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B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 1
Base Station SubsystemGSM 900/1800/1900
Introduction Presentation
Training Document
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 2
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 3
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 4
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 5
Historical Excursion
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 6
Historical ExcursionAnalog Cellular Telephone Systems
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 7
Main parameter of existing analog cellular mobiletelephone networks
Historical Excursion
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 8
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 9
Between 1983 and 1987 the
Historical Excursion
was designed. After the hardware development the firstcellular telephone networks were implemented in 1991.
R
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 10
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 11
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 12
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 13
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 14
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 15
part of ETSI specification
The GSM StandardGSM Recommendations
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 16
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 17
ChallengesMobile Switching Solutions
SMP
SCP
SPP ManagementCenter
SCE
BTS
MSC
ATOM
Toll
MSC
ALMA
SSP STP
BTS
HLR
A935MFS
SGSN GGSN
@BSC
GPRSGPRSBackboneBackbone
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 18
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 19
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 20
GSM Basic System Components
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 21
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 22
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 23
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 ...
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 24
GSM System ComponentsThe Base Station Subsystem BSS
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).
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 25
GSM System ComponentsThe Base Station Subsystem BSS
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 26
Interfaces
A-interface: MSC - BSC (TC)
Atermux interface: TC - BSC
Abis interface: BSC - BTS
Air Interface: BTS - MS
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 27
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 28
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).
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 29
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 30
GSM Services
Three types of mobile network services
Teleservices Bearer Services Supplementary Services
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 31
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 32
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 33
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).
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 34
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 35
Mobility ManagementDefinition of Areas
Service area PLMN area (Public Land Mobile Network) MSC area / VLR area Location area Cell
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 36
Mobility ManagementDefinition of Areas
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 37
Mobility ManagementDefinition of Areas
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)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 38
Mobility ManagementMobile Specific Procedures
Roaming Location Update IMSI attach/detach Idle mode Paging Handover
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 39
Mobility ManagementMobile Specific Procedures
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 40
Mobility ManagementMobile Specific Procedures
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 41
Mobility ManagementMobile Specific Procedures
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 42
Mobility ManagementMobile Specific Procedures
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 43
Mobility ManagementMobile Specific Procedures
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).
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 44
Mobility ManagementMobile Specific Procedures
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:
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 45
Mobility ManagementMobile Specific Procedures
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 46
Mobility ManagementMobile Specific Procedures
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 47
Numbers and Identifiers
MS-ISDN IMSI TMSI LMSI MSRN Handover number IMEI LAI CGI BSIC
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 48
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 49
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 50
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 51
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 52
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 53
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 54
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 55
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 56
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 57
Scenarios in the System
Mobile originated Call MOC
Mobile terminated Call MTC
Handover
Location update
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 58
Scenarios in the SystemMobile Terminated Call (1)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 59
Scenarios in the SystemMobile Terminated Call (2)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 60
Scenarios in the SystemMobile Originated Call (1)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 61
Scenarios in the SystemMobile Originated Call (2)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 62
Scenarios in the SystemHandover (1)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 63
Scenarios in the SystemHandover (2)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 64
Scenarios in the SystemLocation Update (1)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 65
Scenarios in the SystemLocation Update (2)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 66
GSM Security and Encryption
Authentication parameter
Authentication
Encryption
Activation of Encryption
Subscriber Identity Module SIM
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 67
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 68
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 69
GSM Security and EncryptionAuthentication
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 70
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 71
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 72
GSM Security and EncryptionActivation of Encryption
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 73
Air Interface
Radio Resources TDMA Structure Logical Channels Multiframe Structure Physical Channels (Timeslots) Synchronization Criteria Channel Encoding Interleaving Signal Processing Chain
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 74
Radio Spectrum Allocation
Frequency(FDMA)
Time(TDMA)
Timeslot0
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 75
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 76
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
Air InterfaceGSM Channel Specification (2)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 77
Air InterfaceGSM Channel Specification (3)
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 78
Air InterfaceTDMA Principle
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 79
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 80
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)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 81
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 82
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 83
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 84
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 85
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 86
Air InterfaceSummary of Logical Channels
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 87
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 88
0
50
25
FCCH
SCH
BCCH
SDCCH
CCCH
TCH
Air InterfaceMultiframe Structure
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 89
Air InterfaceMultiframe Structure
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 90
Only the downlink is shown!
