bss introduction presentation-06e04

B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 1

Base Station SubsystemGSM 900/1800/1900

Introduction Presentation

Training Document


Contents (1)

Historical Excursion to Mobile Radio Systems The GSM Standard Components of the GSM System Interfaces GSM Services Mobility Management Numbers and Identifiers Scenarios in the System GSM Security and Encryption


Contents (2)

Air Interface (GSM 04.05) Radio resources TDMA principle Logical Channels Multiframe structure Physical Channels GSM Signal Processing Chain

Features BSS cell environment

Cell structures Multiband solution

The Alcatel Evolium BSS


Historical Excursion

First implementation of mobile telephone systems

1946 in St. Louis (Missouri, USA) In the early 50th of the 20th century in Europe

These Systems were: Manually operated Service area restricted Single cell systems with small capacity priority to military systems



Since 1980 the mobile telephone systems became: automatically routed better capacity large scale integration of electronic devices in the 70s introduction of cellular systems continuous integration and improvement of analog technologies

AMPS (Advanced Mobile Phone Service) was the 1st cellularsystem in the US in 1979

in Europe the Scandinavian countries were the first introducingthe NMT (Nordic Mobile Telephone) system in 1981


Historical ExcursionAnalog Cellular Telephone Systems


Main parameter of existing analog cellular mobiletelephone networks



Historical ExcursionSome Restrictions of Analog Technologies

limited frequency ranges no professional digital data transmission within an analog

channel no additional services e.g. call forwarding, short message

service, broadcast message ... no ISDN interface no multimedia interfaces no international roaming


Between 1983 and 1987 the


was designed. After the hardware development the firstcellular telephone networks were implemented in 1991.

R


Historical ExcursionAdvantages of GSM

International Standard compatibility between GSM systems in different countries enable subscriber to use their mobile wherever they are

International Roaming Calls can be routed in many countries

Confidentiality, security High Quality ISDN compatible High capacity


Historical ExcursionHistory of Mobile Telephone Networks in Germany

1st analog mobile telephone system: A-network (1950), onlyused for tests and military, manually operated, in the 50MHzrange.

2nd analog mobile telephone system: B-network(1958), onlyused for military and business, in the 150 MHz range.

3rd analog mobile telephone system: C-network (1986), 1stpublic mobile telephone network, in the 450MHz range,maximum reached subscribers ca. 800000. End of operation inyear 2001


Historical ExcursionGSM Networks in Germany

D 1: GSM 900 network, public system operator:T-Mobil (since 1991)12,1 Million subscriber

D 2: GSM 900 network, private system operator:Mannesmann (since 1991)12,5 Million subscriber

E+: GSM 1800 (DCS) network, private system operator,Thyssen, Veba (since1994)4,7 Million subscriber

E 2: GSM 1800 (DCS) network, private system operator:Viag Interkom (since 1998, Oct.)1,6 Million subscriber


The GSM StandardDevelopment of the GSM Standard

1979 WARC - World Administrative Radio ConferenceDefinition of frequency band between 860 and 960 MHzfor future mobile radio services: 2 x 25 MHz reserved forduplex service

1982 Formation of Group Special Mobile within CEPT (GSM) 1983 GSM takes up operations

Objective: Specification of a paneuropean digital cellularradio system

1985 Development and test of different trial systems 1987 Memorandum of Understanding (MOU) signed by 17

PTT Administrations from 16 European countries


The GSM StandardDevelopment of the GSM Standard

1989 Selection of Air Interface. Start of HW-developmentGSM becomes a committee within ETSI

1990 The most important GSM Recommendations are available

GSM Global System for Mobile Communication

1991 Active operation of GSM900 1992 Start of GSM operation 1993 WARC 2 * 75 MHz in the 1800 MHz band for GSM1800 1994 Active operation of GSM1800 1998 more than 200 members in the MOU of more than 120

countries


part of ETSI specification

The GSM StandardGSM Recommendations


The success story ofThe success story ofGSMGSM

has just begun ...has just begun ...

The GSM Standard Almost Worldwide

Mainly CDMA / TDMA

Mainly GSM

World-wide Subscriber Base (Million)

1999 2001 200320022000

200

400

600

800

GSM 385 M

CDMA 98 M

58 MPDCTDMA 70 M

82 MAnalog

Source Alcatel


ChallengesMobile Switching Solutions

SMP

SCP

SPP ManagementCenter

SCE

BTS

MSC

ATOM

Toll

MSC

ALMA

SSP STP

BTS

HLR

A935MFS

SGSN GGSN

@BSC

GPRSGPRSBackboneBackbone


ChallengesMobile Switching Solutions

AbbreviationsAbbreviations

Intelligent Networks

SPP : Provision PointSCE : Creation EnvironmentSMP : Management PointSCP : Control PointSSP : Switching Point

Mobile Switching

STP : Service Transfer PointMSC : Mobile Switching CenterHLR : Home Location RegisterALMA : Alcatel Management platform for TMNGPRS : General Packet Radio ServiceMFS : Multi BSS Fast Packet ServerSGSN : Service GPRS Support NodeGGSN : Gateway GPRS Support NodeBTS : Base Transceiver StationBSC : Base Station Controller


All-in-OneSM

Alcatel Services for Network Operators

Network Operation& Maintenance

Management &Business Consulting

Network & Service Design Network & ServiceIntegration

Network Implementation

Network & ServiceEnhancementSkills & Resource

Development

Customer Administration


GSM Basic System Components


GSM System ComponentsThe Network Subsystem NSS

Mobile Switching Center (MSC): Central switch between BSS and PSTN Connection to billing center

Home Location Register (HLR): Central database for mobile subscriber specific data

e.g. IMSI, International Roaming, Agreed services...

Visitor Location Register (VLR): temporary database for all Mobile Stations


GSM System ComponentsThe Network Subsystem NSS

Authentication Center (AuC): management of security data used for subscriber authentication

(usually part of the HLR)

Equipment Identity Register (EIR): contains the list of Mobile Station equipment identities.

