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Introduction to theAlcatel 900/1800/1900 GSM netw ork
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Introduction to the Alcatel 900/1800/1900 GSM Network
1 Introduction
2 General Specification
3 Services Provided
4 Radio Interface
5 Interchanges over the Network
6 Alcatel 900 / 1800 / 1900 Solution
Appendix
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Introduction to the Alcatel 900/1800/1900 GSM Network
1 Introduction
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IntroductionContents
1.1 GSM 900 / 1800 / 1900
1.2 History of Cellular Networks
1.3 Lim its of GSM System s
1.4 Overview of Current Standards
1.5 GSM Key-Dates
1.6 International Agreem ents: "M em orandum Of Understanding"
1.7 Contribution of GSM Standard
1.8 Contents of GSM "Recom m endations"
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INTRODUCTION1.1 GSM 900 / 1800 / 1900
GSM : GlobalSystem forMobile com m unication
Pan-European standard for com m unication with m obiles, already adopted by
m ore than 60 countries and now the worldwide reference for m obile radionetworks. Since 1995 (phase 2), this standard harm onizes the 900 M Hz GSM
system and the 1800 or 1900 M Hz Digital Cellular System s (DCS).
GSM 900: 2 x 25 M Hz frequency bands around 900 M Hz.
GSM 1800:
2 x 75 M Hz frequency bands around 1800 M Hz.
GSM 1900: (North and South Am erican variant of the GSM 1800):
2 x 75 M Hz frequency bands around 1900 M Hz.
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INTRODUCTION1.2 History of Cellular Networks
M obile network "Prehistory":
1946:St Louis (M issouri)
1970 - 80: NATEL (Switzerland)
1stGeneration: ANALOGUE cellular netw orks
1979: Chicago: AM PS
1981: Sweden: NM T
1985: UK: TACS
2nd Generation: DIGITAL networks
1992: Europe: G SM
1995: US: IS95 (CDM A)
3rd Generation: Universal(?) Standards
2002: IM T 2000
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INTRODUCTION1.3 Lim its of GSM system s
public
residential
office PABX
PSTN
PABX
PSTN
PSTN
Sm all Cells M edium Cells Large Cells
GSM
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Standard CT2 GSM DCS DECT IS95
System type cordless cellular cellular cordless satellite
Frequencyband (M Hz) 864 - 868 890 - 915 ()1710 -1785 () 1880 -1900 1610 -1626.5 ()
935 - 960 () 1805 -1880 () 2483.5 -2500 ()
Com m ercial Pointel Itinris Bouygues Digital Globalstar
nam es Bi-bop SFR Telecom dom esticcordless
telephones
Com pany
m obiles
INTRODUCTION1.4 Overview of current standards
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INTRODUCTION1.5 GSM key dates
1979 W orld Adm inistrative Radiocom m unications Conference
(W ARC) : 900 M Hz band reserved
1982 Stockholm - Creation of the "Groupe Spcial M obile" within
CEPT (Post & Telecom European Conference)
1986 Creation of a GSM " Standing Com m ittee
CNET Paris : Com parative trials of 8 prototypes
1987 "Broad Avenue" : Choice of m ain techniques:
M edium Band - Digital Transm ission < 16 kbit/s - 8 x Tim e-division m ultiplexing, subsequent developm ent to 16 x - Slow frequency
hopping
1988-89 GSM taken over by ETSI
First publication of the (Draft) "recom m endations"
1990 Beginning of studies for adaptation to 1800 M Hz (at UK's request)
1990-91 "Phase 1" recom m endations fixed (GSM , then DCS)
First GSM prototypes in service (Tlcom '91 Geneva)
1992 First com m ercial GSM networks placed in service
1995 "Phase 2" recom m endations issued (upward com patibility)
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GSM - M oU: M em orandum of understanding
signed on 87/09/07 between european
operators
1991: acceptation of non-european
signatories (UAE, Hong Kong,
New Zealand, Australia)
Scope:
. System deploym ent schedule
. Routing and num bering plancom patibility
. Joint introduction of new services
. Harm onization of tariff setting principles
. Definition of billing procedures
INTRODUCTION1.6 International agreem ents
European G SM -M oU signatories (operators) in 199
3
23 4
3
42
33
2
4
3 34
5
2
3
3
4
2
3
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INTRODUCTION1.7 Contribution of GSM standard
Pan-European standard + M oU
GLOBAL system (standardized infrastructure)
New concept: SIM card ("SIM -roam ing")
Digital transm ission, speech encoding
Introduction of state of the art techniques
Integrated security procedures
Considerable potential m arket
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INTRODUCTION1.8 Contents of GSM recom m endations
GSM recom m endations : series
01 G eneral aspects
02 Definition of services 03 Network Aspects
04 M S - BS interface and protocols
05 Radio Interface: Physical level
06 Speech encoding/ decoding
07 Term inal Adapters
08 BS - M SC interfaces
09 Interworking
11 Equipm ent
12 Operation and M aintenance
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INTRODUCTION1.8 Contents of GSM recom m endations
GPRS General Packet Radio Service (1)
01.60: Requirem ents specification of G PRS
01.61: G PRS ciphering algorithm requirem ents 02.60: Service description; stage 1
03.60: Service description; stage 2
03.64: O verall description of the G PRS radio interface; Stage 2
04.60: M obile Station (M S) - Base Station System (BSS) interface; Radio
Link Control / M edium Access Control (RLC/M AC) protocol
04.64: M obile Station (M S) - Serving G PRS Support Node (SGSN); Logical
Link Control (LLC) layer specification 04.65: M obile Station (M S) - Serving G PRS Support Node (SGSN);
Subnetwork Dependent Convergence Protocol (SNDCP)
07.60: M obile Station (M S) supporting G PRS
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INTRODUCTION1.8 Contents of GSM recom m endations
GPRS General Packet Radio Service (2)
08.14: Base Station System (BSS) - Serving GPRS Support Node (SGSN)
interface; Gb interface layer 1
08.16: Base Station System (BSS) - Serving GPRS Support Node (SGSN)
interface; Network Service
08.18: Base Station System (BSS) - Serving GPRS Support Node (SGSN)
interface; BSS GPRS Protocol (BSSGP) 09.16: Serving G PRS Support Node (SG SN) - Visitors Location Register
(VLR); Gs interface network service specification
09.18: Serving G PRS Support Node (SG SN) - Visitors Location Register
(VLR); Gs interface layer 3 specification
09.60: GPRS Tunnelling Protocol (GTP) across the Gn and G p Interface
09.61: Interworking between the Public Land M obile Network (PLM N)
supporting G PRS and Packet Data Networks (PDN)
12.15: GPRS charging
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INTRODUCTION TO THE Alcatel 900/1800/1900 GSMNETW O RK
2 General Specifications
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GENERAL SPECIFICATIONSContents
2.1 General Concepts in Cellular Networks
2.1.1 PLM N and M obile Stations
2.1.2 Cellular Coverage
2.1.3 Data Transm ission
2.2 GSM Architecture
2.2.1 Types of M obile Stations
2.2.2 PLM N Elem ents
2.2.3 Base Station System
2.2.4 Network and Switching System
2.2.5 GPRS
2.2.6 Operation and M aintenance
2.3 GSM Interfaces and Protocols
2.4 Position of Transcoding Unit (TRAU)
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PLM N = Public Land M obile Netw ork
PSTN = Public Sw itched Telephone Netw ork
ISDN = Integrated Services Digital Netw ork
PDN = Packet Data Netw ork
GENERAL SPECIFICATIONS2.1.1 General Concepts: PLM N and M obile Stations
ISDN
PSTN
PDN
PLMN
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GENERAL SPECIFICATIONS2.1.2 General Concepts: Cellular Coverage
om nidirectional antenna
sectored antenna
directional antenna
Base StationBase Station Controller
KEY
(25)
(25)
(25)
(25)
(25)
150
traffic Erlangs (BSC)150traffic in Erlangs (BTS)(25)
150
150
100 50
300
300
50
50
50
200
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GENERAL SPECIFICATIONS2.1.2 General Concepts: Cellular Coverage
Exam ple of 12-Cell Three-sector Pattern
Frequency Reuse Pattern
12
3 10
14 7 8
692
5
11
12
3 10
14 7 8
692
5
11
12
3 10
14 7 8
692
5
11
12
3 10
14 7 8
692
5
11
12
14 7 8
692
5
11
D
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GENERAL SPECIFICATIONS2.1.2 General Concepts: Cellular Coverage
0 or 4
1 or 5
2 or 6
3 or 7
NCC
International Colour Codes
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GENERAL SPECIFICATIONS2.1.2 General Concepts: Cellular Coverage
Radio Resources are lim ited
To increase Spectrum efficiency,
specific techniques are introduced: Power Control
Handover
Frequency Hopping
Discontinuous
transm ission (DTX)
downlink
uplink VIP
GSM antenna
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GENERAL SPECIFICATIONS2.2 GSM architecture
MSBSSNSS
OSS
OPERATORS
NETWORKS USERSEXTERNAL
GSM
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GENERAL SPECIFICATIONS2.2.2 GSM architecture: PLM N Elem ents
BSC
BTS
BTS
BTS
BTS
BTSBTS
BTS
BSC
M SC
VLR HLR AuC EIR
PSTN,ISDN...