MultiframeStructure
Air Interface
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 91
Air InterfacePhysical Channels
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 92
Normal Burst
FCCH
SCH
Dummy Burst
RACCH
Air InterfaceBurst Types
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 93
Air InterfaceSynchronization Criteria
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 94
Air InterfaceChannel Encoding
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 95
Air InterfaceInterleaving
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 96
Signal Processing Chain
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 97
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 98
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 99
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 100
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 101
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 102
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 103
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 104
BSS
OMC-ROMC-R
CBE terminal
X25
BSSBSS
CBC
Notspecified
GSM 03.41
GSM 03.49
Alcatel BSS FeaturesShort Message Service - Cell Broadcast
SMS-CB Enhanced
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 105
Alcatel BSS FeaturesShort Message Service - Cell Broadcast
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 106
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 107
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)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 108
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 109
Sectorized Cells
Alcatel BSS Cell EnvironmentBSS Cell Structures
Omni Cell
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 110
f1,f2
f3,f4
Concentric Cell
Alcatel BSS Cell EnvironmentBSS Cell Structures
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 111
Alcatel BSS Cell EnvironmentHierarchical Microcell Environment
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 112
Alcatel BSS Cell EnvironmentHierarchical Mini Cell Environment
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 113
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 114
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!
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 115
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 116
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
OMC-ROMC-ROMC-ROMC-R
BSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSSBSS
OMC-ROMC-ROMC-ROMC-R
BTS
BSCBTS
BSSBSSBSSBSSBSSBSSBSSBSS
OMC-ROMC-ROMC-ROMC-R
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
OMC-NOMC-NOMC-NOMC-N
ACACACACACACACAC
OMC-NOMC-NOMC-NOMC-N
HLRHLRHLRHLRHLRHLRHLRHLR
OMC-NOMC-NOMC-NOMC-N
OMC-NOMC-NOMC-NOMC-N
Alcatel BSS HardwareAlcatel BSS in the PSTN
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 117
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 118
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 119
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)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 120
BTS
Alcatel BSS HardwareBase Transceiver Station BTS (2)
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 121
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
Alcatel BSS HardwareBase Transceiver Station BTS (3)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 122
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 HardwareBase Transceiver Station BTS (4)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 123
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 124
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 125
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)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 126
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 127
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 128
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 129
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 130
Alcatel BSS HardwareBase Station Controller BSC G2 (2)
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 131
DTC Digital Trunk ControllerTCU Terminal Control UnitTSC Transcoder Submultiplexer Controller
ASMB Alcatel Submultiplexer Ater MuxBIUA Base Station interface UnitCPRA Common Processor
Alcatel BSS HardwareBase Station Controller BSC G2 (3)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 132
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 HardwareBase Station Controller BSC G2 (4)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 133
Alcatel BSS HardwareG2 BSC Configuration 2
For G2 BSC different configurations are possible (1 ...6).
Maximum configuration (6) includes 3 racks.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 134
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)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 135
Alcatel BSS HardwareLocation of the TSS
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 136
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 137
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 138
Alcatel BSS HardwareTranscoder G2
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 139
Alcatel BSS ConfigurationsConfigurations on Abis (1)
Abis Interface connects the BSC and BTS
Different connections between BSC and BTS possible Chain configuration Ring configuration
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 140
BTS
BSCAbis
BTS
BTS
Abis Abis
Alcatel BSS ConfigurationsConfigurations on Abis (3)
Chain Configuration
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 141
BTS
BSCAbis
BTS
BTS
Abis
Abis
Abis
BTS
Abis
Alcatel BSS ConfigurationsConfigurations on Abis (4)
Ring Configuration
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 142
Alcatel BSS TS AllocationAbis Chain Mapping
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 143
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 144
Alcatel BSS TS AllocationAter Mapping (4:1)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 145
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 146
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
Alcatel BSS Hardware GPRS Architecture (2)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 147
Alcatel BSS Hardware GPRS Architecture (3)
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 148
BSCBTS
MFS
SGSN GGSN
BTS
BSCBTS
BTS
BSC
MFS
MSC 1
MSC 2
Alcatel BSS Hardware GPRS Architecture (4)
Full network coverage for minimal investment One A935 MFS per MSC site A few SGSN and GGSN for the entire network
TC
TC
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 149
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 150
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 151
Alcatel BSS HardwareOMC-R (2)
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.
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 152
Alcatel BSS HardwareOMC-R (3)
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 153
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
Alcatel BSS HardwareOMC-R (4)
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 154
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 155
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 156
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 157
Mobile StationMobile Station MS (2)
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 158
Mobile StationMobile Station MS (3)
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,
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 159
Mobile StationMobile Station MS (4)
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
B6.x Edition 04 (BSS Introduction_06E04.PPT) December 2000 160
Related ReadingBSS Documents
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