212230000 e 04

Alcatel-Lucent GSM

BSS System Introduction

BSS Document

Concept Guide

Release B10

3BK 21223 AAAA TQZZA Ed.04

Status RELEASED

Short title Introduction

All rights reserved. Passing on and copying of this document, useand communication of its contents not permitted without writtenauthorization from Alcatel-Lucent.

BLANK PAGE BREAK

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Contents

Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1 Introduction to GSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.1 Mobile Telecommunications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.1.1 Cellular Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101.1.2 Origin and Evolution of GSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121.1.3 Evolution to (E)GPRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.2 GSM Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161.2.1 Standard GSM PLMN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161.2.2 GSM/(E)GPRS PLMN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171.2.3 Mobile Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171.2.4 Base Station Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181.2.5 Network Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.2.6 BSS Telecommunications Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201.2.7 Network Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

1.3 GSM Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.3.1 Mobile Network Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.3.2 Handling Calls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231.3.3 Location Services (LCS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241.3.4 Location Updating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251.3.5 Network Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261.3.6 Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2 Alcatel-Lucent Base Station Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322.2 Alcatel-Lucent BSS Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.2.1 Alcatel-Lucent Radio Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332.2.2 Base Station Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332.2.3 Base Transceiver Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332.2.4 Multi-BSS Fast Packet Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342.2.5 Transcoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

2.3 External Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352.4 System Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

2.4.1 Call Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362.4.2 Call Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362.4.3 Call Release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

2.5 (E)GPRS-Specific Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402.5.1 (E)GPRS in the PLMN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402.5.2 (E)GPRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412.5.3 (E)GPRS Network Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412.5.4 (E)GPRS Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422.5.5 (E)GPRS Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

2.6 Operations and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452.6.1 Network Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452.6.2 O&M Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 472.6.3 O&M Functions Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

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Figures

FiguresFigure 1: Mobile Telecommunications Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 2: Cellular Network Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 3: Call Setup Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 4: Logical Position of the Alcatel-Lucent BSS and Associated External Components in the PLMN . 32

Figure 5: The Alcatel-Lucent (E)GPRS Solution in the PLMN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Figure 6: Position of the MFS in the BSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Figure 7: TMN Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Figure 8: TMN System Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

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Tables

TablesTable 1: Basic GSM System Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Table 2: Basic Teleservices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Table 3: GSM Channel Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Table 4: Control Channel Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Table 5: Basic Call Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Table 6: Mobile Station Ciphering Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

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Tables

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Preface

Preface

Purpose This document provides a high-level overview of the Alcatel-Lucent BaseStation Subsystem (BSS).

It introduces primary BSS concepts, including:

The principle role and tasks of the Alcatel BSS

Network organization, functions and network management

BSS operations and maintenance.

This document also provides an introduction to GSM operation and (E)GPRS.

Read this document before reading the BSS System Description and otherrelated documentation.

Whats New In Edition 04Update with the new equipment naming.

In Edition 03Illustrations and layout were checked and improved.

Overall document quality was improved following a quality review.

In Edition 02Overall document quality was improved following an editorial review.

Transcoder (Section 2.2.5) was updated.

GboIP was introduced in Multi-BSS Fast Packet Server (Section 2.2.4).

AMR-WB and TFO were introduced inTraffic Channels (Section 1.3.6.1).

TC IP supervision was introduced in Transcoder (Section 2.2.5).

In Edition 01First official release.

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Preface

Audience This document is for personnel requiring a general overview of the functions ofthe Alcatel-Lucent BSS, such as:

Network decision makers who require a basic understanding of system

principles, including:

Network management

Technical management

Training management.

Operations and Support management who require a basic understanding of

how the system operates, including:

Operations management

Maintenance management

Client support management.

Assumed Knowledge You must be familiar with the following external systems or equipment:

Public Land Mobile Network (PLMN)

Network Subsystem (NSS)

Mobile-services Switching Center (MSC)

Mobile Station

Network Management Center (NMC).

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1 Introduction to GSM


This section summarizes the development of mobile telecommunications,including its evolution to (E)GPRS, and introduces some basic mobilecommunications concepts.

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1.1 Mobile TelecommunicationsMobile telecommunications provide the possibility of communicating voice,image, fax, or computer data from a mobile subscriber, regardless of location,to other telephone subscribers. The term "mobile telecommunications" refers tocalls made from and received by either mobile telephones fitted into cars orhand-held telephones. These telephones are referred to as mobile stations(MS), and they allow users to receive and make calls, wherever they may be.

The major difference between fixed and mobile telecommunications networks isthat the mobile stations are not permanently connected to the network in knownlocations. A mobile station does not have to be physically connected to thenetwork (see the figure below). This means that mobile subscribers must belocated and identified by the mobile network before calls can be set up.

MobileTelecommunications

Network

MobileStation

MobileStation

PublicTelephoneNetwork

Figure 1: Mobile Telecommunications Overview

1.1.1 Cellular Systems

The technology used to manage network resources for mobile networkscontinues to evolve since its inception. At the beginning of the 1980s, cellularsystems began to emerge as real competitors to early mobile systems whichwere not divided into cells.

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In cellular systems, the area covered by a mobile network is divided into radiocells, as shown in the figure below. A cell is the geographic zone covered byone radio transmitter and receiver.

Cellular systems take advantage of the concept of radio frequency re-use,whereby the same frequencies are re-used by cells that are far enough apart(i.e., non-adjacent) to limit co-channel interference. Modern systems use cellclusters, with no frequency re-use within the cluster. For example, in eachcluster, cell 1 is assigned a set of frequencies while cell 2 is assigned a differentset of frequencies. As shown in the following figure, cell 1 in one cluster isnever next to cell 1 of the adjacent cluster and the cell pattern is repeated foreach cluster. This results in a more efficient use of limited radio resources.

7

4

1 2

8

5

6

3

91 2

5

6

3

7

4

8

9

7

1 2

8

5

6

3

9

4

Figure 2: Cellular Network Structure

Cellular analog systems present several important disadvantages, such as alack of international standards, roaming limited to networks using the samesystem, and poor speech security. These factors are responsible for restrainingmobile network development, therefore, analog systems are now beingsuperseded by digital radio systems. Digital systems provide greater capacityto deal with increased user traffic due to the proliferation of mobile telephoneuse, and the ever-widening range of user services requiring the transmission ofvoice, image, computer and fax data.

The Alcatel-Lucent BSS uses advanced cell management techniques such asthe use of concentric cells to increase the frequency economy of the network.The BSS also supports a feature called Unbalanced TRX Power. This featuredefines a specific type of concentric cell which allows an even more efficientuse of radio resources.

For more information about these and other Alcatel-Lucent BSS features,refer to the BSS System Description.

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1.1.2 Origin and Evolution of GSM

The Groupe Speciale Mobile was originally part of the European Conferenceof Posts and Telecommunications (CEPT) group. This organization wasresponsible for developing the first mobile telecommunication standards. Itproduced recommendations for mobile services, radio transmission, networkarchitecture and interfaces between subsystems. The resulting cellular radiotelephone system is known as the Global System for Mobile Communications,or GSM. GSM standardization was later taken over by the global Europeanstandards organization, the ETSI, and in 1998 a collaboration agreement wasestablished between a number of telecommunications standards bodies,resulting in the 3rd Generation Partnership Project Agreement (3GPP).