OM COM C
NM C
X.25 links
GSM interfaces
Voicem ail Server
SM -SC
M S(M obile Station)
BSS(Base Station System )
NSS
(Network & Switching System )
OSS(Operation & m aint. Sub System )
GCR
Base station system BSS
BTS Basic Transceiver Station
BSC Base Station Controller
Network and switching systemMSC Mobile Switching Centre
HLR Home Location Register
VLR Visitors Location Register
AuC Authentication Centre
Optional
EIR Equipment Identification Register
Voicemail Server
SM-SC Short Message Service Centre
GCR Group Call Register
Operation and maintenance subsystem OSS
OMC Operation and Maintenance Centre
[NMC Network Management Centre]
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GENERAL SPECIFICATIONS2.2.3 GSM architecture: Base Station System
BSC
BTS
BTS
BTS
BTS
BTS
BTS
BTS
BSC
NSS CBC
MAIN FUNCTIONS:
BTS
PHYSICAL CHANNEL MANAGEMENT(on Radio channel)
BSC
MANAGEMENT OF INTERFACES WITHNSS & OSS
MANAGEMENT OF RADIO "LOGICAL"
CHANNELS
BTS MONITORING
CBC : Cell Broadcast Centre (optional)
Buffer STORAGE and Generation of
CELL BROADCAST SHORT MESSAGES
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GENERAL SPECIFICATIONS2.2.4 GSM architecture: Network and Switching System
M SC
VLR HLR AuC
PSTN,ISDN...
BSS
MSC
CALL HANDLING (subscriber exchange)
RADIO RESOURCE MANAGEMENT
- VLR/HLR database updating
- Subscriber radio paging- Handover management
GATEWAY FUNCTION
for terminating calls
HLR
Reference DATABASE (for a region)
STORES: Identities - Directory numbers -
Services subscribed + Approx. location (VLR)
VLRLOCAL DATABASE
(associated with one or more MSCs)COPIES HLR data for VISITING subscribers
ACCURATE LOCATION of visiting subscribers
Call redirection DATA
AuC
SECURITY DATABASE
(authentication and encryption)
GENERATION of KEYS
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GENERAL SPECIFICATIONS2.2.4 GSM architecture: Network and Switching System
M SC
SM -SC
EIR
BSS
Voice M ail Server
GCR
MAIN FUNCTIONS:
EIRMobile EQUIPMENT DATABASE
CONCEPT of "white", "grey" and "black" mobile
Voice Mail ServerVOICE MESSAGING SERVER
(not specified in GSM standard)
SM-SCSHORT MESSAGE STORAGE
during subscriber unavailability
GCR : Group Call Register(optional)
VOICE CALL GROUP SERVER
(new services in phase 2+, PMR type)
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GENERAL SPECIFICATIONS2.2.5 GSM architecture: GPRS
Data
MSC/VLR
GSM+GPRS
BSS with
PCU
ISDN
GPRS
Backbone
SGSN
Internet
GGSN
GPRSGPRS
MobileMobile
Voice
BSS
HLR
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NSS
(O M C-M or S)(O M C-R)
NM C
BSS
OM C: ConfigurationFault
Perform ance
Security
Cost
NM C: Telecom M anagem ent Network
(optional)
GENERAL SPECIFICATIONS2.2.6 GSM architecture: Operation and M aintenance
GPRS
(O M C-G )
OM C
G S C C O S
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GENERAL SPECIFICATIONS2.3 GSM interfaces and protocols
BTS
BTS
BTS
BTS
BTS
BTS
BTS
BSC
M SC
VLR HLR AuC EIR
PSTN,ISDN...
