GSM networks

AAL

ATM Adaptation Layer

ABR

Available Bit Rate

A-bis

Interface between the BSC and BTS in a GSM network

AB

Access Burst; used for random access and characterised by a longer guard period to allow for burst transmission from a MS that does not know the correct timing advance when first contacting a network

ACTE

Approvals Committee for Terminal Equipment

ACTS

Advanced Communications Technologies and Services, an European technology initiative

ACU

Antenna Combining Unit

ADPCM

Adaptive Differential Pulse Code Modulation; a form of voice compression that typically uses 32kbit/s

AFC

Automatic Frequency Control

AGCH

Access Grant Channel; downlink only, BTS allocates a TCH or SDCCH to the MS, allowing it access to the network

Air interface

In a mobile phone network, the radio transmission path between the base station and the mobile terminal

A-interface

Interface between the MSC and BSS in a GSM network

AM

Amplitude Modulation

AMPS

Advanced Mobile Phone System, the analogue mobile phone technology used in North and South America and in around 35 other countries. Operates in the 800MHz band using FDMA technology

AMR

Adaptive Multi-Rate codec. Developed in 1999 for use in GSM networks, the AMR has been adopted by 3GPP for 3G

Analogue

The representation of information by a continuously variable physical quantity such as voltage

ANSI

American National Standards Institute. An non-profit making US organisation, which does not carry out standardisation work but reviews the work of standards bodies and assigns them category codes and numbers

ANSI-136

See D-AMPS

API

Application Program Interface

AoC

Advice of Charge

ARIB

Association of Radio Industries and Businesses. An organisation established by Japan&-8217;s Ministry of Posts and Communications to act as the standardisation authority for radio communication and broadcasting

ARPU

Average Revenue Per User

ASCII

American Standard Code for Information Interchange

ASIC

Application Specific Integrated Circuit

ASP

Application Service Provider

Asymmetric Transmission

Data transmissions where the traffic from the network to the subscriber is at a higher rate than the traffic from the subscriber to the network

A-TDMA

Advanced Time Division Multiple Access

ATM

Asynchronous Transfer Mode; a multiplexed information transfer and switching method in which the data is organised into fixed length 53-octet cells and transmitted according to each application.s instantaneous need

AUC

Authentication Centre; the element within a GSM network which generates the parameters for subscriber authentication

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Bandwidth

A term meaning both the width of a transmission channel in terms of Hertz and the maximum transmission speed in bits per second that it will support

BCH

Broadcast Channels; carry only downlink information and are mainly responsible for synchronisation and frequency correction (BCCH, FCCH and SCH)

BCCH

Broadcast Control Channel; the logical channel used in cellular networks to broadcast signalling and control information to all mobile phones within the network

B-CDMA

Broadband Code Division Multiple Access

B-ISDN

Broadband ISDN

BER

Bit Error Rate; the percentage of received bits in error compared to the total number of bits received

BERT

Bit Error Rate Test

Bit

A bit is the smallest unit of information technology. As bits are made up using the binary number system, all multiples of bits must be powers of two, i.e., a kilobit is actually 1024 bits and a megabit 1048576 bits. Transmission speeds are given in bits per second (bit/s)

Bluetooth

A low power, short range wireless technology designed to provide a replacement for the serial cable. Operating in the 2.4GHz ISM band, Bluetooth can connect a wide range of personal, professional and domestic devices such as laptop computers and mobile phones together wirelessly

BHCA

Busy Hour Call Attempts; the number of call attempts made during a network&-8217;s busiest hour of the day

BSC

Base Station Controller; the network entity controlling a number of Base Transceiver Stations

BSS

Base Station System/Subsystem

BTS

Base Transceiver Station; the network entity, which communicates with the mobile station

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CAI

Common Air Interface; a standard developed for the UK&-8217;s public CT2 networks which enabled the same handset to be used on different networks

CAMEL

Customised Application for Mobile network Enhanced Logic; an IN feature in GSM networks that enables users to carry personal services with them when roaming into other networks that support CAMEL

CSE

CAMEL Service Environment

Capacity

A measure of a cellular network&-8217;s ability to support simultaneous calls

CB

Cell Broadcast

CC

Call Control; manages call connections

CCB

Customer Care and Billing

CCCH

Common Control Channels; a group of uplink and downlink channels between the MS and the BTS (see PCH, AGCH and RACH)

CCS7

Common Channel Signalling No. 7

CDMA

Code Division Multiple Access; also known as spread spectrum, CDMA cellular systems utilise a single frequency band for all traffic, differentiating the individual transmissions by assigning them unique codes before transmission. There are a number of variants of CDMA (see W-CDMA, B-CDMA, TD-SCDMA et al)

CDMAone

The first commercial CDMA cellular system; deployed in North America and Korea; also known as IS-95

CDMA2000

A member of the IMT-2000 3G family; backwardly compatible with cdmaOne

CDMA 1X

The first generation of cdma2000; the standardisation process indicated that there would be CDMA 2X and CDMA 3X but this no longer appears likely

CDMA 1X EV-DO

A variant of CDMA 1X which delivers data only

CDPD

Cellular Digital Packet Data; a packet switched data service largely deployed in the USA. The service uses idle analogue channels to carry the packetised information

CDPSK

Coherent Differential Phase Shift Keying

CDR

Call Detail Records; the record made within the cellular network of all details of both incoming and outgoing calls made by subscribers, The CDR is passed to the billing system for action

Cell

The area covered by a cellular base station. A cell site may sectorise its antennas to service several cells from one locationCell site

The facility housing the transmitters/receivers, the antennas and associated equipment

Cell splitting

The process of converting a single cell to multiple cells by sectorising the antennas in the cell site or constructing additional cells within a cell site

CELP

Code Excited Linear Prediction; an analogue to digital voice coding scheme, there are a number of variants used in cellular systems

CEPT

Conference of European Posts and Telecommunications. A organisation of national posts, telegraphs and telephone administrations. Until 1988, when this work was taken over by ETSI, the main European body for telecommunications standardisation. CEPT established the original GSM standardisation group

CF

Call Forwarding

CI

Carrier to Interference ratio

CIBER

Cellular Intercarrier Billing Exchange Roamer Record

CID

Caller Identification

Circuit switching

A method used in telecommunications where a temporary dedicated circuit of constant bandwidth is established between two distant endpoints in a network. Mainly used for voice traffic; the opposite of packet switching

CLID

Calling Line Identification

CLIP

Calling Line Identification Presentation

CLIR

Calling Line Identification Restriction

CM

Connection Management; is used to set up, maintain and take down call connections

CMOS

Complementary Metal Oxide Substrate

Codec

A word formed by combining coder and decoder, the codec is a device, which encodes and decodes signals. The voice codec in a cellular network converts voice signals into and back from bit strings. In GSM networks, in addition to the standard voice codec, it is possible to implement Half Rate (HR) codecs and Enhanced Full Rate (EFR) codecs

Control signal

A signal sent to a cellular phone from a base station or vice versa which carries information essential to the call but not including the audio portion of a conversation

CPE

Customer Premises Equipment; all the equipment on the end user.s side of the network interface

CPU

Central Processing Unit

CRC

Cyclic Redundancy Check

CRM

Customer Relationship Management

CSS

Customer Support System

CT

Cordless Telephony

CT0

Zero generation cordless telephony; the earliest domestic cordless phones which used analogue technology and which had severe limitations in terms of range and security

CT1

First generation cordless telephony; Improved analogue phones with greater range and security; a number of European nations produced CT1 standards

CT2

Second generation cordless telephony; Using digital technology CT2 phones offered greater range, improved security and a wide range of new functionalities. Used in both domestic and cordless PABX deployments, CT2 was standardised as an interim ETS but was overwhelmed by DECT

CT2-CAI

Second generation cordless telephony-common air interface

CTA

Cordless Terminal Adaptor; a DECT term

CTM

Cordless Terminal Mobility

CTR

Common Technical Regulation; part of the ETSI standardisation process

CUG

Closed User Group

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D/A

Digital to Analogue conversion

DAC

Digital to Analogue Converter

DAMA

Demand Assigned Multiple Access

D-AMPS

Digital AMPS, a US wireless standard also known as IS-136

DAN

DECT Access Node

DCA

Dynamic Channel Assignment

DCCH

Dedicated Control Channels; responsible for roaming, handovers, encryption, etc., (See SDCCH, SACCH and FACCH)

