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SYSTEM TRAINING

Introduction to GSM

Training Document



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The information in this document is subject to change without notice and describes only theproduct defined in the introduction of this documentation. This document is intended for theuse of Nokia Networks' customers only for the purposes of the agreement under which thedocument is submitted, and no part of it may be reproduced or transmitted in any form ormeans without the prior written permission of Nokia Networks. The document has beenprepared to be used by professional and properly trained personnel, and the customer

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The information or statements given in this document concerning the suitability, capacity, orperformance of the mentioned hardware or software products cannot be considered bindingbut shall be defined in the agreement made between Nokia Networks and the customer.However, Nokia Networks has made all reasonable efforts to ensure that the instructionscontained in the document are adequate and free of material errors and omissions. NokiaNetworks will, if necessary, explain issues which may not be covered by the document.

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Copyright © Nokia Oyj 2003. All rights reserved.



Contents

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Contents

1 Module objectives................................................................................ 5

2 Introduction.......................................................................................... 6 2.1 Mobile communications: Basic concepts................................................ 6 2.2 Channel organisation in GSM/GPRS ................................................... 11 2.2.1 Physical channel and TDMA frame...................................................... 12 2.3 The Public Land Mobile Network ......................................................... 13 2.4 GSM Specifications ............................................................................. 14 2.5 GSM background and requirements .................................................... 15 2.6 Advantages of GSM............................................................................. 16

3 Evolution of GSM............................................................................... 17 3.1 The next step: UMTS........................................................................... 21

4 Review questions .............................................................................. 22



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Preface

Already in the early days, GSM was superior to analogue mobile networks.When the standardisation work for GSM began in 1982, CEPT (Conférence

Européenne des Postes et Télécommunications) could use experiences fromanalogue networks such as NMT (Nordic Mobile Telephone) and TACS (Total

Access Communication System) to create a better digital network.

One main reason for the great success of GSM is that it was a European-wide

project already from the very beginning. Furthermore, the digital mobile system

enabled the supply of more sophisticated services, such as SMS (Short MessageService), and bearer services for data transmission.

Thanks to the global popularity of GSM, we may now use our mobile stations inmore than 130 countries, a fact that has made both business and leisure

travellers' lives much more convenient.

Still today, standardisation continues to specify new features for GSMnetworks. This ambitious work creates opportunities for the operators to

differentiate themselves in a competitive environment. Today, we are more andmore focusing on faster wireless transmission and the introduction of packet

switched data.

There is also an ongoing standardisation for specifying 3G (Third Generation)

networks. The 3G version that is being standardised in, for instance, Europe, is

named UMTS (Universal Mobile Telecommunications System). Its air interfacewill be based on WCDMA (Wideband Code Division Multiple Access)

transmission.

This technically oriented material will help you to better understand the window

of opportunities – today and in the near future. Your active participation will bean essential ingredient for a successful and fulfilling training.



Module objectives

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1 Module objectives

After completing this module, the participant should be able to:

• Name the key terms in mobile communications• List the main improvements from 1G to 2G mobile communications

systems

• Identify five events in the GSM evolution and connect each with the

correct year

without using any references.



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2 Introduction

2.1 Mobile communications: Basic concepts

From ancient to modern times, mankind has been looking for means of long

distance communications. For centuries, letters proofed to be the most reliableway to transmit information. Fire, flags, horns, etc. were used to transmit

information faster.Technical improvements in the 19th century simplified long distance

communications: Telegraphy, and later on telephony. Both techniques werewireline.In 1873, J. C. Maxwell laid the foundation of the electro-magnetic theory by

summarising empirical results in four equations, which are still valid today.

Still, several decades passed by, till Marconi made economic use of this theory by developing devices for wireless transmission of Morse signals (about 1895).Already 6 years later, the first transatlantic wireless transmission of Morse

signals took place. Voice was transmitted the first time in 1906 (R. Fesseden),and one of the first radio broadcast transmission 1909 in New York.