VLR
M SCE
B C
D
F
G
H
GCR
I
BSC
Abis
Um (Radio)
A
B
C
D
E
FG
H
I
PSTN
ISDN
BTS - BSC
BSC-M SC (SS7 basic)
M SC-VLR
(SM -G )M SC-HLR
HLR-VLR
(SM -G )M SC-M SC (SS7 basic)
M SC-EIRVLR-VLR
HLR-AuC
M SC-G CR
M SC-PSTN (SS7 basic)
M SC-ISDN
LAPDm(GSM specific)
LAPD(ISDN type)
+ BSSAP
+ M AP
+ TUP or ISUP
M
S
M
S M
S
M
S
M
SM
S M S - BTS
GSM Circuit-switching:
GENERAL SPECIFICATIONS
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Gc G G SN-HLR (IP)/SS7
LAPD(ISDN type)
LAPDm(GSM specific)
GENERAL SPECIFICATIONS2.3 GSM interfaces and protocols
BTS
BTS
BTS
BTS
BTS
BTS
BTS
BSCBSC
Gs
Gb
Um (Radio)
Abis
G i G G SN-Data Netw orkIP
M
S
M
S M
S
M
S
M
SM
S
BTS - BSC
BSC-SG SN
Gr SS7SG SN-HLR
Gf SS7SG SN-EIR
SG SN-M SC/VLR
G n
IP
IP
SGSN-GG SN
SG SN-SG SN
M S - BTS
SGSN
HLR
Data Netw ork
M SCGs
EIR
G fGr
SGSN Gn
GGSN
G n
Gi
Gc
SS7
GSM Packet-switching (GPRS):
GENERAL SPECIFICATIONS
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GENERAL SPECIFICATIONS2.4 Position of Transcoding Unit (TRAU)
BTS BSC M SCVLRTRAU
BTS BSC M SCVLRTRAU
BTS BSC M SCVLRTRAU
Abis interface A interface
16 kbit/s transm ission64 kbit/s transm ission
KEY :
INTRODUCTION TO THE Alcatel900/1800/1900 GSM
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INTRODUCTION TO THE Alcatel 900/1800/1900 GSMNETW O RK
3 Services Provided
SERVICES PROVIDED
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SERVICES PROVIDEDContents
3.1 Teleservices
3.1.1 Teleservices and Bearer Services
3.1.2 Categories of Teleservices
3.1.3 Principle
3.1.4 Data transm ission in circuit m ode
3.1.5 Data transm ission in packet m ode
3.2 Supplem entary services 3.2.1 Num ber Identification Services
3.2.2 Call Forwarding Services
3.2.3 Call Com pletion Services
3.2.4 M ulti-Party Services
3.2.5 Billing Services
3.2.6 Call Barring Services
3.2.7 Phase 2+ Services
3.2.8 Sundry Services
SERVICES PROVIDED
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SERVICES PROVIDED3.1.1 Teleservices and Bearer Services
Teleservice:Transm ission capability including term inals and applications
Bearer Service:Transm ission capability between defined userInterfaces
Transparent and Non-Transparent Services and Bearer Services
Transparent :Fixed rate, no flow control: fast but high error ratio
Non-Transparent :RLP added: low error ratio, slower transm ission
G SM
PLM NIW F IW F
Transit
netw ork,
if any
Term inating
netw ork
TE = Term inal Equipm ent IW F = InterW orking Function
Teleservices
Bearer services
TE
TE
SERVICES PROVIDED
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SERVICES PROVIDED3.1.2: Categories of Teleservices
Voice Services:
Telephony
Em ergency Calls
Voice Call G roups (Groups of m obiles sharing lim ited radio resources)
(Voice M essaging: not identified by the G SM as a specific service)
Short M essage Services (SM S):
PO INT-TO-PO INT, Network to M obile (SM S - M T/PP)
PO INT-TO-PO INT, M obile to Network (SM S - M O/PP)
BROADCAST, Network to M obile (SM S - CB)
Other Non-Voice Services
SERVICES PROVIDED
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SERVICES PROVIDED3.1.3 Teleservices: principles
By com parison with PSTN access, the entire GSM infrastructure can be treated as a DTE-DCE line
between the term inal and the M ODEM which is inserted by the network.
PSTN user PSTN userAudio m odem Audio m odem
3.1 kHz audio line
PSTN
Conventional connection PSTN user < -- > PSTN user
GSM user
Audio m odem
3.1 kHz audio line
PSTN
Audio m odemPSTN user
GSM infrastructure
Connection G SM user < -- > PSTN user
(DTE) (DCE)
Standard interface
(DCE) (DTE)
Standard interface
Standardized transm ission
Standard interfaceIW F
GSM transm ission Standardized transm ission(DCE) (DCE)(DTE)(DTE)
Standard interface
SERVICES PROVIDED
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S C S O3.1.3 Teleservices: principles
General Principles:
DIGITAL transm ission on the radio channel
AUDIO M O DEM inserted at the interworking point (IW F) between the two
networks (generally in the M SC)
Data Transm ission Services:
Usable M ODEM TYPES defined by the GSM standard:
V21: 300 bit/s asynchronous
V22: 1200 bit/s, asynchronous or synchronous
V22 bis: 2400 bit/s synchronous
V23: 1200/75 bit/s asynchronous
V26 ter: 2400 bit/s synchronous
V32: 4800 or 9600 bit/s synchronous
SERVICES PROVIDED
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3.1.4 Teleservices: Data transm ission in circuit m ode
DIG ITAL radio transm ission ==> FAX adapter function (including audio m odem + T30 functions)
Standard TAF: synchronous inform ation bearer (as for data transm ission services)
Audio M O DEM : includes V21 - V27 ter and V29 protocols essential for dialogue betw een FAX m achines
3.1 kHz audio line
PSTN
Conventional connection PSTN user < -- > PSTN user
Audio m odem3.1 kHz audio line
PSTNG SM infrastructure
Connection G SM user < -- > PSTN user
Standard FAX m achineAudio m odem
Standard FAX m achineAudio m odem
Standard FAX m achine
Audio m odemStandard FAX m achine
Audio m odemAudio m odem
TAF
FAX adapter
G SM user
SERVICES PROVIDED
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3.1.5 Teleservices: Data transm ission in packet m ode
Services provided:
All Personal m obilityapplication
Internet Access
Car Traffic m anagem ent
G SM Netw ork Packet Data Netw ork
Virtual Circuit
Internet
Datagram
User 1
User 2
User 3
GGSN
GGSN
SGSN
W ith Quality Of Service profiles:
Service Precedence (Priority) Reliability
(Transfer) Delay
Use Data Throughput
SERVICES PROVIDED
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3.2.1 Supplem entary Services
Num ber identification services
CLIP Calling Line Identification Presentation (term inating call)
Lets the called party receive the caller's identity (applicable to all
services except SM S)
CLIR Calling Line Identification Restriction (originating call)
Lets the caller withhold his num ber from the called party
(either perm anently or on a per-call basis) CoLP Connected Line Identification Presentation (originating call)
Indicates the party's num ber when the call has been set up
CoLR Connected Line Identification Restriction (term inating call)
Lets the called party withhold his num ber from the caller
(either perm anently or on a per-call basis)
M CI M alicious Call Identification
Lets the network store call param eters
(called and calling party num bers - date - tim e)
SERVICES PROVIDED
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3.2.2 Supplem entary Services
Call forwarding services
CFU Call Forwarding Unconditional
These four services are used to forward calls to the local PLM N or to
another PLM N (Id = International num ber)
CFB Call Forwarding on m obile subscriber Busy
Up to five consecutive forwarding operations(system param eter)
CFNRy Call Forwarding on No ReplyCalling/called party notification possible
CFNRc Call Forwarding on m obile subscriber Not Reachable
O verall deactivation possible
CD Call Deflection
Lets the m obile subscriber screen out calls (with CLIP) and forward
calls as required on a per-call basis
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SERVICES PROVIDED
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3.2.4 Supplem entary Services
M ulti-Party services
M PTY M ulti Party service
Conventional options: Hold - Retrieval of first call or transition to
conference
CUG Closed User Group
O ptional allowing or barring of incom ing or outgoing calls
(OA/IA - O CB/ICB) - Preferential CUG allowed ECT Explicit Call Transfer
W ith m obile A connected to two parties, B and C, these two parties
can be connected and A can withdraw (telephone call only)
SERVICES PROVIDED3 2 5 l i
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3.2.5 Supplem entary Services
Billing services
AoCI Advice of Charge - Inform ation
Advice of call charge at end of call or in real tim e. Applicable to all
services, except short m essages and packet data
AoCC Advice of Charge - Charging
Calls barred when the m obile is located in a PLM N not providing this
service
REVC Reverse Charging Service elim inated in phase 2
SERVICES PROVIDED3 2 6 S l t S i
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3.2.6 Supplem entary Services
Call Barring services
BAOC Barring of All Outgoing Calls