DCE

Data Communications Equipment

DCH

Data Clearing House

DCPSK

Differentially Coherent Phase Shift Keying

DCS1800

Digital Cellular System at 1800MHz, now known as GSM1800

DECT

Digitally Enhanced Cordless Telecommunications system, a second generation digital cordless technology standardised by ETSI

DEPSK

Differential Encoded Phase Shift Keying

DES

Digital Encryption Standard

DFSK

Double Frequency Shift Keying

Digital

a method of representing information as numbers with discrete values; usually expressed as a sequence of bits

DPCM

Differential Pulse Code Modulation

DPSK

Digital Phase Shift Keying

DQPSK

Digital Quadrature Phase Shift Keying

DS-CDMA

Direct Sequence CDMA

DSP

Digital Signal Processing

DSRR

Digital Short Range Radio; a UK standard for a low power, short range radio system designed for small voice and data networks

DTE

Data Terminal Equipment

DTMF

Dual Tone MultiFrequency; better know as Touch Tone. The tones generated by touching the keys on the phone are used for a variety of purposes including voice mail systems and voice messaging

DTX

Discontinuous Transmission

Dual Band

The capability of GSM infrastructure elements and handsets to work across both the 900MHz and 1800MHz bands. The capability to seamlessly handover between the two bands offers operators major capacity gains

DB

Dummy Burst; transmitted as a filler in unused timeslots of the carrier

Duplex

The wireless technique where one frequency band is used for traffic from the network to the subscriber (the downlink) and another, widely separated, band is used for traffic from the subscriber to the network (the uplink)

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EDGE

Enhanced Data rates for GSM Evolution; effectively, the final stage in the evolution of the GSM standard, EDGE uses a new modulation schema to enable theoretical data speeds of up to 384kbit/s within the existing GSM spectrum. An alternative upgrade path towards 3G services for operators, such as those in the USA, without access to new spectrum. Also known as Enhanced GPRS (E-GPRS)

EEPROM

Electrically Erasable Programmable Read Only Memory

EFR

Enhanced Full Rate; an alternative voice codec that provides improved voice quality in a GSM network (see codec)

EFT

Electronic Funds Transfer

EGSM

Extended (frequency range) GSM

EIR

Equipment Identity Register; a database that contains a list of all valid mobile stations within a network based on their IMEI

EIRP

Effective Isotropic Radiated Power

EPOC

The mobile phone operating system developed by Symbian. Derived from epoch-the beginning of an era-EPOC is a 32-bit operating environment, which comprises a suite of applications, customisable user interfaces, connectivity options and a range of development tools.

EPROM

Erasable Programmable Read Only Memory

Erlang

A dimensionless unit of average traffic density in a telecommunications network

ERMES

Enhanced Radio Messaging System; a paging technology developed by ETSI which was intended to allow users to roam throughout Europe. Adopted by a number of European and Middle Eastern countries, ERMES, like paging in general, was overtaken by the ubiquity of GSM

ERO

European Radiocommunications Office

ERP

Effective Radiated Power

ESMR

Enhanced Special Mobile Radio; a US PMR variant (see SMR)

ESN

Electronic Serial Number; a 32-bit number that uniquely identifies a mobile phone

ESPRIT

European Strategic Programme for Research and Development in Information Technology

ETACS

Extended TACS; the extension of TACS by the addition of new frequencies

ETSI

European Telecommunications Standards Institute: The European group responsible for defining telecommunications standards

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FACCH

Fast Associated Control Channel; similar to the SDCCH but used in parallel for operation of the TCH. If the data rate of the SACCH is insufficient borrowing mode is used

FB

Frequency Correction Burst; used for frequency synchronisation of the mobile

FCC

Federal Communications Commission; the US regulatory body for telecommunications

FCCH

Frequency Correction Channel; downlink only, correction of MS frequencies, transmission of frequency standard to MS, etc.

FDD

Frequency Division Duplex; a radio technique, which uses paired spectrum; UMTS has an FDD element

FDMA

Frequency Division Multiple Access-a transmission technique where the assigned frequency band for a network is divided into sub-bands, which are allocated to a subscriber for the duration of their calls

FEC

Forward Error Correction

FH

Frequency Hopping

FH-CDMA

Frequency Hopping CDMA

FMC

Fixed Mobile Convergence

FMI

Fixed Mobile Integration

FPLMTS

Future Public Land Mobile Telecommunications System, the original title of the ITU&-8217;s third generation concept now known as IMT-2000

FRA

Fixed Radio Access; see WLL

FSDPSK

Filtered Symmetric Differential Phase Shift Keying

FSK

Frequency Shift Keying; a method of using frequency modulation to send digital information

FSOQ

Frequency Shift Offset Quadrature Modulation

FSS

Fixed Satellite ServiceGb

The interface between the PCU and the SGSN in a GSM/GPRS network

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Gc

The interface between the GGSN and the HLR in a GSM/GPRS network

Gd

The interface between the SGSN and the SMSC in a GSM/GPRS network

Gf

The interface between the SGSN and the EIR in a GSM/GPRS network

Gi

The interface between the GGSN and the Internet in a GPRS network

Gn

The interface between the GGSN and the SGSN in a GPRS network

Gp

The interfaces between the GGSN/SGSN and the Border Gateway in a GPRS network

Gr

The interface between the SGSN and the HLR in a GPRS network

Gs

The interface between the SGSN and the MSC in a GSM/GPRS network

GAIT

GSM/ANSI 136 Interoperability Committee

GAP

Generic Access Profile; a DECT term

Gbit/s

A unit of data transmission rate equal to one billion bits per second

GMSC

Gateway Mobile Services Switching Centre; the gateway between two networks

GCF

Global Certification Forum

Geostationary

Refers to a satellite in equatorial orbit above the earth which appears from the surface to be stationary

GERAN

GSM-EDGE Radio Access Network; the name for the evolution of GSM towards 3G based on EDGE

GGRF

GSM Global Roaming Forum

GGSN

Gateway GPRS Support Node; the gateway between a cellular network and a IP network.

GHz

A unit of frequency equal to one billion Hertz per second

GMPCS

Global Mobile Personal Communications by Satellite

GMSK

Gaussian filtered Minimum Shift Keying; a refinement of FSK which minimises adjacent channel interference

GPRS

General Packet Radio Service; standardised as part of GSM Phase 2+, GPRS represents the first implementation of packet switching within GSM, which is a circuit switched technology. GPRS offers theoretical data speeds of up to 115kbit/s using multislot techniques. GPRS is an essential precursor for 3G as it introduces the packet switched core required for UMTS

GPS

Global Positioning System; a location system based on a constellation of US Department of Defence satellites. Depending on the number of satellites visible to the user can provide accuracies down to tens of metres. Now being incorporated as a key feature in an increasing number of handsets

GRX

GPRS Roaming Exchange

GSM

Global System for Mobile communications, the second generation digital technology originally developed for Europe but which now has in excess of 71 per cent of the world market. Initially developed for operation in the 900MHz band and subsequently modified for the 850, 1800 and 1900MHz bands. GSM originally stood for Group Special Mobile, the CEPT committee, which began the GSM standardisation process

GSM MoU

The GSM Memorandum of Understanding, an agreement signed between all the major European operators to work together to promote GSM. The precursor of the GSM Association

GSM-R

GSM-Railway, A variant of GSM designed to meet the special communications needs of international train operators

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Handoff

The transfer of control of a cellular phone call in progress from one cell to another, without any discontinuity

Hands-free

The operation of a cellular phone without using the handset; usually installed in vehicles.

