GSM Fundamentals Asiacell Telecom Platform Course 1 GSM Fundamentals.

GSM Fundamentals

Asiacell Telecom Platform Course 1

GSM Fundamentals

GSM Fundamentals


Contents Contents

Basic Concepts of Cellular Mobile SystemBasic Concepts of Cellular Mobile System

GSM Network Components

Terrestrial Interface

Service Area and Number Planning

Channels on The Air Interface

Radio Techniques

The Future Development

GSM Fundamentals

Asiacell Telecom Platform Course

GSM DevelopmentGSM Development

Standard Protocol for GSM take effect

System was named as Global System for Mobile Communication

GSM system began to provide service in Europe(2G)

Provide services for the whole world

Micro Cell Technique is used in GSM system

1989

1991

1992

1994

1996

GSM Fundamentals


Channel Bandwidth: 200KHz

Duplex Separation: 45 MHz

The Frequency SpectrumThe Frequency Spectrum

925 960 MHz

915880 890 935

GSMEGSM GSMEGSM

Uplink Downlink

GSM Fundamentals


Frequency Spectrum in GSM SystemFrequency Spectrum in GSM System

ARFCN: Absolute Radio Frequency Channel Number

UpLink DownLink

EGSM 880 - 890 925 - 935 10 MHz 50 974 - 1023

GSM 890 - 915 935 - 960 25 MHz 125 0 - 124

GSM 1800 1710 - 1785 1805 - 1880 75 MHz 375 512 - 886

GSM 1900 1850 - 1910 1930 - 1990 60 MHz 300 512 - 811

ARFCNSystemFrequency

BandwidthChannel Number

GSM Fundamentals


Frequency Allocation in IraqFrequency Allocation in Iraq

ARFCN: Absolute Radio Frequency Channel Number

GSM Fundamentals


Cell StructureCell Structure

1

120degree

1

2

3

Omni CellOmni Cell Sector CellSector Cell

120degree120

degree

GSM Fundamentals


Cell Structural in SulymaniyahCell Structural in Sulymaniyah

GSM Fundamentals


Frequency Re-UseFrequency Re-Use

Because frequency resource of mobile system is very limited,

The different Subscribers must use the same frequency in different place.

Of course, the quality of communication must be ensured.

What is Frequency Re-Use?What is Frequency Re-Use?

GSM Fundamentals



How can we reuse frequency?How can we reuse frequency?

7(Site)X 1(Cell) Re-use

2

1

2

3

4

5

6

7

2

1

2

3

4

5

6

7

GSM Fundamentals



4(Site)X 3(Cell)

Re-use

10

212

8

4

11

7

3

9

5

1

6

5

1

9 6

10

2

7

3

11 8

4

12

7

3

115

9

1

6

10

2

8

12

4

GSM Fundamentals


Contents Contents

Basic Concepts of Cellular Mobile System

GSM Network ComponentsGSM Network Components




Radio Techniques


GSM Fundamentals


GSM Network ComponentsGSM Network Components

BTSBSC

BTSBSC

SS7

SMS system

PSTNISDN

MSC/VLR GMSC

HLR/AUC

Other PLMN

MS

MS

BTS

BTS

MS

MS

MS

M2000 Server

GSM Fundamentals


Mobile Station—MSMobile Station—MS

International Mobile Equipment Identity (IMEI)

– Mobile Equipment

MS=ME+SIMMS=ME+SIM

International Mobile Subscriber Identity (IMSI)

– Subscriber Identity Module

GSM Fundamentals


Subscriber Identity Module – SIMSubscriber Identity Module – SIM


Temporary Mobile Subscriber Identity (TMSI)

Location Area Identity (LAI) Subscriber Authentication Key

(Ki)



Location Area Identity (LAI) Subscriber Authentication Key

(Ki)

* PIN and PUK are used to SIM security

GSM Fundamentals


Base Station Subsystem (BSS)Base Station Subsystem (BSS)

- Base Station Controller (BSC)

- Base Transceiver Station (BTS)

- Transcoder and Sub multiplexer (TCSM) or Transcoder and Rate Adaptation Unit (TRAU)

- Base Station Controller (BSC)

- Base Transceiver Station (BTS)

- Transcoder and Sub multiplexer (TCSM) or Transcoder and Rate Adaptation Unit (TRAU)

BTS

BSC

BTS

TCSM MSC/VLR

BSS

MS

MS

GSM Fundamentals


Base Transceiver Station (BTS)Base Transceiver Station (BTS)

BTS (Base Transceiver Station):

Transmit & Receive signal with MS then transfer to Base Station

Controller (BSC)

Signal Process: Speech Coding, Channel Coding, Interleaving,

Ciphering, Modulation

However, one BTS has coverage area limited. Size of coverage

area depend on population of subscriber.