DuplexSimplex

o n e - w a y

two-way

Figure 1. Transmission

The economically most successful wireless application in the first half of the20th century was radio broadcast. There is one transmitter, the so-called radio

station. Information, such as news, music, etc. is transmitted from the radio

station to the receiver equipment, the radio device. This type of one-way

transmission is called simplex transmission. The transmission takes place onlyin one direction, from the transmitter to the receiver. When we take a human



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conversation, a technical solution is required, where the information flow cantake place in two directions. This type of transmission is called duplex

transmission. Walky-talky was already available the early 30ies. This systemalready allowed a transmission of user data in two directions, but there was a

limitation: The users were not allowed to transmit at the same time. In other

words, you could only receive or transmit user information. This type oftransmission is therefore often called semi-duplex transmission. For telephonyservices, a technical solution is required, whereby subscribers have the

impression that they can speak (transmit) and hear (receive) simultaneously.This type of transmission solution is regarded as full duplex transmission.

The first commercial wireless car phone telephony service started in the late

1940 in St. Louise, Missouri (USA). It was a car phone service, because at thattime, the mobile phone equipment was bulky and heavy. Actually, in the start-

up, it filled the whole back of the car. But it was a real full duplex transmission

solution. In the 50ies, several vehicle radio systems were also installed inEurope. These systems are nowadays called single cell systems. The user data

transmission takes place between the mobile phone and the base station (BS).

A base station transmits and receives user data. While a mobile phone is onlyresponsible for its user’s data transmission and reception, a base station iscapable to handle the calls of several subscribers simultaneously. The

transmission of user data from the base station to the mobile phone is called

downlink (DL), the transmission from the mobile phone to the base station

uplink (UL) direction. The area, where the wireless transmission betweenmobile phones and the base station can take place, is the base stations supplyarea, called cell.

cell = supply area

Basestation

Downlink (DL)

Uplink (UL)

Figure 2. Single Cell System

Single cell systems are quite limited. The more and more distant the subscriber

is from the base station, the lower the quality of the radio link. If the subscriberis leaving the supply area of the cell, no communication is possible any more. In



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other words, the mobile communication service was only available within thecell. In order to overcome this limitation, cellular systems were introduced. A

cellular mobile communication system consists of several cells, which canoverlap. By doing so, a whole geographical area can be supported with the

mobile communication service.

Figure 3. Cellular System

But what happens when a subscriber moves during a call from one cell to

another cell? It would be very annoying, if the call were dropped. If thesubscriber is leaving a cell, and in parallel is entering a new cell, then the

system makes new radio resources available in the neighbouring cell, and thenthe call is handed over from on cell to the next one. By doing so, service

continuation is guaranteed, even when the subscriber is moving. The process is

called handover (HO).

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Mobile phone is active,e.g. a call takes place

Service continuationwithout interruption

Figure 4. Handover

A handover takes place during a call, i.e. when the mobile phone is the active(dedicated) mode. A mobile phone can also be in the idle mode. In this case, the

mobile phone is switched on, but no resources were allocated to it and the base

station to allow user data transmission. In this mode, the mobile phone is stilllistening to information, broadcasted by the base station. Why?

Image, there is a mobile terminated call. The mobile phone is then paged in thecell, informed about the situation, that there is a mobile terminated call. But a

cellular system may consist of hundreds of cells. If the network does not know,in which cell the mobile phone is located, it must be paged in all of them. This

costs resources on the radio interface, especially when millions of mobile phones must be paged in the supply area of a mobile operator. Therefore, theoperator of a cellular mobile communications system groups cells in

administrative units called location areas (LA). A mobile phone is paged inonly one location area.

