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GSM Architecture
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rouprouppcialpcial
obileobile
GG
GSMGSM
SS
MM
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loballobalystem forystem for
obile Communicationsobile Communications
GGSS
MM
GSM ArchitectureGSM Architecture
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GSM - Public Land MobileGSM - Public Land MobileNetworkNetwork
INDIA has adopted GSM standard.INDIA has adopted GSM standard. Digital Cellular System based onDigital Cellular System based on
Narrowband ISDN.Narrowband ISDN. Operates at 900 MHz range.Operates at 900 MHz range. International Roaming facility.International Roaming facility.
Power class 0.8 to 20W.Power class 0.8 to 20W. Cell Radius upto 30 Kms.Cell Radius upto 30 Kms. Maximum mobility speed 250 Km/hr.Maximum mobility speed 250 Km/hr.
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Design Objectives of GSMDesign Objectives of GSM
Good speech quality.Good speech quality. Security and privacy.Security and privacy.
Low terminal and service cost.Low terminal and service cost.
Handheld terminals.Handheld terminals. International roaming.International roaming.
Range of new services & facilities.Range of new services & facilities. Digital radio.Digital radio. Spectral efficiency.Spectral efficiency.
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Communication PSTNCommunication PSTN
Telephone Exchanges
Subscriber
Line(2W)
Inter-Exchange
Junction
Subscriber
Line(2W)
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Communication - PLMNCommunication - PLMN
TelephoneExchange
Subscriber
Line(2W)
Inter-Exchange
Junction
Mobile SwitchingCentre (MSC)
BSC BTSMS
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Mobility IssuesMobility Issues
Demand on scarce Radio Resources.Demand on scarce Radio Resources. Authentication.Authentication. Security and Privacy.Security and Privacy. Providing service across networks.Providing service across networks. Maintain UNIQUE Service Profile.Maintain UNIQUE Service Profile. Keep track of users.Keep track of users. Maintain established communication.Maintain established communication. Power & Timing management of MS.Power & Timing management of MS. Roaming and Billing & AccountingRoaming and Billing & Accounting
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Wired Vs Wireless SANWired Vs Wireless SAN
Space Division MultiplexingSpace Division Multiplexing Available space much more than required and henceAvailable space much more than required and hencededicated access to each.dedicated access to each.
Teledensity of an area does not pose any problem.Teledensity of an area does not pose any problem. Static Network snapshots.Static Network snapshots.
WIREDWIRED
NETWORKNETWORK Lay as muchcable as needed
to meet the
demand.
TelephoneExchangeSubscriber
Line(2W)
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Wired Vs Wireless SANWired Vs Wireless SAN
Frequency/Time Division MultiplexingFrequency/Time Division Multiplexing Limited RF spectrum and hence RF channels assigned on demandLimited RF spectrum and hence RF channels assigned on demand Dynamically changing teledensity in each area.Dynamically changing teledensity in each area. Dynamic Network snapshots.Dynamic Network snapshots.
Mobile SwitchingCentre (MSC)
BSC BTS
MS
ONLY a windowof RF Spectrum
is available
RF Channels
WIRELESSWIRELESS
NETWORKNETWORK
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7 Cell Cluster Structure7 Cell Cluster Structure
F1
F7
F2
F3
F4
F5
F6
F1
F4
F5
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F1
F2F4
F5
F6
F7
F1
F2F4
F5
F6
F7
GSM - Cell layoutGSM - Cell layout
Farthest Separation
F3
F3
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GSM TerminologyGSM Terminology
Home networkHome network
Visited networkVisited network
Location AreaLocation Area RoamingRoaming
HandoverHandover POIPOI
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System ArchitectureSystem Architecture
Functional Architecture broadly divided intoFunctional Architecture broadly divided intosix parts:six parts:
Mobile Station.Mobile Station.Base Station Subsystem (BSS).Base Station Subsystem (BSS).
Network Switching SubsystemNetwork Switching Subsystem
(NSS).(NSS).Operation and MaintenanceOperation and MaintenanceSubsystem.Subsystem.
Enhanced Services SystemEnhanced Services System
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GSM Network OverviewGSM Network Overview
MEME
SIMSIMSIMSIM
BTS
BTS
BSC
BSC
MSC
HLR
EIR
VLR
AuCMobileStation Base Station Subsystem Network Subsystem
PSTNISDNPSPDNCSPDN
Um Abis
AOMC
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GSM Network ArchitectureGSM Network Architecture
MSS BTS BSCBSS VLR
AuCuC
MSCEIR
AuC
HLR
HLRLROMC
EIRIR
Bill ingCentreEnhancedServiceNodeSTN
OtherMSCsAir
Interface
VoiceVoice
SS7 CallProc
& Mtce
RS-232EIA
SS7Mtce
X.25
MAP MAP
MAP
ISUP
X.25
SS7ETSIBRAVoice Path
Signalling Path
XCD
R
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GSM Network ArchitectureGSM Network Architecture
MSS BTS BSCBSS VLR
AuCuC
MSCEIR
AuC
HLR
HLRLROMS
EIRIR
B&CCSnhancedServiceNodesSTN
OtherMSCsAir
Interface
Voice PathSignalling Path
XCDR
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GSM Reference ModelGSM Reference Model
A
MSMS BTS BSC
UmAbis
MSC HLR
EIR
VLR
AuC
VLROMC
MSC PSTN ISDN
E
FC
B D
G
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Mobile StationMobile Station
Mobile Station is really two distinctMobile Station is really two distinctentities.entities.