BOIC Barring of Outgoing International Calls
BOIC-ex HC Barring of Outgoing International Calls, except those
directed to the Hom e PLM N Country
BAIC Barring of All Incom ing Calls
BIC-Roam Barring of All Incom ing Calls w hen Roam ing
outside the Hom e PLM N country*
for all:
Barring except em ergency calls
Subscription possible for any com bination
Activation protected by password
SERVICES PROVIDED3 2 7 S l t S i
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3.2.7 Supplem entary Services
Phase 2+ services
UUS User to User Signalling
Allows sending or receiving of user-to-user short m essages during a
com pleted call or during call set-up
eM LPP Enhanced M ulti_Level Precedence & Preem ption
Allows one of seven precedence levels to be assigned to som e m obiles
so that they can set up calls rapidly (no authentication), in som e cases
cutting off calls of lower precedence
SNPN Support of Private Num bering Plan
Access to a virtual private network (VPN) with private num ber
translation handled by an external PN m anager
SERVICES PROVIDED3 2 8 Supplem entary Services
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3.2.8 Supplem entary Services
Sundry services
M SP M ultiple Subscriber Profile
Allows up to 4 subscriber profiles for the sam e SIM card
NITZ Network Identity and Tim e Zone
Transfers the network identity and local tim e to the term inating m obile
PDS Packet Data on Signalling Channel
PTP transfer (circuit-oriented) of very short data packets between am obile and a host
ODB Operator Determ ined Barrings
Allows the service provider to apply24 different types of call barring
CAM EL Custom ized Applications for M obile network Enhanced
Logic
Allows for supplem entary services specific to a given operator (for
exam ple, INSS) outside the origin PLM N
SO R Support of Optim al Routing
O ptim ized call forwarding to avoid "trom boning"
INTRODUCTION TO THE Alcatel 900/1800/1900 GSMNETW O RK
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NETW O RK
4 Radio Interface
RADIO INTERFACEContents (1)
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Contents (1)
4.1 Introduction 4.1.1 Im portance of the Radio Interface
4.1.2 Traffic and Signalling
4.1.3 M obile Station Status (Circuit and Packet Switched M ode)
4.1.4 Radio Resources
4.2 Physical Channels : M ultiple Access Diagram 4.2.1 Frequencies
4.2.2 TDM A Fram e 4.2.3 Norm al Burst
4.3 Logical Channels 4.3.1 Principle
4.3.2 Tim e-Division M ultiplexing on a Physical Channel 4.3.3 Channel M apping
4.3.4 Tim ing Advance
4.3.5 Paging
4.3.6 Access to the Network 4.3.7 Logical Channel Sum m ary
RADIO INTERFACEContents (2)
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Contents (2)
4.4 Speech Processing
4.4.1 Radio Channel Generation
4.4.2 Discontinuous Transm ission 4.4.3 GM SK M odulation
4.5 Radio Techniques
4.5.1 Frequency Hopping
4.5.2 Power Control
4.5.3 Space Diversity
RADIO INTERFACE4.1.1 Im portance ofthe radio interface
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4.1.1 Im portance of the radio interface
RADIO INTERFACE : essential part of GSM specifications because of:
Inter-PLM N CO M PATIBILITY ==> Com plete Specification
(to the nearest bit)
Very elaborate SPECTRUM EFFICIENCYoptim ization techniques:
Reduction of INTERFERENCE to M anage a large num ber of M obiles per km
RADIO INTERFACE4.1.2 Traffic and Signalling
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4.1.2 Traffic and Signalling
TRAFFIC :
INFORM ATION interchanged from USER-TO-USER, after setting up the
call, requiring dedicated radio resource allocation.
In GSM , TRAFFIC can be an interchange of SPEECH or DATA
SIGNALLING :INFORM ATION interchanges (in som e cases, without the user's
knowledge) between the M OBILE EQUIPM ENT and NETW ORK
M ACHINES
Out of Call : required for m anaging m obiles, eg. : location update
During a Call : required for various reasons, eg. : handover, access to
a supplem entary service, call release
RADIO INTERFACE4.1.3 M S status
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Detac
hAttac
h
"Connected"
"Power Off"
"Idle"
Endo
f
tra
nsactio
nNe
tworkA
ccess
Circuit Switching M ode
M S not
reachable
M S
reachable
RADIO INTERFACE4.1.3 M S status
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"Idle"Attachm
entto
network
Deta
chment
O ut of Tim e
Packet Tx or Rx
Detachm
ento
rOut
ofTim
e
"Ready""Stand-by"
Packet Switching M ode
M S not
reachable
M S
reachable
RADIO INTERFACE4.1.4 Radio Resources
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Dedicated
Signalling
Channels
Com m on
Access
Channels
Com m on
Broadcast
Channels
Typical M obile - Network Transaction:
M obile
pre-synchronization
"Idle" Status "Connected" Status
Netw ork Access O ut of call
signalling phaseTRAFFIC phase
Access
procedure
(O ptional)
Channels
to be used
Dedicated
Traffic
Channels
M ain
Tasksand
Inter-
change
Types
Frequency
search
Tim ing
Synchro
System
Param eter
Analysis
(Paging)
Access
Request
Dedicated
Channel
Assignm ent
Authentication
Location Updating
Short M essages
(Traffic Channel
Assignm ent)
Traffic
Signalling
Frequency
Monitoring
RADIO INTERFACE4.2.1 Frequencies
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UPLINKBAND
(M S -> BTS)
DOW NLINK
BAND
(BTS -> M S)
frequencyaxis
900 bands
possible extension of G SM bands
(2 x 25 M Hz : 124 carriers)
(2 x 33 M Hz : 164 carriers)
1800 bands(2 x 75 M Hz : 374 carriers)
M Hz
M Hz
200 kHz
890
935
960
915
8801710
1785
1805
1880
915
960
925
RADIO INTERFACE4.2.2 TDM A Fram e
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1 BTS (eg. 3 carriers)
Frequency shift
45 M Hz in 900,
95 M Hz in 1800,
22
17
7 cell "beacon" frequency
22
17
7
UPLINKBAND(M S -> BTS)
DO W NLINKBAND(BTS -> M S)
frequencyaxis
RADIO INTERFACE4.2.2 TDM A fram e
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1 BTS (eg. 3 carriers)
TDM A fram e = 4.615 m s
1 "CHANNEL" (in 1 direction)
Sam e "CHANNEL" (if bidirectional)
tim e axis
Tim e slot (or burst w indow )
1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70
1 2 3 4 5 6 70 1 2 3 4 5 6 70 1 2 3 4 5 6 70
22
17
7
22
17
7
UPLINK
BAND
(M S -> BTS)
DO W NLINK
BAND(BTS -> M S)
frequency
axis
Tim e shift betweentransm it and receive : 3 TS
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RADIO INTERFACE4.2.3 Norm al Burst
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TRAINING SEQ UENCES :8 different bit patterns, chosen so that:
They are easily recognizable (very accurate auto-correlation function)
They are easily distinguishable from one another (little correlationbetween each pattern)
STEALING FLAGS:
26 bits
"Stealing Flags"
S = 0
S = 1
57 bits 57 bits+
+
TCH ( or SDCCH )
FACCH
Training sequence
57 bits 57 bits
RADIO INTERFACE4.3.1 Logical Channels
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1 2 3 5 6 7TS
"Beacon" frequency
Tim ing synchronization
System inform ation
Subscriber paging
Response to access request
Out of call signalling -> M Si
Power Control -> M Si
Traffic sam ples -> M Sj
In call signalling -> M Sj
BTS M S
Traffic sam ple decoding
In call signalling receipt
Power Control
Out of call signalling receipt
M obile presynchronization
Subscriber paging
Response to access request
exam ple : "Beacon" frequency, downlink:
FCCH
SCH
BCCH
PCH
AGCH
SDCCH
SACCH
TCH
FACCH
FCCH
BCCH
PCH
AGCH
SDCCH
SACCH
TCH
FACCH
0 4
SCH
RADIO INTERFACE4.3.1 Logical Channel
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Use of Logical Channelsduring transactions between Network and M obile Station
1 If the transaction is "M obile Term inated" (incom ing call), the m obile m ust be paged
2 The m obile accesses the PLM N network
3 The network allocates a dedicated channel to the m obile for signalling 4 Signalling interchange (SDCCH and SACCH).
If necessary, the network allocates a TRAFFIC channel to the m obile
5 Traffic interchange (speech or data) on TCH, with associated signalling in SACCH
(background tasks) and FACCH if required
SACCH FACCH
PCH RACH SDCCH + SACCHAG CH TCH / FACCH + SACCH
1 2 3 4 5
RADIO INTERFACE4.3.2 Tim e Division M ultiplexing
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0 1 2 3 4 5 6 7TS
1 2 3 4 5 6 7 8 9 10 20 30 40 5051 1
1 2 3 4 5 6 7 8 9 10 20 23242526
M ultifram e = 51 fram es, giving 235 m s approx.