But how does the cellular system know, in which location area the mobile phone is located? And how does the mobile phone know? In every cell, system

information is continuously transmitted. The system information includes thelocation area information. In the idle mode, the mobile phone is listening to this

system information. If the subscriber moves hereby from one cell to the nextcell, and the new cell belongs to the same location area, the mobile stays idle. If

the new cell belongs to a new location area, then the mobile phone has to

become active. It starts a communication with the network, informing it about it

new location. This is stored in databases within the mobile network, and if thereis a mobile terminated call, the network knows where to page the subscriber.

The process, where the mobile phone informs the network about its newlocation is called Location Update Procedure (LUP).



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Location Area 1

Location Area 2

Location Area 3

no Location Update

Location Update

Location Area=

registrationarea of onesubscriber

Figure 5. Location Update and Paging

With the introduction of cellular mobile communication systems, we talk about

‘generations”. First generation mobile communication systems are

• TACS (Total Access Communications System)

• NMT (Nordic Mobile Telephony)

• AMPS (Advanced Mobile Phone Service)

• C450

• Etc.

All of them were commercially launched in the 80s of the last century.The 1st generation mobile communication systems often offered national wide

coverage. But there were still limitations:

Most of them did not support roaming. Roaming is the ability to use anotheroperator’s network infrastructure. International roaming is the ability to go even

to another country and use the local operator’s infrastructure.



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Roaming=

ability to use

differentoperator‘s

infrastructure

GSM subscriberfrom Spain

can use GSM networkin Australia, givenroaming agreementbetween home operatorand visited operator

Example:

Figure 6. Roaming

Most 1st generation mobile communication systems only support speech

transmission, but not data transmission, such as fax. Supplementary services,

well known from ISDN, were not available, such as number indication and callforwarding, when busy. The transmission takes place unprotected via the radio

interface – as a consequence, eavesdropping is possible. Finally, mobile

communication started to become a mass market. And the radio interface is themain bottleneck in terms of capacity. Improved solutions were urgently

required. This led to the inauguration of the 2nd generation mobile

communication systems, one of which is GSM.

2.2 Channel organisation in GSM/GPRS

In GSM 900, 25 MHz spectrum has been frequency divided into 124 bands,each having a bandwidth of 200 kHz. On each of the 200 kHz bands a carrier

can be transmitted at the centre frequency of the band. So the carriers arefrequency division multiplexed.



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UPLINK DOWNLINK

GSM900: 890 MHz - 915 MHz 935 MHz - 960 MHz

GSM1800: 1710 MHz - 1785 MHz 1805 MHz - 1880 MHz

1 2 3 ...

Channel 1 - 124

1 - 374

200 kHz

1 2 3 ...

Duplex frequency 45 MHz / 95 MHz

guard band

Figure 7. FDD and FDMA organisation in GSM

Each carrier is further time divided into timeslots (TSL) and each timeslot isreferred to as a physical channel as information can be transmitted in it. It is

possible to share a physical channel amongst many processes or users. Theseare referred to as logical channels.

2.2.1 Physical channel and TDMA frame

TDMA frame=8 timeslots

01

23

45

76

01

23

45

76

01

23

45

200 kHz

Physcial channel,e.g. allocatedto one

subscriber with FR voice &no frequency hopping

frequency

t i m

e

TDMA frame

Figure 8. TDMA, TDMA frame and physical channel



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Time Division Multiple Access (TDMA), as the name suggests, is a method ofsharing a resource (in this case a radio frequency) between multiple users, by

allocating a specific time (known as a time slot) for each user. This is incontrast to the analogue mobile systems where one radio frequency is used by a

single user for the duration of the conversation. In Time Division Multiple

Access (TDMA) systems each user either receives or transmits bursts ofinformation only in the allocated time slot. These time slots are allocated forspeech only when a user has set up the call. Some timeslots are, however, used

to provide signalling and location updates etc. between calls.

In GSM, a TDMA frame is defined as a grouping TSs that are numbered 0 to 7

as shown above. It has duration of 4.615ms (8 x 577µs).

TDMA frames are transmitted one after another. Every TDMA frame isallocated a frame number.