Mobile equipment or Mobileterminal.
SIM Card.
Mobile equipment, which is the actualMobile equipment, which is the actualHardware, is almost anonymous.Hardware, is almost anonymous.
SIM card, implemented as a smart cardSIM card, implemented as a smart cardholds the subscriber information.holds the subscriber information.
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Mobile TerminalMobile Terminal
Different terminals distinguishedDifferent terminals distinguishedprincipally by their power andprincipally by their power andapplication.application.
Fixed terminals 20WPortable terminals for cars 8WHandheld terminals 2W
Sophisticated terminals 0.8W Every terminal has an InternationalEvery terminal has an International
Mobile Equipment Identity (IMEI).Mobile Equipment Identity (IMEI).
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The SIMThe SIM
SIM provides Personal Mobility.SIM provides Personal Mobility. Holds a unique identifier calledHolds a unique identifier called
International Mobile Subscriber IdentityInternational Mobile Subscriber Identity
(IMSI), Service profile, Secret key for(IMSI), Service profile, Secret key forauthentication, etc.authentication, etc.
Provides user access to all subscribedProvides user access to all subscribed
services. SIM makes the terminalservices. SIM makes the terminaloperational.operational.
Can be password protected by a 4 to 8 digitCan be password protected by a 4 to 8 digitPersonal Identification Number.Personal Identification Number.
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The SIMThe SIM
SIM is classified on the basis of:SIM is classified on the basis of:Operating voltage.
RAM capacity. Operating Voltages:Operating Voltages:
3V and 5V.
RAM Capacity:RAM Capacity:8K, 16K, 32K and 64K
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System ArchitectureSystem Architecture
Functional Architecture broadly divided intoFunctional Architecture broadly divided intosix parts:six parts:
Mobile Station.Mobile Station.Base Station Subsystem (BSS).Base Station Subsystem (BSS).
Network Switching SubsystemNetwork Switching Subsystem
(NSS).(NSS).Operation and MaintenanceOperation and MaintenanceSubsystem.Subsystem.
Enhanced Services SystemEnhanced Services System
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BSS ConnectivityBSS Connectivity
BSC
BTS
BTS
BTS
To
MSCXCDR
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Base Station SubsystemBase Station Subsystem
BSS connects the MS and the NSS.BSS connects the MS and the NSS.
Composed of three parts:Composed of three parts:
The Base Transceiver Station (BTS)also called Base Station (BS)Transcoder and. Base Station Controller (BSC).
BSS provides the radio interface functions.BSS provides the radio interface functions.
Completely digital.Completely digital.
Base Transceiver StationBase Transceiver Station
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Base Transceiver StationBase Transceiver Station(BTS)(BTS)
BTS houses the radio transceivers thatBTS houses the radio transceivers thatdefine a cell.define a cell.
Handles the radio-link protocols withHandles the radio-link protocols withthe Mobile Stationthe Mobile Station
Each BTS can support a number ofEach BTS can support a number oftransceivers depending on the densitytransceivers depending on the densityof subscribers in the cell.of subscribers in the cell.
Needs to be rugged, reliable, portable.Needs to be rugged, reliable, portable.
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Base Station ControllerBase Station Controller
BSC manages the radio resourcesBSC manages the radio resourcesfor one or a group of BTSs.for one or a group of BTSs.
Handles radio-channel setup,Handles radio-channel setup,frequency hopping, handovers,frequency hopping, handovers,and control of the RF power levels.and control of the RF power levels.
Establishes connection betweenEstablishes connection betweenthe mobile station and the MSC.the mobile station and the MSC.
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System ArchitectureSystem Architecture
Functional Architecture broadly divided intoFunctional Architecture broadly divided intosix parts:six parts:
Mobile Station.Mobile Station.Base Station Subsystem (BSS).Base Station Subsystem (BSS).
Network Switching SubsystemNetwork Switching Subsystem
(NSS).(NSS).Operation and MaintenanceOperation and MaintenanceSubsystem.Subsystem.
Enhanced Services SystemEnhanced Services System
Network & SwitchingNetwork & Switching
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Network & SwitchingNetwork & SwitchingSubsystemSubsystem
Manages the communication betweenManages the communication betweenthe mobile users and other users.the mobile users and other users.
Provides all the functionality needed toProvides all the functionality needed tohandle a mobile subscriber such as:handle a mobile subscriber such as:Registration.Authentication and security.
Location updating.Handovers andRouting to roaming subscribers.
Network & SwitchingNetwork & Switching
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Network & SwitchingNetwork & SwitchingSubsystemSubsystem
Central component is the MSCCentral component is the MSC(Mobile Services Switching Centre).(Mobile Services Switching Centre).
It performs the switching functionsIt performs the switching functionsof the network.of the network.
Gateway Mobile Services SwitchingGateway Mobile Services SwitchingCentre interfaces between theCentre interfaces between themobile network and PSTN.mobile network and PSTN.