"gray list" for all unauthorized IMEI categories (only temporaryvalid)

"black list" for individual IMEI which are not authorized, e.g.because they have been stolen

white list for all IMEIs which are not in the gray or black list


GSM System ComponentsThe Base Station Subsystem BSS

Transcoder Submultiplexer (TCSM) Interface between the BSS (Atermux interface) and the MSC

(A-interface). Speech coding/decoding and rate adaptation between the 64 kbit/s

PCM TCHs in the MSC and the 16 kbit/s TCHs in the BSS. The G2 TC includes the Submultiplexer equipment (SM). Reduces the number of terrestrial channels needed between the BSC

and the TC. management of speech related features e.g.: DTX, DRX, comfort

noise insertion ...



Base Station Controller (BSC) Central switch in the BSS Handling of BSS software Radio resource management between MS and MSC Mobility Management for the MS Fault Management Performance Measurement handling Configuration Management Interface to the Operation and Maintenance Center Radio (OMC-R).



Base Transceiver Station (BTS) Provision of the radio link to Mobile Station (MS) Signal processing from digital signal to RF-signal (uplink/downlink) Provision and support of signaling and traffic channels on the Air

interface and on the Abis interface Reception and demodulation Performance of radio measurements for the mobility management


Interfaces

A-interface: MSC - BSC (TC)

Atermux interface: TC - BSC

Abis interface: BSC - BTS

Air Interface: BTS - MS


BSCMSCMSC

TC

SM

SM

A-ter mux

A-Interface (GSM)

A-ter (Alcatel)

InterfacesThe A-Interface

The A-Interface is used for communication between the MSC andthe BSC. The connection between MSC and BSC is realized viaPCM30/32 (2 Mbit lines) and can be done via Terrestrical lines,satellite connections or micro wave links.


BSC

BTS

Abis InterfaceBIE

BIE

InterfacesThe Abis Interface

The Abis Interface is used for communication between the BSCand the BTS. The BTSs can be connected in differentconfigurations to the BSC by using PCM 30/32 (2 Mbit lines).


BTS

InterfacesThe Air Interface

The Air Interface is the radio interface between the BTS and the MS

The Air Interface is divided by frequency and time


GSM Services

Three types of mobile network services

Teleservices Bearer Services Supplementary Services


GSM ServicesDefinition of Services

Teleservices provide the complete capability including terminal equipment

functions for communication between users, according to protocolsestablished by agreement between network operators.

Bearer Services Bearer Services provide the capability of signals (i.e. data)

transmission between access points. These access points are in ISDNterminology called user-network interfaces.

Supplementary Services Supplementary Services are control data for Teleservices.


Service DescriptionTelephony GSM supports telephony with the ability to send or

receive calls anywhere in the world.Emergency call GSM allows calls to be routed to an emergency

service. Emergency calls have priority. If there areinsufficient radio resources, the call request is queuedat the highest priority.

Data Calls GSM supports the transmission of data and offers arange of transmission types.

Fax High speed telefax messages can be sent to orreceived from a standard fax machine anywhere in theworld.

Short Message Service The short message service allows the transmission ofmessages containing up to 160 alphanumericcharacters to be sent to a subscriber. The SMS centerinterfaces with other network services such as paging,message handling and voice messaging.

Cell Broadcast Cell broadcast is a short message service which allowsshort messages to be sent to all phones in ageographical area.

GSM ServicesTeleservices


GSM ServicesBearer Services

Bearer services provide basic transmission functions

Bearer services are basic data transport services which allow thedata transport in data rates from 300 bit/s up to 14.4 kbit/s per TS.

It can be used for example for fax or data transmission.

General Packet Radio Services GPRS combines TCHs for high datatransmission up to 160 Kbit/s per carrier (8 TS).


GSM ServicesSupplementary Services

The supplementary services provide additional to the teleservicesthe following options:

Call forwarding (mobile subscriber busy, mobile not reachable)

Call barring (outgoing , incoming , incoming when roaming abroad)

Call waiting, call hold and three party services

Conference Call

Call Line Identification Presentation CLIP


Mobility ManagementDefinition of Areas

Service area PLMN area (Public Land Mobile Network) MSC area / VLR area Location area Cell



Service area is the territory in which a mobile radio station can be used. A service area can cover several PLMNs.

PLMN area (Public Land Mobile Network) the geographic territory in which a telecommunication company

provides mobile telephone services consists of a number of MSC areas with a common numbering

system (e.g. identical national dialing prefixes) plus a commonswitching system



MSC area / VLR area network territory covered from one MSC one VLR can supply one or more MSC areas

Location areaarea where a MS can move from cell to cell (in idle mode)without updating the visitor location area identity (LAI)

Cell smallest logical area, usually covered by one sector of a base

transceiver station (BTS) identified by the cell global identifier (GSM 03.03)


Mobility ManagementMobile Specific Procedures

Roaming Location Update IMSI attach/detach Idle mode Paging Handover



Roamingavailability of the MS in the network. International roaming is thepossibility to use and reach a MS worldwide.(roaming contract between network operators required)

The MS in idle mode is continuously monitoring the strongestavailable carrier frequencies. The 6 strongest carriers of theserving network are stored. The MS uses the strongest carrier forthe next call. Receiving a new LAI (Location Area Identity) on thestrongest carrier the MS initiates a Location update.



Location Updateupdate of the LAI (Location Area Identity) in the VLR

Moving MSThe MS is moving into a new location area receiving a new LAI.

Regular location updateA MS not leaving its location area is reporting its location (LAI) inregular intervals to the VLR. The interval can be adjusted at theOMC-R

A location update is always and only initiated by the MS A location update is never done during a call For more details refer to GSM 03.12.



IMSI attach/detach If the MS is switched off the subscriber data in the VLR is not

immediately deleted. The subscriber is only detached. This fastens the next switch on of the MS in the same location area,

the subscriber data will only be attached.