3GPP is responsible for defining recommendations for the advanced use ofcellular radio telephone systems.

The GSM working group based their system on digital transmissiontechnology. Digital transmission provides greater reliability, higher trafficdensity, and better quality than earlier analog methods. The original GSMrecommendation specified a common frequency band around 900 MHz formobile communication. Systems using this band are referred to as GSM 900systems. To provide additional coverage in densely populated urban areas, asecond band around 1800 MHz/1900 MHz was reserved. This is referred to asGSM 1800/1900 and uses the same GSM standards operating at the higherfrequency range. The GSM 900 systems have been extended into the 900 MHzprimary band (P-GSM band) and the 900 MHz extension band (G1 band).

The GSM 850 MHz band was introduced in Release 1999 of the 3GPPStandard in 1999, but is supported by all mobile station releases since 1997, toallow operators to progressively replace the D-AMPS and CDMA technologiesthat were using these frequencies. In addition to certain Asian countries, theGSM 850 MHz band concerns many Latin American countries where operatorsalready use the GSM system with the GSM 1900 MHz in their network, toextend or replace their existing D-AMPS network.

The Alcatel-Lucent BSS supports the following multiband networkconfigurations, and any monoband network configuration involving one of thefollowing frequency bands:

BSS with a mix of GSM 850 and GSM 1900 cells

BSS with a mix of GSM 850 and GSM 1800 cells

BSS with a mix of GSM 900 and GSM 1800 cells.

For more information about the BSS and its components, including theMulti-BSS Fast Packet Server (MFS), and their place in the PLMN, refer to the:

BSS System Description

Alcatel-Lucent 9135 MFS Description.

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The following table shows the basic system specifications for GSM networks.

Parameter Values

GSM 850 Frequency band Uplink: 824 MHz - 849 MHz

Downlink: 869 MHz - 894 MHz



GSM 900 ExtensionFrequency band

Uplink: 880 MHz - 890 MHz






Duplex distance GSM 900: 45 MHz

GSM 1800/1900: 95 MHz

Carrier separation 200 kHz

Modulation Gaussian Minimum Shift Keying (GMSK),Phase Shift Keying (8-PSK)

Transmission rate 270 kbit/s

Access method Time Division Multiple Access (TDMA)

Table 1: Basic GSM System Specifications

Standardization of GSM technology, although originally developed for theEuropean market, is now implemented by network operators and regulatoryauthorities around the world.

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GSM provides the following advantages:

StandardizationInternational standards ensure compatibility between systems in differentcountries, enabling subscribers to use their mobile stations locally andinternationally.

International roamingRoaming is no longer limited to areas covered by the cells of a givennetwork operator. Calls can be processed and charged to subscriberswhether they call from their home network or from a network in another cityor another country.

Consistent QualityDue to improved radio resource control, digital equalizing, encoding andfrequency hopping, mobile networks can provide a consistent level of quality.

Call Security/ProtectionImproved authentication and ciphering techniques for all signaling anduser data allow protected subscriber access to the network and ensureuser confidentiality.

The 3GPP specifications ensure further advantages by the implementation ofnew management and mobile subscriber features such as:

General Packet Radio Service ((E)GPRS). Refer to Evolution to (E)GPRS(Section 1.1.3).

Voice Group Call Service (VGCS), which allows the efficient radio resource

management of multiple mobile stations on the same call

Quality of Service (QoS) and Packet Flow Control (PFC), which allow

the differentiation and resulting management of traffic classes, to ensure

efficient use of radio resources and more effective user service.

Refer to the BSS System Description for more information about these GSMand 3GPP features as they are implemented in the Alcatel-Lucent BSS.

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1.1.3 Evolution to (E)GPRS

The success of GSM has taken place in parallel with the explosion of interestin the Internet and related data services. Originally, data transmission overthe Air Interface was limited to 9.6 kbits/s, which was too slow for use bygraphics-intensive services such as the World Wide Web and personalvideo conferencing. In addition, the circuit-switched method used for datatransmission makes inefficient use of radio resources which are underincreasing pressure from the ever-increasing number of GSM subscribers andthe services they require.

The solution chosen by 3GPP for the double challenge of increased demandfor data service and pressure on radio resources is called General PacketRadio Service ((E)GPRS). The 3GPP recommendations establish a standardfor inserting an alternative transmission method for data in the PLMN: packetswitching instead of circuit switching.

Packet switching is described in the Packet Switching section of the BSSSystem Description.

GPRS was first introduced in Release 1997 of 3GPP standards, and then(E)GPRS was introduced in Release 1999 to increase the data rates and toimprove link adaptation performances, therefore permitting new services suchas video-streaming, rich multimedia content, and other data-intensive services.

The (E)GPRS solution exceeds GPRS capabilities for data transmission ratesby using new modulation and coding schemes on the Air Interface.

The Alcatel-Lucent (E)GPRS solution is closely aligned to the 3GPP 1999Release recommendations.

The Alcatel-Lucent BSS supports GPRS and (E)GPRS in all frequency bandssupported in GSM.

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1.2 GSM ArchitectureA functional structure exists to ensure compatibility between the differentsubsystems, their components and the communication interfaces. Thedefinition is based on the GSM recommendations.

1.2.1 Standard GSM PLMN

The standard GSM Public Land Mobile Network, shown in the figure below,consists of:

Mobile stations, to transmit and receive calls

At least one BSS, to act as the radio part that connects the mobile stationto the switching part of the PLMN

The Network Subsystem, to manage switching, interconnection andsubscriber data.

BSS

BTS

BTS

BTS

BTS

BTSBTS

Mobile Stations

BSC BSC

BTS

NSS

TranscoderTranscoder

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1.2.2 GSM/(E)GPRS PLMN

A GSM/(E)GPRS PLMN, shown in the figure below, consists of:

Mobile stations, to transmit and receive calls

At least one BSS, to act as the radio part that connects the mobile stationto the switching part of the PLMN

At least one MFS (see Multi-BSS Fast Packet Server (Section 2.2.4)).

BSS

BTS

BTS

BTS

BTS

BTSBTS

Mobile Stations

BSC BSC

BTS

NSS

MFSTranscoder

MFS : Multi-BSS Fast Packet Server

1.2.3 Mobile Stations

Mobile stations (MS) are the only items of mobile telecommunicationsequipment the subscriber physically uses. MS can be vehicle mounted orportable kits, but the most popular models are hand-held stations.

Mobile stations provide generic radio and processing functions, allowingsubscribers to access the mobile network via a radio interface called the "AirInterface". Modern MS and their associated service providers propose manyfeatures, including Short Message Services (SMS), Multimedia Services(MMS), the ability to transfer data to and from computers and faxes, televisionand radio streaming, and the possibility of creating and manipulating photosand video imaging.

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1.2.4 Base Station Subsystem

The BSS supports the Air Interface and connects the mobile stations to theswitching part of the GSM PLMN, as shown in the figure below.

MobileStations


PUBLIC LAND MOBILE NETWORK

Base Station Subsystem

Air Interface

NetworkSubsystem

BSC

BTS

BTS

MFS

Transcoder


A BSS comprises:

At least one Base Transceiver Station (BTS), which provides the radio linksbetween the mobile stations and the Base Station Controller (BSC)

A BSC, which controls several BTSs

A Transcoder, located between the BSC and the NSS.