Network & SwitchingNetwork & Switching
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Network & SwitchingNetwork & SwitchingSubsystemSubsystem
Services provided in conjunctionServices provided in conjunctionwith four intelligent databases.with four intelligent databases.
Home Location Register (HLR)Home Location Register (HLR) Visitor Location Register (VLR)Visitor Location Register (VLR)
Authentication Centre (AuC)Authentication Centre (AuC) Equipment Identity Register (EIR)Equipment Identity Register (EIR)
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Home Location RegisterHome Location Register
Contains all administrativeContains all administrativeinformation of each subscriberinformation of each subscriber
registered in an GSM network.registered in an GSM network. Logically there is one HLR perLogically there is one HLR perGSM/PLMN network.GSM/PLMN network.
Can be implemented as distributedCan be implemented as distributeddatabase also.database also.
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Home Location RegisterHome Location Register
International Mobile Subscriber IdentityInternational Mobile Subscriber Identity(IMSI). Also in SIM of MS as(IMSI). Also in SIM of MS asIMSI/TMSI.IMSI/TMSI.
Mobile Subscriber ISDN NumberMobile Subscriber ISDN Number(MSISDN).(MSISDN).
Permanent copy of subscriber data.Permanent copy of subscriber data.
Mobile Station Roaming NumberMobile Station Roaming Number(MSRN), typically the CCS#7 SP code of(MSRN), typically the CCS#7 SP code ofthe visited MSC/VLR.the visited MSC/VLR.
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Visitor Location RegisterVisitor Location Register
For managing originating andFor managing originating andterminating calls under its coverageterminating calls under its coverage
area, each MSC need subscriber dataarea, each MSC need subscriber dataheld in HLR.held in HLR.
To avoid high signalling load betweenTo avoid high signalling load between
MSCs and HLR, subscriber data areMSCs and HLR, subscriber data aredownloaded at registration and held indownloaded at registration and held ina local database called VLR.a local database called VLR.
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Visitor Location RegisterVisitor Location Register
VLR Contains selected administrativeVLR Contains selected administrativeinformation from HLR needed forinformation from HLR needed for
call control and provision ofcall control and provision ofsubscribed services for each mobilesubscribed services for each mobile
located in the geographical arealocated in the geographical areacontrolled by the MSC.controlled by the MSC.
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Visitor Location RegisterVisitor Location Register
In the canonical architecture, each VLRIn the canonical architecture, each VLRcorresponds to one MSC, even though acorresponds to one MSC, even though a
VLR can hold data for one or severalVLR can hold data for one or several
MSCs of the same PLMN.MSCs of the same PLMN. Holds IMSI, MSRN, HLR copy (Sub data).Holds IMSI, MSRN, HLR copy (Sub data).
Temporary Mobile Subscriber IdentityTemporary Mobile Subscriber Identity
(TMSI).(TMSI). Location Area Code (LAC) of MS.Location Area Code (LAC) of MS.
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Authentication CentreAuthentication Centre
A protected database used for securityA protected database used for securitypurposes.purposes.
Replicates the copy of the secret keyReplicates the copy of the secret key
(Authentication Key (Authentication Key KiKi) stored in each) stored in eachsubscribers SIM card.subscribers SIM card.
Provides all the parameters needed forProvides all the parameters needed for
authentication and encryption overauthentication and encryption overradio channels.radio channels.
Considered to be part of HLR.Considered to be part of HLR.
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Equipment Identity RegisterEquipment Identity Register
A database that contains a list of all validA database that contains a list of all validmobile equipment in the network.mobile equipment in the network.
Generates Valid, Suspect & FraudulentGenerates Valid, Suspect & Fraudulentlists of Mobile Equipment through the uselists of Mobile Equipment through the useof International Mobile Equipmentof International Mobile EquipmentIdentity (IMEI).Identity (IMEI).
Forbid calls fromForbid calls from unauthorisedunauthorised terminalsterminals(non-standard terminals)(non-standard terminals)
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System ArchitectureSystem Architecture
Functional Architecture broadly divided intoFunctional Architecture broadly divided intosix parts:six parts:
Mobile Station.Mobile Station.Base Station Subsystem (BSS).Base Station Subsystem (BSS).
Network Switching SubsystemNetwork Switching Subsystem
(NSS).(NSS).Operation and MaintenanceOperation and MaintenanceSubsystem.Subsystem.
Enhanced Services SystemEnhanced Services System
Operation & SupportOperation & Support
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Operation & SupportOperation & SupportSubsystemSubsystem
OMS comprises of :OMS comprises of : Operation and Maintenance
Centre (OMC) for Radio OMC-R. OMC for Switch OMC-S
Configures, controls and monitorsConfigures, controls and monitors
the GSM system.the GSM system. Controls the traffic load in BSSs.Controls the traffic load in BSSs.
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OMCOMC
The maintenance control point for allThe maintenance control point for allnetwork elements in a GSM system.network elements in a GSM system.
Office Data Management.Office Data Management.
Operation and Administration.Operation and Administration.
Data and Software storage for networkData and Software storage for network
elements.elements.
Traffic reporting and analysis.Traffic reporting and analysis.
Must comply with TMN architecture.Must comply with TMN architecture.