"TRAFFIC" type M ULTIFRAM E :
"SIGNALLING" type M ULTIFRAM E :
1 TDM A fram e = 120/26 # 4.615 m s
1 2 3 4 5 6 7 8 9 10 20 23242526
M ultifram e = 26 fram es, giving 120 m s
GSM (Circuit Switching)
RADIO INTERFACE4.3.2 Tim e Division M ultiplexing
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1 2 3 4 5 6 7 8 9 10 20 30 40 5051 1
M ultifram e = 52 fram es, giving 240 m s.
52 Fram e - M ultifram e on pdch:52
0 1 2 3 4 5 6 7TS
1 TDM A fram e = 120/26 # 4.615 m s
GPRS (Packet Switching) (1)
Block 0 Block 1 Block 2 Block 3 Block 4 Block 5 Block 6 Block 7 Block 8 Block 9 Block 10 Block 11
RADIO INTERFACE4.3.2 Tim e Division M ultiplexing
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1 2 3 4 5 6 7 8 9 10 20 30 40 5051 1
M ultifram e = 52 fram es, giving 240 m s.
52
GPRS (Packet Switching) (2)
Block 0 Block 1 Block 2 Block 3 Block 4 Block 5 Block 6 Block 7 Block 8 Block 9 Block 10 Block 11
TFI: Tem porary Flow Identifier:
created w hen data has to be transm itted and until all data have been transm itted
BSN: Block Sequence Num ber
Data Flow to User BData Flow to User A Data Flow to User C
TFI 43 TFI 2 TFI 39
TFI =43
Data
BSN =21
TFI =43
Data
TFI =43
Data
BSN =22BSN =23
TFI =43
Data
BSN =24
TFI =43
Data
TFI = 2
Data
BSN =25BSN =12
TFI = 2
Data
BSN =13
TFI = 2
Data
TFI = 2
Data
BSN =14BSN =15
TFI = 39
Data
BSN =75
TFI = 39
Data
TFI = 39
Data
BSN =76BSN =77
RADIO INTERFACE4.3.3 Channel M apping
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STRUCTURE of the M ULTIFRAM E in "TIM E SLOT" 0 (DOW NLINK channel)
F S B B B B c c c c
31
-
51 1
M ultifram e of 51 fram es (giving 235 m s approx.)
F S F S F SF SF Sc c c c
21
c c c c c c c c c c c c c c c c c c c c c c c cc c c c
1 2 3 4 5 6 7 8 9 10 20 41
F = FCCH S = SCH B = BCCH
LOG ICAL
CHANNEL
FCCH
Frequency
Correction
1 every 10 fram es
(46 m s)
OCCURRENCE
and/or USABLE BIT
RATE
as FCCH (46 m s), 8 TSafter
SCH
Synchro
BCCH
Broadcast
Control
1 TS every 4 consec. fram esevery51 fram es,
giving 456 usable bits
every 235 m s
-G eneral inform ation (system ) concerning the station:- Identity of operator, access authorized or not,
- O rganization of logical channels in the cell (paging...),
- Frequencies used, Frequency hopping...,
- Tim e-O uts applicable...
- Locking the m obile local oscillator on the exact frequency
- Roughly estim ating the position of the receive window
- Exact synchronization of receive window
- Decoding the Fram e Num ber(from 0 to 2,715,647)
RO LES and USES of INFORM ATIO N CARRIED
RADIO INTERFACE4.3.3 Channel M apping
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STRUCTURE of the M ULTIFRAM E in "TIM E SLOT" 0 (Non-com bined BCCH)
LOG ICAL
CHANNEL
RACH
Random
Access
O nlyuplink
OCCURRENCE
and/or USABLE BITRATE
These 2 sub-channels
share the "CCCH"
channel based on variable
rules according to cell and
operator
AG CHAccess
Grant
PCH
Paging
- used by the network to signal a call to a m obile:
Short form at identity, unam biguous in the cell
- used by them obile to request accessto the network
("Channel Request" m essage with m obile short form at identity)
- used by the network to acknowledge the access request andassign a dedicated channel to the m obile ("im m ediate
assignm ent" m essage with identity echo)
RO LES and USES of INFORM ATIO N CARRIED
-
R = RACH
DO W NLINKf s b b b b C C C C
31 51 1211 2 3 4 5 6 7 8 9 10 20 41
f s f s f s f sC C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C -
(Multiframes of 51 frames)
f = FCCH s = SCH b = BCCH
f s
C C C C = CC CH (PCH or AGCH )
UPLINK
R R R RR R R R R R R RR R R R R R R RR R R R R R R RR R R R R R R RR R R RR R R RR R R R R R
RADIO INTERFACE4.3.3 Channel M apping
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- O ut of call signalling, such as location update, authentication,
transition to encrypted m ode, assignm ent of a traffic
channel...
SACCH
Slow
AssociatedControl
SDCCHStandalone
Dedicated
Control
STRUCTURE of the M ULTIFRAM E in "TIM E SLOT" 1
LOG ICAL
CHANNEL
8 TSs every 2x51 fram es,giving 456 bits / 235 m s
---> 1.94 kbit/s
OCCURRENCE
and/or USABLE BIT
RATE
4 TSs every 2x51 fram es,
giving 456 bits / 470 m s
---> 950 bit/s
- Non-urgent procedures (background), occurrence ~0.5
sec:m easurem ent reports, power m onitoring, tim ing advance,
+ Short M essage Service (SM S)
RO LES and USES of INFORM ATIO N CARRIED
DO W NLINK
(M ultifram es of 51 fram es)
D = SDCCH A = SACCH
UPLINK
-
-- -
- -D0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3 D4 D5 D6 D7
A0
A4
A1 A2 A3
A5 A6 A7
D0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3 D4 D5 D6 D7 A0
A4
A1 A2 A3
A5 A6 A7
-
-- -
- -
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RADIO INTERFACE4.3.3 Channel M apping
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0 1 2 3 4 5 6 7
TS
0 1 2 3 4 5 6 7
0 1 2 3 4 5 6 7
0 1 2 3 4 5 6 7
"Beacon" frequency
O therfrequencies
FCCH + SCH + BCCH + PCH + AGCH
uplink direction
downlink direction
RACH
TS 0 :
TS 1 : 8 SDCCH/8 + 8 SACCH/8 in each direction
other TSs: TCH (+ SACCH / FACCH) in each direction
BTS
Exam ples : Num ber of Frequencies Num ber of TCH Channels ERLANG S(form ula B, blocking 2% )
3 22 15
4 30 225 38 29
RADIO INTERFACE4.3.3 Channel M apping
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0 1 2 3 4 5 6 7TS
0 1 2 3 4 5 6 7
"Beacon" frequency
Other
frequency
FCCH + SCH + BCCH + PCH + AGCH + RACH + 4 SDCCH /4 + 4 SACCH/4TS 0 of beacon frequency:
other TSs: TCH (+ SACCH / FACCH)
BTS
STRUCTURE of the M ULTIFRAM E in "TIM E SLO T" 0 (Config. n 1: com bined BCCH) :
R = RACH
DO W NLINK (M ultifram es of 51 fram es)
F = FCCH S = SCH B = BCCH C = CC CH (PCH or AG CH )
UPLINK
F S B C F S F S F S -F SC C D0 D1 D2 D3 A0 A1
F S B C F S F S F S -F SC C D0 D1 D2 D3 A2 A3
R R R R R R R R R R R R R R R R R R R R R R R R R R RD3 A2 A3 D0 D1 D2
R R R R R R R R R R R R R R R R R R R R R R R R R R RD3 A0 A1 D0 D1 D2
Dn/An = SDCCH/SACCH/4
RADIO INTERFACE4.3.4 Tim ing Advance
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BTS
M S
Presynchronized
BTSTx
Rx
Tx
RxM S1
TS i
TS i
T.A. m easured by BTS
Access Burstforward propagation tim e
BTSTx
Rx
Tx
RxM S1
TS iTS i
(after TA)
- TA
forward propagation tim e
return propagation tim e
RADIO INTERFACE4.3.5 Subscriber Paging
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The NETW ORK know s the LOCATION AREA (LA) in w hich the m obile is
travelling.