The BSS can include additional transmission equipment to perform multiplexingand monitoring functions.

With (E)GPRS data traffic, the BSS also includes an MFS to manage datapackets and perform Location Services (LCS) through Serving Mobile LocationCenter (SMLC) functions within the MFS. For more information about the MFSsposition in the BSS, refer to Alcatel-Lucent BSS Components (Section 2.2).

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1.2.5 Network Subsystem

The main role of the NSS is to manage communication within the PLMNand with the public telephone network. The NSS manages the subscriberadministration databases. The figure below shows the components of a typicalNSS.

MobileStations


MSC

HLR

VLR

AUC

EIR

NetworkSubsystem

BaseStation

Subsystem

PUBLIC LAND MOBILE NETWORK

SGSN GGSN

AUC : Authentication Center

EIR : Equipment Identity Register

GGSN : Gateway GPRS Support Node

HLR : Home Location Register

MSC : Mobile Switching Center

SGSN : Serving GPRS Support Node

VLR : Visitor Location Register

An NSS comprises:

The MSC, which co-ordinates outgoing and incoming call set up for GSMsubscribers for voice and other user traffic

The Home Location Register (HLR), which is the central database within a

given network for mobile subscriber-specific data

The Visitor Location Register (VLR), which temporarily stores information

about the mobile stations entering its coverage area

The Authentication Center (AUC), which manages the security data used forsubscriber authentication

The Equipment Identity Register (EIR), which contains the lists of mobile

station equipment identities.

To handle (E)GPRS data traffic, the NSS also includes:

The Serving (E)GPRS Support Node (SGSN), which handles packet (i.e.data) traffic, including security functions, and the interface to the HLR

The Gateway (E)GPRS Support Node (GSGN), which provides interworking

with external packet-switched networks.

Outgoing inter-PLMN handovers allow operators to define handover adjacencylinks towards external cells belonging to foreign PLMNs (to which externalOMC-R cells belong).

The Multi-PLMN feature allows operators to define several PLMNs in order tosupport network sharing, inter-PLMN handovers and cell reselections betweentwo different PLMNs.

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The BSC cannot be shared and therefore remains mono-PLMN (i.e. allBSC cells belong to the same PLMN). This feature defines several PLMNs,inter-PLMN handovers, and cell reselections between two different PLMNs.New BSC counters as well as Outgoing Inter-PLMN handovers monitorprocedures involving all types of inter-PLMN handover.

1.2.6 BSS Telecommunications Layers

The telecommunications functions of a GSM network are split into two basiclayers:

The Application layer, split into sub-layers which control:

Call management

Mobility management

Radio resource management.

The Transmission layers, which provide transmission to various components.

For a detailed description of the BSS telecommunications layers, refer to theBSS Telecommunications Layers section of the BSS System Description.

1.2.7 Network Management

In GSM, the PLMN is managed according to a network management conceptreferred to as the Telecommunication Management Network (TMN). TheTMN defines a set of network management functions according to the ISOsystems management rules. For more information, see Network Management(Section 2.6.1).

Operations and Maintenance (O&M) describes the set of actions that monitor,control, and record how the system is functioning.

O&M activities are divided into three functional groups:

Configuration Management

Fault Management

Performance Management.

The exact implementation of these functional groups for network managementis not strictly defined within GSM. Therefore, Alcatel-Lucent has developed itsO&M concept to ensure high performance.

For further information on O&M, refer to the following documents:

Operations & Maintenance in the BSS System Description

Operations & Maintenance Principles

9153 Getting Started.

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1.3 GSM FunctionThe primary function of a GSM network is to provide a consistent mobiletelecommunication service. To do so, GSM supports a number of standardizedservices, some of which guarantee basic telephony services and others whichprovide an extra level of comfort for the user.

1.3.1 Mobile Network Services

Network operators can implement three types of mobile network services:

Teleservices

Bearer services

Supplementary services.

1.3.1.1 Teleservices

Service Description

Telephony GSM supports telephony with the ability to send or receive calls anywhere in theworld where there is GSM or fixed network coverage.

Emergency call GSM allows calls to be routed to an emergency service. Emergency calls havepriority. If there are insufficient radio resources, the call request is queued at thehighest priority.

Data Calls GSM supports the transmission of a wide range of data and offers a variety oftransmission types. (E)GPRS increases the throughput of data traffic.

Fax High speed telefax messages can be sent to or received from a standard fax machineanywhere in the world.

Videotex GSM supports the transmission of videotex information such as is used in the Minitel.

SMS SMS allows the transmission of messages containing up to 160 alphanumericcharacters to be sent to a subscriber. The SMS center interfaces with other networkservices such as paging, message handling and voice messaging.

MMS MMS allows the transmission of messages containing test, voice and images to besent to a subscriber. The MMS center interfaces with other network services suchas paging, message handling and voice messaging.

Cell Broadcast Cell broadcast is a short message service which allows short messages to be sent toall phones in a geographical area.

Table 2: Basic Teleservices

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1.3.1.2 Bearer ServicesBearer services provide basic transmission functions. GSM uses a variety ofbearer services to provide the different speeds and communications typesrequired to run a range of service applications, including data transmission.

1.3.1.3 Supplementary ServicesIn addition to the teleservices provided by a mobile network, the networksupports the following supplementary services that are provided by the CN.

These are administered by the network operator and offered to the mobilesubscriber as options:

Call forwarding (unconditional, mobile subscriber busy, no reply, mobile

not reachable)

Call barring (outgoing, outgoing international, outgoing international exceptto home country, incoming, incoming when roaming abroad)

Call waiting, call hold, and multi-party service such as the Voice GroupCall Service (VGCS)

Call prioritization, using features such as Enhanced Multi Level Priority

and Pre-emption (eMLPP)

Billing advice.

GSM defines a comprehensive set of recommendations concerning themanagement and implementation of these services, in conjunction with 3GPPand other standardization groups.

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1.3.2 Handling Calls

Communication to or from a mobile station must be:

Initiated

Authenticated

Established

Maintained

Analyzed

Terminated.

When a call between a mobile station and a fixed network telephone is set up,the data is transmitted on the radio path between the mobile station and theBSS over a Traffic Channel (TCH). The information is then routed to the fixednetwork under the control of the MSC. A call between two mobiles in the samelocation area is also set up by the MSC.

The figure below illustrates the basic call setup procedure involved for amobile-originated call.


BTS BSC Transcoder MSC

Dialled number + subscriber information

Authentication accept

Dedicated control resource

Traffic channel




Traffic channel




Traffic channel

MobileStation

NetworkSubsystem

Figure 3: Call Setup Procedure

To ensure that calls are not interrupted when a mobile station moves from onecell to another during a call, handover occurs so that the call path follows themobile station. Handover is the transfer of the call from one communicationchannel to another channel of the same type. Handover is transparent tothe user.

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1.3.3 Location Services (LCS)

LCS is an optional, end-user service that provides the geographical location(longitude, latitude, and, optionally, altitude) of mobile stations.