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Enhanced Services SystemEnhanced Services System
Unified Messaging Services (UMS)Unified Messaging Services (UMS)Voice Mail (VM)FAX Mail (FM)E-Mail (EM)Short Message Service (SMS)
Wireless Application Protocol (WAP)Wireless Application Protocol (WAP) Intelligent Network (IN)Intelligent Network (IN)
Billing & Customer CareBilling & Customer Care
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Billing & Customer CareBilling & Customer CareSystemSystem
Mediation DeviceMediation Device Interconnect Billing SubsystemInterconnect Billing Subsystem
Billing SubsystemBilling SubsystemRating Module
Billing ModuleRoaming settlement subsystemCustomer Service ModuleOrder Management ModuleSmart Card Handling Module
Service Provisioning SubsystemService Provisioning Subsystem Networking SubsystemNetworking Subsystem
Printing SubsystemPrinting Subsystem
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GSM FunctionsGSM Functions
GSM functions are broadly classified intoGSM functions are broadly classified into5 main functional Blocks:5 main functional Blocks:
TransmissionTransmission
Radio Resources Management (RR)Radio Resources Management (RR)
Mobility Management (MM)Mobility Management (MM)
Communication Management (CM)Communication Management (CM) Operation, Administration andOperation, Administration andMaintenance (OAM)Maintenance (OAM)
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Spectral Allocation in GSMSpectral Allocation in GSM
DOWNLINK
935-960 MHz
UPLINK
890-915 MHz
n erconnec on on erconnec on o
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n erconnec on on erconnec on oFunctionsFunctions
PHY
LAPDm
RR
MM
CM
PHY
LAPDm
RR
PHY
LAPDm
BTSM
MTP
SCCP
BSSAP
MM
CM
PHY
LAPDm
BTSM
MTP
SCCP
BSSAP
Um AAbisMSMSMSMS BTSBTSBTSBTS BSCBSCBSCBSC MSCMSCMSCMSC
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TransmissionTransmission
A combination of FDMA and TDMA isA combination of FDMA and TDMA isused.used.
25MHz band divided into 125 carrier25MHz band divided into 125 carrierfrequencies spaced 200KHz apart.frequencies spaced 200KHz apart.
One or more carrier assigned to eachOne or more carrier assigned to each
base station.base station. Each carrier band divided using TDMA.Each carrier band divided using TDMA.
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TransmissionTransmission
Organisation of physical channels intoOrganisation of physical channels intotraffic and control channels.traffic and control channels.
Speech coding (RPE-LPC) 13KbpsSpeech coding (RPE-LPC) 13Kbps
Channel coding and modulationChannel coding and modulation
Organisation of hierarchical multiframeOrganisation of hierarchical multiframestructures.structures.
Burst structure and assembly.Burst structure and assembly.
MultipathMultipath equalisationequalisation..
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FDMA/TDMA SchemeFDMA/TDMA Scheme
BP1 BP2 BP3 BP4 BP5 BP6 BP7 BP8 BP1 BP2t
890.0
890.2
890.4
890.6
890.8
891.0
891.2
915
f
GUARD BAND
SLOTSLOT
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Logical Channel ArchitectureLogical Channel Architecture
PHYSICALCHAN
NELS
Control channels
(CCH)
Traffic channels(TCH)
Paging
Access
User Speech/Data
Associated controland Supervision
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Logical Channel ArchitectureLogical Channel Architecture
PHYSI
CALCHA
NNELS
PHYSI
CALCHANNELS
Traffic channels(TCH)
Traffic channels(TCH)
User Speech/DataUser Speech/Data
Associated controland Supervision
Associated controland Supervision
Broadcastchannels (BCH)
Broadcastchannels (BCH)
Synchronisation (DL)Synchronisation (DL)
Frequency Correction (DL)Frequency Correction (DL)
Broadcast Control(DL)Broadcast Control(DL)
Common Controlchannels (CCH)
Common Controlchannels (CCH)
Paging (DL)Paging (DL)
Access and Grant (BW)Access and Grant (BW)
Speech - Radio Waves -Speech - Radio Waves -
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Speech Radio Waves Speech Radio Waves SpeechSpeech
Speech Coding
Channel Coding
Interleaving
Burst Assembling
Ciphering
Modulation
Speech decoding
Channel decoding
De-interleaving
Burst disassembling
De-ciphering
De-modulation
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Speech CodingSpeech Coding
Analog to Digital conversion.Analog to Digital conversion.
RPE-LPC with long term predictor loopRPE-LPC with long term predictor loop
based on the assumption that based on the assumption thatsamples does not change very quickly.samples does not change very quickly.
Speech divided into 20mSec samples,Speech divided into 20mSec samples,
each of which is encoded as 260 bits.each of which is encoded as 260 bits. The total bit rate is 13Kbps.The total bit rate is 13Kbps.
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Speech CodingSpeech Coding
13Kbps coding is called the Full-Rate13Kbps coding is called the Full-Ratespeech coding.speech coding.
Enhanced Full-Rate (EFR) speechEnhanced Full-Rate (EFR) speech
coding algorithms implemented incoding algorithms implemented inGSM1900 provide improved speechGSM1900 provide improved speechquality at 13Kbps.quality at 13Kbps.