Idle modeThe MS is switched on and the location update was successful.The VLR knows the subscriber data and LAI of the MS, the HLRknows the VLR which handles the MS. The MS is reachable.

PagingSearching call for a MS into a location area



Handover HOForwarding a call from one radio channel to an other

HO within one cell (intra cell-HO) between the carriers of the same base station quality improvement (interferer level) only if frequency hopping is not used

HO between cells (intra BSC-HO; inter cell-HO) between base stations, connected to the one BSC. The handover is reported to the MSC.



Handover HO

HO between BSCs (Intra MSC HO; inter BSC-HO) between two BSCs connected to the same MSC

HO between MSC (inter MSC-HO)

Handover between PLMNs(special roaming contract required).



Handover initiation A handover is always initiated by the BSS Handover decision and performance is handled in the BSC using the

measurements on the Air interface:



Handover causes (1) In Alcatel release B6 25 different handover causes are defined.

These handover causes can be sorted into two categories:

emergency handover causes e.g.: low level on uplink low level on downlink low quality on uplink low quality on downlink long MS BTS distance



Handover causes (2)

better condition handover causes e.g.: power budget (better cell handover) high level in neighbor lower layer for slow MS high level in neighbor cell in the preferred band


Numbers and Identifiers

MS-ISDN IMSI TMSI LMSI MSRN Handover number IMEI LAI CGI BSIC


CC: Country Code for the country in which the MS is registered

NDC: National Destination Code (PLMN specific)SN: Subscriber Number

Numbers and IdentifiersMS-ISDN

MS-telephone number Used for dialing Searching index for HLR


MCC: Mobile Country CodeMNC: Mobile Network Code (Identification of home PLMN)MSIN: Mobile Subscriber Identification Number

(Identification of the subscriber within the PLMN)NMSI: National Mobile Subscriber Identity

Numbers and IdentifiersIMSI

International Mobile Station Identity MS-telephone number in GSM network unique for each SIM

MCC country262 Germany260 Poland425 Israel


Numbers and IdentifiersTMSI

Temporary Mobile Station Identity is used for security reasons -> Confidentiality of the mobile radio

subscriber IDs, TMSI instead of IMSI on the air interface identifies each unique MS is assigned in the current VLR is only important in the VLR area 4 byte length (structure is not defined in GSM) required for call setup, location update, etc. is assigned after the successful authentication


Numbers and IdentifiersLMSI

Local Mobile Station Identity is assigned in the VLR at location updating 4 byte length to speed up the search for subscriber data in the VLR exact identity of the mobile station in the VLR

Note: The TMSI and the LMSI are both provider specific, i.e. theyare not defined in the GSM rec.


Numbers and IdentifiersMSRN

Mobile Station Roaming Number This number is assigned to a MS from the VLR either temporarily for

each individual call (query mode) or by updating the MS locationdata (the Alcatel BSS uses the first procedure explained)

Structure similar to MS-ISDN (CC + NDC + SN), max. 15 digits SCCP global address header to identify the responsible MSC

(required for PSTN/ISDN circuit-switching) Max. lifetime 90 sec. (when assigned separately for each call) Unique for each MS moving about a specific range of numbers,

valid only for a VLR area Used by the HLR to re-direct calls (MT calls) towards the destination

MSC (VMSC) => establishment of ISUP


Numbers and IdentifiersHO Number

Handover number temporary number used for the link establishment between MSCs to forward a call HO number similar to MSRN assigned in the (new) MSC


Numbers and IdentifiersIMEI

International Mobile Station Equipment Identity hardware identifier for the MS equipment

TAC: Type Approval Code FAC: Final Assembly Code, location identifier of production/final assembly; SNR: Serial Number, equipment identifier SP: Spare Position, one digit used for future purposes.


MCC MNC LAC CI

3 digits 2digits max. 2octets max. 2octets

Location Area Identity LAI

Numbers and IdentifiersCGI & LAI

Cell Global Identity cell identifier on the air interface

MCC: Mobile Country CodeMNC: Mobile Network Code (Identification of home PLMN)LAC: Location Area Code (flexible length up to max. 2 octets)CI: Cell Identity


NCC BCC3 bit 3 bit

Numbers and IdentifiersBSIC

Base Station Identity Code cell identifier on the air interface for fast network and cell selection

NCC: Network Colour Code, to distinguish different networksBCC: Base Station Colour Code, to distinguish cells with the same BCCH frequency


Scenarios in the System

Mobile originated Call MOC

Mobile terminated Call MTC

Handover

Location update


Scenarios in the SystemMobile Terminated Call (1)


Scenarios in the SystemMobile Terminated Call (2)


Scenarios in the SystemMobile Originated Call (1)


Scenarios in the SystemMobile Originated Call (2)


Scenarios in the SystemHandover (1)


Scenarios in the SystemHandover (2)


Scenarios in the SystemLocation Update (1)


Scenarios in the SystemLocation Update (2)


GSM Security and Encryption

Authentication parameter

Authentication

Encryption

Activation of Encryption

Subscriber Identity Module SIM


GSM Security and EncryptionAuthentication Parameter (1)

RAND (random number) generated in the AuC length 16 byte

Kc (ciphering key) calculated in the AuC and in the MS used for the encryption of the subscriber data length 8 byte

SRES (signed response) calculated in the AuC and in the MS used to control authentication length 4 byte


GSM Security and EncryptionAuthentication Parameter (2)

Ki (key identifier) unique for each subscriber stored in the AuC and on the SIM never transmitted on the air interface length 16 byte

CKSN (ciphering key sequence number) used to select a Kc during call setup length 3 bit


GSM Security and EncryptionAuthentication


GSM Security and EncryptionAuthentication

Authentication parameterKi and RAND are the input parameters for the algorithms A3 andA8.

The VLR compares the signed responses SRES calculated in theAuC and in the MS with algorithm A3.

The authentication is successful if both SRES are identical.

The ciphering key Kc is calculated with algorithm A3.