An LCS client can request location information for one or more target mobilestation from the LCS server, supported by the PLMN.

LCS is applicable to any target mobile station, whether or not the mobilestation supports LCS. However, restrictions apply to the choice of positioningmethods when LCS, or individual positioning methods, are not supported bythe mobile station.

Several positioning methods are possible:

Time Advance (TA) positioning

Conventional GPS positioning, whereby the mobile uses GPS to provideits position

Assisted GPS (A-GPS) positioning, which provides two different A-GPSpositioning methods:

Mobile station-based A-GPS, where the mobile provides its position usingA-GPS, but with the help of assistance data provided by the network

Mobile station-assisted A-GPS, where the network provides both

assistance data to the mobile and also fixes the position (i.e. the mobile

is fully "assisted" in this positioning method).

An A-GPS server provides assistance data (and on request, fixes the position).This A-GPS server is mandatory to get a position when using A-GPSpositioning methods.

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1.3.4 Location Updating

Location updating allows the network to know the location of a mobile station atany given time. It lets the mobile station identify a change in cell location andinitiate automatic updating procedures.

The HLR is the reference database for subscriber information. The VLRcontains copies of most of the data stored in the HLR, but is a temporarydatabase of subscriber information for wherever the subscriber is physicallylocated within a PLMN. This eliminates the need for time-consuming referencesto the HLR.

When the mobile station enters a new VLR area, it uses a Temporary MobileSubscriber Identity (TMSI) that was allocated by the last VLR. The mobilestation communicates its last Location Area Identifier (LAI), which allows thenew VLR to identify the former VLRs address. Then the new VLR requests themobile stations IMSI and related information. The VLR sends the updatedinformation to the HLR.

MSC

MSCBSCBTS

BSC

Mobile Station connectingin a new location area

VLR

VLR

MobileStation

MobileStation BTS

BSC

BSCProtocol Messages



The HLR replaces old location data with the location update information sentfrom the VLR, which also assigns a new TMSI to the mobile station. TheHLR can refuse the location updating information if, for example, the mobilesubscriber does not have permission to communicate in the new VLR area.

Once a mobile station has been recognized, accepted, and allocated a TMSI,it can set up calls.

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1.3.5 Network Security

This section describes the security functions available to the network operatorto minimize the risk of fraudulent use of the network.

1.3.5.1 Subscriber Identity ConfidentialityEach subscriber has a personal SIM. The SIM is a smart card which stores allthe information a subscriber requires to use a GSM mobile telephone, andcan be transferred to any mobile equipment. The SIM is protected againstunauthorized access by a PIN.

The network must identify the mobile subscriber at the beginning of eachtransaction between a mobile station and the network. The mobile stationsends its related IMSI, stored on the SIM, to the network. The IMSI must beprotected when sent over the Air Interface. Therefore, the VLR can assign theIMSI a TMSI. The TMSI is ciphered when transmitted to the mobile station,where it is stored.

1.3.5.2 Keys and TripletsA secret identification key is associated with each IMSI. One copy of this datais stored on the SIM. A second copy of the data is stored in the AUC, whichverifies security data for each subscriber attached to it.

1.3.5.3 AuthenticationFor authentication purposes, the VLR chooses a triplet and sends the value ofthe random number to the mobile station. The mobile station calculates thevalue of the signed response and returns it to the VLR, where it is comparedwith the value in the selected triplet. If the signed response value is the same,then the mobile station is ready for use. If not, no calls are permitted forthe mobile station.

A mobile station which is unknown to the PLMN and which enters a VLRsterritory is authenticated if there is a roaming agreement with the mobilestations home network. If not, no calls are permitted for the mobile station.

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1.3.6 Channels

The following table shows the used frequency channels between the mobilestation and the BTS.

The Alcatel-Lucent BSS supports the E-GSM band:

The 900 MHz primary band (P-GSM band, 890-915 MHz in uplink, 935-960MHz in downlink) and

The 900 MHz extension band (G1 band, 880-890 MHz in uplink, 925-935MHz in downlink).

The following table shows all the supported frequency bands and the numberof channels for each band.

Parameter GSM 850 GSM 900 GSM 1800 GSM 1900

Transmit band 869 - 894 MHz 925 - 960 MHz 1805 - 1880 MHz 1930 - 1990 MHz

Receive band 824 - 849 MHz 880 - 915 MHz 1710 - 1785 MHz 1850 - 1910 MHz

Number ofchannels

124 174 374 299

Table 3: GSM Channel Characteristics

The radio carriers are separated by 200 kHz. Each radio carrier is dividedover time to give an eight timeslot frame. This is a TDMA frame. In TDMA,the callers are assigned timeslots as they are needed, and their signals areinterleaved within the one channel as the sequence is transmitted.

A channel uses a particular timeslot at each occurrence of a frame.

(E)GPRS traffic uses the same radio resources as circuit-switched traffic, andis carried on the same type of physical channel.

There are two types of GSM radio channels:

Traffic Channels (TCH)

Control Channels (CCH).

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1.3.6.1 Traffic ChannelsTCHs are used as speech traffic channels (for ciphered speech) or as datatraffic channels.

Speech traffic channels are defined as:

Half-rate traffic channels which use half a timeslot, at a rate of 6.5 kbits/s

Full-rate traffic channels which use a full timeslot, at a rate of 13 kbits/s

Enhanced full-rate traffic channels which use a full timeslot, at a rate of 13

kbits/s, but offer better speech quality.

Adaptive MultiRate (AMR) is a technology that allows the real-time optimizationof the speech coding scheme with respect to actual radio propagationconditions.

The AMR Wideband (AMR-WB) codec is developed as a multi-rate codec withseveral codec modes like the AMR codec. As in AMR, the codec mode ischosen based on the radio conditions. This feature is not compatible with TFO.

AMR provides the following improvements in capacity and quality:

Speech quality is improved, both in full-rate and half-rate

The offered capacity is increased due to the provision of half-rate channelswhenever radio propagation conditions are suitable.

Data traffic channels also use a full timeslot or half a timeslot at rates of 300bit/s to 9,600 bit/s. (E)GPRS implements flexible sharing of timeslots whichpermits much faster data transfer rates.

The Alcatel-Lucent BSS uses a feature called Packet Flow Context (PFC)to differentiate between different types of traffic on the radio interface, byreading a service profile defined by the mobile subscriber. The BSS can thenprovide optimum service by favouring certain types of traffic by reserving radioresources according to the type of traffic. For more information about PFC,refer to the Packet Flow Context section of the BSS System Description.

The channel used for VGCS is referred to as a VGCH. A VGCH is simply anormal TCH timeslot that is used for VGCS. One VGCH channel is allocatedby the BSS in each cell involved in a VGCS call. For more information aboutVGCS, refer to the VGCS section of the BSS System Description.

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1.3.6.2 Control ChannelsA CCH carries signaling information and channel control information. Controlchannels have individual functions and operate at different rates.

This control channel... Is used to...

Slow Associated Control CHannel (SACCH) Control and supervise the associated TCHs.

Fast Associated Control CHannel (FACCH) Handle irregular control requirements, for example,handovers.

Dedicated Control CHannel (DCCH) Manage location updating, authentication, call setup, and SMS.