Half Rate codecs are available and canHalf Rate codecs are available and candouble RF channel capacity.double RF channel capacity.
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Channel CodingChannel Coding
260 bits classified as260 bits classified asClass Ia 50 bits Most sensitiveClass Ib 132 bits Moderatelysensitive to bit errors.
Class II 78 bits Least sensitive
to bit errors Coding adapted to needs.Coding adapted to needs.
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Channel CodingChannel Coding
Block Convolutional CodesBlock Convolutional Codes Used for basic error correction. Allows classical
decoding methods. Able to use soft informationprovided by modulation
Fire CodesFire Codes Used for error detection/correction for signalling.
Decoder can detect/correct errors in bursts.
Simple CodesSimple Codes Used for error detection, for signalling and for
highly significant bits in the speech frames.
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Frequency HoppingFrequency Hopping
t890.0890.2
890.4
890.6
890.8
891.0
891.2
915f
GUARD BAND
BP1 BP2 BP3 BP4 BP5BP6 BP7 BP8BP1 BP2 BP3 BP4 BP5BP6 BP7 BP8 BP1 BP2 BP3 BP4 BP5BP6 BP7 BP8
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Frequency HoppingFrequency Hopping
MS is frequency agile for transmitMS is frequency agile for transmitand receive bursts.and receive bursts.
Slow frequency hopping to:Slow frequency hopping to:Randomise the co-channelinterference effect.
Alleviate multipath fading. FH algorithm broadcast on BCCH.FH algorithm broadcast on BCCH.
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InterleavingInterleaving
Convolutional codes work better whenConvolutional codes work better whenerrors are evenly spread.errors are evenly spread.
Modulation and transmission are suchModulation and transmission are suchthat errors after demodulation tend tothat errors after demodulation tend tocome in bursts.come in bursts.
Interleaving avoids both proximity inInterleaving avoids both proximity inthe burst as well as in coding the data.the burst as well as in coding the data.
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InterleavingInterleaving
A code word (456 bits) on 4 burstsA code word (456 bits) on 4 bursts Block rectangular interleaver. Block rectangular interleaver.
A code word on 8 half bursts A code word on 8 half bursts Block diagonal interleaver.Block diagonal interleaver.
A complex interleaving used forA complex interleaving used for
high rate data (TCH/F9.6 andhigh rate data (TCH/F9.6 andTCH/H4.8)TCH/H4.8)
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Burst AssemblyBurst Assembly
0 2047
Hyperframe = 2048 Superframes
3 Hours 28 Minutes 53 Seconds and 760 milliseconds
500
250
Superframe = 26 51 multiframes
6.12 Seconds
51 MultiframeApprox 235 mS
26 Multiframe120 mS
2524210 50494810
76543210
TDMA frame4.615 mS
OrganisationOrganisation of Speech &of Speech &
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OrganisationOrganisation of Speech &of Speech &DataData
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
BP 7BP 6BP 5BP 4BP 3BP 2BP 1BP 0
8.253571261573
Frames 0-11 : TCH Frames 12 : SACCH Frames 13-24 : TCH Frames 25 : Unused
26 frame multiframeDuration: 120 ms
TDMA frameDuration: 60/13 ms
=4.615 ms
TrainingTrainingsequencesequence
StealingStealingbitbit
StealingStealingbitbit
Data bitsData bits Data bitsData bitsTailTailbitsbits
TailTailbitsbits
GuardGuardbitsbits
Normal burstNormal burstDuration 15/26 msDuration 15/26 ms
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CipheringCiphering
Used to protect signalling and userUsed to protect signalling and userdata.data.
Ciphering Key (Kc) computed usingCiphering Key (Kc) computed using
algorithm A8 + Ki + RAND.algorithm A8 + Ki + RAND. Kc + Algorithm A5 + burst numberKc + Algorithm A5 + burst number
114 bits sequence.114 bits sequence.
114 bits sequence is XORed with two114 bits sequence is XORed with two54 bit blocks of data included in the54 bit blocks of data included in thenormal burst.normal burst.
Modulation andModulation and
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Modulation andModulation andDemodulationDemodulation
Gaussion-filtered Minimum ShiftGaussion-filtered Minimum ShiftKeying (GMSK).Keying (GMSK).
Modulation rate is 270 5/6 KbaudsModulation rate is 270 5/6 Kbaudsfor 270 5/6 Kbits.for 270 5/6 Kbits.
Minimised side lobes by limitingMinimised side lobes by limitingspurious emissions.spurious emissions.
Modulation andModulation and
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Modulation andModulation andDemodulationDemodulation
Constant envelopeConstant envelopeSpectrum compactness andDemodulation performance
DemodulationDemodulationEqualisation
Correct quality of reception withmultipath spread upto 20Sec.