Um is the acronym for the GSM radio interface. It is an open interface, i.e. it isvery accurately specified. A subscriber can use mobile phones of any

manufacturer without bothering about the operator’s GSM infrastructure and

supplier, as long as the network elements are compliant with the GSMspecifications.

2.3 The Public Land Mobile Network

A mobile operator’s network is called Public Land Mobile Network. It issubdivided into three parts:

• Base Station Subsystem (BSS)

• Network Switching Subsystem (NSS)

• Network Management Subsystem (NMS)

The Network Switching Subsystem is responsible for switching, mobility

management, and traffic element, i.e. that here network elements such asexchanges and databases can be found. The exchanges are responsible for

switching, while the databases are used to keep track of the current location of

the subscriber and his mobile phone. Imagine, a subscriber can be anywhereworldwide, and someone is calling him. There are millions of cells, where the

subscriber and his mobile phone can be located.The Base Station Subsystem is responsible to for a link between the mobile

phone and the exchange, which is presently serving it. The radio interfacerequires hereby a lot of attention. User data must be protected. Therefore

ciphering of user data is done in the base station and the mobile phone. The

transmission must be reliable. If a mobile subscriber wants to make a call, physical resources must be allocated to him. The tasks of the BSS can be

summarised under the key terms Radio Resource Management (RRM) andRadio Link Management (RLM).



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The Network Management System supports the operator in remote networksupervision. Fault, configuration, and performance management are central

tasks performed within the NMS.

Very important open interfaces are the Um interface and the A-interface. Open

interfaces guarantee interworking of network elements from different vendors.An operator may select the NSS from manufacturer 1, the BSS frommanufacturer 2, while the subscriber uses a mobile phone from manufacturer 3.

A

NMSNMS

NSSNSSBSSBSS

O&M

Air

MS

Network SwitchingSubsystem

• Switching• Mobility Management• Connection Management• Charging

Base Station Subsystem

• Radio Resource Management• Radio Link Management

Network Management System•Fault Management•Configuration Management•Performance Management

Figure 9. The Public Land Mobile Network (PLMN)

2.4 GSM SpecificationsOne reason for the major success of GSM is, that it is very accuratelystandardised. The standard is open, i.e. it is available to everyone. The European

Standards Telecommunications Institute (ETSI) is responsible for the GSM

standards. The GSM technical specifications are grouped in this way:

01 General Description of a GSM PLMN02 Services

03 Network Functions04 MS - BSS Interface

05 Radio Path

06 Speech Processing Functions

07 Terminal Adaptation Functions08 BSS - MSC Interface09 Network Inter Working

[10 Service Inter Working]11 Type Approval Procedures

12 Operation and Maintenance



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2.5 GSM background and requirements

At the beginning of the 1980s it was realised that the European countries were

using many different, incompatible mobile phone systems. These systems are

related to as 1G (first generation) systems. In Europe, the most common 1Gsystems were NMT (Nordic Mobile Telephone) and TACS (Total Access

Communications System). In the United States, as well as in other Americancountries, AMPS (Advanced Mobile Phone System) was, and still is, a widely

established system.

With the passage of time, the need for telecommunication services wasremarkably increased. Due to this, CEPT (Conférence Européenne des Postes et

Télécommunications) founded a group to specify a common mobile system forWestern Europe. This group was named “Groupe Spéciale Mobile” and the

system name GSM arose.

This abbreviation has since been interpreted in other ways, but the most

common expression nowadays is Global System for Mobile communications.

GSM is a 2G (second generation) system

Figure 10. GSM – Global System for Mobile communications

At the beginning of the 1990s, the lack of a common mobile system was seen to

be a general, worldwide problem. For this reason the GSM system has now

spread also to the Eastern European countries, Africa, Asia and Australia. TheUSA, South America in general, and Japan had made a decision to adopt othertypes of mobile systems, which are not compatible with GSM. However, in the

USA the Personal Communication System (PCS) has been adopted, which usesGSM technology with a few variations.



