Tài liệu GSM SYSTEM SURVEY ppt

OBJECTIVES: Upon completion of this chapter the student will be able to: • Describe the concept of a standard for mobilecommunications • Describe the history of GSM development • Describ

STUDENT TEXT EN/LZT 123 3321

R2C

This book is a training document and contains simplifications.Therefore, it must not be considered as a specification of thesystem

The contents of this document are subject to revision withoutnotice due to ongoing progress in methodology, design andmanufacturing

Ericsson assumes no legal responsibility for any error or damageresulting from the usage of this document

This document is not intended to replace the technicaldocumentation that was shipped with your system Always refer

to that technical documentation during operation andmaintenance

This document was produced by Ericsson Radio Systems AB

• It is used for training purposes only and may not be copied

or reproduced in any manner without the express writtenconsent of Ericsson

• This document number, EN/LZT 123 3321, R2C supportscourse number LZU 108 852

EN/LZT 123 3321 R2C

Copyright © 1999 by Ericsson Radio Systems AB

e t n I

GSM System Survey

Table of Contents

1 Introduction to Mobile Telecommunications and GSM 1

2 Overview of Ericsson’s GSM Systems 25

3 Wireless Concepts 37

4 Channel Concepts 71

5 Introduction to AXE 83

6 Switching System 111

7 Base Station System 131

8 Mobile Stations 155

9 Traffic Cases 181

10 Cell Planning 211

11 Operation and Maintenance Systems 231

12 Subscriber Services 255

13 Charging and Accounting 265

14 Appendix A: Mobile Intelligent Network Services 277

15 Appendix B: Data Services 293

16 Appendix C: Case Study: New Telerica’s GSM networks 301

17 Appendix D: The Future of GSM 317

18 Appendix E: Ericsson’s Customer Services 325

19 Index 329

e t n I

Chapter 1

This chapter is designed to provide the student with anintroduction to mobile telecommunications and an overview ofthe GSM standard It introduces the main system components,the network structure and basic terminology used

OBJECTIVES:

Upon completion of this chapter the student will be able to:

• Describe the concept of a standard for mobilecommunications

• Describe the history of GSM development

• Describe the philosophy of GSM as a global commonstandard

• Describe the GSM network components

• Describe the GSM geographical network structure

• Describe the GSM frequency bands

• Describe the terminology used in GSM traffic cases

e t n I

1 Introduction to Mobile Telecommunications and GSM

Table of Contents

MOBILE TELEPHONY 1

HISTORY OF WIRELESS COMMUNICATION 1

MOBILE STANDARDS 3

ERICSSON IN MOBILE 5

GLOBAL SYSTEM FOR MOBILE COMMUNICATION (GSM) 6

HISTORY OF GSM 6

GSM SPECIFICATIONS 9

GSM PHASES 10

GSM NETWORK COMPONENTS 12

SWITCHING SYSTEM (SS) COMPONENTS 14

BASE STATION SYSTEM (BSS) COMPONENTS 16

NETWORK MONITORING CENTERS 16

MOBILE STATION (MS) 17

GSM GEOGRAPHICAL NETWORK STRUCTURE 18

CELL 18

LOCATION AREA (LA) 18

MSC SERVICE AREA 19

PLMN SERVICE AREA 19

GSM SERVICE AREA 20

GSM FREQUENCY BANDS 22

GSM 900 22

GSM 1800 22

GSM 1900 22

KEY TERMS 23

e t n I

networks and cordless telephones In the future, cellular systemsemploying digital technology will become the universal method

of telecommunication

HISTORY OF WIRELESS COMMUNICATION

The origins of mobile communications followed quickly behindthe invention of radio in the late 1800s The first applications ofmobile radio were related to the navigation and safety of ships atsea As radio concepts developed, so did it’s use as a

communications tool The major milestones in the development

of wireless communications are summarized in the followingtable:

Date Activity

1906 Reginald Fesseden successfully transmits human

voice over radio Up until that time, radiocommunications consisted of transmissions of MorseCode