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GMSK ModulatorGMSK Modulator
IntegrationGaussian
Filter
COS
SIN
+
Cost
Sint
Cos(t+f)f
GAUSSUAN MINIMUM SHIFTKEYING
Radio ResourcesRadio Resources
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ad o esou cesad o esou cesManagementManagement
Channel AssignmentChannel Assignment HandoverHandover
Frequency HoppingFrequency Hopping
Power-level controlPower-level control
Discontinuous TransmissionDiscontinuous Transmission
Discontinuous ReceptionDiscontinuous Reception Timing AdvanceTiming Advance
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HandoverHandover
Intra-cell handoverIntra-cell handover Intra-BSC handoverIntra-BSC handover
Inter-BSC/intra-MSC handoverInter-BSC/intra-MSC handover Inter-MSC handoverInter-MSC handover
Minimum acceptable performanceMinimum acceptable performance Power budget algorithmPower budget algorithm
Discontinuous TransmissionDiscontinuous Transmission
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Discontinuous TransmissionDiscontinuous Transmission(DTX)(DTX)
Speech activity only 40% of time.Speech activity only 40% of time. Needs Voice activity detection.Needs Voice activity detection. Determination of voice thresholdDetermination of voice threshold
vis--vis noise.vis--vis noise. Annoying clicks/inefficient DTX.Annoying clicks/inefficient DTX.
Generation of Comfort Noise atGeneration of Comfort Noise atreceiver to avoid the feeling of thereceiver to avoid the feeling of theset being dead.set being dead.
Di i R i
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Discontinuous ReceptionDiscontinuous Reception
Used to conserve mobile stationsUsed to conserve mobile stationspowerpower
Paging channel divided into sub-Paging channel divided into sub-channelschannels
Assign specific sub-channel to eachAssign specific sub-channel to eachmobile station.mobile station.
Listen to the sub-channelListen to the sub-channel Sleep until next sub-channel slot.Sleep until next sub-channel slot.
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Timing AdvanceTiming Advance
BP1BP2
BP0
BP6BP7
BP7
BP0
BP2
i i d
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Timing AdvanceTiming Advance
Mobiles at different distances from theMobiles at different distances from thebase station cause different delay forbase station cause different delay forsignal arrival at BS.signal arrival at BS.
Timing advance is to synchronise theTiming advance is to synchronise thearrival of signal at BS.arrival of signal at BS.
BS measures the time delay and adviseBS measures the time delay and advise
MS to advance the transmission of itsMS to advance the transmission of itsbursts appropriately.bursts appropriately.
C l
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Power ControlPower Control
BS while performing measurement ofBS while performing measurement oftiming also performs the measurementtiming also performs the measurement
of the power level of each MS.of the power level of each MS. Power control commands are send toPower control commands are send tomobiles to adjust the transmit powermobiles to adjust the transmit power
level of each mobile station so as tolevel of each mobile station so as toensure that BS receives all the burstsensure that BS receives all the burstsalmost at the same power.almost at the same power.
M bili M (MM)
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Mobility Management (MM)Mobility Management (MM)
MM layer is built on top of the RR layer.MM layer is built on top of the RR layer. Handles all functions arising out of theHandles all functions arising out of the
mobility of the subscriber.mobility of the subscriber.
Handles authentication & security.Handles authentication & security. Concerned with the procedures to knowConcerned with the procedures to know
the current location of the powered-onthe current location of the powered-onmobile.mobile.
k iN k A i GSM
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PUBLIC LAND MOBILE NETWORK (PLMN) AREA
Network Areas in GSMNetwork Areas in GSM
MSC Area
Location Area
Location Area
Location Area
MSC Area
Cell
Location Area
Location Area
Location Area
Cell
bili ( )M bilit M t (MM)
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Mobility Management (MM)Mobility Management (MM)
Hierarchical area for pagingHierarchical area for paging Page every cell Vs location updatePage every cell Vs location update
Reliability through periodic locationReliability through periodic locationupdating procedure.updating procedure.
Trade off between signalling loadTrade off between signalling load
and speed of recovery.and speed of recovery. IMSI attach and detach procedureIMSI attach and detach procedure
A h i i d S iA th ti ti d S it
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Authentication and SecurityAuthentication and Security
Is the user the one he claims to beIs the user the one he claims to beAuthentication involves:Authentication involves:
SIM in the mobile.Authentication Centre.
Secret Key stored in SIM & AuCSecret Key stored in SIM & AuC
Generation of Signed Response byGeneration of Signed Response byboth and verification.both and verification.
Di N b All iDi t N b All ti
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Directory Number AllocationDirectory Number Allocation
PSTNPSTNLOCALLOCAL
EXCHANGEEXCHANGE
MSC
MSCMSC
MSISDN
MSRNMSRN
Used to referhome subscribers
Used to referUsed to referroamingroamingsubscriberssubscribers
Home Location RegisterHome Location Register(HLR)(HLR)
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gg(HLR)(HLR)
MSISDN IMSI MSRN Subscriber Data
xx
xx
xx
IMSI
MSISDN
Visitor Location RegisterVisitor Location Register(VLR)(VLR)
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gg(VLR)(VLR)
MSISDN IMSI MSRN LAC TMSI Subscriber Data
xx
xx
MSRN
xx
xx
IMSI
TMSI
S t S itS t S it
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System SecuritySystem Security
Equipment identity confidentiality.Equipment identity confidentiality. Data confidentialityData confidentiality
User identity confidentiality.User identity confidentiality.