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During the time the GSM system was being specified, nationaltelecommunication markets were deregulated. Requirements for openness and

competition were built into the specifications as follows:

• There should be several network operators in each country. This would

lead to competition in tariffs and service provisioning and it would ensurethe rapid expansion of the GSM system. The prices of the equipmentwould fall and the users would find the cost of calls reducing.

• The GSM system must be an open system, meaning that it should contain

well-defined interfaces between different system parts. This enables theequipment from several manufacturers to coexist and hence improves the

cost efficiency of the system from the operator's point of view.

• GSM networks must be built without causing any major changes to thealready existing Public Switched Telephone Networks (PSTN).

In addition to the commercial demands, some other objectives were defined:

• The system must be Pan European.

• The system must maintain a good speech quality.

• The system must use radio frequencies as efficiently as possible.

• The system must have high/adequate capacity.

• The system must be ISDN compatible (Integrated Services Digital

Network) and compatible with other data communication specifications.

• The system must maintain good security both for subscriber andtransmitted information.

2.6 Advantages of GSMDue to the requirements set for the GSM system, many advantages will be

achieved. These advantages can be summarised as follows:

• GSM uses radio frequencies efficiently, and due to the digital radio path,

the system tolerates more intercell disturbances.

• The average speech quality is better than in analogue systems.

• Data transmission is supported throughout the GSM system.

• Speech is encrypted and subscriber information security is guaranteed.

• With ISDN compatibility, new services are offered.

• International roaming is technically possible within all countries using theGSM system.

• The large market increases competition and lowers the prices both forinvestments and usage.



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3 Evolution of GSM

One key factor for the success of GSM was that the standardisation work wasnot completed after 1989. It was initially decided that GSM would evolve over

time. With improvements in computing and radio access technology, GSM willoffer continuous improvement and more services. In 1995 the “Phase 2” recommendations were frozen. The GSM 900 and GSM 1800 specifications

were merged and additional supplementary services were defined, the shortmessage service was improved and improvements in radio access and SIMcards were introduced.

After the Phase 2 recommendations, GSM continues to evolve at full speed.

Many new features are being introduced to GSM and the number ofimprovements is so large that together they are called "Phase 2+" features.

These Phase 2+ features are frozen at regular intervals under what are known as"Releases".

The following list highlights some important years in the short history of GSM:

1982 CEPT initiated a new cellular system. The European Commission

(EC) issued a directive that required member states to reservefrequencies in the 900 MHz band for GSM to allow for roaming.

1986 CEPT tested eight experimental systems in Paris.

1987 Memorandum of Understanding (MoU). Allocation of the frequencies:- 890 - 915 MHz uplink (from mobile to base station)

- 935 - 960 MHz downlink (from base station to mobile)

1988 European Telecommunications Standard Institute (ETSI) was created.

ETSI includes members from administrations, industry, and usergroups.

1989 Final recommendations and specifications for GSM Phase 1.1990 Validation systems implemented and the first GSM World Congress

in Rome with 650 participants.

1991 First official call in the world with GSM on 1st July.

1992 World's first GSM network launched in Finland. First roamingagreement. By December there were 13 networks operating in 7 areas.

Australian operators were the first non-European signatories of theGSM MoU. New frequency allocation for GSM 1800 (DCS 1800).

- 1710 - 1785 MHz (uplink)

- 1805 - 1880 MHz (downlink)

1993 GSM demonstrated for the first time in Africa at Telkom '93 in Cape

Town. Roaming agreements between several operators. By December1993 there were 32 GSM networks operating in 18 areas.

1994 The first GSM network in Africa was launched in South Africa. TheGSM Phase 2 data/fax bearer services were launched. By December

1994 there were 69 GSM networks in operation.