HCS

Hierarchical Cell Structure; the architecture of a multi-layered cellular network where subscribers are handed over from the macro to the micro to the pico layer depending on the current network capacity and the needs of the subscriber

HDLC

High level Data Link Control

HIPERLAN

High Performance Radio Local Access Network; a wireless local area network being standardised by ETSI (Also HIPERLAN2)

HLR

Home Location Register; the database within a GSM network which stores all the subscriber data. An important element in the roaming process

HSCSD

High Speed Circuit Switched Data; a special mode in GSM networks which provides higher data throughput By cocatenating a number of timeslots, each delivering 14.4kbit/s, much higher data speeds can be achieved

HSPSD

High Speed Packet Switched DataIub

The interface between the Node B and the RNC in a UMTS network

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Iur

The interface between RNCs in a UMTS network

Iups

The connection between the RNC and the packet switched network in a GSM/GPRS/UMTS network

Iucs

The connection between the RNC and the circuit switched network in a GSM/GPRS/UMTS network

I-ETS

Interim European Telecommunications Standard

I-mode

A service developed by Japanese operator NTT DoCoMo, I-mode delivers a huge range of services to subscribers and has proved enormously popular with some 30 million regular users. The revenue sharing model used for I-mode is being adopted by other operators as the basis for the new services enabled by GPRS and 3G

IMEI

International Mobile Equipment Identity

IMSI

International Mobile Subscriber Identity; an internal subscriber identity used only by the network

IMT-2000

The family of third generation technologies approved by the ITU. There are five members of the family: IMT-DS, a direct sequence WCDMA FDD solution IMT-TC, a WCDMA TDD solution IMT-MC, a multicarrier solution developed from cdma2000 IMT-SC, a single carrier solution developed from IS-136/UWC-136 IMT-FT, a TDMA/TDD solution derived from DECT

IN

Intelligent Network

INAP

Intelligent Network Application Part

Internet

A loose confederation of autonomous databases and networks. Originally developed for academic use the Internet is now a global structure of millions of sites accessible by anyone

Intranet

A private network which utilises the same techniques as the Internet but is accessible only by authorised users

IP

Internet Protocol

IPR

Intellectual Property Rights

IPv6

The next generation of IP addressing designed to replace the current system IPv4 which uses a 32 bit address code which limits the number of possible addresses. IPv6 uses a 128 bit code ensuring that the possible number of IP addresses will be virtually limitless

IrDA

Infra red Data Association

Iridium

A low earth orbit satellite communications system developed initially by Motorola.

IS-54

The first evolution in the USA from analogue to digital technology. Used a hybrid of analogue and digital technology, superseded by IS-136

IS-95

Cellular standard know also as cdmaOne

IS-136

Cellular standard also known as TDMA or D-AMPS

ISDN

Integrated Services Digital Network

ISO

International Standards Organisation

ISP

Internet Service Provider

ITU

International Telecommunications Union

ITU-R

ITU Telecommunications Radio Sector

ITU-T

ITU Telecommunications Standardisation Sector

IWF

Interworking Function

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Java

A programming language developed by Sun Microsystems Java is characterised by the fact that programs written in Java do not rely on an operating system

JPEG

Joint Photographic Experts Group

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LAN

Local Area Network

LANS

Local Area Network Services

LAP

Link Access Protocol

LEO

Low Earth Orbit; refers to satellites, which orbit the Earth at around 1,000 kilometres

LMSS

Land Mobile Satellite Service

LOS

Line of Sight

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MAC

Media Access Control; the lower sublayer of the OSI system

MAN

Metropolitan Area Network

MAP

Mobile Application Part

Mbit/s

Megabit; a unit of data transmission speed equal to one million bits per second

MHz

Megahertz; a unit of frequency equal to one million Hertz

MCPA

Multi Carrier Power Amplifier

MeXe

Mobile Execution Environment; likely to be based on Java, MeXe enables WAP-enabled devices to offer a wider range of features with greater security and flexibility, as well as greater control of telephony features

MFSK

Multiple Frequency Shift Keying

MMI

Man Machine Interface

MMS

Multimedia Messaging Service; an evolution of SMS, MMS goes beyond text messaging offering various kinds of multimedia content including images, audio and video clips

MMSK

Modified Minimum Shift Keying

MNO

Mobile Network Operator

Modulation

The process of imposing an information signal on a carrier. This can be done by changing the amplitude (AM), the frequency (FM) or the phase, or any combination of these

MoU

Memorandum of Understanding &-8211; see GSM MoU

MPEG

Motion Picture Experts Group; MPEG4 is a technology for compressing voice and video so that the information can be transmitted over normally difficult links such as mobile radio

MS

Mobile Station

MSC

Mobile Switching Centre; the switching centre of a mobile phone network, the MSC has interfaces to the BSCs, HLR, VLR and other MSCs

MSISDN

Mobile Station International ISDN Number

MSK

Minimum Shift Keying; Another term for FFSK

Multiplexing

A telecommunications technique where several channels can be combined to share the same transmission medium. The most common forms are Time Division Multiplexing (TDM) and Frequency Division Multiplexing (FDM)

MVPN

Mobile Virtual Private Network

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N-AMPS

Narrowband AMPS

NB

Normal Burst; used to carry traffic and control channels except RACH

NET

Norme Europeenne de Telecommunications

NMT

Nordic Mobile Telephone system; an analogue cellular technology deployed in the Nordic countries in the late 1970.s; variations were also deployed in the Benelux countries and in Russia. NMT operated in the 450 and 900MHz bands and was the first technology to offer international roaming, albeit only in the Nordic countries

Node B

The element in a UMTS network which interfaces with the mobile station, analogous to a BTS in a GSM network

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OTA

Over the air activation (of services and tariff changes)

O&M

Operations and Maintenance

OMC

Operations and Maintenance Centre

OMC-R

The radio OMC

OMC-S

The switching OMC

OSI

Open Systems Interconnection; a seven layer model for protocols defined by ISO

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PACS

Personal Access Communication System; a digital cordless technology developed initially by Bell Labs in the US, PACS was designed to compete with DECT

Packet switching

A communication system wherein the information is transmitted in packets of a set size. These packets have address headers and find their way to their destination by the most efficient route through the network. Compared to circuit switching where a connection is occupied until the traffic exchange is completed, packet switching offers considerable efficiencies as connections can be used by a number of users simultaneously

PAMR

Public Access Mobile Radio; Commercial service using trunking techniques in which multiple groups of users can set up their own closed systems within a shared public network

PAP

Public Access Profile; a DECT term

PCH

Paging Channel; downlink only, the MS is informed of incoming calls by the BTS via the PCH

PCM

Pulse Code Modulation; the standard digital voice format at 64kbit/s

PCMCIA

Personal Computer Memory Card Interface Association the body responsible for defining the standards and formats for memory expansion cards for laptop computers and PDAs. Now extended to cover cards for mobile phones

PCN

Personal Communications Network; a designation initially used in the UK to refer to networks operating in the 1800MHz band (see also DCS1800). No longer in use

PCS 1900

Personal Communications Systems 1900MHz; the terminology used in the US to describe the new digital networks being deployed in the 1900MHz band; rarely used today

PCU

Packet Control Unit; an element in a GPRS/UMTS network

PDA

Personal Digital Assistant

PDC

Personal Digital Communications; a digital cellular technology developed and deployed uniquely in Japan. A TDMA technology, PDC is incompatible with any other digital cellular standard

PEDC

Pan European Digital Communications; A designation occasionally used in the early 1990.s to describe GSM. No longer in use

Penetration

The percentage of the total population which owns a mobile phone

PHS / PHP

Personal HandyPhone System/Phone; a digital cordless technology developed in Japan which achieved great success. Deployed by NTT DoCoMo and other Japanese operators PHS offered two-way communications, data services and Internet access and eventually won some 28 million customers. Now in decline as cellular.s wide area capabilities offer better service

PIN

Personal Identifier Number

PKI

Public Key Infrastructure

PLMN

Public Land Mobile Network; any cellular operator.s network

PMR

Private Mobile Radiocommunications; two-way radio technology widely used for despatch and delivery services, taxi companies and the like. See TETRA

POCSAG

Post Office Code Standardisation Group; a now defunct industry grouping, which standardised pager addressing systems

PoP

Points of Presence; a method of measuring the value of a cellular licence; the approximate number of potential customers within a geographical area

POTS

Plain Old Telephone Service

PROM

Programmable Read Only Memory

PSK

Phase Shift Keying

PSRCP

Public Safety Radio Communications Project; an initiative by the UK Government to standardise all emergency services communications on to a single digital technology (see TETRA)

PSDN

Public Switched Data Network

PSPDN

Public Switched Packet Data Network

PSTN

Public Switched Telephone Network

PSU

Power Supply Unit

PTO

Public Telecommunication Operator

PTT

Posts, Telephone and Telegraph Administration

PTT

Push-to-Talk; a feature of PMR systems

PWT

Personal Wireless Telecommunications; a variant of DECT developed for use in the USA

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QAM

Quadrature Amplitude Modulation

QAPSK

Quadrature Amplitude Phase Shift Keying

QCELP

Quadrature Code Excited Linear Prediction

QoS

Quality of Service; a broad term to describe the performance attributes of an end-to-end connection