Broadcast Control CHannel (BCCH) Provide general network information such as the cellin which the mobile station is located.

Paging CHannel (PCH) Call mobile stations when there is an incoming call.

Random Access CHannel (RACH) Inform the network that there is a mobilestation-originated call.

Access Grant CHannel (AGCH) Assign a dedicated control channel to the mobilestation.

Cell Broadcast CHannel (CBCH) Transmit cell broadcast information.

Table 4: Control Channel Types

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2 Alcatel-Lucent Base Station Subsystem


This section describes the Alcatel-Lucent 900/1800/1900 BSS architecture,functions and features, as well as the (E)GPRS feature.

It includes:

Alcatel-Lucent BSS components

External components

System Functions

(E)GPRS-specific implementation

Operation and Maintenance.

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2.1 IntroductionAlcatel-Lucents GSM/(E)GPRS/LCS offering meets the ever increasingdemand for cellular service. In todays changing environment, Alcatel-Lucentsdesign approach to network engineering permits network capacity to beextended and maximized according to customer requirements.

The Alcatel-Lucent BSS provides radio coverage for communication with GSMsubscribers in a defined area. Its principal role is to provide and support control,signaling and traffic channels between mobile stations and the NSS acrossthe PLMN. Management of the O&M functions of the BSS is performed at theOMC-R. Although not physically part of the BSS, the functions and featuressupplied by the OMC-R form part of the BSS functionality. The following figureillustrates the BSS within the PLMN.


MobileStations

NetworkSubsystem

FixedNetwork

PLMN

OMCR

NMC

MFS

MSC

Transcoder

PSDN

HLR

AbisInterface

Ater Interface

Gb Interface

AInterfaceBTS

BTS

BTS

BSC

PSTN

GGSNSGSNSMLC

LCSClientGMLC

Router

AGPSServer


GMLC : Gateway Mobile Location Center

HLR : Home Location Register


NMC : Network Management Center

PSDN : Packet Switched Data Network

PSTN : Public Switched Telephone Network


SMLC : Serving Mobile Location Center

Figure 4: Logical Position of the Alcatel-Lucent BSS and Associated External Components in the PLMN

For more information about (E)GPRS-specific information, refer to(E)GPRS-Specific Implementation (Section 2.5).

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2.2 Alcatel-Lucent BSS ComponentsThe BTS, BSC, and MFS components are linked within the BSS by transmissionelements. Together they provide the physical layer, and provide support for thedata link layer for the internal interfaces.

2.2.1 Alcatel-Lucent Radio Solutions

To respond to rapidly evolving and constantly increasing BSS requirements,Alcatel-Lucent offers the Alcatel-Lucent Radio Solutions.

The Alcatel-Lucent Radio Solutions include the following BSS equipment:

9120 BSC

9130 BSC Evolution

BTS G1 MKII and G2 with DRFU

BTS 9100 (Alcatel-Lucent 9100)

Micro-BTS Alcatel-Lucent 9110, 9110-E

G2 Transcoder

9125 Compact Transcoder

9135 MFS

9130 MFS Evolution.

2.2.2 Base Station Controller

The BSC provides resource and equipment management facilities for theBSS in a circuit-switched system. It allocates resources to manage the flowof information between the BTS and the NSS, acting as a switching unit byestablishing a path between them.

For a detailed description of the BSC, see the Alcatel-Lucent BSC/TC OverallDescription documents.

For a detailed description of the 9130 BSC Evolution, see the 9130 BSCEvolution Hardware Description and 9130 BSC Evolution FunctionalDescription documents.

2.2.3 Base Transceiver Station

The area covered by a BSS is divided into cells and each cell is managed by oneor more BTS. Each BTS consists of radio transmission and reception devices,including antennae and signal processing equipment for the Air Interface.

For a detailed description of the BTS, see the following:

BTS Functional Description

Alcatel-Lucent BTS 9100 / 9110 / 9110-E Functional Description.

3BK 21223 AAAA TQZZA Ed.04 33 / 52


2.2.4 Multi-BSS Fast Packet Server

The MFS provides resource and equipment management facilities for thepacket-switched system ((E)GPRS) in the BSS. It allocates resources to themobile station and the BTS. It manages the flow of information between themobile station and the BTS, and the BTS and the NSS. The MFS managesthe interface with the SGSN in the NSS. The MFS supports multiple BSSsand MSCs, and can be connected to several SGSNs. The Gb interfacecorresponding to this link can be through a frame relay or over IP net. SeveralMFSs can be connected to the same OMC-R. The SMLC in the MFS performslocation services for the set of BSCs served by the MFS.

For a detailed description of the 9135 MFS, see the Alcatel-Lucent 9135MFS Description.

For a detailed description of the 9130 MFS, see the9130 MFS EvolutionHardware Description and 9130 MFS Evolution Functional Description.

2.2.5 Transcoder

The transcoder is a network element that links the BTS, BSC, MFS, and MSC,and provides support for the internal interfaces of the BSS.

The transcoder provides the following functions:

Communication between the BSC and the MSC (encoded traffic)

Data-rate adaptation

Submultiplexing on the Ater interface.

There are two types of transcoders:

G2

G2 TC equipped with ASMC and TRCU

G2 TC equipped with ASMC/TRCU + MT120 boards (in the caseof an extension).

9125The 9125 TC can be equipped with up to 48 sub-units (referred to asMT120 boards).The 9125 Compact TC can have two 9125 TC STM-1 boards, active andstandby. They are inserted in a dedicated 9125 TC STM-1 subrack, whichis located in the bottom part of the TC rack. Each TC MT120 board isconnected to both TC 9125 STM-1 boards (dual star).

For further information concerning the transcoder, refer to the following:

BSS Components in the BSS System Description

Alcatel-Lucent BSC/TC Overall Description

Alcatel-Lucent 9125 Compact TC Description.

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2.3 External ComponentsThe BSS communicates with three external components:

The OMC-R

The Network Subsystem (Section 1.2.5)

Mobile Stations (Section 1.2.3).

Figure 4 shows the logical position of the external components in relation to theBSS components. External components are shown as shaded.

The OMC-R supervises one or more BSSs. It performs the following functions:

Manages the BSS software version

Acts as the central repository for configurations

Manages fault and performance measurement reports

Handles supervision of alarms and events.

The reported data is available to the operator from the OMC-Rs centraldatabase. The OMC-R only performs O&M activities. It does not perform usertraffic processing, or call establishment and control activities.

Operator actions via the OMC-R terminal interface trigger commandsthroughout the BSS. The OMC-R provides object-oriented managementinformation. Its interface supports different user profiles with different accessrights.

For more information about the OMC-R, refer to the BSS System Descriptionand the Operations & Maintenance Principles documents.

2.4 System FunctionsThe 3GPP recommendations define the system functions.

The Alcatel-Lucent BSS provides the following functions:

Call setup

Call handling

Call release

Operations and maintenance.

For detailed information concerning the BSS functions, refer to the BSSFunctions section of the BSS System Description.

For detailed information on O&M, refer to Operations & Maintenance Principles.

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2.4.1 Call Setup

The Call Setup function is used for speech and data calls. The following tabledescribes the three basic types of call.

This Call Type... Is used...