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1995 There were 117 GSM networks operating around the world. Fax, data,and SMS roaming was implemented. The GSM phase 2

standardisation was completed, including adaptation for GSM 1900(PCS 1900). The first GSM 1900 network was implemented in the

USA. Telecom '95 was held in Geneva where Nokia demonstrated

33.6 Kbits/s multimedia data via GSM.

1996 By December there were 120 networks operating. The 8K SIM was

launched in addition to prepaid GSM SIM cards.

1998 HSCSD (High Speed Circuit Switched Data) trials in Singapore. Over2 million GSM 1900 users in the USA and a total of 120 million GSM

900/1800/1900 users worldwide.

1999 The first mobile data call using GPRS (General Packet Radio Service)in a live network was made. The first HSCSD (High Speed Circuit

Switched Data) networks are launched. In December, the 271 million

subscribers sent over 3 billion short messages (G-mails) worldwide. InJanuary 2000 there were 359 GSM networks operating in 132

different countries.GSM 850 support: UL: 824 – 849 MHz and DL: 869 – 894 MHz (for North America).Location Based Services (LBS) services standardised. LBS can be

combined with GPS (Global Positioning System), so that a subscribercan determine his geographical location extremely accurately.

Operator Specific Access (OSA) specified: with it, open application

programming interfaces between an operator’s network infrastructureand external VASP are given. It allows service provision from

external VASP without knowledge of the operator’s internal networkinfrastructure.

The 3G mobile communications system UMTS was specified inDecember. It is based on the GSM standards to allow a smooth

evolution from the 2nd

generation to the 3rd

generation. This ought toguarantee an investment protection for GSM operators.

2000 The first GPRS network is launched.

Second release of UMTS delayed to year 2001

2001 The Multimedia Messaging Service (MMS) has been standardised.

GSM 700 supported; UL: 747 – 762 MHz and DL: 777 – 792 MHz

UMTS and GSM standardised at 3GPP; UMTS/GSM Rel. 4

standardised

2002 UMTS/GSM Rel. 5 standardised (IMS) was standardised forGSM/GPRS and UMTS.

More than 40 MMS services have been launched this year in countriessuch as Czech Republic, Hungary, Germany, and Hong Kong. MMS

(Multimedia Messaging Service) enables personalised multimedia

messages, which can include images, texts, photos, etc. The analystFoster has forecasted that in the year 2007, MMS will account for

more than 30% of the mobile messaging revues. MMS is especially

flexible, when transmitted via the GPRS infrastructure.



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At the end of the year 2002, more that 120 operators are commerciallyoffering GPRS, and more than 40 operators are testing GPRS or

building up a GPRS infrastructure.Smartphones are under development for GSM/GPRS and UMTS – to

allow a wide range of mobile services, such as mobile Internet, mobile

gambling, enhanced LDAs, video messaging, agnostic services, etc.

2003 First commercial starts of UMTS network operators in Europe.

Worldwide, there are more than 1 Billion mobile subscribers, ¾ of

which use GSM.

0

200

400

600

800

1000

1200

1400

Dec 97 Dec 98 Dec 99 Dec 00 Dec 01 Dec 02 Dec 03 Dec 04 Dec 05

Figure 11. GSM customers worldwide and customer forecast (Dec 2002)

There where over 1 Billion wireless subscribers in September 2002 (globally).GSM is the most successful mobile communications system: about 70% use it.



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Figure 12. GSM subscribers worldwide, Sep. 2002

0

5

10

15

20

25

30

J a n 0 0

A p r 0 0

J u l 0 0

O k t 0 0

J a n 0 1

A p r 0 1

J u l 0 1

O k t 0 1

J a n 0 2

A p r 0 2

J u l 0 2

Billion

Jan 00 Jul 00 Jul 01 Jul 02 Jan 00 Jan 02

Source: GSM Association

Figure 13. SMS growth during the last three years

In some European countries, SMS has reached saturation, e.g. it only slightly

growing on a very high level. It is assumed, that MMS will substitute SMS overthe next years.