EncryptionAfter successful authentication the encryption with algorithm A5 isenabled.The subscriber data and the ciphering key Kc are theinput parameters for the encryption.


GSM Security and EncryptionSpeech Encryption with Algorithm A5

A 5.0no encryption

A 5.1standard encryption

A 5.2enhanced encryption

A 5.3 to 5.7 definedfor future use


GSM Security and EncryptionActivation of Encryption


Air Interface

Radio Resources TDMA Structure Logical Channels Multiframe Structure Physical Channels (Timeslots) Synchronization Criteria Channel Encoding Interleaving Signal Processing Chain


Radio Spectrum Allocation

Frequency(FDMA)

Time(TDMA)

Timeslot0


Air InterfaceGSM Channel Specification (1)

GSM 900 frequency band consists of 124 radio carriers betweenthe Mobile Station and the BTS (Uplink) and 124 radio carriersbetween the BTS and the Mobile Station (Downlink).

GSM 1800 frequency band consist of 374 radio carriers for eachdirection (Uplink, Downlink).

GSM 1900 frequency band consist of 299 radio carriers for eachdirection.

The radio carriers spacing is 200 kHz. Each radio carrier is divided into 8 Timeslot (TS), a frame. This is

a Time Division Multiple Access (TDMA) frame. The TS are configured with different logical channel types:

Traffic and Control Channels.


Parameter Values

GSM 900 Frequency band Uplink: 890 MHz 915 MHz

Downlink: 935 MHz 960 MHz

GSM 1800 Frequency band Uplink: 1710 MHz 1785 MHz

Downlink: 1805 MHz 1880 MHz

GSM 1900 Frequency band Uplink: 1850 MHz - 1919 MHz

Downlink: 1930 MHz - 1990 MHz

Duplex distance GSM 900: 45 MHz

GSM 1800: 95 MHz

GSM 1900: 80 MHz

Carrier separation 200 kHz

Modulation Gaussian Minimum Shift Keying (GMSK)

Transmission rate 270 kbit/s

Access method Time Division Multiple Access (TDMA)

Channel 1..124

Channel 512...885

Channel 512...810




GSM 900Ful(n)=890,2 MHz + 0,2 x (n-1) MHzFdl(n)=Ful(n) + 45 MHz

GSM 1800Ful(n)=1710,2MHz + 0,2 x(n-512) MHzFdl(n)=Ful(n) + 95 MHz

GSM 1900Ful(n)=1850,2 MHz + 0,2x(n-512) MHzFdl(n)=Ful(n) + 80 MHz


Air InterfaceTDMA Principle


BCC Broadcast TS SDC TS (SDCCH-TS) TCH-TS

Air InterfaceTDMA Principle

Time Division Multiple Access (TDMA)With 8 timeslots per carrier a maximum of 8 MS can be handledper carrier frequency.

A frame concatenates 8 TS. The duration of a frame is 4.615ms (=> 0.577ms/TS) Some TS are dedicated to signaling TS, they can not handle user

data. Types of timeslots


Air InterfaceTraffic Channels

Traffic channels are used as speech traffic channels or as data trafficchannels. Speech traffic channels are defined as: TCH:

Fullrate traffic channels which use a full TS, (net 13 kbit/s) Halfrate traffic channels which use half a TS, (net 6.5 kbit/s) Data traffic channels also use a full TS or half a TS at rates of

300 bit/s up to 14.4 kbit/s.

PDCH Traffic channel for General Packet Radio Service (GPRS)


Air InterfaceControl Channels (CCH)

A Control CHannel (CCH) carries signaling information andchannel control information. Control channels have individualfunctions, and operate at different rates:

Fast associated control channels which handle irregular controlrequirements, for example handovers

Dedicated control channels, are used for location updating,authentication, call setup, and short message services

Broadcast control channels, are transmitting basic informationdedicated to all users, for example a LAC of a cell

Slow associated control channels control and supervise theassociated TCHs


Air InterfaceBroadcast Channels (BCH)

FCCH Frequency Correction Channel: used on the downlink (onthe BCCH timeslot) for frequency correction of the MS withthe BTS.

SCH Synchronization Channel : used on the downlink (on theBCCH timeslot) for frame synchronization of the MS withthe BTS.

BCCH Broadcast Control Channel: used to broadcast system information to the MS on the downlink Number of CCCH Paging organization CGI, LAI BCCH frequencies of neighbor cells Maximum transmit power, which is allowed in the cell


Air InterfaceCommon Control Channels (CCCH)

CCCH Common Control Channel: to transmit controlinformation before a dedicated channel is assigned.It comprises the RACH, AGCH and PCH.

RACH Random Access Channel: used on the uplink(on the CCCH TS) by the MS for initial access to thenetwork.

AGCH Access Grant Channel: used on the downlink(on the CCCH TS) gives to the MS access informationbefore a dedicated channel is assigned.

PCH Paging Channel: used on the downlink(on the CCCH TS) for paging messages to the MS.


Air InterfaceDedicated control channels (DCCH)

SDCCH Stand-alone Dedicated Control Channel.Main signaling link for call setup

CBCH Cell Broadcast Channel:used instead of one SDCCH subchannel forShort Message Service -Cell Broadcast messages


Air InterfaceAssociated Control Channels (ACCH)

SACCH Slow Associated Control Channel: used to exchange measurements and control informationduring a call (e.g. for power control, comfort noise,timing advance)

FACCH Fast Associated Control Channel: used for handover process signaling, IMSI-attach/detach orcall setup. This ACCH takes additional frames forsignaling from a TCH, using then stealing flag.


Air InterfaceSummary of Logical Channels


BCC Broadcast TS SDC TS (SDCCH-TS)

TCH-TS26 Multiframe for:

51 Multiframe for:

Air InterfaceMultiframe Structure

Different logical channels using the same TS can only betransmitted serial after each other in different TDMA frames.

The transmission of the different channels is repeatedperiodically.