An LA can cover m ore than one cell.
The PCH channel is used to signal a CALL to a m obile.
The sam e "Paging" m essage is transm itted to all cells in the area (shadedareas above).
Only a m obile in "IDLE" state (pre-synchronized) can respond to paging.
BSC
RADIO INTERFACE4.3.6 Access to the Network
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An access request is always initiated by the M OBILE
(when a m obile is called, the "paging" procedure is used).
The RACH channel is used to transm it the "CHANNEL REQUEST" m essage.
The channel is called "random " since the m obile chooses the call TS
random ly.
This m eans that there is a risk of collision.
Collisions are resolved by retransm ission after pseudo-random delays.
M S1
M S5
M S2 M S3 M S4 M S4
M S5
RADIO INTERFACE4.3.7 Logical Channel Sum m ary
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Abbreviation Nam e Type Role/Info carried Burst form at
Frequency Correction CHannel M P --> M S Frequency for synthesizer alignm ent Frequency
Synchronization CHannel M P --> M S Tim ing sync - Fram e N Sync
Broadcast Com m on CHannel M P --> M S Broadcast system inform ation Norm al
Random Access CHannel PP M S Subscriber paging (paging) Norm al
Access G rant CHannel PP --> M S SDCCH channel assignm ent (Im m .Ass) Norm al
Cell Broadcast Control CHannel M P --> M S Broadcast short m essages (SM S/CB) Norm al
Notification CHannel M P --> M S Accessibility notification (VGCS/VBS) Norm al
Dedicated
signalling
(out of call)
Standalone Dedicated Ctrl CH. PP Out of call signalling Norm al
Slow Associated Control CH. PP M easurem ents - P Contr. - Tim ing adv. Norm al
Traffic / Full Rate CHannel PP 13 kbit/s traffic Norm al
Traffic / Half Rate CHannel PP 5.6 kbit/s traffic (phase 2) Norm al
Slow Associated Control CH. PP M easurem ents - P Contr. - Tim ing adv. Norm al
Fast Associated Control CH. PP In call signalling (cycle stealing) Norm al
Fam ily
FCCH
SCHBCCH
Broadcast
CCCH
Dedicated
Traffic +
signalling
(during call)
RACH
PCH
AGCHCBCH
NCH
SDCCH
SACCHTCH/F
TCH/H
SACCH
FACCH
GSM (circuit switching)
RADIO INTERFACE4.3.7 Logical Channel Sum m ary
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NCH
Abbreviation Nam e Type Role/Info carried Burst form at
Packet Broadcast Com m on CH. M P --> M S Broadcast system inform ation Norm al
Random Access CHannel PP M S Subscriber paging (paging) Norm al
Access G rant CHannel PP --> M S SDCCH channel assignm ent (Im m .Ass) Norm al
Notification CHannel M P --> M S Accessibility notification (VGCS/VBS) Norm al
Packet Data Transfer Channel PP Norm al
Packet Associated Control Ch. PP Norm al
Packet Tim ing Control Ch. PP Tim ing advance Norm al
Fam ily
PBCC
H
Broadcast
CCCH
pdch
PRACH
PPCH
PAGC
H
PDTCH
PACC
HPTCCH
Acknowledge - Power Control
User Data
GPRS
RADIO INTERFACE4.4.1 Radio Channel generation
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ChannelEncoding
Speech
Digitizationand
Encoding
Interleaving
Burst
Form attingEncryption M odulation Transm ission
ReceptionDem odulationDecryptionBurst
Deform atting
De-
interleavingChannel
DecodingSpeech
Decoding
POW ER M O NITO RING
260 bits / 20 m s :13 kbit/s 22.8 kbit/s
(per channel)
270.8 kbit/sSpeech fram es :
(m odulated)
RADIO INTERFACE4.4.1 Radio Channel generation
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Bit Rate on Um interface
GSM circuit-switched
Full Rate (FR) / Enhanced Full rate (EFR) speech: 13 Kbit/s
Half rate (HR) speech: 5.6 Kbit/s
Data transm ission: m axim um 14,4 Kbit/s
GSM packet-switched (GPRS) : 4 Coding Schem es
CS-1 : 9,05 Kbit/s (per TS)
CS-2 : 13,4 Kbit/s (per TS)
CS-3 : 15,6 Kbit/s (per TS)
CS-4 : 21,4 Kbit/s (per TS)
RADIO INTERFACE4.4.2 Discontinuous Transm ission
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Principles (M andatory in the m obile and on the BTS uplink path) :
DTX (Discontinuous Transm ission) : reduced rate transm ission (~ 500 bit/s)
during silences
VAD (Voice Activity Detection): M easurem ent of signal strength for detectingm om ents of "silence (neither speech nor tone) - adaptive-threshold FILTER
Com fort Noise Generation:
In receive m ode, reconstitution of background noise based on the
characteristics received in Silence Descriptor (SID) fram es, to avoid giving thereceiving user the im pression that the line has been cut off
S*
S S' S'S'S' S'S'S'S"
480 m s BTS
TRAU --> BTS
M S BTS
SPEECH
SILENCE
SID FRAM E
TRAU
RADIO INTERFACE4.4.3 GM SK M odulation
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GM SK = Gaussian M inim um Shift Keying:
Principle close to offset quadri-phase shift keying
(OQ PSK) m odulation, obtained by convolution of
an M SK ram p of height/2 and width 1 bit, by aGaussian function: "gradual" 0-1 or 1-0 transitions of /2 :
PROPERTIES :
Gradual transitions avoid the need to filter signal harm onics which arevery weak
Spectrum efficiency of the order of 1 bit/Hertz
(270.8 kbaud/200 kHz)
M odulation spectrum :
==> To prevent catastophic interference,
it is essential to avoid using
adjacent frequencies in adjacent cells.