QPSK

Quadrature Phase Shift Keying

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RACE

Research in Advanced Communications in Europe

RACH

Random Access Channel; uplink only, allows the MS to request an SDCCH in response to a page or for a call

RAM

Random Access Memory

RFP

Radio Fixed Part; equivalent to a base station in a DECT system

RCC

Radio Common Carrier

RELP

Regular pulse Excitation Linear Prediction coding

Reuse

The assignment of frequencies or channels to cells so that adjoining cells do not use the same frequencies and cause interference whereas more distant cells can use the same frequencies. Reuse expands the capacity of a cellular network by enabling the use of the same channels throughout the network

RP

Radio Part

RNC

Radio Network Controller; the element which controls the Node Bs within a UMTS network. It is roughly analogous to a BSC in a GSM network

Roaming

A service unique to GSM which enables a subscriber to make and receive calls when outside the service area of his home network, e.g., when travelling abroad

Router

A device which forwards information in a network on a connectionless basis

RRM

Radio Resource Management, part of the UMTS infrastructure

RT

Remote Terminal

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SACCH

Slow Associated Control Channel; transmits continuous measurements in parallel with operation of TCH or SDCCH; needed for handover decisions

SAR

Specific Absorption Rate

SB

Synchronisation Burst; used for time synchronisation of the mobile

S-CDMA

Synchronous CDMA (see CDMA)

SCH

Synchronisation Channel; downlink only frame synchronisation and identification of base station

SCP

Switching/Service Control Point

SDCCH

Stand-alone Dedicated Control Channel; communications channel between the MS and the BTS. Used for signalling during call set-up before a TCH is allocated

SDLC

Synchronous Data Link Control

SDMA

Spatial Division Multiple Access

SGSN

Serving GPRS Support Node; the gateway between the RNC and the core network in a GPRS/UMTS network

SIM

Subscriber Identity Module; A smart card containing the telephone number of the subscriber, encoded network identification details, the PIN and other user data such as the phone book. A user.s SIM card can be moved from phone to phone as it contains all the key information required to activate the phone

SoHo

Small Office/Home Office

Streaming

An Internet derived expression for the one-way transmission of video and audio content

STK

SIM ToolKit: specified within the GSM standard, this allows operators to add additional functions to the phone menu in order to provide new services such as mobile banking or email

SMR

Specialised Mobile Radio; the US term for private mobile radio (See PMR)

SMS

Short Message Service; a text message service, which enables users to send short messages (160 characters) to other users. A very popular service, particularly amongst young people, with 400 billion SMS messages sent worldwide in 2002

SMSC

SMS Centre &-8211; the network entity, which switches SMS traffic

SMSCB

SMS Cell Broadcast

SMS-MO

SMS Mobile Originated

SMS-MT

SMS Mobile Terminated

SMS-PP

SMS Point to Point

SP

Service Provider

SQAM

Staggered Quadrature Amplitude Modulation

SQPSK

Staggered Quadrature Phase Shift Keying

SS

Supplementary Service Support; handles special services

SS7

Signalling System Number 7 (See CCS7)

SSP

Service Switching Point

STM

Synchronous Transfer Mode

Symbian

A company created by Psion, Nokia, Ericsson and Motorola in 1998 with the aim of developing and standardising an operating system which enable mobile phones from different manufacturers to exchange information

The operating system is known as EPOC. Matsushita has subsequently joined Symbian

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TACS

Total Access Communications System (an AMPS variant deployed in a number of countries principally the UK)

TAP

Transferred Account Procedure; the essential charging methodology for international GSM roaming. There have been four TAP standards, TAP1, TAP2, TAP2+ and TAP3. The latter offers variable record length and is sufficiently flexible to support all future requirements arising from the move to 3G

TBR

Technical Basis for Regulation (part of the ETSI standardisation process)

TCH

Traffic Channel

TD-CDMA

Time Division CDMA

TD-SCDMA

Time Division-Synchronous CDMA; a CDMA variant developed by Chinese vendors which is claimed to offer high data rates and greater coverage

TDD

Time Division Duplex; a radio technology for use in unpaired spectrum. WCDMA/UMTS includes a band for TDD mode usage and both PHS and DECT use this technology

TDMA

Time Division Multiple Access; a technique for multiplexing multiple users onto a single channel on a single carrier by splitting the carrier into time slots and allocating these on a as-needed basis

Telematics

A wireless communications system designed for the collection and dissemination of information, particularly refers to vehicle-based electronic systems, vehicle tracking and positioning, on-line vehicle navigation and information systems and emergency assistance

TETRA

Terrestrial Trunked Radio; a European developed digital private mobile radio technology which is now being extensively deployed worldwide

Tetrapol

A competitive digital PMR technology to TETRA developed by French vendors

TFTS

Terrestrial Flight Telephone System

Timeslot

A frame within a TDMA schema; has a time interval of 576 microseconds. Physical content of a timeslot is known as a burst. Five different burst types exist, they are distinguished by different TDMA frame divisions (see NB, FB, SB, AB and DB)

TIPHON

Telecommunications and Internet Protocol Harmonisation over Networks; an ETSI project designed to support the market for voice communications and voice band communications. In particular TIPHON will ensure that users on IP-based networks can communicate with those on circuit switched networks

TMN

Telecommunications Management Network

TMSI

Temporary Mobile Subscriber Identity; covers the IMSI to prevent over-the-air interception and tracing

TRAU

Transcoder Rate Adapter Unit; the transport unit for a 16kbit/s traffic channel on the A-bis interface

Tri-band

Refers to a mobile phone able to operate on the three internationally designated GSM frequencies- 900, 1800 and 1900MHz

TrueSync

A technology which enables the optimal synchronisation of calendars, address books, action lists and memoranda. It enables multi-point, one-step synchronisation of wireless and wireline devices, desktop computers and server-based applications and services

TRX

Transmitter/receiver (transceiver)

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UI

User Interface

Um

The air interface between the BTS and the MS in a GSM network

Uu

The air interface between the Node B and the MS in a UMTS network.

UMTS

Universal Mobile Telecommunications System; the European entrant for 3G; now subsumed into the IMT-2000 family as the WCDMA technology.

UPN

Universal Personal Number

UPT

Universal Personal Telecommunications

URL

Uniform Resource Locator; the addressing system of the Internet

USO

Universal Service Obligation

UTRA

Universal Terrestrial Radio Access; the air interface component of WCDMA.

UTRAN

Universal Terrestrial Radio Access Network; the UMTS radio access network comprising the RNC, Node B and the air interface

USIM

Universal Subscriber Identity Module; the 3G equivalent of the GSM SIM

UWB

Ultra Wide Band

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VAS

Value Added Services

VBR

Variable Bit Rate

VHE

Virtual Home Environment

VLR

Visitor Location Register

Vocoder

Voice coder

VoIP

Voice over Internet Protocol

VPN

Virtual Private Network

VSAT

Very Small Aperture Terminal

VSELP

Vector Sum Excited Linear Prediction

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WAP

Wireless Application Protocol; a de facto standard for enabling mobile phones to access the Internet and advanced services. Users can access websites and pages which have been converted by the use of WML into stripped-down versions of the original more suitable for the limited display capabilities of mobile phones

WARC

World Administration Radio Conference; an ITU conference held at regular intervals to determine the allocation of spectrum for various services

WCDMA

Wideband CDMA; the technology created from a fusion of proposals to act as the European entrant for the ITU IMT-2000 family

WLL

Wireless Local Loop; a technique for providing telephony and low speed data services to fixed customers using wireless. Regarded as having considerably potential for rapidly addressing the telecommunications gap in developing countries. A number of different WLL solutions have been marketed based on cellular and cordless technologies

WLAN

Wireless Local Area Network; a short range radio network normally deployed in traffic hotspots such as airport lounges, hotels and restaurants. WLAN enables suitably equipped users to access the fixed network wirelessly, providing high speed access (up to 11Mbit/s download) to distant servers. The key WLAN technologies are the IEEE802.11 family and ETSI HIPERLAN/2

WML

Wireless Markup Language; a markup language developed specifically for wireless applications. WML is based on XML

WQAM

Weighted Quadrature Amplitude Modulation

WWW

World Wide Web

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XML

eXtended Markup Language

The Consumer Mobile Glossary

Advice of charge

A service which provides the user with information on the cost of calls from a mobile phone