Mobility Management To gather information about the mobile station by exchanging protocolmessages. It only uses a signaling channel. Location updates are doneusing mobility management calls.

Supplementary Service To pass small amounts of information between the mobile station and theBTS. It only uses a signalling channel. SMS and MMS use supplementaryservice calls.

User Traffic For user traffic, such as speech or data (including fax, image and othercomputer data) calls to a correspondent, to pass large amounts ofinformation. Since they require greater bandwidth than that available on asignaling channel, these calls use traffic channels.

Table 5: Basic Call Types

2.4.2 Call Handling

During the lifetime of a call, the mobile station can change to another cell, ormove to and from data and speech. To allow these processes, call handlingfunctions include:

In-call modification

Handover

Ciphering

Overload control, to manage the call load on the system.

2.4.2.1 In-Call ModificationIn-call modification consists of alternating between speech and the varioustypes of data.

For more information, see the In-Call Modification section of the BSS SystemDescription.

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2.4.2.2 HandoverHandovers are active calls that are switched from one channel to another.Handover occurs when the BSS detects that the call quality has dropped belowa predefined level. When this happens, the call can be better supported by adifferent channel. Handover is only required for voice traffic.

Reasons for a handover are:

A drop in call quality because of cell problems

A mobile station moves to an area where the radio coverage from anothercell is better

A lower power level can be used in an adjacent cell

Congestion in a cell.

The principal types of handover are:

Internal/ExternalInternal and external handovers are performed because of cell problemsaffecting call quality. A mobile station moves to an area where the radiocoverage from another cell is better, either to a cell controlled by the sameBSC for an Internal handover, or to a cell controlled by a different BSCfor an External handover

Directed RetryDirected Retry handovers occur when there is congestion in a cell. ADirected Retry is only allowed for TCH assignments that can be queued.

Fast trafficThe fast traffic handover searches in the whole cell for a mobile which canbe handed over to a neighboring cell if the received signal level is goodenough. Fast traffic handover is much more efficient than the forced directedretry when the overlap of adjacent cells is reduced.

For more information about cell-environment handovers, see the Handoversection of the BSS System Description.

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2.4.2.3 CipheringCiphering is used to protect information transmitted on the Air Interfacebetween the BTS and the mobile station. It protects the information by usingencryption. There are three types of ciphering modes, the use of whichdepends on the mobile station classmark and the capability of the BTS.

The following table shows the ciphering capabilities for each type of mobilestation.

For further information about the ciphering capabilities of the BTS, refer tothe following:

Telecommunication Functions - Baseband in the BTS Functional Description

Alcatel-Lucent BTS 9100 / 9110 / 9110-E Functional Description.

For more information about classmarks, refer to the Classmark Handlingsection of the BSS System Description.

Mobile Station Type Capability

Phase 1 No encryption and A5/1

Phase 2 Extended No encryption and A5/1 and A5/2

Phase 2 No encryption

No encryption and A5/1

No encryption and A5/2

No encryption and A5/1 and A5/2

Table 6: Mobile Station Ciphering Capabilities

Note: The algorithms used for ciphering in the Alcatel-Lucent BSS are named A5/1and A5/2 in the GSM specifications. The modes used depend on the classmarkof the mobile station.

For further information, see the Ciphering section of the BSS SystemDescription.

Only phase 2 mobile stations can turn off ciphering, or change the cipheringmode, during a channel change procedure such as a handover. The cipheringcapability of a mobile station is signaled to the BSS in the mobile stationclassmark.

2.4.2.4 Overload ControlTo protect the system against overload, and therefore a possible loss ofcommunications, the system can bar access to mobile stations. This consistsof controlling the telecoms processors in the BTS, the BSC, and the MFS toensure that they do not become overloaded.

See the following for further information:

For the BTS and the BSC, refer to the Overload Control section of the

BSS System Description

For the MFS, refer to the GPRS Overload Control section of the BSSSystem Description.

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2.4.3 Call Release

When resources allocated to a call are no longer required, the Call Releasefunction ensures that all resources are free for reuse.

Specifically, the Call Release function includes:

Call Release in normal service:

Calls terminated by call management

Calls terminated following a channel change.

Special cases:

Call release following a reset

BSC-initiated release

BTS-initiated release

Mobile station-initiated release

MSC-initiated release for VGCS calls.

For more information, see the Call Release section of the BSS SystemDescription.

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2.5 (E)GPRS-Specific Implementation

2.5.1 (E)GPRS in the PLMN

The following figure shows the position of the major elements of Alcatel-Lucents(E)GPRS solution in the PLMN.

BTS

MS

BSC

To PSTN

BSS

GGSN

BTS

BSCGP

GCH

Ater

Gb

Packet

GCH

Abis

SGSN

To Public DataNetworks

GCH

TrafficSwitched

FRDN Gb

MSC/VLR

OMCR

MFS

Circuit

TrafficSwitched

Transcoder

TCH

TCH

TCH

BSCGP : BSC (E)GPRS Protocol

FRDN : Frame Relay Data Network

GCH : (E)GPRS Channel


PSTN : Public Switched Telephone Network



Figure 5: The Alcatel-Lucent (E)GPRS Solution in the PLMN

The BSS has (E)GPRS-specific equipment - the MFS - and software whichenable it to manage (E)GPRS radio resources and to communicate withthe (E)GPRS nodes.

(E)GPRS traffic is routed through dedicated servers which handlepacket-switched data, instead of passing through the MSC.

Therefore, traffic is handled by the following network nodes:

The MSC handles circuit-switched - i.e., voice traffic

The SGSN handles packet - i.e., data traffic, including security functionsand interface to the HLR

The GGSN provides interworking with external packet-switched networks.

The (E)GPRS nodes use specific interfaces for transmission and signaling.

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2.5.2 (E)GPRS

(E)GPRS increases GPRS capabilities for data transmission by using newmodulation and coding schemes on the Air Interface. Data throughputis optimized by Link Adaptation, which changes Modulation and CodingSchemes (MCS) according to radio conditions. When radio conditions worsen,a protected MCS with more redundancy is selected, leading to a lowerthroughput. Inversely, when radio conditions improve, a less protected MCS(less redundancy) is chosen for higher throughput.

2.5.3 (E)GPRS Network Configurations

The 3GPP recommendations provide three possible network configurations.

These configurations specify three possible positions for the Packet ControlUnit (PCU) function:

The BTS

The BSC

The SGSN.

The Alcatel-Lucent solution provides a smooth and cost effective introduction of(E)GPRS in the BSS. Existing network elements do not need any hardwaremodification. Only software upgrades are required in the BTS, BSC, andOMC-R.

The BSS contains a new network element, the MFS. The MFS sits betweenthe BSC/Transcoder on one side, and the SGSN on the other (see Figure 5and the figure below).

BSC

MFSPCU

PCU

Abis

Gb

Ater

BSC

BTS

BTS


PCU : Packet Control Unit

Figure 6: Position of the MFS in the BSS

The MFS works with other network elements, using the following rules:

All the BSSs connected to the same MFS are managed by the same OMC-R

One OMC-R can communicate with several MFSs

BSSs connected to the same MFS can be connected to different MSCs

One MFS can communicate with several SGSNs.