1915 J A Fleming invents the vacuum tube making it

possible to build mobile radios

1921 The Detroit police department used a 2 MHz

frequency in the department's first vehicular mobileradio The system was only one way and police had

to find a wireline phone to respond to radiomessages

1930s Amplitude Modulation (AM) two-way mobile

systems were in place in the U.S that tookadvantage of newly developed mobile transmittersand utilized a "push-to-talk" or half-duplex

transmission By the end of the decade channelallocation grew from 11 to 40

1935 Invention of Frequency Modulation (FM) improved

audio quality FM eliminated the need for large AMtransmitters and resulted in radio equipment whichrequired less power to operate This made the use oftransmitters in vehicles more practical

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1940s The Federal Communications Commission (FCC)

recognized a communication service it classified asDomestic Public Land Mobile (DPLM) radioservice The first DPLM system was established in

St Louis in 1946 and it utilized the 150 MHz band

The following year, a "highway" system wasdeveloped along the New York - Boston corridorusing the 35-40 MHz band

1947 D.H Ring, working at Bell Laboratories, envisions

the cellular concept

1948 Shockley, Bardeen and Brittain, at Bell Laboratories,

invent the transistor which enables electronicequipment, including the radio to be miniaturized

1949 Radio Common Carriers (RCCs) were recognized

1949,1958

Bell Systems made broadband proposals

1964 AT&T introduces Improved Mobile Telephone

System (IMTS)

1968 The FCC began to address issue of new US spectrum

requirements

1969 Nordic countries of Denmark, Finland, Iceland,

Norway and Sweden agree to form a group to studyand recommend areas of cooperation in

telecommunication This led to the standardization

of telecommunications for all members of the NordicMobile Telephone (NMT) group, the first

comprehensive international standardization group

1973 The NMT group specifies a feature allowing mobile

telephones to be located within and across networks

This feature would become the basis for roaming

1979 The FCC authorized the installation and testing of

the first developmental cellular system in the US(Illinois Bell Telephone Company)

1981 Ericsson launches the world’s first cellular system in

Saudi Arabia based on the analog NMT 450standard

1991 The first digital cellular standard (GSM) is launched

1998 The number of mobile subscribers world-wide has

grown to over 200 million

Table 1-1 Milestones in development of wireless communications

Ericsson predicts that

in the year 2000, the

number of mobile

subscribers worldwide

will be approximately

500 million.

MOBILE STANDARDS

Standards play a major role in telecommunications by:

• Allowing products from diverse suppliers to beinterconnected

• Facilitating innovation by creating large markets for commonproducts

The standards-making process is one of co-operation at manylevels, both nationally and internationally and includes co-operation between:

• Industrial concerns within a country

• These industrial concerns and their governments

• National governments at an international levelThe primary purpose of a standard for mobile communications

is to specify how mobile phone calls are to be handled by amobile network For example, this includes specification of thefollowing:

• The signals to be transmitted and received by the mobilephone

• The format of these signals

• The interaction of network nodes

• The basic network services which should be available tomobile subscribers

• The basic network structure (i.e cells, etc.)

– 4 – EN/LZT 123 3321 R2C

Since the development of NMT 450 in 1981, many standards formobile communication have been developed throughout theworld Each mobile standard has been developed to meet theparticular requirements of the country or interest groupsinvolved in its specification For this reason, although a standardmay be suitable for one country, it may not be suitable foranother The main standards and the main markets in which theyare used are summarized in the following table

Year Standard Mobile Telephone System Technology

Primary Markets

1981 NMT 450 Nordic Mobile Telephony Analogue Europe,

1985 TACS Total Access

1992 GSM 1800 Global System for Mobile

Table 1-2 The main cellular standards

The country with the

highest per capita

ERICSSON IN MOBILE

Ericsson is one of the leading telecommunication companies inthe world, with customers in more than 130 countries Ericsson’skey product is the AXE digital exchange which is in service inthe most sophisticated public networks in Europe, the Americas,Australia, Africa and Asia One of the key reasons for thesuccess of AXE is that it is modular in design which allows it toadapt easily to a wide variety of applications The concept ofopen systems and standardized interfaces is fundamental to thedevelopment of all new telecommunication products withinEricsson