One transmission period on a TS (BCC, SDC or TCH) is called: => Multiframe


0

50

25

FCCH

SCH

BCCH

SDCCH

CCCH

TCH



Only the downlink is shown!

MultiframeStructure

Air Interface


Air InterfacePhysical Channels


Normal Burst

FCCH

SCH

Dummy Burst

RACCH

Air InterfaceBurst Types


Air InterfaceSynchronization Criteria


Air InterfaceChannel Encoding


Air InterfaceInterleaving


Signal Processing Chain


Alcatel BSS FeaturesFeatures

Power Control Frequency Hopping Discontinuous Transmission DTX Discontinuous Reception DRX Fullrate Halfrate Enhanced Fullrate SMS-Cell Broadcast Antenna Diversity Night Time Concentration GPRS


Alcatel BSS FeaturesPower Control

Radio Power Control reduction of interference level increase of frequency reuse rate

BTS Radio Power Control Range from maximum down in 15 steps (or less) of 2 dB down

to minimum power of 20 mW Step size n * 2 dB

MS Radio Power Control increase of stand by time Range from maximum down to minimum 20 mW Step size n * 2 dB


FrequencyGenerator1

Frequencygenerator2

TRE/Carrier

TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7

=> better quality

Alcatel BSS FeaturesFrequency Hopping

Frequency Hopping every TS can use an other frequency reduce interference level Gain 3 dB better frequency reuse rate


Alcatel BSS FeaturesDTX / VAD

Discontinuous Transmission / Voice Activity Detection

Is used to decrease the average interference level and to save thebattery in the MS

Discontinuous Transmission (DTX): During quiet periods, comfortnoise information is sent based on synthesis of background noise.

Voice Activity Detection (VAD): VAD is used to detect when there isspeech or silence. In case of silence the MS transmitter is switchedoff, it only transmits SID Frames (Silence Indication Frames). The TCuses this SID Frames to generate the comfort noise and forwards itto the A-channel.


Alcatel BSS Features DRX

Discontinuous Reception

Is used to save battery by switching of the receiver and dataprocessing in the idle mode. The mobile station only listens tothat part of of the paging channel corresponding to its paginggroup.


Alcatel BSS FeaturesEnhanced Fullrate / Halfrate

Enhanced Fullrate (EFR) allows the use of codecs with animproved speech coding algorithm, which provide enhancedspeech quality on fullrate channels.

Half-Rate (HR) allows to increase the system capacity. The datareduction is much higher as in fullrate mode. Now it is possible toshare 1 TS by 2 calls.


Alcatel BSS FeaturesShort Message Service - Cell Broadcast

SMS-CB simplified Operation request from OMC-R (no Cell Broadcast Center) One message per cell One page per message No Performance Management counters


BSS

OMC-ROMC-R

CBE terminal

X25

BSSBSS

CBC

Notspecified

GSM 03.41

GSM 03.49


SMS-CB Enhanced



CBC/BSS connection One CBC can be connected to several BSSs One BSS can only be connected to one CBC

CBC is in charge to (GSM 03.41) Updating the current messages Collecting the cell failures from the BSS Submitting messages to the BSS

Message Identifier One page contents (up to 93 character per page) List of cells Number of broadcast to be performed Requested rate of the broadcast


Alcatel BSS FeaturesAntenna Diversity / Single Antenna solution

Antenna Diversity use of two receivers and two receiving antennas usually mounted in

a distance of about 10* (wave length) to compensate the multipath propagation loss improvement of the uplink quality 3 dB


Alcatel BSS FeaturesNight Time Concentration / GPRS

Night Time Concentration Concentration of many BSS to one Operation and Maintenance

Center for central network supervision

General Packet Radio Services (GPRS) improved packed switched data transmission using several TS of one

transmitter (max. 8 TS) as data channel only for data transfer (IP, X25) billing by volume not by connection time connection to the Internet / Intranet only permanent virtual connections provided additional Packet Control Unit (PCU) needed no change of BSS hardware (Alcatel solution)


Alcatel BSS Cell EnvironmentBSS Cell Structures

Different Cell types to meet the requirements of the geographyand the strategies of the Network Operator.

Omni Cell Sectorized Cell Concentric Cell Umbrella Cell Mini Cell Microcell Multiband Cell


Sectorized Cells


Omni Cell


f1,f2

f3,f4

Concentric Cell



Alcatel BSS Cell EnvironmentHierarchical Microcell Environment


Alcatel BSS Cell EnvironmentHierarchical Mini Cell Environment


1800MHz cells

ALCATELMULTIBAND BSC

900MHz cells

900MHz MS

Multiband MS(900+1800MHz)

EmergencyHandover

Preferred band HO

1800MHz MS

Classical band

Preferred band

Alcatel BSS Cell EnvironmentMultiband Solution


Alcatel BSS Cell EnvironmentMultiband MS Measurement Reporting

Allocated on a per cell basis Measurement reporting for dual band mobiles

The MS is measuring the neighbor cells and has to report thestrongest cells according to the following multiband reporting:

6 strongest cells irrespective of the band 1 strongest cell (other band) + 5 strongest cells (SC band) 2 strongest cells (other band) + 4 strongest cells (SC band) 3 strongest cells (other band) + 3 strongest cells (SC band).

SC = Serving Cell

Multiband cell possible since software release B6!