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2.5.4 (E)GPRS Network

The different elements shown in Figure 5 represent a parallel system to thecircuit-switched system used in GSM. In the Alcatel-Lucent solution, only theMFS with its associated interfaces is the BSS element. All other componentsare external to the BSS.

A High Speed Data Service (HSDS) provides CS3 and CS4 for GPRS, andMCS1 to MCS9 for (E)GPRS. It also offers additional functions that adapt radioresource allocation with (E)GPRS mobile stations to avoid Ater blocking, byallocating more transmission resources on the Abis and Ater to a radio timeslotmanaging HSDS capability on a TRE basis.

2.5.4.1 (E)GPRS MobilesThere are three classes of (E)GPRS-capable mobile stations:

CLASS A can handle circuit-switched voice and (E)GPRS trafficsimultaneously

CLASS B can be IMSI attached and (E)GPRS attached at the same time,

but use only one service (circuit-switched or (E)GPRS) at a time

CLASS C can be either IMSI attached or (E)GPRS but not both, and canuse circuit-switched or (E)GPRS services alternately.

Currently, only class B and C mobile stations are supported.

2.5.4.2 The SGSNThe SGSN is a (E)GPRS network entity at the same hierarchical level as theMSC. It is external to the BSS and communicates with it via Frame Relayover the Gb interface. The SGSN is involved in requesting specific networkresources for (E)GPRS traffic. It performs (E)GPRS paging, authentication, andcipher setting procedures based on the same algorithms, keys, and criteriaas in circuit-switched GSM traffic.

When the SGSN does not support the Inter-NSE Re-routing (INR) R4 option,the BSS performs LLC PDU re-routing on a cell change. If the SGSN supportsthis option, autonomous rerouting does not occur.

One SGSN can be connected to multiple MSCs and multiple MFSs.

2.5.4.3 The GGSNThe GGSN is connected with SGSNs via an IP-based backbone. It providesinterworking between the (E)GPRS network and external packet switchednetworks. It is external to the BSS.

The GGSN also works with other network elements in the routing and relayingof packets from one node to another.

2.5.4.4 The MFSThe MFS is preferably located at the Transcoder/MSC site and is internal to theBSS. The MFS provides PCU functions and the Gb interface protocol stack.

The MFS converts (E)GPRS frames, carried on multiple 16 kbits/s linksfrom multiple BTSs, to one or more frame relay channels connected to theSGSN on the Gb interface. See (E)GPRS Interfaces (Section 2.5.5) for moreinformation about the Gb interface.

The MFS controls the setup of Packet Data Channels (PDCHs). It alsonegotiates resources with the BSC and routes (E)GPRS packets.

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2.5.5 (E)GPRS Interfaces

The following sections describe the (E)GPRS-specific interfaces.

2.5.5.1 The Gb InterfaceThe Gb interface uses frame relay techniques to link the PCU function (MFS)and the SGSN.

Physically, it can be routed:

As a direct connection between the MFS and SGSN

Via a public Frame Relay Data Network (FRDN)

Via the MSC

Via the Ater Mux interface through the Transcoder to the MSC. In thiscase, it carries a combination of packet-switched and circuit-switched

traffic and signaling.

Combinations of these methods are also possible. See Figure 5 for the positionof the Gb interface in the system.

The Gb interface provides end-to-end signaling between MFS and SGSN, andserves as the BSS-(E)GPRS backbone.

2.5.5.2 The BSCGP InterfaceThe BSCGP interface provides communication between the BSC and the MFS(see Figure 5 ). The BSC (E)GPRS Protocol controls two LAPD connectionsper GPU, using 64 kbits/s timeslots.

2.5.5.3 The M-EGCH InterfaceThe M-EGCH interface provides a synchronous connection between the MFSand the BTS, using 16 kbits/s timeslots.

It ensures the following functions:

Transfer of PDUs between the MFS and BTS (therefore packet data is notdirectly handled by the BSC but passes transparently through it on the

M-EGCH interface). The transfer of PDUs containing CS3/CS4 GPRSblocks or (E)GPRS blocks uses several 16 kbps channels per PDCH.

Synchronization with the radio interface at M-EGCH link establishment

Correction of clock drifts between Abis and BTS clocks.

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2.5.5.4 The BSCLP InterfaceThe BSCLP Alcatel-Lucent proprietary interface is for LCS and provides thesignaling protocol between the BSC and the SMLC.

This interface allows the SMLC to:

Receive mobile station location requests

Choose a positioning method depending on mobile station capabilities

Perform location procedures

Respond to an initial request, providing the calculated mobile station

position estimate

Provide the mobile station with assistance data when using the A-GPS

positioning method.

2.5.5.5 The SAGI InterfaceThe SAGI interface is an Lb interface on TCP/IP that exchanges messagesbetween the SMLC and the external GPS server following an A-GPS positioningrequest in the circuit-switched domain.

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2.6 Operations and MaintenanceOperations and Maintenance provide the operator interface for the managementand control of the BSS, and its interconnection to the NSS.

2.6.1 Network Management

Alcatel-Lucents approach to network management is described within theareas of:

TMN

Management Information Tree (MIT)

Q3 Interface

Network Management Center functions.

2.6.1.1 TMNThe TMN supports a wide variety of management areas. These cover theplanning, installation, operation, administration, maintenance and provisioningof telecommunication networks and services. The following figure showsthe TMN hierarchy.

OMCR

BTS BSC MFS

NMC/OMCR

Business Management

Service Management

Network Management

Element Management

Network Element

TC



TC : Transcoder

Figure 7: TMN Hierarchy

2.6.1.2 Management Information TreeAs in the TMN model, Alcatel-Lucents network management model is basedon an object-oriented design using Managed Objects. Managed Objects areorganized in a hierarchical structure called a Management Information Tree(MIT). In the Alcatel-Lucent implementation, Managed Objects are organizedin an MIT with three main levels, as shown in Figure 8. A Managed Objectcan be a physical element, such as a BSS, BTS, BSC, or a hardware modulewithin one of these elements. It can also be a logical entity, such as a cellor a signaling link.

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2.6.1.3 Q3 InterfaceCommunication between the NMC and the OMC-R takes place across theQ3 interface (see the figure below). The Q3 interface allows supervisionof a complete network by an NMC.

OMCR

BSC

BTSBTS

BTS

OSSDomain

Q3 Interface

Q Interfaces

BSSDomain

AbisAbis

Abis

Network Management

Network Managementat region level

NMC Operator(Network Supervisor)

OMCR Operator(Resource and Equipment

Management)

Maintenance Technician(Equipment Management)

NMC

Q3 Interfaces

MFS

Network ElementManagement

Network ElementManagement



OSS : Operation Support System

Figure 8: TMN System Hierarchy

2.6.1.4 Network Management Center FunctionsStandard network management is performed by the OMC-R and an NMC.Some operators choose to have an NMC supervising one or more OMC-Rs in ahierarchical relationship represented by the MIT.

For further information, refer to the Object-oriented O&M Model section of theOperations & Maintenance Principles document.

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2.6.2 O&M Management

Network management and control functions are proprietary to the systemsupplier. In keeping with ITU and 3GPP standard communication protocols,the current release supports the concept of network management. This iscompatible with all equipment, even that of different manufacturers.