12.1Russia

4.6South America

16.5North America

8.5India

371.6Europe

5.3East Central Asia

22.7Africa

284.7Asia Pacific

21.5Arabic States

Number ofSubscribers(in Mio.)

Area

747.5 MillionGSM

subscribers

1080 Millionmobile

subscribers


12.1Russia

4.6South America

16.5North America

8.5India

371.6Europe

5.3East Central Asia

22.7Africa

284.7Asia Pacific

21.5Arabic States

Number ofSubscribers(in Mio.)

Area

747.5 MillionGSM

subscribers

1080 Millionmobile

subscribers



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3.1 The next step: UMTS

The third generation solution UMTS, is expected to complete the globalisation

process of the mobile communication. UMTS will mostly be based on GSM

technical solutions due to two reasons. Firstly, the GSM technology dominatesthe market, and secondly, great investments made to GSM should be utilised as

much as possible. Based on this, the specification bodies created a vision abouthow mobile telecommunication will develop within the next decade. Through

this vision, some requirements for 3G were short-listed as follows:

• The system to be developed must be fully specified (like GSM). Thespecifications generated should be valid worldwide.

• The system must bring clear added value when comparing to the GSM in

all aspects. However, in the beginning phase(s) the 3G system must be backward compatible at least with GSM and ISDN.

• Multimedia and all of its components must be supported throughout the

system.

• The radio access of the 3G must be generic. The services for the end-

users must be independent of the access: radio access and the network

infrastructure must not limit the services to be generated. That is, thetechnology platform is one issue and the services using the platform

another issue.

The 3G system is expected to run a very high data rate that will allow us to have

multimedia traffic through the wireless network. Enhanced packet switchingand routing techniques are to be deployed to support video traffic and other

real-time traffic in the 3G wireless network. The 3G system will use the

Broadband Integrated Services Digital Network (B-ISDN) to provide dataservices between the existing data networks and the wireless network.

The technology related to the 3G system is currently in development in manycountries, and the standards associated with it are at the early stages. The Global3G Partnership Project (3GPP) incorporating many organisations (ITU-T, ETSI,

ARIB and ANSI) is currently in the process of developing such standards forthe 3G systems. These documents can be viewed at www.3gpp.org.



Introduction to GSM

22 (23) © Nokia Oyj 6-66861v 2-0

4 Review questions

In the following questions, please select one alternative that you think is the

best answer for the particular question. There may not be a perfect answer,

select the one you think is the most correct.

1. Name advantages of cellular systems to single cell systems.

2. Explain the difference between handover and location update procedure.

3. Which of the following is a requirement for the GSM specifications?

a. The system must be compatible with existing mobile standards.

b. The system must be standardised globally.

c. The system must be built without causing any major changes in the

existing Public Switched Telephone Networks (PSTN).

d. All of the above.

4. Which two statements in the following are generally seen as advantages

of GSM over analogue networks?

a. Data transmission is supported in the whole GSM network.

b. It is only possible to use an analogue mobile telephone in the ownnetwork.

c. GSM mobile stations can be used in other digital mobile networks,

for instance in NMT and TACS networks.

d. GSM is a more secure system than analogue systems with respect

to subscriber information and transmission.



Review questions

6 66861 © Nokia Oyj 23 (23)

5. Match the year in the left-hand column with the corresponding significantGSM event in the middle column.

Year Event Correct year

1982 Allocation of GSM frequencies

2000 Experimental test in Paris

1995 Frequency allocation for GSM 1800

1989 First official GSM call in the world

1991 Initiation of a new system

1987 ETSI begins the specification work for 3G/UMTS

1992 Final recommendations Phase 1

1999 Phase 2 recommendations frozen

1986 Total GSM subscribers exceeds 300 million

01-2GSYSTRA_INTRODUCTION TO GSM_6-66861.pdf

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