Ericsson has been designing cellular radio systems since the1970’s It offers network products for all major standards, bothanalogue and digital The largest Ericsson markets, measured innumber of subscribers using an Ericsson system are NorthAmerica and Europe

Ericsson is the world's most successful supplier of mobilenetwork infrastructure equipment and supplies 40% of theworld's mobile telephony market Ericsson supplies 50% of theworld's digital telephony market This means that half of all theworld's digital mobile telephone calls are switched throughEricsson exchanges

Mobile Standard Ericsson Product

NMT 450 CMS 45AMPS CMS 8800TACS CMS 8810NMT 900 CMS 89

D-AMPS CMS 8800-DGSM 1800 CME 20

PCS 1900 (using GSM) CMS 40PCS 1900 (using DAMPS) CMS 8800-D

Table 1-3 Ericsson’s cellular systems

1982-• Conférence Européenne des Postes etTélécommunications (CEPT) began specifying

a European digital telecommunicationsstandard in the 900 MHz frequency band Thisstandard later became known as Global

System for Mobile communication (GSM)

1986 • Field tests were held in Paris to select which

digital transmission technology to use Thechoice was Time Division Multiple Access(TDMA) or Frequency Division MultipleAccess (FDMA)

1987 • A combination of TDMA and FDMA was

selected as the transmission technology forGSM

• Operators from 12 countries signed aMemorandum of Understanding committingthemselves to introducing GSM by 1991

1988 • CEPT began producing GSM specifications

for a phased implementation

• Another five countries signed the MoU

1989 • European Telecommunication Standards

Institute (ETSI) took over responsibility forGSM specification

1990 • Phase 1 specifications were frozen to allow

manufacturers to develop network equipment

1991 • The GSM 1800 standard was released

• An addendum was added to the MoU allowingcountries outside CEPT to sign

1992 • Phase 1 specifications were completed.

• First commercial Phase 1 GSM networks werelaunched

• The first international roaming agreement wasestablished between Telecom Finland andVodafone in UK

1993 • Australia became the first non-European

country to sign the MoU

• The MoU now had a total of 70 signatories

GSM networks were launched in Norway,Austria, Ireland, Hong Kong and Australia

• The number of GSM subscribers reached onemillion

• The first commercial DCS 1800 system waslaunched in the U.K

1994 • The MoU now had over 100 signatories

covering 60 countries

• More GSM networks were launched

• The total number of GSM subscribersexceeded 3 million

1995 • The specification for the Personal

Communications Services (PCS) wasdeveloped in the U.S.A This version of GSMoperates at 1900 MHz

• GSM growth trends continued steadily through

1995, with the number of GSM subscribersincreasing at the rate of 10,000 per day andrising

• In April 1995, there were 188 members of theMoU from 69 countries

1996 • The first GSM 1900 systems became available

These comply with the PCS 1900 standard

1998 • At the beginning of 1998 the MoU has a total

of 253 members in over 100 countries andthere are over 70 million GSM subscribersworld-wide GSM subscribers account for 31%

of the world’s mobile market

– 8 – EN/LZT 123 3321 R2C

Figure 1-1 GSM worldwide (indicated by darker areas)

Because GSM provides a common standard, cellular subscriberscan use their telephones over the entire GSM service area whichincludes all the countries around the world where the GSMsystem is used

In addition, GSM provides user services such as high speed datacommunication, facsimile and a Short Message Service (SMS)

The GSM technical specifications are also designed to workwith other standards as it guarantees standard interfaces

Finally, a key aspect of GSM is that the specifications are ended and can be built upon to meet future requirements

The countries with the

highest numbers of

GSM subscribers are

the United Kingdom

and Italy.