The O&M management for the BSS is organized into the following functionalmanagement domains:

Configuration management

Fault management

Performance management.

2.6.2.1 Configuration ManagementThe main benefit of the configuration management feature implemented in the9153 OMC-R is the reduced time needed to perform operations and reducetelecom outages. This is achieved by having fewer operator commands andproviding smooth migration and equipment configuration.

The main functions of configuration management include:

Radio configuration management

Supervised configuration view

Provisioning radio configuration

Extensive logical configuration update

Logical parameters templates

Usage states on demand

(E)GPRS service handling

Activation of features such as TRX Unbalancing

Radio configuration import/export.

Equipment management

Hardware online extension-reduction

Hierarchical browser (network element, rack, shelf, board, transmission)

Remote inventory of hardware and firmware configuration

Equipment configuration export.

2.6.2.2 Performance ManagementThe 9153 OMC-R provides measurements and statistics about variousevents and resource used in the BSC and MFS. Indicators computed by theOMC-R enrich the raw data retrieved from the field. The operator can displaymeasurements as graphs and activate alerters to send alarms when presetthresholds are crossed. The OMC-R also generates QoS alarms to notify theoperator of potential network problems.

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2.6.2.3 Fault ManagementThe main functions of fault management include:

Detection

Graphic synthesis view

Fault localization

Alarm counters

Alarm severity assignment.

Tracking

Alarm views with sort and filter

Alarm reservation

Event/alarm logging.

Resolution

Alarm acknowledgment

Fault correction.

Post analysis

Alarm history

Evolution of events.

At the OMC-R, the AS alarm manager collects all network events in real timeand presents default or customized alarm lists dynamically, using colors toindicate levels of urgency in each sublist.

To reduce the number of alarms in the OMC-R, alarms are filtered to minimizethe number of fault alarms reported, and displayed to the operator in orderof severity. The operator sees fewer alarms and is informed that alarms arefiltered, since the number of filtered alarms, if any, is indicated in AS.

The AS collects alarms issued by applications residing in the variousmanagement layers and processes them. The operator can see whetherunacknowledged alarms are still present.

Alarms can be managed on a large number of network elements in real time,with the radio and equipment views providing a clear status on radio resourcesand equipment. Alarm sublists can be customized using powerful sort andfilter services, enabling the operator to react quickly.

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2.6.3 O&M Functions Implementation

The different O&M functions are implemented in all of the BSS components.Not all functions are present in each component. The following sections providean overview of O&M functions by component.

2.6.3.1 OMC-RThe OMC-R is the central O&M base for one or more BSSs. It manages BSSsoftware versions, and acts as the central repository for configuration, fault, andperformance measurement reports. This data is available to the operator fromthe OMC-R central database. The OMC-R only performs O&M activities. It doesnot perform user traffic processing or call establishment and control activities.

The OMC-R provides an object-oriented, X-Terminal graphical interface forthe operator to access configuration, performance, and fault managementfunctions. Operator actions through this interface trigger commands throughoutthe BSS to perform these functions. The terminal interface supports differentuser profiles with different access rights.

The OMC-R proposes a proprietary backup and restore function which worksfor all OMC-R configurations. This network storage management applicationbacks up and recovers data across an entire network of computers. Thesoftware protects data by automatically backing up, storing, and indexing eachdata item, allowing recovery of any particular data item.

For more information, refer to the OMC-R section of the Operations &Maintenance Principles and the 9153 Getting Started documents.

2.6.3.2 BTSThe BTS performs self-maintenance functions to ensure reliable BTS operation.It is supervised by its own O&M controller which passes O&M information to theBSC. The BSC returns fault resolution information to the BTS O&M controller,which then carries out the instructions

The BTS is designed with key component redundancy and support for"hot insertion". Some key components are duplicated within the BTS. Ifa component fails, the duplicate takes over automatically, and the faultycomponent can be replaced without powering down. In both cases, there isno interruption of service. The BTS configuration can be updated from theOMC-R, or by an autonomous reconfiguration managed by the BSC.

BTS O&M includes functions such as BTS start up.

The BTS provides a terminal interface for local O&M. Refer to the BTS TerminalUser Guide for further information.

For more information about BTS O&M functions, refer to the O&M Functionssection of the BTS Functional Description document, and to the O&M andSupport Functions section of the Alcatel-Lucent BTS 9100 / 9110 / 9110-EFunctional Description document.

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2.6.3.3 BSCAs the controller of the BSS in a circuit-switched system, the BSC acts as thecontrol point for collecting and processing O&M data. The BSC software anddatabase are used to manage its O&M functions.

The BSC software constantly monitors its internal components. The BSCinstigates its own fault solution procedures and updates its databaseaccordingly.

Performance measurements taken in the BSS subsystems are sent to theBSC. The BSC creates performance measurement reports and sends theseto the OMC-R.

Alarms produced in the BSS are sent to the BSC, which forwards them tothe OMC-R. The BSC keeps its own alarm records on the database. If theBSS/OMC-R link fails, the BSC stores the alarms and forwards them to theOMC-R when the link is restored.

The BSC provides a local terminal interface. The menu-based interfaceenables operators to perform O&M functions on the BSC and the BTS. Formore information, refer to the BSC Terminal User Guide for the 9120 BSC orthe 9130 BSC Evolution Terminal User Guide for the 9130 BSC.

For more information about the BSC and its components, refer to theAlcatel-Lucent BSC/TC Overall Description for the 9120 BSC or the 9130 BSCEvolution Functional Description document.

2.6.3.4 TranscoderThe TSCA performs supervisory, control, and measurement functions for theTranscoder. The TSCA is connected to the Transcoder via the Qmux bus.

For additional information, refer to the Alcatel-Lucent BSC/TC OverallDescription.

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2.6.3.5 MFSEven though the MFS is included in the BSS, the BSC does not act as acontrol point for collecting and processing O&M data for the MFS. The MFSdoes this itself and sends the necessary alarm and performance data directlyto the OMC-R.

The MFS is designed with built-in redundancy for the (E)GPRS ProcessingUnit (GPU), the MFS Hub subsystem, and the server subsystem for 9135MFS and switches plus control stations for 9130 MFS. One GPU operates ina redundant mode and replaces, when needed, a faulty GPU for 9135 MFS,therefore a floating GPU recovers the faulty GPU in 9130 MFS. The Hub hasduplicated 100 Mbit/s Ethernet networks, with one operating in redundantmode. The server subsystem consists of two UNIX servers, one of whichoperates in redundant mode for 9135 MFS and 2 ATCA boards with HDD inLinux Montavista for 9130 MFS. In the event of the active station failing, thestandby station becomes the active station.

The MFS manages its equipment, including low level software management. Italso manages the GPU telecom operations, and is responsible for telecomresource configuration and supervision. The MFS provides a terminal interface,the IMT, for local O&M.

For additional information about the MFS, refer to the:

Alcatel-Lucent 9135 MFS Description

9130 MFS Evolution Hardware Description

9130 MFS Evolution Functional Description.

For more information about the IMT, refer to the Alcatel-Lucent 9130 MFS IMTUser Guide or theAlcatel-Lucent 9135 MFS IMT User Guide.

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