Airtime

The amount of time a subscriber spends using his/her mobile phone

Battery status/Battery charge display

An indication of the amount of battery life remaining

Battery

A chargeable device which provides the mobile phone with power. A variety of battery technologies have been used for mobile phones including nickel cadmium (NiCad), nickel metal hydride (NiMH) and lithium ion (Li-ion)

Call barring

A service which enables users to bar certain incoming or outgoing calls on their mobile phones

Call timer

A service which keeps track of the amount of airtime being used by the subscriber on a cumulative basis

Call divert

The capability to divert incoming calls to another phone (fixed or mobile) or to an answering service

Call hold

The ability to put an ongoing call on hold whilst answering or making a second call

Caller ID

Caller Identification; displays the name/number of the person calling a mobile phone. Also known as CLI

CLI

See Caller ID

CLR

Clear; the key on a cellular phone which is pressed to remove information from the display

Data capable

Mobile phones which have the capability to enable transmission of data from a laptop computer or PDA via the phone

Dual band

Mobile phones which support transmission and reception of calls on the 900MHz and 1800MHz bands with seamless handover between the two frequency bands

EFR

Enhanced Full Rate (codec); an improved version of the standard voice codec used in GSM phones; offers improved speech quality without impacting on network capacity

END

The key on a cellular phone which is pressed to terminate a call

Infrared data port

A facility on a mobile phone to allow information to be exchanged with other devices e.g. a PC using infra red technology

Lock

A function on a cellular phone which, when activated, prevents use of the phone until the user enters a security code

No Service

An indication on the display of a cellular phone that indicates that the user is in an area where cellular service is unavailable

One-touch dialling

The ability to dial frequently called numbers using a single key stroke; see Speed Dialling

PCN

Personal Communications Networks; an outdated term for GSM services in the 1800MHz band

PDA

Personal Digital Assistant; a sophisticated handheld device with advanced display facilities and a range of business-oriented software programs

Phone book

A list of personal names and numbers stored in a mobile phone.s internal memory or in the SIM card. These numbers can be called by accessing the appropriate memory and making a single key stroke

PIN

Personal Identity Number; a number, usually four digits, that must be keyed into a mobile phone to make it work. A security measure to prevent unauthorised usage

RCL

The function on a cellular phone which recalls a phone number from memory

Roaming

The ability to make and receive calls on the same mobile phone when travelling outside the area of the home network operator

Smartphone

a combination of mobile phone and personal digital assistant

SND

Send; The key on a cellular phone which initiates a call or answers an incoming call

Speed dialling

See One-touch dialling

Standby time

The length of time a battery can power a mobile phone when it is switched on but not making or receiving calls

Talk-time

The length of time a battery can power a mobile phone when making or receiving calls

Voicemail

A service offered by network operators whereby calls received when the mobile is in use, switched off or out of coverage can be diverted to an answering service which can be personalised by the user

WAP

Wireless Application Protocol; a standard whereby mobile phones can gain access to specially tailored Internet websites

WML

Wireless Markup Language; a specially designed markup language used for tailoring WAP content. WML enables optimum usage of the limited display capabilities of the mobile phone 

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GSM &-8211; Home

GSM &-8211; Overview

GSM &-8211; Architecture

GSM &-8211; Specification

GSM &-8211; Addressing

GSM &-8211; Operations

GSM &-8211; Protocol Stack

GSM &-8211; User Services

GSM &-8211; Security

GSM &-8211; Billing

GSM &-8211; Mobile Phones

GSM &-8211; Quick Guide

GSM &-8211; Useful Resources

GSM &-8211; Acronyms

GSM &-8211; Discussion

UPSC IAS Exams Notes

Developer&-8217;s Best Practices

Questions and Answers

Effective Resume Writing

HR Interview Questions

Computer Glossary

Who is Who

GSM – Useful Resources

GSM &-8211; Useful Resources &-8211; this Article or News was published on this date:2019-05-13 20:45:57 kindly share it with friends if you find it helpful

GSM &-8211; Useful Resources


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The following resources contain additional information on GSM Please use them to get more in-depth knowledge on this topic.

  • GSM World − Official Website of GSM Association. Find all the latest news, inventions and standards available at this site.

  • GSM @ Wikipedia − A very useful article on GSM technology and further more links to useful sites.

  • GPRS @ Wikipedia − A very useful article on GPRS technology and further more links to useful sites.

Useful Books on GSM

  • From GSM to LTE: An Introduction to Mobile Networks and Mobile Broadband
  • GSM Networks: Protocols, Terminology and Implementation (Artech House Mobile Communications)
  • The GSM System for Mobile Communications
  • GSM - Architecture, Protocols and Service
  • An Introduction to GSM (Artech House Mobile Communication Series)
  • GSM Switching, Services, and Protocols

To enlist your site on this page, please drop an email to [email protected]



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GSM &-8211; Home

GSM &-8211; Overview

GSM &-8211; Architecture

GSM &-8211; Specification

GSM &-8211; Addressing

GSM &-8211; Operations

GSM &-8211; Protocol Stack

GSM &-8211; User Services

GSM &-8211; Security

GSM &-8211; Billing

GSM &-8211; Mobile Phones

GSM &-8211; Quick Guide

GSM &-8211; Useful Resources

GSM &-8211; Acronyms

GSM &-8211; Discussion

UPSC IAS Exams Notes

Developer&-8217;s Best Practices

Questions and Answers

Effective Resume Writing

HR Interview Questions

Computer Glossary

Who is Who

GSM – Quick Guide

GSM &-8211; Quick Guide &-8211; this Article or News was published on this date:2019-05-13 20:45:55 kindly share it with friends if you find it helpful

GSM &-8211; Quick Guide


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GSM &-8211; Overview

What is GSM?

If you are in Europe or Asia and using a mobile phone, then most probably you are using GSM technology in your mobile phone.

  • GSM stands for Global System for Mobile Communication. It is a digital cellular technology used for transmitting mobile voice and data services.

  • The concept of GSM emerged from a cell-based mobile radio system at Bell Laboratories in the early 1970s.

  • GSM is the name of a standardization group established in 1982 to create a common European mobile telephone standard.

  • GSM is the most widely accepted standard in telecommunications and it is implemented globally.

  • GSM is a circuit-switched system that divides each 200 kHz channel into eight 25 kHz time-slots. GSM operates on the mobile communication bands 900 MHz and 1800 MHz in most parts of the world. In the US, GSM operates in the bands 850 MHz and 1900 MHz.

  • GSM owns a market share of more than 70 percent of the world&-8217;s digital cellular subscribers.

  • GSM makes use of narrowband Time Division Multiple Access (TDMA) technique for transmitting signals.

  • GSM was developed using digital technology. It has an ability to carry 64 kbps to 120 Mbps of data rates.

  • Presently GSM supports more than one billion mobile subscribers in more than 210 countries 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 other streams 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 telephone company services

  • Support for new services

GSM History

The following table shows some of the important events in the rollout of the GSM system.

Years Events
1982 Conference of European Posts and Telegraph (CEPT) establishes a GSM group to widen the standards for a pan-European cellular mobile system.
1985 A list of recommendations to be generated by the group is accepted.
1986 Executed field tests to check the different radio techniques recommended for the air interface.
1987 Time Division Multiple Access (TDMA) is chosen as the access method (with Frequency Division Multiple Access [FDMA]). The initial Memorandum of Understanding (MoU) is signed by telecommunication operators representing 12 countries.
1988 GSM system is validated.
1989 The European Telecommunications Standards Institute (ETSI) was given the responsibility of the GSM specifications.
1990 Phase 1 of the GSM specifications is delivered.
1991 Commercial launch of the GSM service occurs. The DCS1800 specifications are finalized.
1992 The addition of the countries that signed the GSM MoU takes place. Coverage spreads to larger cities and airports.
1993 Coverage of main roads GSM services starts outside Europe.
1994 Data transmission capabilities launched. The number of networks rises to 69 in 43 countries by the end of 1994.
1995 Phase 2 of the GSM specifications occurs. Coverage is extended to rural areas.
1996 June: 133 network in 81 countries operational.
1997 July: 200 network in 109 countries operational, around 44 million subscribers worldwide.
1999 Wireless Application Protocol (WAP) came into existence and became operational in 130 countries with 260 million subscribers.
2000 General Packet Radio Service(GPRS) came into existence.
2001 As of May 2001, over 550 million people were subscribers to mobile telecommunications.