Alcatel BSS Cell EnvironmentMultiband Cell

Outer zone

Inner zone

f3,f4f3,f4f3,f4f3,f4

f1,f2f1,f2f1,f2f1,f2

outer zone includes:BCCH, SDCCH, and TCHin the access band(e.g. 900 MHz) inner zone includes TCH in

the second band(e.g. 1800 MHz)

(900)(900)(900)(900)

(1800)(1800)(1800)(1800)

Multiband Cell


Abis Interface

A-Interface

B

a

s

e

S

t

a

t

i

o

n

S

u

b

s

y

s

t

e

m

BSSBSSBSSBSSBSSBSSBSSBSSBTS

BSCBTS

BSSBSSBSSBSSBSSBSSBSSBSSBTS

BSCBTS

OMC-ROMC-ROMC-ROMC-R


BSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSS


BTS

BSCBTS

BSSBSSBSSBSSBSSBSSBSSBSS


OMC-ROMC-ROMC-ROMC-ROMC-ROMC-ROMC-ROMC-R

Air Interface

PPPPSSSSTTTTNNNN--------IIIISSSSDDDDNNNN

Network Subsystem

OMC-NOMC-NOMC-NOMC-NOMC-NOMC-NOMC-NOMC-NVLRVLRVLRVLRVLRVLRVLRVLR

MSCMSC

MSCMSCVLRVLRVLRVLRVLRVLRVLRVLR

OMC-NOMC-NOMC-NOMC-N

EIREIREIREIREIREIREIREIR


ACACACACACACACAC


HLRHLRHLRHLRHLRHLRHLRHLR



Alcatel BSS HardwareAlcatel BSS in the PSTN


Base Transceiver Station BTS Base Station Controller BSC Transcoder TC Operation & Maintenance

Center-Radio OMC-R

Mobile Switching Center MSC Visitor Location Register VLR Home Location Register HLR Authentication Center AuC Equipment Ident. Register EIR

Base Station Subsystem BSS Network Subsystem NSS

Terminal Equipment

Mobile Station MS

Alcatel BSS Hardware Elements of the GSM System


Alcatel BSS HardwareTasks of the Base Station Subsystem

Channel allocation and link supervision Channel encoding and decoding Encryption and decryption of signaling information and user data Generation of frequency hopping sequences Power control procedures internal handover between cells Transcoding of digital speech Rate adaptation for data Operation & maintenance functions


BTS

Alcatel BSS HardwareBase Transceiver Station BTS (1)

The area covered by a BSS is divided into cells and the cells aremanaged by BTSs. Each BTS consists of radio transmission andreception devices including antennas and signal processingequipment for the Air interface.

Different Types / Generations of BTS G2

micro mini, standard (also as outdoor)

G3 EVOLIUM micro (A910) mini, medi (A9100) (also as outdoor)


BTS


Tasks of a BTS Provide 2 Interfaces:

Air Interface into the direction MS Abis Interface into the direction BSC

Handle the MS Provide the carrier signal Measure the Time of Arrival of the signal for active channels Measure the uplink quality and receive level Collect the measurements from BTS and MS into

measurement reports which are sent to the BSC Control the output power to decrease interference


Each BTS consists of: digital signal processing part Frame Unit radio transmitter and receiver Carrier Unit antenna network Antenna Network Operation and Maintenance unit OMU Master clock generator Submultiplexer for Abis Interface BIU

TRE

SUM

AN

Hardware



Base Transceiver Station (BTS)

AN Antenna NetworkBIE Base Station Ifc EquipmentCLOCK Clock GeneratorEAC External Alarm ConnectionOMU Operation & Maintenance UnitSUM Station Unit ModuleTRE Transmitter Receiver Equipment



Alcatel BSS HardwareEvolium BTS Features (1)

Standard Features according to GSM

DR (Dual Rate), EFR (Enhanced Full Rate coder); options to theoperator

Dual Band Network supporting of 900 and 1800 bands in one network with

appropriate handover algorithms and frequency band allocation

All known A5 algorithms are supported; HW provisions done


Alcatel BSS HardwareEvolium BTS Features (2)

Standard Features due to new Architecture and new SW Releases: SUS (Station Unit Sharing)

Only one central control unit (SUM) in the BTS cabinet

Multiband BTS (GSM 900/1800) in one cabinet

Static RSL (Release 4) and statistical OML/RSL (Release 6)submultiplexing on Abis

Better use of Abis Interface capacity

More BTS/TRX to be supported in a multidrop loop

Introduction of GPRS and High Speed Circuit Switching Data HSCSDwithout HW changes


ANx, ANy: Antenna NetworksTRX: Transmit/Receive ModuleSUM: Station Unit ModuleBCF: BBBBase Station CCCControl FFFFunction

Antennas

Duplexer Stage

Twin Combiner Stage

ANx

ANy

ANx

Transceiver level TRX

Antennacouplinglevel

BCF level SUM

TRX

Abis interface

Alcatel BSS Hardware Evolium BTS Architecture (3)


TRE TRE TRE TRE

ANY

ANX

ANX

ANY

TRETRE TRE TRE

FAN FAN FAN

CONNECTION AREA

TRETRE TRE TRE

FAN FAN FAN

TRETRE TRE TRE

FAN FAN FAN

ANX

ANY

ANX

ANY

SUMTRE TRE TRE TRE

ANY

ANX

TRE TRE TRE TRE

ANY

ANX

Alcatel BSS HardwareEvolium BTS

EVOLIUM medi indoor3 sectors with 4 TRE each


BSC

Alcatel BSS HardwareBase Station Controller BSC

The BSC provides resource and equipment management facilitiesfor the BSS. It allocates resources to manage the flow ofinformation between the BTS and the NSS, acting as a switchingunit by establishing a path between them.


Base Station Controller : Maximum Capacity (up to 352 TRX)

Confi-guration

Trafficcapacity in

Erlang

Transceivers(Typic/Max)

Cells Ainterfacetrunks

SS7 links(256

SCCP)

Abis interfacetrunks

(chain/loop)

Cabinets Abis/A-terTSU

1 160 30/32 21 16 4 6/3 1 1/2

2 576 110/128 95 24 6 24/12 1 4/3

3 960 160/192 140 40 10 36/18 2 6/5

4 1152 250/288 212 48 12 54/27 2 9/6

5 1500 300/352 255 64 16 66/33 3 11/8

6 1500 352/352 255 72 16 84/42 3 14/9

Alcatel BSS HardwareBSC G2 Configuration


Alcatel BSS HardwareBase Station Controller BSC G2 (1)

Capacity Maximum physical capacity: 352 FR TRX or 176 DR TRX in 255 BTS Traffic and signaling capacity: up to 1500 Erlang