GSM SPECIFICATIONS

GSM was designed to be platform-independent The GSMspecifications do not specify the actual hardware requirements,but instead specify the network functions and interfaces indetail This allows hardware designers to be creative in how theyprovide the actual functionality, but at the same time makes itpossible for operators to buy equipment from different suppliers

The GSM recommendations consist of twelve series which are

listed in the table below These series were written by different

working parties and a number of expert groups A permanentnucleus was established in order to coordinate the workingparties and to manage the editing of the recommendations Allthese groups were organized by ETSI

Series Content

01 General

02 Service aspects

03 Network aspects

04 MS - BSS interface and protocol

05 Physical layer on the radio path

06 Speech coding specification

07 Terminal adaptor for MS

08 BSS - MSC interface

09 Network interworking

10 Service interworking

11 Equipment and type approval specifications

12 Operation and maintenance

Table 1-5 GSM Recommendations

The GSM 1800 section is written as a delta part within the GSMrecommendations, describing only those differences betweenGSM 900 and GSM 1800 GSM 1900 is based on GSM 1800and has been adapted to meet the American National StandardsInstitute (ANSI) standard

– 10 – EN/LZT 123 3321 R2C

GSM PHASES

In the late 1980s, the groups involved in developing the GSMstandard realized that within the given time-frame they could notcomplete the specifications for the entire range of GSM servicesand features as originally planned Because of this, it wasdecided that GSM would be released in phases with phase 1consisting of a limited set of services and features Each newphase builds on the services offered by existing phases

Idea Standardization Implementation/usage

• Closed user groups

• Additional data communications capabilities

Phase 2+

The standardization groups have already begun to define thenext phase, 2+ The phase 2+ program will cover multiplesubscriber numbers and a variety of business oriented features

Some of the enhancements offered by Phase 2+ include:

• Multiple service profiles

• Private numbering plans

• Access to Centrex services

• Interworking with GSM 1800, GSM 1900 and the DigitalEnhanced Cordless Telecommunications (DECT) standardPriorities and time schedules for new features and functionsdepend primarily on the interest shown by operating companiesand manufacturers and technical developments in related areas

– 12 – EN/LZT 123 3321 R2C

GSM NETWORK COMPONENTS

The GSM network is divided into two systems Each of thesesystems are comprised of a number of functional units which areindividual components of the mobile network The two systemsare:

• Switching System (SS)

• Base Station System (BSS)

In addition, as with all telecommunications networks, GSMnetworks are operated, maintained and managed fromcomputerized centers

Signaling transmissionCall connections and signaling transmission

Base Station System

Othernetworks

BSC GMSC

VLR

Figure 1-3 System model

AUC AUthentication CenterBSC Base Station ControllerBTS Base Transceiver StationEIR Equipment Identity RegisterHLR Home Location Register

MS Mobile StationMSC Mobile services Switching CenterNMC Network Management CenterOMC Operation and Maintenance CenterVLR Visitor Location Register

The SS is responsible for performing call processing andsubscriber related functions It includes the following functionalunits:

• Mobile services Switching Center (MSC)

• Home Location Register (HLR)

• Visitor Location Register (VLR)

• AUthentication Center (AUC)

• Equipment Identity Register (EIR)The BSS performs all the radio-related functions The BSS iscomprised of the following functional units:

• Base Station Controller (BSC)

• Base Transceiver Station (BTS)The OMC performs all the operation and maintenance tasks forthe network such as monitoring network traffic and networkalarms The OMC has access to both the SS and the BSS

MSs do not belong to any of these systems

– 14 – EN/LZT 123 3321 R2C

SWITCHING SYSTEM (SS) COMPONENTS

Mobile services Switching Center (MSC)

The MSC performs the telephony switching functions for themobile network It controls calls to and from other telephonyand data systems, such as the Public Switched TelephoneNetwork (PSTN), Integrated Services Digital Network (ISDN),public data networks, private networks and other mobilenetworks

Gateway Functionality

Gateway functionality enables an MSC to interrogate anetwork’s HLR in order to route a call to a Mobile Station (MS)

Such an MSC is called a Gateway MSC (GMSC) For example,

if a person connected to the PSTN wants to make a call to aGSM mobile subscriber, then the PSTN exchange will accessthe GSM network by first connecting the call to a GMSC Thesame is true of a call from an MS to another MS