GSM &-8211; Architecture

A GSM network comprises of many functional units. These functions and interfaces are explained in this chapter. The GSM network can be broadly divided into:

Given below is a simple pictorial view of the GSM architecture.

GSM Architecture

The additional components of the GSM architecture comprise of databases and messaging systems functions:

  • Home Location Register (HLR)
  • Visitor Location Register (VLR)
  • Equipment Identity Register (EIR)
  • Authentication Center (AuC)
  • SMS Serving Center (SMS SC)
  • Gateway MSC (GMSC)
  • Chargeback Center (CBC)
  • Transcoder and Adaptation Unit (TRAU)

The following diagram shows the GSM network along with the added elements:

GSM Elements

The MS and the BSS communicate across the Um interface. It is also known as the air interface or the radio link. The BSS communicates with the Network Service Switching (NSS) center across the A interface.

GSM network areas

In a GSM network, the following areas are defined:

  • Cell : Cell is the basic service area; one BTS covers one cell. Each cell is given a Cell Global Identity (CGI), a number that uniquely identifies the cell.

  • Location Area : A group of cells form a Location Area (LA). This is the area that is paged when a subscriber gets an incoming call. Each LA is assigned a Location Area Identity (LAI). Each LA is served by one or more BSCs.

  • MSC/VLR Service Area : The area covered by one MSC is called the MSC/VLR service area.

  • PLMN : The area covered by one network operator is called the Public Land Mobile Network (PLMN). A PLMN can contain one or more MSCs.

GSM &-8211; Specification

The requirements for different Personal Communication Services (PCS) systems differ for each PCS network. Vital characteristics of the GSM specification are listed below:

Modulation

Modulation is the process of transforming the input data into a suitable format for the transmission medium. The transmitted data is demodulated back to its original form at the receiving end. The GSM uses Gaussian Minimum Shift Keying (GMSK) modulation method.

Access Methods

Radio spectrum being a limited resource that is consumed and divided among all the users, GSM devised a combination of TDMA/FDMA as the method to divide the bandwidth among the users. In this process, the FDMA part divides the frequency of the total 25 MHz bandwidth into 124 carrier frequencies of 200 kHz bandwidth.

Each BS is assigned with one or multiple frequencies, and each of this frequency is divided into eight timeslots using a TDMA scheme. Each of these slots are used for both transmission as well as reception of data. These slots are separated by time so that a mobile unit doesn’t transmit and receive data at the same time.

Transmission Rate

The total symbol rate for GSM at 1 bit per symbol in GMSK produces 270.833 K symbols/second. The gross transmission rate of a timeslot is 22.8 Kbps.

GSM is a digital system with an over-the-air bit rate of 270 kbps.

Frequency Band

The uplink frequency range specified for GSM is 933 &-8211; 960 MHz (basic 900 MHz band only). The downlink frequency band 890 &-8211; 915 MHz (basic 900 MHz band only).

Channel Spacing

Channel spacing indicates the spacing between adjacent carrier frequencies. For GSM, it is 200 kHz.

Speech Coding

For speech coding or processing, GSM uses Linear Predictive Coding (LPC). This tool compresses the bit rate and gives an estimate of the speech parameters. When the audio signal passes through a filter, it mimics the vocal tract. Here, the speech is encoded at 13 kbps.

Duplex Distance

Duplex distance is the space between the uplink and downlink frequencies. The duplex distance for GSM is 80 MHz, where each channel has two frequencies that are 80 MHz apart.

Misc

  • Frame duration : 4.615 mS

  • Duplex Technique : Frequency Division Duplexing (FDD) access mode previously known as WCDMA.

  • Speech channels per RF channel : 8.

GSM &-8211; Addresses and Identifiers

GSM treats the users and the equipment in different ways. Phone numbers, subscribers, and equipment identifiers are some of the known ones. There are many other identifiers that have been well-defined, which are required for the subscriber’s mobility management and for addressing the remaining network elements. Vital addresses and identifiers that are used in GSM are addressed below.

International Mobile Station Equipment Identity (IMEI)

The International Mobile Station Equipment Identity (IMEI) looks more like a serial number which distinctively identifies a mobile station internationally. This is allocated by the equipment manufacturer and registered by the network operator, who stores it in the Equipment Identity Register (EIR). By means of IMEI, one recognizes obsolete, stolen, or non-functional equipment.

Following are the parts of IMEI:

  • Type Approval Code (TAC) : 6 decimal places, centrally assigned.

  • Final Assembly Code (FAC) : 6 decimal places, assigned by the manufacturer.

  • Serial Number (SNR) : 6 decimal places, assigned by the manufacturer.

  • Spare (SP) : 1 decimal place.

Thus, IMEI = TAC + FAC + SNR + SP. It uniquely characterizes a mobile station and gives clues about the manufacturer and the date of manufacturing.

International Mobile Subscriber Identity (IMSI)

Every registered user has an original International Mobile Subscriber Identity (IMSI) with a valid IMEI stored in their Subscriber Identity Module (SIM).

IMSI comprises of the following parts:

  • Mobile Country Code (MCC) : 3 decimal places, internationally standardized.

  • Mobile Network Code (MNC) : 2 decimal places, for unique identification of mobile network within the country.

  • Mobile Subscriber Identification Number (MSIN) : Maximum 10 decimal places, identification number of the subscriber in the home mobile network.

Mobile Subscriber ISDN Number (MSISDN)

The authentic telephone number of a mobile station is the Mobile Subscriber ISDN Number (MSISDN). Based on the SIM, a mobile station can have many MSISDNs, as each subscriber is assigned with a separate MSISDN to their SIM respectively.

Listed below is the structure followed by MSISDN categories, as they are defined based on international ISDN number plan:

  • Country Code (CC) : Up to 3 decimal places.

  • National Destination Code (NDC) : Typically 2-3 decimal places.

  • Subscriber Number (SN) : Maximum 10 decimal places.

Mobile Station Roaming Number (MSRN)

Mobile Station Roaming Number (MSRN) is an interim location dependent ISDN number, assigned to a mobile station by a regionally responsible Visitor Location Register (VLA). Using MSRN, the incoming calls are channelled to the MS.

The MSRN has the same structure as the MSISDN.

  • Country Code (CC) : of the visited network.

  • National Destination Code (NDC) : of the visited network.

  • Subscriber Number (SN) : in the current mobile network.

Location Area Identity (LAI)

Within a PLMN, a Location Area identifies its own authentic Location Area Identity (LAI). The LAI hierarchy is based on international standard and structured in a unique format as mentioned below:

  • Country Code (CC) : 3 decimal places.

  • Mobile Network Code (MNC) : 2 decimal places.

  • Location Area Code (LAC) : maximum 5 decimal places or maximum twice 8 bits coded in hexadecimal (LAC FFFF).

Temporary Mobile Subscriber Identity (TMSI)

Temporary Mobile Subscriber Identity (TMSI) can be assigned by the VLR, which is responsible for the current location of a subscriber. The TMSI needs to have only local significance in the area handled by the VLR. This is stored on the network side only in the VLR and is not passed to the Home Location Register (HLR).

Together with the current location area, the TMSI identifies a subscriber uniquely. It can contain up to 4 × 8 bits.

Local Mobile Subscriber Identity (LMSI)

Each mobile station can be assigned with a Local Mobile Subscriber Identity (LMSI), which is an original key, by the VLR. This key can be used as the auxiliary searching key for each mobile station within its region. It can also help accelerate the database access. An LMSI is assigned if the mobile station is registered with the VLR and sent to the HLR. LMSI comprises of four octets (4&-215;8 bits).

Cell Identifier (CI)

Using a Cell Identifier (CI) (maximum 2 × 8) bits, the individual cells that are within an LA can be recognized. When the Global Cell Identity (LAI + CI) calls are combined, then it is uniquely defined.

GSM &-8211; Operations

Once a Mobile Station initiates a call, a series of events takes place. Analyzing these events can give an insight into the operation of the GSM system.

Mobile Phone to Public Switched Telephone Network (PSTN)

When a mobile subscriber makes a call to a PSTN telephone subscriber, the following sequence of events takes place:

  • The MSC/VLR receives the message of a call request.

  • The MSC/VLR checks if the mobile station is authorized to access the network. If so, the mobile station is activated. If the mobile station is not authorized, then the service will be denied.

  • MSC/VLR analyzes the number and initiates a call setup with the PSTN.