Flexibility 6 Abis interfaces per BIE module with integrated cross connect

function Integrated in BSC subracks (no cabling), 100% Alcatel No BSC internal recabling for network extensions/modifications

(add/delete BTS) 4:1 A-ter multiplexing between BSC G2 and TC G2



Compactness Maximum BSC configuration in three standard Alcatel 1000 S12

cabinets (90 cm width, 52 cm depth)

Technology Two stage Alcatel 1000 S12 switching technology Distributed processing in trunk control units and processing

resources


DTC Digital Trunk ControllerTCU Terminal Control UnitTSC Transcoder Submultiplexer Controller

ASMB Alcatel Submultiplexer Ater MuxBIUA Base Station interface UnitCPRA Common Processor



BIUA

TCUC

TCUC

TCUC

TCUC

TCUC

TCUC

TCUC

TCUC

AS

DTCC

DTCC

DTCC

DTCC

DTCC

DTCC

DTCC

AS

DTCC

CPRC CPRC CPRC CPRC CPRC CPRC CPRC CPRC

AS

6 xG.703AbisI/F

2 xG.703AtermuxedI/F

Abis TSU Ater TSU

Common Functions TSU

Group Switch8 Planes2 Stages

TSCA

TSL

ASMB

ASMB

Q1 bus

Broadcast bus

self-routing, non-blocking



Alcatel BSS HardwareG2 BSC Configuration 2

For G2 BSC different configurations are possible (1 ...6).

Maximum configuration (6) includes 3 racks.


Alcatel BSS HardwareTransmission Subsystem TSS

The TSS connects the BTS, BSC and the MSC by using standardPCM 30/32, 2 Mbit lines.

The TSS components within the BSS are: Base Station Interface Equipment (BIE) Submultiplexer (SM) Transcoder (TC) Transmission Submultiplexer Controller (TSC)


Alcatel BSS HardwareLocation of the TSS


Alcatel BSS HardwareTranscoder TC

The Transcoder provides the interface between the BSS and theMSC. This is the A Interface. The TC also provides the interface tothe Base Station Controller (BSC). This is the Atermux Interface.Additionally, the TC can provide an interface between the BSSand the Operations and Maintenance Center-Radio (OMC-R).

The G2 TC includes the submultiplexing equipment.


Alcatel BSS HardwareTranscoder Basic Functions

Provides conversation between the 16 kbit/s signal exchangedwith the BSC, and the 64 kbit/s received from and sent to theMSC. To do this it performs speech coding/decoding and rateadaptation. The TRCU performs this function.

Reduces the number of channels needed between the BSC andthe TC by:

Multiplexing the 16 kbit/s sub-channels into 64 kbit/s timeslots Demultiplexing the 64 kbit/s timeslot into 16 kbit/s sub-channels


Alcatel BSS HardwareTranscoder G2


Alcatel BSS ConfigurationsConfigurations on Abis (1)

Abis Interface connects the BSC and BTS

Different connections between BSC and BTS possible Chain configuration Ring configuration


BTS

BSCAbis

BTS

BTS

Abis Abis


Chain Configuration


BTS

BSCAbis

BTS

BTS

Abis

Abis

Abis

BTS

Abis


Ring Configuration


Alcatel BSS TS AllocationAbis Chain Mapping


3:1 4:1G1 -> TC+BSC possible not possibleG2 -> TC+BSC possible possible

Alcatel BSS TS AllocationAter TS Allocation

PCM 30 with 32 Channels (0..31) 4 x 16 kbit/s channels in one 64 kbit/s channel A-ter Interface mapping

TS0 Transparency 2 configurations possible

4:1 multiplexing only with G2 BSC and G2 TC 3:1 multiplexing with G2 BSC and G2 TC


Alcatel BSS TS AllocationAter Mapping (4:1)


Alcatel BSS Hardware GPRS Architecture (1)

PacketPacketDataData

NetworkNetworkGPRS GPRS

BackboneBackbone

Developed with

Developed with

Developed with

Developed with

Developed with

Developed with

Developed with

Developed withCISCOCISCOCISCOCISCOCISCOCISCOCISCOCISCO

Developed by

Developed by

Developed by

Developed by

Developed by

Developed by

Developed by

Developed by CISCO CISCO CISCO CISCO CISCO CISCO CISCO CISCO

SGSN

GGSN

MSC HLR

TC

PublicPublicSwitchedSwitchedNetworkNetwork

no change of ha

rdware

no change of ha

rdware

no change of ha

rdware

no change of ha

rdware

no change of ha

rdware

no change of ha

rdware

no change of ha

rdware

no change of ha

rdware

in the BSS

in the BSS

in the BSSin the BSSin the BSS

in the BSS

in the BSSin the BSS

A935 MFS

GbBSC

BTS

BTS

GSL


MFS (PCU Packet Unit Control implemented in the A935 MFS) Packet segmentation/re-assembly and scheduling Radio resource management and control Transmission error detection and retransmission (ARQ) Power control

SGSN (Serving GPRS Support Node), the interface to the BSS GPRS switch Channel Coding VLR functionality for GPRS Billing

GGSN (Gateway GPRS Support Node),the interface to the Packet Data Network




GPRS : GPRS : New type of serviceNew type of service

MFS : Multi BSS Fast packet ServerSGSN : Serving GPRS Support NodeGGSN : Gateway GPRS Support NodeBG : Border Gate

New elements

OMC : Big ImpactMSC : Low ImpactMS : New TypeBTS : Software impactBSC : Software impactTC : Software Impact

Existing elements


BSCBTS

MFS

SGSN GGSN

BTS

BSCBTS

BTS

BSC

MFS

MSC 1

MSC 2


Full network coverage for minimal investment One A935 MFS per MSC site A few SGSN and GGSN for the entire network

TC

TC


Alcatel BSS HardwareO&M

Operations & Maintenance

O&M provides the operator interface for the managementand control of the BSS, and its interconnection to the NSS.O&M is divided into three principal areas:

Configuration Management Fault Management Performance Management


Alcatel BSS HardwareOMC-R (1)

Central O&M base for one or more BSSs. It manages BSS software versions, and acts as the central

repository for configuration, fault and performance measurementreports. This data is available to the operator from the OMCRcentral database.