Any MSC in the mobile network can function as a gateway byintegration of the appropriate software

Home Location Register (HLR)

The HLR is a centralized network database that stores and

manages all mobile subscriptions belonging to a specificoperator It acts as a permanent store for a person’s subscriptioninformation until that subscription is canceled The informationstored includes:

• Subscriber identity

• Subscriber supplementary services

• Subscriber location information

• Subscriber authentication informationThe HLR can be implemented in the same network node as theMSC or as a stand-alone database If the capacity of a HLR isexceeded by the number of subscribers, additional HLRs may beadded

Visitor Location Register (VLR)

The VLR database contains information about all the mobilesubscribers currently located in an MSC service area Thus,there is one VLR for each MSC in a network The VLRtemporarily stores subscription information so that the MSC canservice all the subscribers currently visiting that MSC servicearea The VLR can be regarded as a distributed HLR as it holds

a copy of the HLR information stored about the subscriber

When a subscriber roams into a new MSC service area, the VLRconnected to that MSC requests information about the

subscriber from the subscriber’s HLR The HLR sends a copy ofthe information to the VLR and updates its own location

information When the subscriber makes a call, the VLR willalready have the information required for call set-up

AUthentication Center (AUC)

The main function of the AUC is to authenticate the subscribersattempting to use a network In this way, it is used to protectnetwork operators against fraud The AUC is a databaseconnected to the HLR which provides it with the authenticationparameters and ciphering keys used to ensure network security

Equipment Identity Register (EIR)

The EIR is a database containing mobile equipment identityinformation which helps to block calls from stolen,

unauthorized, or defective MSs It should be noted that due tosubscriber-equipment separation in GSM, the barring of MSequipment does not result in automatic barring of a subscriber

Although useful, the

– 16 – EN/LZT 123 3321 R2C

BASE STATION SYSTEM (BSS) COMPONENTS

Base Station Controller (BSC)

The BSC manages all the radio-related functions of a GSMnetwork It is a high capacity switch that provides functions such

as MS handover, radio channel assignment and the collection ofcell configuration data A number of BSCs may be controlled byeach MSC

Base Transceiver Station (BTS)

The BTS controls the radio interface to the MS The BTS

comprises the radio equipment such as transceivers and antennaswhich are needed to serve each cell in the network A group ofBTSs are controlled by a BSC

NETWORK MONITORING CENTERS

Operation and Maintenance Center (OMC)

An OMC is a computerized monitoring center which isconnected to other network components such as MSCs andBSCs via X.25 data network links In the OMC, staff arepresented with information about the status of the network andcan monitor and control a variety of system parameters Theremay be one or several OMCs within a network depending on thenetwork size

Network Management Center (NMC)

Centralized control of a network is done at a NetworkManagement Center (NMC) Only one NMC is required for anetwork and this controls the subordinate OMCs The advantage

of this hierarchical approach is that staff at the NMC canconcentrate on long term system-wide issues, whereas localpersonnel at each OMC can concentrate on short term, regionalissues

OMC and NMC functionality can be combined in the samephysical network node or implemented at different locations

MOBILE STATION (MS)

An MS is used by a mobile subscriber to communicate with themobile network Several types of MSs exist, each allowing thesubscriber to make and receive calls Manufacturers of MSsoffer a variety of designs and features to meet the needs ofdifferent markets

The range or coverage area of an MS depends on the outputpower of the MS Different types of MSs have different outputpower capabilities and consequently different ranges Forexample, hand-held MSs have a lower output power and shorterrange than car-installed MSs with a roof mounted antenna

Figure 1-4 Ranges for different types of MSs

GSM MSs consist of:

• A mobile terminal

• A Subscriber Identity Module (SIM)Unlike other standards, in GSM the subscriber is separated fromthe mobile terminal Each subscriber’s information is stored as a