  • MSC/VLR asks the corresponding BSC to allocate a traffic channel (a radio channel and a time slot).

  • The BSC allocates the traffic channel and passes the information to the mobile station.

  • The called party answers the call and the conversation takes place.

  • The mobile station keeps on taking measurements of the radio channels in the present cell and the neighbouring cells and passes the information to the BSC. The BSC decides if a handover is required. If so, a new traffic channel is allocated to the mobile station and the handover takes place. If handover is not required, the mobile station continues to transmit in the same frequency.

PSTN to Mobile Phone

When a PSTN subscriber calls a mobile station, the following sequence of events takes place:

  • The Gateway MSC receives the call and queries the HLR for the information needed to route the call to the serving MSC/VLR.

  • The GMSC routes the call to the MSC/VLR.

  • The MSC checks the VLR for the location area of the MS.

  • The MSC contacts the MS via the BSC through a broadcast message, that is, through a paging request.

  • The MS responds to the page request.

  • The BSC allocates a traffic channel and sends a message to the MS to tune to the channel. The MS generates a ringing signal and, after the subscriber answers, the speech connection is established.

  • Handover, if required, takes place, as discussed in the earlier case.

To transmit the speech over the radio channel in the stipulated time, the MS codes it at the rate of 13 Kbps. The BSC transcodes the speech to 64 Kbps and sends it over a land link or a radio link to the MSC. The MSC then forwards the speech data to the PSTN. In the reverse direction, the speech is received at 64 Kbps at the BSC and the BSC transcodes it to 13 Kbps for radio transmission.

GSM supports 9.6 Kbps data that can be channelled in one TDMA timeslot. To supply higher data rates, many enhancements were done to the GSM standards (GSM Phase 2 and GSM Phase 2+).

GSM &-8211; Protocol Stack

GSM architecture is a layered model that is designed to allow communications between two different systems. The lower layers assure the services of the upper-layer protocols. Each layer passes suitable notifications to ensure the transmitted data has been formatted, transmitted, and received accurately.

The GMS protocol stacks diagram is shown below:

GSM Protocol Stack

MS Protocols

Based on the interface, the GSM signaling protocol is assembled into three general layers:

  • Layer 1 : The physical layer. It uses the channel structures over the air interface.

  • Layer 2 : The data-link layer. Across the Um interface, the data-link layer is a modified version of the Link access protocol for the D channel (LAP-D) protocol used in ISDN, called Link access protocol on the Dm channel (LAP-Dm). Across the A interface, the Message Transfer Part (MTP), Layer 2 of SS7 is used.

  • Layer 3 : GSM signalling protocol’s third layer is divided into three sublayers:

    • Radio Resource Management (RR),
    • Mobility Management (MM), and
    • Connection Management (CM).

MS to BTS Protocols

The RR layer is the lower layer that manages a link, both radio and fixed, between the MS and the MSC. For this formation, the main components involved are the MS, BSS, and MSC. The responsibility of the RR layer is to manage the RR-session, the time when a mobile is in a dedicated mode, and the radio channels including the allocation of dedicated channels.

The MM layer is stacked above the RR layer. It handles the functions that arise from the mobility of the subscriber, as well as the authentication and security aspects. Location management is concerned with the procedures that enable the system to know the current location of a powered-on MS so that incoming call routing can be completed.

The CM layer is the topmost layer of the GSM protocol stack. This layer is responsible for Call Control, Supplementary Service Management, and Short Message Service Management. Each of these services are treated as individual layer within the CM layer. Other functions of the CC sublayer include call establishment, selection of the type of service (including alternating between services during a call), and call release.

BSC Protocols

The BSC uses a different set of protocols after receiving the data from the BTS. The Abis interface is used between the BTS and BSC. At this level, the radio resources at the lower portion of Layer 3 are changed from the RR to the Base Transceiver Station Management (BTSM). The BTS management layer is a relay function at the BTS to the BSC.

The RR protocols are responsible for the allocation and reallocation of traffic channels between the MS and the BTS. These services include controlling the initial access to the system, paging for MT calls, the handover of calls between cell sites, power control, and call termination. The BSC still has some radio resource management in place for the frequency coordination, frequency allocation, and the management of the overall network layer for the Layer 2 interfaces.

To transit from the BSC to the MSC, the BSS mobile application part or the direct application part is used, and SS7 protocols is applied by the relay, so that the MTP 1-3 can be used as the prime architecture.

MSC Protocols

At the MSC, starting from the BSC, the information is mapped across the A interface to the MTP Layers 1 through 3. Here, Base Station System Management Application Part (BSS MAP) is said to be the equivalent set of radio resources. The relay process is finished by the layers that are stacked on top of Layer 3 protocols, they are BSS MAP/DTAP, MM, and CM. This completes the relay process. To find and connect to the users across the network, MSCs interact using the control-signalling network. Location registers are included in the MSC databases to assist in the role of determining how and whether connections are to be made to roaming users.

Each GSM MS user is given a HLR that in turn comprises of the user’s location and subscribed services. VLR is a separate register that is used to track the location of a user. When the users move out of the HLR covered area, the VLR is notified by the MS to find the location of the user. The VLR in turn, with the help of the control network, signals the HLR of the MS’s new location. With the help of location information contained in the user’s HLR, the MT calls can be routed to the user.

GSM &-8211; User Services

GSM offers much more than just voice telephony. Contact your local GSM network operator to the specific services that you can avail.

GSM offers three basic types of services:

  • Telephony services or teleservices
  • Data services or bearer services
  • Supplementary services

Teleservices

The abilities of a Bearer Service are used by a Teleservice to transport data. These services are further transited in the following ways:

Voice Calls

The most basic Teleservice supported by GSM is telephony. This includes full-rate speech at 13 kbps and emergency calls, where the nearest emergency-service provider is notified by dialing three digits.

Videotext and Facsmile

Another group of teleservices includes Videotext access, Teletex transmission, Facsmile alternate speech and Facsmile Group 3, Automatic Facsmile Group, 3 etc.

Short Text Messages

Short Messaging Service (SMS) service is a text messaging service that allows sending and receiving text messages on your GSM mobile phone. In addition to simple text messages, other text data including news, sports, financial, language, and location-based data can also be transmitted.

Bearer Services

Data services or Bearer Services are used through a GSM phone. to receive and send data is the essential building block leading to widespread mobile Internet access and mobile data transfer. GSM currently has a data transfer rate of 9.6k. New developments that will push up data transfer rates for GSM users are HSCSD (high speed circuit switched data) and GPRS (general packet radio service) are now available.

Supplementary Services

Supplementary services are additional services that are provided in addition to teleservices and bearer services. These services include caller identification, call forwarding, call waiting, multi-party conversations, and barring of outgoing (international) calls, among others. A brief description of supplementary 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.

    • Calling Line Identification Restriction : A person not wishing their number to be presented to others subscribes to this service.

    • 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&-8217;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.

GSM &-8211; Security and Encryption

GSM is the most secured cellular telecommunications system available today. GSM has its security methods standardized. GSM maintains end-to-end security by retaining the confidentiality of calls and anonymity of the GSM subscriber.

Temporary identification numbers are assigned to the subscriber’s number to maintain the privacy of the user. The privacy of the communication is maintained by applying encryption algorithms and frequency hopping that can be enabled using digital systems and signalling.

This chapter gives an outline of the security measures implemented for GSM subscribers.

Mobile Station Authentication

The GSM network authenticates the identity of the subscriber through the use of a challenge-response mechanism. A 128-bit Random Number (RAND) is sent to the MS. The MS computes the 32-bit Signed Response (SRES) based on the encryption of the RAND with the authentication algorithm (A3) using the individual subscriber authentication key (Ki). Upon receiving the SRES from the subscriber, the GSM network repeats the calculation to verify the identity of the subscriber.

The individual subscriber authentication key (Ki) is never transmitted over the radio channel, as it is present in the subscriber&-8217;s SIM, as well as the AUC, HLR, and VLR databases. If the received SRES agrees with the calculated value, the MS has been successfully authenticated and may continue. If the values do not match, the connection is terminated and an authentication failure is indicated to the MS.

The calculation of the signed response is processed within the SIM. It provides enhanced security, as confidential subscriber information such as the IMSI or the individual subscriber authentication key (Ki) is never released from the SIM during the authentication process.

Signalling and Data Confidentiality

The SIM contains the ciphering key generating algorithm (A8) that is used to produce the 64-bit ciphering key (Kc). This key is computed by applying the same random number (RAND) used in the authentication process to ciphering key generating algorithm (A8) with the individual subscriber authentication key (Ki).