The OMCR only performs O&M activities. It does not performuser traffic processing or call establishment and control activities.



The OMC-R provides all the management and control functionsrequired by the BSS. Network management and functions areproprietary to the system supplier in keeping with ITU and ETSIstandard.

Configuration management includes the autonomous systemconfiguration of the BSS and configuration by an operator at theOMC-R. An operator can display and change the parameters ofhardware and software modules, and download the BSSsoftware.



Configuration management includes the following functions: Hardware configuration management Logical parameter configuration management Cell configuration management Software and database management

Night Time concentration is possible


BTS TransmissionEquipment

TSC

TransmissionEquipment

MSC

OMC-R

BSC Terminal

BTS Terminal

RS232

X.25 orRS232

X.25* directconnection

BSC

Router

X.25*via TC

X.25*viaCisco-Router

* only one connection type is in use



0 1000 2000 3000 4000

Small

Standard

Large

3600TRX900BTS 35BSC

480TRX120BTS 6BSC

1200TRX300BTS 20BSC

E 4000/4500

Host ConfigurationHost ConfigurationHost ConfigurationHost Configuration

E 4000/4500

E 450

TRX:TRX:TRX:TRX:

Alcatel BSS HardwareOMC-R Dimensioning


Mobile StationMobile Station MS

Mobile Stations provide generic radio and processing functionsallowing subscribers to access the mobile network via a radiointerface, the "Air Interface".

A Mobile Station can be a build in car phone handheld phone car/portable combination


Mobile StationMobile Station MS (1)

The MS consists of mainly two components

Mobile Equipment GSM power classes:

1 2 3 4 520W 8W 5W 2W 0.8W for 900 MHz1W 0.25W for 1800 MHz

Improvement of Mobile Equipment GSM phase 1: speech calls only GSM phase 2: data transfer (9.6 kbit/s), SMS, SMS-CB,

FAX, HR GSM phase 2+: multiband, EFR, A5.2 GSM phase 2+ GPRS: GPRS Mobile required



SIM Subscriber Identity Module The SIM card stores all data from the subscriber for the

access control and for encryption. Therefore the subscribercan use different phones with one SIM card. This is called SIMroaming.

Main parameters permanently stored on the SIM: Subscriber profile (roaming, call, FAX, data services... .) A3 and A8 IMSI and Ki Telephone book, PIN, PUK

Main parameters temporary stored on the SIM: TMSI LAI, Kc BCCH information, Timer



SIM Subscriber Identity Module CPU 5MHz, 8 or 16 bit 2 - 8 Kbytes of EEPROM, for phase 2 16 Kbytes 3 - 10 Kbytes of ROM 128 - 256 bytes of RAM operating voltage 3 V DC,



Tasks of a mobile station Control the output power according to the requirements to

save the battery and to decrease interference Measurement of up to 32 neighbour cells and forwarding the

6 strongest measurements to the BTS Measure the downlink quality and receive level and report the

data to the BTS Location updates

The GSM Mobile Station is adapted to the ISDN Standard


Related ReadingBSS Documents

BSS Documents NMC and OMC-R Interworking 3BK 20092 AAAA TQZZA System Description 3BK 20302 AAAA TQZZA System Introduction 3BK 02997 AAAA TQZZA

BSC Documents BSC Software description 3BK 02967 AAAA TQZZA G1 BSC Functional description 3BK 02972 AAAA TQZZA G2 BSC Functional description 3BK 20229 AAAA TQZZA G1 BSC Hardware description 3BK 02966 AAAA TQZZA G2 BSC Hardware description 3BK 20133 AAAA TQZZA


Related ReadingBTS Documents

BTS Functional Description 3BK 02984 AAAA TQZZA BTS Software Description 3BK 02991 AAAA TQZZA Micro-BTS Software Description 3BK 20086 AAAA TQZZA BTS Functional Units Configurations 3BK 02989 AAAA TQZZA G2 BTS Hardware Description 3BK 02990 AAAA TQZZA Micro-BTS Hardware Description 3BK 20087 AAAA TQZZA BTS A9100 Functional Description 3BK 20207 AAAA TQZZA BTS A9100 Software Description 3BK 20208 AAAA TQZZA BTS A9100 Hardware Description 3BK 20209 AAAA TQZZA


Related ReadingTSS Documents

G1 TSC Functional Description 3BK 02994 AAAA TQZZA G1 TSC Hardware Description 3BK 20247 AAAA TQZZA G2 Transcoder Functional Description 3BK 20110 AAAA TQZZA G2 Transcoder Hardware Description 3BK 20111 AAAA TQZZA G2 BSC Functional Description 3BK 20229 AAAA TQZZA G2 BSC Hardware Description 3BK 20133 AAAA TQZZA


Related ReadingO&M Documents

BSC Terminal User Guide 3BK 02973 AAAA TQZZA BTS Terminal User Guide 3BK 02983 AAAA TQZZA BTS A9100 Terminal User Guide 3BK 20240 AAAA TQZZA CMA User Guide 3BK 20117 AAAA TQZZA GND User Guide 3BK 20234 AAAA TQZZA Network Modification Handbook 3BK 20196 AAAA TQZZA OMC-R Confg. Manag. Services 3BK 20000 AAAA TQZZA Operations & Maintenance Principles 3BK 02975 AAAA TQZZA Operator Handbook 3BK 20120 AAAA TQZZA TSC Terminal User Guide 3BK 20230 AAAA TQZZA

bss introduction presentation-06e04

Documents

x edition

analog mobile telephone

gsm systems

mobile radio systems

stpublic mobile telephone

system gsm security

gsm standard components

air interface gsm