"smart card" SIM The SIM can be plugged into any GSMmobile terminal This brings the advantages of security andportability for subscribers For example, subscriber A’s mobileterminal may have been stolen However, subscriber A’s ownSIM can be used in another person’s mobile terminal and thecalls will be charged to subscriber A

– 18 – EN/LZT 123 3321 R2C

GSM GEOGRAPHICAL NETWORK STRUCTURE

Every telephone network needs a specific structure to routeincoming calls to the correct exchange and then on to thesubscriber In a mobile network, this structure is very importantbecause the subscribers are mobile As subscribers movethrough the network, these structures are used to monitor theirlocation

CELL

A cell is the basic unit of a cellular system and is defined as thearea of radio coverage given by one BS antenna system Eachcell is assigned a unique number called Cell Global Identity(CGI) In a complete network covering an entire country, thenumber of cells can be quite high

Cell

Figure 1-5 A cell

LOCATION AREA (LA)

A Location Area (LA) is defined as a group of cells Within thenetwork, a subscriber’s location is known by the LA which theyare in The identity of the LA in which an MS is currentlylocated is stored in the VLR

When an MS crosses a boundary from a cell belonging to one

LA into a cell belonging to another LA, it must report its newlocation to the network1 When an MS crosses a cell boundarywithin an LA, it does need to report its new location to thenetwork When there is call for an MS, a paging message isbroadcast within all cells belonging to an LA

LAs.

MSC SERVICE AREA

An MSC service area is made up of a number of LAs and represents the geographical part of the network controlled byone MSC In order to be able to route a call to an MS, thesubscriber’s MSC service area is also recorded and monitored

The subscriber’s MSC service area is stored in the HLR

LA5 LA4

as the area in which an operator offers radio coverage and access

to its network In any one country there may be several PLMNservice areas, one for each mobile operator’s network

– 20 – EN/LZT 123 3321 R2C

GSM SERVICE AREA

The GSM service area is the entire geographical area in which asubscriber can gain access to a GSM network The GSM servicearea increases as more operators sign contracts agreeing to worktogether Currently, the GSM service area spans dozens ofcountries across the world from Ireland to Australia and SouthAfrica

International roaming is the term applied when an MS movesfrom one PLMN to another

GSM Service Area PLMN Service Area (one per operator) MSC Service Area Location Area Cell

Figure 1-7 Relation between areas in GSM

The figures below show alternative views of the same network:

• The first figure shows the network nodes and their layoutacross the network For simplicity, this may be referred to asthe hardware view of the network

• The second figure shows the geographical networkconfiguration For simplicity, this may be referred to as thesoftware view of the network

HLR EIR AUC

GMSC ILR

MSC/VLR 1 PSTN

MSC Service Area 2 MSC Service Area 1

LEGEND MSC Boundary

BSC Boundary PCM Links Base Station

MSC/VLR 2 BSC 1B

BSC 1C

BSC 2B

BSC 1A

BSC 2A BSC 2C

Figure 1-8 “Hardware” view of a sample network

GMSC ILR

MSC/VLR 1 PSTN

MSC Service Area 2 MSC Service Area 1

LEGEND MSC Boundary

BSC Boundary PCM Links Base Station

MSC/VLR 2

LA 2-C

Figure 1-9 “Software” view of a sample network

The original frequency band specified for GSM was 900 MHz.

Most GSM networks worldwide use this band In somecountries and extended version of GSM 900 can be used, whichprovides extra network capacity This extended version of GSM

is called E-GSM, while the primary version is called P-GSM

GSM 1800

In 1990, in order to increase competition between operators, theUnited Kingdom requested the start of a new version of GSMadapted to the 1800 MHz frequency band Licenses have beenissued in several countries and networks are in full operation

By granting licenses for GSM 1800 in addition to GSM 900, acountry can increase the number of operators In this way, due toincreased competition, the service to subscribers is improved

The main differences between the American GSM 1900standard and GSM 900 is that it supports ANSI signaling

This was originally

KEY TERMS

During the development of mobile systems, many terms arosewhich are used to describe the call cases and situations

involving MSs The primary terms used are described below

An MS can have one of the following states:

• Idle: the MS is ON but a call is not in progress

• Active: the MS is ON and a call is in progress

• Detached: the MS is OFF

The following table defines the key terms used to describe GSMmobile traffic cases (there are no traffic cases in detachedmode):

Idle Registration This is the process in which an MS

informs a network that it is attached

Roaming When an MS moves around a network in

idle mode, it is referred to as roaming

InternationalRoaming

When an MS moves into a network which

is not its home network, it is referred to asinternational roaming MSs can only roaminto networks with which the home

network has a roaming agreement

LocationUpdating

An MS roaming around the network mustinform the network when it enters a new

LA This is called location updating

Paging This is the process whereby a network

attempts to contact a particular MS This

is achieved by broadcasting a pagingmessage containing the identity of thatMS

Active Handover This is the process in which control of a

call is passed from one cell to anotherwhile the MS moves between cells

Table 1-6 Key terms

– 24 – EN/LZT 123 3321 R2C

MS Registration and Roaming

When an MS is powered off it is detached from the network

When the subscriber switches power on, the MS scans the GSMfrequencies for special channels called control channels When itfinds a control channel, the MS measures the signal strength itreceives on that channel and records it When all controlchannels have been measured, the MS tunes to the strongest one

When the MS has just been powered on, the MS must registerwith the network which will then update the MS’s status to idle

If the location of the MS is noticed to be different from thecurrently stored location then a location update will also takeplace

As the MS moves through the network, it continues to scan thecontrol channels to ensure that it is tuned to the strongestpossible channel If the MS finds one which is stronger, then the

MS retunes to this new control channel2 If the new controlchannel belongs to a new LA, the MS will also inform thenetwork of its new location

Chapter 2

This chapter is designed to provide the student with an overview

of Ericsson’s GSM systems: CME 20 and CMS 40

OBJECTIVES:

Upon completion of this chapter the student will be able to:

• Describe the CME 20/CMS 40 network elements and theirmain functionality

e t n I

2 Overview of Ericsson’s GSM Systems

Table of Contents

ERICSSON IN GSM 25 ERICSSON’S GSM SYSTEM ARCHITECTURE 26

ERICSSON’S SS IMPLEMENTATION 28 ERICSSON’S BSS IMPLEMENTATION 29 ERICSSON’S OMC AND NMC IMPLEMENTATION 30 ADDITIONAL ERICSSON NETWORK COMPONENTS 33

e t n I

ERICSSON IN GSM

Ericsson has been involved in GSM since its inception and took

an active part in the GSM specification process

Ericsson is the largest supplier of GSM equipment in the worldwith a market share of approximately 50% Over 100 GSMnetworks worldwide are supplied by Ericsson

Ericsson is also one of the world’s largest suppliers of GSMmobile phones and has an estimated 24% share of the worldmarket

2

Figure 2-1 Ericsson GSM worldwide (indicated by darker areas)

Germany was the

location for the first

Ericsson GSM

network.

– 26 – EN/LZT 123 3321 R2C

ERICSSON’S GSM SYSTEM ARCHITECTURE

Ericsson provides two systems for GSM networks:

• Cellular Matra Ericsson (CME) 20: for GSM 900 and GSM

1800 networks

• Cellular Mobile System (CMS) 40: for GSM 1900 networksLike the GSM system model itself, Ericsson’s GSM systems aresplit into two primary systems: the Switching System (SS) andthe Base Station System (BSS) However, depending on therequirements of a network operator, Ericsson’s GSM systemscan incorporate other functions and nodes, such as MobileIntelligent Network (MIN) nodes and post processing systems

Note: Ericsson’s wide range of MSs are not considered to bepart of either the CME 20 or CMS 40 product, due to the factthat an MS from any supplier can work with network equipmentfrom any other supplier

Switching System

ILR

AUC EIR

Other PLMNs PSTN

ISDN

Public Data Networks

TRC BSC

RBS

MSC/VLR SSF

Signaling Information Speech and signaling information

Base Station System

Figure 2-2 Ericsson GSM network system model

CME stands for