p/2
t
0 T 2T-T-2T
dB0
-10
-20
-30
-70
0 100 200 300 400-100-200 kHz
RADIO INTERFACE4.5.1 Frequency Hopping
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" f "
"G AP" in frequency " f " reception
RADIO INTERFACE4.5.1 Frequency Hopping
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N-frequency hopping groups can be defined for each TS (N>=4)
The overall system capacity rem ains unchanged (eg. : 32 m obiles on 4
frequencies)
0 1 2 3 4 5 6 7TS
"Beacon" frequency
O ther
frequencies
FCCH/ SCH/ BCCH/ CCCH
SDCCHNo Hopping
TS0 : Hopping over 4 frequencies TS3 : Hopping over 5 frequencies
RADIO INTERFACE4.5.2 Power Control
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M easurem ent Ratios sent every 470 or 480 m s (SACCH occurrences) by M S Power Control algorithm run in the BSC (or BTS)
M odulation of the pow er transm itted by the BTS and m essage transm ission to the M S
(in SACCH)
Possible M ODULATION : 2 dB m ax. every 60 m sec,within a range from 6 to 21 x2 dB (DL) and optionally 15 x2 dB (UL):
8 W
20 m W
2 15
26 dB
0
13
39
dBm
pow er steps0
13
39dBm
19 17 31 31 29 dBm
tim e
60 m scontrols
Level
EXAM PLE for a portable M O BILE
2 W33 33 P m ax M S 2W
RADIO INTERFACE4.5.3 Space Diversity
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In Receive M ode, 2 independent paths in the base station
A Discrim inator identifies the best signal.
PATH 1
PATH 2
RESULT
INTRODUCTION TO THE Alcatel 900/1800/1900 GSMNETW O RK
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5 Interchanges over the Network
INTERCHANG ES OVER THE NETW ORKContents
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5.1 GSM Num bers and Identities
5.1.1 GSM Subscribers: m ain types of identification
5.1.2 M obile Equipm ent identification
5.1.3 Geographic identification
5.2 BSS / NSS Protocols and Software M odules
5.2.1 General
5.2.2 Radio Interface (Um ) : Layer 3 : "RIL 3" protocol
5.2.3 GPRS protocols
5.3 Typical Sequence for an Originating Call
5.4 Level 3 GSM Procedures
5.4.1 Setting up the radio connection
5.4.2 Security Functions
5.4.3 M obile O riginating Call (M O)
5.4.4 M obile Term inating Call (M T)
5.4.5 Exam ple of an International Call
5.4.6 Location Updating
5.4.7 Change of Cell during the Call ("Handover")
INTERCHANG ES OVER THE NETW ORK5.1.1 GSM num ber and identities: Subscriber identifications
IM SI M S ISDN
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IM SI M S - ISDN
( International M obile Subscriber Identity )
International Identity E212 com pliantNature
(M obile Station - Integrated Service Digital Netw ork n )
Directory Num ber ISDN type, E.164/E.213 com pliant
M CC M NC M SINH1 H2 x x x ........ x x x
M obileCountryCode
M obileNationalCode
M obile Subscriber Identity Num berincluding H 1 H2 = N of physical HLR
Form at
M eaning
N of digits
Exam ples
Characteristics
3 2 m ax 10
234
208 01
10
Stored in SIM m odule and AuC
CC NDCSN
M 1 M 2 x x x x x x x x
CountryCode
National
Code*Destination
Subscriber Num ber( national identity )
including M 1 M 2 identifying the logical HLR
(ZAB) (PQ)
1 to 3 2 to 4
44 802 Cellnet GSM44 385 Vodafone GSM44 956 M ercury DCS44 973 Hutchinson DCS
33
33
607/8
609
61 M C DU to 69 M C DU LYON
01 M C DU to 09 M C DU M ASSENA
11 xxxx to 3x xxxx LA FOURCHE
Allocated to an IM SI (by M M C) in the HLR
69 xx xx xx xx LYON
94 xx xx xx xx M ASSENA
?
France
U.K.
France Tlcom
SFR
total up to 15
* instead of identifying a geographic area, the NDC identifies an O PERATOR:
( national identity )NM SI
INTERCHANG ES OVER THE NETW ORK5.1.2 GSM num ber and identities: M obile Equipm ent identification
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IM EI / IM EISV
( International M obile Equipm ent Identity )
TAC FAC SNR SP
Type Approval CodeFinal Assem bly Code
Serial Num beR
(SPare)
Stored in the Equipm ent (Term inal)
Used to replace the IM SI or TM SI if they cannot be used
(exam ple : em ergency calls with no SIM card) or at the network's request (m aintenance)
Can be used to update the EIR database (if there is one)
( International M obile Equipm ent Identity and Software Version num ber) (Phase 2+)
TAC FAC SNR SVN
Software Version Num ber
IM EI
:
IM EISV:
INTERCHANG ES OVER THE NETW ORK5.1.3 GSM num ber and identities: Geographic identification
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LAI: Location Area Identification
M CC = M obile Country Code
M NC = M obile Network Code
LAC = Location Area Code
Use of LAI:
Paging
Location Area Updating
Security
CGI Cell Global Identification
CI = Cell Identifier
M CC M NC LAC CI
LAI
CGI
INTERCHANG ES OVER THE NETW ORK5.1.3 GSM num ber and identities: Geographic identification
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RAI: Routing Area Identification
M CC = M obile Country Code
M NC = M obile Network Code
LAC = Location Area Code
RAC = Routing Area Code
Use of RAI:
Paging
Routing Area Updating
M CC M NC LAC RAC
RAI
For GPRS:
INTERCHANG ES OVER THE NETW ORK5.2.1 BSS / NSS Protocols and Software M odules: general
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S.C.1S.C.1 S.C.1S.C.1
SCCP
M TP 3
M TP 2
S.C.1
SCCP
M TP 3
M TP 2
S.C.1
TCAP
M AP
TCAP
M AP
SCCP
M TP 3
M TP 2
S.C.1
DTAP
SCCP
M TP 3
M TP 2
S.C.1
DTAP
LAPDLAPDm LAPD
SS (SM S)SS (SM S)
BSSM AP
M M
CC
BSSM APRR
RR
RR' BTSMBTSM
LAPDm
(SM S)
SSCC
M M
(Relays)
M S BTS BSC M SC / VLR NSS
(eg. : HLR)
Um A bis A (D)
1
2
3
(Relays)
INTERCHANG ES OVER THE NETW ORK5.2.2BSS / NSS Protocols and Software M odules: Radio Interface
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-Call handling and routing
- DTM F facilities
- Access to Supplem entary
Services
- Short M essage Service
-Paging m anagem ent
- Ciphering m ode m anagem ent
- Frequency redefinition
- Dedicated channel assignm ent
- Handover m anagem ent- M easurem ents and pow er control
Radio Interface Layer 3 protocol
Protocol
Discrim inator
RR Radio Resource
M anagem ent
M eaning