A th ti ti d S itA th ti ti d S it
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Authentication and SecurityAuthentication and Security
Computation of Ciphering keyComputation of Ciphering key Kc + FDMA FN + A5 generate 114 bitsKc + FDMA FN + A5 generate 114 bits
sequencesequence
XORed with burst data bitsXORed with burst data bits Interleaving, encoding enable furtherInterleaving, encoding enable further
securitysecurity
Use of IMEI white, grey & black listedUse of IMEI white, grey & black listedmobile terminalsmobile terminals
CommunicationCommunicationM tM t
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ManagementManagement
Responsible forResponsible forCall Control (CC)Supplementary Services ManagementShort Message Service Management
Call control as per ISDN specificationCall control as per ISDN specificationrecommended in Q.931recommended in Q.931
Mobility & Roaming incorporatedMobility & Roaming incorporated
CC manage call setup, service mgt & callCC manage call setup, service mgt & callreleaserelease
C ll R tiC ll R ti
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Call RoutingCall Routing
Mobile Subscriber ISDN numberMobile Subscriber ISDN numberdefined by E.164 Numbering Plan.defined by E.164 Numbering Plan.
Call Routing involve:Call Routing involve:MSISDNMSRN
IMSITMSI
N b i PlN mbering Plan
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Numbering PlanNumbering Plan
MOBILEMOBILE
COUNTRYCOUNTRY
CODECODE
MOBILEMOBILE
NETWORKNETWORK
CODECODE
MOBILE SUBSCRIBERMOBILE SUBSCRIBER
IDENTIFICATION NUMBERIDENTIFICATION NUMBER
3 2 Maximum 10 digits
TMSIMSI
COUNTRYCOUNTRY
CODECODE
NATIONALNATIONAL
DESTINATIONDESTINATION
CODECODE
SUBSCRIBER NUMBERSUBSCRIBER NUMBER
1-3 1-3 Maximum 10 digits
MSISDN/MSRNSISDN/MSRN98 XYZ - ABCDE
N b i PlNumbering Plan
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Numbering PlanNumbering Plan
MCCMCC MNCMNCLACLAC
1-3 1-3 Flexible length
GCICI
CELLCELL
INDENTITYINDENTITY
TMSITMSIMOBILEMOBILE
COUNTRYCOUNTRY
CODECODE
MOBILEMOBILE
NETWORKNETWORK
CODECODE
LOCATIONLOCATION
AREA CODEAREA CODE
3 2 4 Hex
TMSI with in a LAMSI with in a LA
4 Hex
4 Hex
N b i PlNumbering Plan
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Numbering PlanNumbering Plan
SPARE (SP)SPARE (SP)TYPETYPE
APPROVALAPPROVAL
CODE (TAC)CODE (TAC)
FINALFINAL
ASSEMBLYASSEMBLY
CODE(FAC)CODE(FAC)
SERIALSERIAL
NUMBERNUMBER
(SNR)(SNR)
6 2 6
IMEIMEI
1
PLMN Colour CodePLMN Colour Code
NCCNCC
3Bits
BSICSIC
BS Colour CodeBS Colour Code
BCCBCC
3Bits
Ser ices Pro ided b GSMServices Provided by GSM
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Services Provided by GSMServices Provided by GSM
Design objective is to haveDesign objective is to haveinteroperability with ISDN.interoperability with ISDN.
Services provided are a subset ofServices provided are a subset ofISDN services.ISDN services.
Support for various data servicesSupport for various data servicesupto 9600 bps.upto 9600 bps.
GSM ServicesGSM Services
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Teleservices
SupplementaryServices
Bearer Services
TELECOMMUNICATION SERVICES
GSM ServicesGSM Services
Classification of GSMClassification of GSMServicesServices
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ServicesServices
E1 introduced at the start of the service.E1 introduced at the start of the service.
E2 introduced at the end of 1991.E2 introduced at the end of 1991. Eh introduced on availability of half-rateEh introduced on availability of half-rate
channels.channels.
A services that are optional.A services that are optional.
Teleservices in GSMTeleservices in GSM
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Teleservices in GSMTeleservices in GSM
Telephony (E1 & Eh).Telephony (E1 & Eh). Facsimile Group 3 (E1).Facsimile Group 3 (E1).
Emergency Calls (E1 & Eh).Emergency Calls (E1 & Eh).
Teletex.Teletex.
Short Message Services (E1,E2 & A).Short Message Services (E1,E2 & A).
Fax mail.Fax mail.Voice mail.Voice mail.