GSM provides an additional level of security by having a way to change the ciphering key, making the system more resistant to eavesdropping. The ciphering key may be changed at regular intervals as required. As in case of the authentication process, the computation of the ciphering key (Kc) takes place internally within the SIM. Therefore, sensitive information such as the individual subscriber authentication key (Ki) is never revealed by the SIM.

Encrypted voice and data communications between the MS and the network is accomplished by using the ciphering algorithm A5. Encrypted communication is initiated by a ciphering mode request command from the GSM network. Upon receipt of this command, the mobile station begins encryption and decryption of data using the ciphering algorithm (A5) and the ciphering key (Kc).

Subscriber Identity Confidentiality

To ensure subscriber identity confidentiality, the Temporary Mobile Subscriber Identity (TMSI) is used. Once the authentication and encryption procedures are done, the TMSI is sent to the mobile station. After the receipt, the mobile station responds. The TMSI is valid in the location area in which it was issued. For communications outside the location area, the Location Area Identification (LAI) is necessary in addition to the TMSI.

GSM &-8211; Billing

GSM service providers are doing billing based on the services they are providing to their customers. All the parameters are simple enough to charge a customer for the provided services.

This chapter provides an overview of the frequently used billing techniques and parameters applied to charge a GSM subscriber.

Telephony Service

These services can be charged on per call basis. The call initiator has to pay the charges, and the incoming calls are nowadays free. A customer can be charged based on different parameters such as:

  • International call or long distance call.
  • Local call.
  • Call made during peak hours.
  • Call made during night time.
  • Discounted call during weekends.
  • Call per minute or per second.
  • Many more other criteria can be designed by a service provider to charge their customers.

SMS Service

Most of the service providers charge their customer&-8217;s SMS services based on the number of text messages sent. There are other prime SMS services available where service providers charge more than normal SMS charge. These services are being availed in collaboration of Television Networks or Radio Networks to demand SMS from the audiences.

Most of the time, the charges are paid by the SMS sender but for some services like stocks and share prices, mobile banking facilities, and leisure booking services, etc. the recipient of the SMS has to pay for the service.

GPRS Services

Using GPRS service, you can browse, play games on the Internet, and download movies. So a service provider will charge you based on the data uploaded as well as data downloaded on your mobile phone. These charges will be based on per Kilo Byte data downloaded/uploaded.

Additional parameter could be a QoS provided to you. If you want to watch a movie, then a low QoS may work because some data loss may be acceptable, but if you are downloading a zip file, then a single byte loss will corrupt your complete downloaded file.

Another parameter could be peak and off peak time to download a data file or to browse the Internet.

Supplementary Services

Most of the supplementary services are being provided based on monthly rental or absolutely free. For example, call waiting, call forwarding, calling number identification, and call on hold are available at zero cost.

Call barring is a service, which service providers use just to recover their dues, etc., otherwise this service is not being used by any subscriber.

Call conferencing service is a form of simple telephone call where the customers are charged for multiple calls made at a time. No service provider charges extra charge for this service.

Closed User Group (CUG) is very popular and is mainly being used to give special discounts to the users if they are making calls to a particular defined group of subscribers.

Advice of Charge (AoC) can be charged based on number of queries made by a subscriber.

GSM &-8211; Mobile Phones

GSM Arena is the biggest source of information about the latest GSM mobile phones. This page is being displayed here as a courtesy of GSM Arena. If you are planning to buy a GSM mobile phone, then we suggest you go through all the review comments and then decide which phone is suitable for you.

Alcatel phones Amoi phones
Apple phones Asus phones
Benefon phones BenQ phones
BenQ-Siemens phones Bird phones
BlackBerry phones Bosch phones
Chea phones Ericsson phones
Eten phones Fujitsu Siemens phones
Gigabyte phones Haier phones
HP phones HTC phones
i-mate phones Innostream phones
Kyocera phones LG phones
Maxon phones Mitac phones
Mitsubishi phones Motorola phones
NEC phones Neonode phones
Nokia phones O2 phones
Palm phones Panasonic phones
Pantech phones Philips phones
Qtek phones Sagem phones
Samsung phones Sendo phones
Sewon phones Sharp phones
Siemens phones Sony phones
Sony Ericsson phones Tel.Me. phones
Telit phones Thuraya phones
Toshiba phones Vertu phones
VK Mobile phones WND phones
XCute phones

GSM Enabled Phones

Samsung GT-S6102 Galaxy Y DUOS Unlocked Dual SIM Phone White HTC A9192 Inspire 4G Unlocked Phone with Android OS, 3G Support, 8 MP Camera, Wi-Fi, and GPS--(Black) Blackberry 9530 Storm Unlocked For Any GSM Carrier Worldwide
LG Optimus Chat C555 Unlocked GSM Slider Cell Phone - Black/Silver I9220(N9000) 5.0 Capacitive Android 4.0 Dual SIM Smart Phone With 8GB ROM GSM Quadband Voice Dialing Watch Cell Phone Unlocked


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GSM &-8211; User Services

GSM &-8211; Security

GSM &-8211; Billing

GSM &-8211; Mobile Phones

GSM &-8211; Quick Guide

GSM &-8211; Useful Resources

GSM &-8211; Acronyms

GSM &-8211; Discussion

UPSC IAS Exams Notes

Developer&-8217;s Best Practices

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GSM – Billing

GSM &-8211; Billing &-8211; this Article or News was published on this date:2019-05-13 20:45:53 kindly share it with friends if you find it helpful

GSM &-8211; Billing


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GSM service providers are doing billing based on the services they are providing to their customers. All the parameters are simple enough to charge a customer for the provided services.

This chapter provides an overview of the frequently used billing techniques and parameters applied to charge a GSM subscriber.

Telephony Service

These services can be charged on per call basis. The call initiator has to pay the charges, and the incoming calls are nowadays free. A customer can be charged based on different parameters such as:

  • International call or long distance call.
  • Local call.
  • Call made during peak hours.
  • Call made during night time.
  • Discounted call during weekends.
  • Call per minute or per second.
  • Many more other criteria can be designed by a service provider to charge their customers.

SMS Service

Most of the service providers charge their customer&-8217;s SMS services based on the number of text messages sent. There are other prime SMS services available where service providers charge more than normal SMS charge. These services are being availed in collaboration of Television Networks or Radio Networks to demand SMS from the audiences.

Most of the time, the charges are paid by the SMS sender but for some services like stocks and share prices, mobile banking facilities, and leisure booking services, etc. the recipient of the SMS has to pay for the service.

GPRS Services

Using GPRS service, you can browse, play games on the Internet, and download movies. So a service provider will charge you based on the data uploaded as well as data downloaded on your mobile phone. These charges will be based on per Kilo Byte data downloaded/uploaded.

Additional parameter could be a QoS provided to you. If you want to watch a movie, then a low QoS may work because some data loss may be acceptable, but if you are downloading a zip file, then a single byte loss will corrupt your complete downloaded file.

Another parameter could be peak and off peak time to download a data file or to browse the Internet.

Supplementary Services

Most of the supplementary services are being provided based on monthly rental or absolutely free. For example, call waiting, call forwarding, calling number identification, and call on hold are available at zero cost.

Call barring is a service, which service providers use just to recover their dues, etc., otherwise this service is not being used by any subscriber.

Call conferencing service is a form of simple telephone call where the customers are charged for multiple calls made at a time. No service provider charges extra charge for this service.

Closed User Group (CUG) is very popular and is mainly being used to give special discounts to the users if they are making calls to a particular defined group of subscribers.

Advice of Charge (AoC) can be charged based on number of queries made by a subscriber.



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GSM &-8211; Home

GSM &-8211; Overview

GSM &-8211; Architecture

GSM &-8211; Specification

GSM &-8211; Addressing

GSM &-8211; Operations

GSM &-8211; Protocol Stack

GSM &-8211; User Services

GSM &-8211; Security

GSM &-8211; Billing

GSM &-8211; Mobile Phones

GSM &-8211; Quick Guide

GSM &-8211; Useful Resources

GSM &-8211; Acronyms

GSM &-8211; Discussion

UPSC IAS Exams Notes

Developer&-8217;s Best Practices

Questions and Answers

Effective Resume Writing

HR Interview Questions

Computer Glossary

Who is Who