M M M obility M anagem ent-Paging m anagem ent
- Ciphering m ode m anagem ent
- Frequency redefinition
- Dedicated channel assignm ent
Function
Call Control
Supplem entary Services
Short M essage Service
CC
SM S
SS
Entities
M S - BSC
(and BTS)
M S -
M SC / VLR
M S - M SC
(+ HLR)
(+ SM S-C)
INTERCHANG ES OVER THE NETW ORK5.2.3 BSS / NSS Protocols and Software M odules: GPRS protocols
GPRS operation:basicprocedures
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IP NetworkBSS
SGSNM S1
GGSN1
GGSN2
PDN1
PDN2
LLC
TLLI1
Attachm ent
TID2
= IMSI + session2
GTP
TID1
= IMSI + session1
Opening
Session(s)
GPRS operation: basic procedures
INTERCHANG ES OVER THE NETW ORK5.2.3 BSS / NSS Protocols and Software M odules: GPRS protocols
IP overview
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ipip ipip ip
http httpftp ftpsm tp sm tpgtp gtp
GGSNSGSN
1tcp1tcp
wap wap
IP overview
Routers
IP network
Client Server
INTERCHANG ES OVER THE NETW ORK5.2.3 BSS / NSS Protocols and Software M odules: GPRS Protocols
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GTPSNDCP SNDCP
BSSGP
LLC
M S BSS SGSN GGSN
Um Gn
Layer M odel for Transm ission plan (GPRS)
relay
L1 bis
Fram e
Relay
L1
L2
L1
L2
PhysicalLayer
M AC
L1 bis
Fram e
Relay
PhysicalLayer
M AC
RLC
LLC
Gb
GTP
IP
UDP &
TCP
IP / X25Appli
BSSG
PRLC
IP
UDP &
TCP
IP / X25
LayerM odelforTransm ission plan (GPRS)(2)
INTERCHANG ES OVER THE NETW ORK5.2.3 BSS / NSS Protocols and Software M odules: GPRS protocols
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Layer M odel for Transm ission plan (GPRS) (2)
Header Data
Header Data
LLC
PHYSICAL
CRC CRC CRCRLC M AC
IP/X25
SNDCP
Division of the SDU in 2 blocks
Com pression of each part
Label added for each block
LLC EncapsulationCRC
RLC Encapsulation
LLC fram e splitted
into blocks
Header
= < 1520 BytesHeader
Channel Coding CS1 to CS4
Block 1Block 2Block 3Block 4Block 5Block 6Block 7Block 8
Block 1 Block 2 Block 3 Block 8
CRCHeader
Header
INTERCHANG ES OVER THE NETW ORK5.2.3 BSS / NSS Protocols and Software M odules: GPRS protocols
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GTPGM M
BSSGP
LLC
M S BSS SGSN GSN
Um Gn
Layer M odel for Signalling plan (GPRS)
relay
L1 bis
Fram e
Relay
L1
L2
L1
L2
L1 RF
M AC
L1 bis
Fram e
Relay
L1 RF
M AC
RLC
LLC
Gb
IP
UDP
SM
BSSG
PRLC
IP
GSM S
UDP
GM M
SMG
SM S
GTP
GSN
INTERCHANG ES OVER THE NETW ORK5.3 Typical Sequence for an Originating Call
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M O BILE GSM NETW ORK
CHANNEL REQUEST
IM M EDIATE ASSIG NM ENT
CM SERVICE REQUEST
AUTHENTICATION REQ UEST
AUTHENTICATION RESPO NSE
CIPHERING M O DE CM DCIPHERING M O DE CO M PLETE
SET UP
CALL PRO CESSING
ASSIGNM ENT CM D
ASSIGNM ENT CO M
ALERTING
CONNECT
CO NNECT ACK
SET-UP of anRR CO NNECTION (M O)
SERVICE INDICATION
AUTHENTICATIO N
TRANSITIO N to CIPHERING M ODE
START of CALL
TRAFFIC CHANNEL
CALL CO NFIRM ATION
CALL ACCEPTED
ASSIGNM ENT
PSTN or ISDN
INTERCHANG ES OVER THE NETW ORK5.4.1 Level 3 GSM procedures: Setting up the radio connection
U
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SDCCH N
M M CM _SERVICE REQ UEST
SDCCH N
RACH
M SCHANNEL REQUEST
IM M EDIATE ASSIGN.
BTS BSC M SC
Um A bis A
CHANNEL REQUIRED
ASSIG NM ENT of anSDCCH Channel
CHANNEL ACTIV.
ACTIVATION of
Channel indicated CHANNEL ACTIV. ACK
AG CH
CONNECTION to theSDCCH Channel
SDCCHSABM ESTABLISH INDIC.
SCCP CONNECT REQUEST
SCCP CO NNECT CO NFIRM
T3101
T9105
IM M . ASSIG N. CM D
RR
RR
M M CM _SERVICE REQ UEST
RR
BTSM
BTSM
BTSM
SDCCH UA
M M CM _SERVICE REQ UEST
M M CM _SERVICE REQ UEST
INTERCHANG ES OVER THE NETW ORK5.4.2 Level 3 GSM procedures: Security Functions
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Authentication
Checks that the M obile Station is the required station and not an intruder
Ciphering
All Inform ation (Signalling, Speech and Data) is sent in cipher m ode, to avoid
m onitoring and intruders (who could analyze signalling data)
Tem porary Identification
Each tim e the network is accessed for whatever reason, a different num ber isused to identify a subscriber, so that the subscriber identity cannot be used by
an intruder: On each access operation a new tem porary num ber is sent in
cipher m ode, and provides identification for the next access operation.
INTERCHANG ES OVER THE NETW ORK5.4.2 Level 3 GSM procedures: Security Functions
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SIM card
A3
AuCRadio Channel
A8
Ki Ki
Random num ber selection
A3
A8
A3 A3
A8A8
A5A5
= ?
Identification key (128 bits)
RAND (128 bits)
RAND
Signed ref. (32 bits) SRES SRES
Cipher com m and
OK
Kc : Cipher key
for the call (64 bits)
Kc
Speech - Data - Signalling Speech - Data - Signalling Ciphered data
Ciphering/Deciphering Ciphering/Deciphering
BTS
A5A5
INTERCHANG ES OVER THE NETW ORK5.4.2 Level 3 GSM procedures: Security Functions
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MS BTS HLRMSC / VLR OMCAuC
SIM card
IMSI
KiA3A8
RAND
SRES
Kc
Ciphering
Function
A5
Ciphering
FunctionRANDSRES
Kc
RANDSRES
Kc
Kc
= ?
TripletsTriplet
Generation
RAND
Ki
KiIMSI
A4Ki
IMSI
(ciphered)
A4
A2
SpeechDataSign
SpeechDataSign
(ciphered)
RAND
SRES
A8
A3
Ki
IMSI
IMSIA8
A3
Ki
IMSIIMSITMSI
A5 Kc
TMSI
A5
Kc
INTERCHANG ES OVER THE NETW ORK5.4.3 Level 3 GSM procedures: M obile Originating Call
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M OBILE GSM NETW ORK
CHANNEL REQUEST
IM M EDIATE ASSIG NM ENT
CM SERVICE REQUEST
AUTHENTICATIO N
CIPHERING
SET UP
ASSIGNM ENT CM D
ASSIGNM ENT CO M
ALERTING
CONNECT
CO NNECT ACK
VEA : Very Early Assignm ent :
CALL CO NFIRM ATION
CALL ACCEPTED
or SET UP if VEA
ASSIGNM ENT CM DASSIGNM ENT CO M 1/2 O ACSU :
ASSIGNM ENT CM D
ASSIGNM ENT CO MO ACSU com plete
Im m ediate assignm ent of a TCH :
No authentication or ciphering
(Signalling carried on FACCH)
EA : Early Assignm ent :
TCH allocated BEFO RE call confirm ation
om itted if VEA
TCH allocated after called party ringing
TCH allocated after called party answ er"Queuing"
PSTN or ISDN