Bearer Services in GSMBearer Services in GSM
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Bearer Services in GSMBearer Services in GSM
300 to 9600 bps (E1)300 to 9600 bps (E1)Asynchronous and synchronous dataAsynchronous and synchronous dataAlternate speech and dataAlternate speech and data
Asynchronous PAD accessAsynchronous PAD access
2400-9600 bps (E2)2400-9600 bps (E2)
Synchronous dedicated packet dataSynchronous dedicated packet dataaccessaccess
Supplementary Services (E1)Supplementary Services (E1)
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Supplementary Services (E1)Supplementary Services (E1)
Call Forwarding Busy (CFB)Call Forwarding Busy (CFB) Call Forwarding Unreachable (CFNRc)Call Forwarding Unreachable (CFNRc)
Call Forwarding No reply (CFNRy)Call Forwarding No reply (CFNRy)
Call Forwarding Unconditional (CFU)Call Forwarding Unconditional (CFU) Barring of All Outgoing Calls (BAOC)Barring of All Outgoing Calls (BAOC)
Barring of Outgoing International Calls (BOIC)Barring of Outgoing International Calls (BOIC)
BOIC except those directed towards HomeBOIC except those directed towards HomePLMN Country (BOIC-exHC)PLMN Country (BOIC-exHC)
Barring of All Incoming Calls (BAIC)Barring of All Incoming Calls (BAIC)
Supplementary Services (E2)Supplementary Services (E2)
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Supplementary Services (E2)Supplementary Services (E2)
Call Hold (CH)Call Hold (CH)
Call Waiting (CW)Call Waiting (CW)
Advice of Charge (AoC)Advice of Charge (AoC)
Multi-party serviceMulti-party service
Supplementary Services (A)Supplementary Services (A)
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Supplementary Services (A)Supplementary Services (A)
Barring of Incoming Calls while roamingBarring of Incoming Calls while roaming
Closed User Group (CUG)Closed User Group (CUG)
Calling Line Identification Presentation (CLIP)Calling Line Identification Presentation (CLIP) Calling Line Identification Restriction (CLIR)Calling Line Identification Restriction (CLIR)
Connected Line Identification Presentation (COLP)Connected Line Identification Presentation (COLP)
Connected Line Identification Restriction (COLR)Connected Line Identification Restriction (COLR) Operator Determined BarringOperator Determined Barring
Fixed to Mobile Call RoutingFixed to Mobile Call Routing
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Fixed to Mobile Call RoutingFixed to Mobile Call Routing
MSISDN
IMSI/TMSI
MSRN IMSI/TMSI
MSISDN MSRN
MSISDN IMSI/TMSI
VLR
PSTPST
NNMSCMSC
HLR
BSS
BSS
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Call Management Call Management Request forRequest forServiceService
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ServiceService
UmBA
MSMSMSMS BSSBSSBSSBSS MSCMSCMSCMSC VLRVLRVLRVLR
Channel Request
Dedicated Sig.Chl.
assignment
Service Request
Service Request
Service Request
1
2
3
4
5
Call Management Call Management AuthenticationAuthentication
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AuthenticationAuthentication
DBMSMSMSMS MSCMSCMSCMSC VLRVLRVLRVLR HLRHLRHLRHLR
6
7
8
9
12
AuCAuCAuCAuC
Get Authparameters Get Auth
parameters
AuthparametersGet Auth
parametersAuthenticateMobile Stn
AuthenticateMobile Stn
10
11
AuthenticationResponse
13Authentication
Response
Call Management CipheringCall Management Ciphering
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Call Management CipheringCall Management Ciphering
UmBA
MSMSMSMS BSSBSSBSSBSS MSCMSCMSCMSC VLRVLRVLRVLR
Cipher modeComplete
Cipher modeCommand
Cipher Command
Set Ciphering14
15
16
17
18
Cipher mode
Complete
Call Management EqtCall Management EqtValidationValidation
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ValidationValidation
FMSMSMSMS MSCMSCMSCMSC EIREIREIREIR
IMEI Check Results
IMEI Request19
20
21
22
Check IMEI
IMEI Response
PSTN Call Setup withPSTN Call Setup withMobileMobile
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MobileMobile
Call setupRequest
TCH Assign
Call Proceeding
Access Sub data
Select bestaccess CCH
UmBA
MSMSMSMS BSSBSSBSSBSS MSCMSCMSCMSC VLRVLRVLRVLR
Sub data
Validate
Assign TK & Radio
Tune to TCH
TCH ConfirmTK & Radio
Confirm
a e up w anu wNWNW
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NWNW
Connect
Alert Mobile
Outpulse digits
UmBA
MSMSMSMS BSSBSSBSSBSS MSCMSCMSCMSC PSTNPSTNPSTNPSTN
Answer
Select OG Trunk
Connect ACK
Connect path
Incoming Call to MobileIncoming Call to MobileStationStation
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StationStation
Incoming Call
UmBA
MSMSMSMS BSSBSSBSSBSS MSCMSCMSCMSC PSTNPSTNPSTNPSTN
Ring BackValidate
Listening onPCCH
Page in LAPage
Tune to best ACCH
Page Response Page Response
ValidateSet UpTCH Assign
TCH ConfirmAlert
MS Ring Answer Remove RBT
Connect Path
Cellular Call SetupCellular Call Setup
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Cellular Call SetupCellular Call Setup
Mobile Originated Call.Mobile Originated Call.Key in the correct number to be dialled in
the cellular phone before connecting to
the network.Press the send button to originate the
call.Base station identifies the celfone and
passes the information to the MSC.MSC sets up the call.When the called party answers, voice
connection is completed.
Cellular Call SetupCellular Call Setup
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Cellular Call SetupCellular Call Setup
Mobile Terminated Call.Mobile Terminated Call. Call arrives at the home MSC. MSC converts received digits to Mobile
identification number. Broadcast a paging message over the locationarea.
Celfone recognises the page and responds. MSC selects an idle voice channel. Celfone switches to the assigned voice chl. Celfone alerted and RBT connected to caller. When Celfone answers, connection
established.
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