A unit of coverage area is called “Cell”

BTS

BSC

BTSBTS BTS

MSMS

GSM Fundamentals


Base Station Controller (BSC)Base Station Controller (BSC)

BSC:

Store cell information and parameter: eg. Cell ID, BSIC, Cell

frequency (ARFCN), Output power

Control BTS to process: eg. Call set up, Handover Process,

Frequency Hopping, Power Control.

Receive BTS alarm and send BTS & BSC alarm to OMC

Measurement traffic statistic

Remote BTS O&M via BSC

BTS

BSC

BTS

BSC

MS MS

GSM Fundamentals


Transcoder and Sub-MultiplexerTranscoder and Sub-Multiplexer

GSM Fundamentals


Network Switching System (NSS)Network Switching System (NSS)

SS7PSTNISDN

Other PLMN

MSC/VLR GMSC

HLR/AUC

EIREIR

NSS

MSC = Mobile Switching CenterGMSC = Gateway MSCHLR = Home Location RegisterIWF = Inter-Working Function

MSC = Mobile Switching CenterGMSC = Gateway MSCHLR = Home Location RegisterIWF = Inter-Working Function

VLR = Visitor Location Register AuC = Authentication CenterEIR = Equipment Identity RegisterEC = Echo Canceller

VLR = Visitor Location Register AuC = Authentication CenterEIR = Equipment Identity RegisterEC = Echo Canceller

BSS

ECEC

IWFIWF

GSM Fundamentals


Mobile Service Switching Center – MSC

Mobile Service Switching Center – MSC

Call Processing

Operations and Maintenance

Support

Inter-network & Inter-working

Billing

Call Processing

Operations and Maintenance

Support

Inter-network & Inter-working

Billing

GSM Fundamentals


Home Location Register (HLR) Home Location Register (HLR)

Subscriber ID (IMSI and MSISDN)

Current subscriber VLR (current location)

Supplementary service information

Subscriber status (registered/deregistered)

Authentication key and AuC functionality

Subscriber ID (IMSI and MSISDN)

Current subscriber VLR (current location)

Supplementary service information

Subscriber status (registered/deregistered)

Authentication key and AuC functionality

GSM Fundamentals


Visitor Location Register – VLR Visitor Location Register – VLR

Mobile Status (IMSI detached/ attached / busy /

idle etc)

Location Area Identity(LAI)


Mobile Station Roaming Number (MSRN)

Mobile Status (IMSI detached/ attached / busy /

idle etc)

Location Area Identity(LAI)


Mobile Station Roaming Number (MSRN)

GSM Fundamentals


IMEIIs Checked against White List

IMEIIs Checked against Black/Grey List

If NOT found

EIR focus on the equipment, not the subscriber!!

•White List•Black List•Grey List

Equipment Identity Register – EIR Equipment Identity Register – EIR

GSM Fundamentals


Authentication Center (AuC)Authentication Center (AuC)

KI （ M)KI （ N)

IMSI(m)

RANDGENERATOR

A8 A3

KI(IMSI)

IMSIBUFFER

RAND

RANDRAND

RAND

KC

12

5

KC KC

KC

SRES

SRESSRES

SRES

TEMPDATA

AUC HLR

AUTH REQ

RANDKC

SRES

RANDA8 A3

SRES

EQUAL

CKSN

KC BSS

KI(IMSI)

VLR SIM

RAND 16byte KI 16byte kc 8byte SRES 4byte CKSN low 3bits of 1byte

IMSI(n)

SRESKI I MSI +RAND（） A3

KI (I MSI )+RAND A8 KCM+KC A5 KC(M)

(MS/ BSS)

KC(M)+KC MA5(MS/ BSS)

SRES

GSM Fundamentals


• Rate Conversion• Protocol Adaptation

PSTN

MSCMSC

ECEC IWF

Inter-Working Function – IWFInter-Working Function – IWF

Eg. Fax, ModemEg. Fax, Modem

GSM Fundamentals


Echo takes place by GSM system delay caused by call processing,speech encoding and decoding etc.An Echo Canceller is used on the PSTN side of the MSC for all voice circuits

2-wire4-wire

2- wire

Hybrid Hybrid

Generation of Echo at 2-wire to 4-wire Interface

Echo Canceller － ECEcho Canceller － EC

GSM Fundamentals


NOC

OMCOMC

OMC

Region2

Region 1

Region 3

Operation and Maintenance Sub SystemOperation and Maintenance Sub System

GSM Fundamentals


OMC Functional ArchitectureOMC Functional Architecture

OS

MMI

DB

Event/AlarmManagement

SecurityManagement

ConfigurationManagement

Performance Management

Fault Management

GSM Fundamentals


Example: Baghdad OMCExample: Baghdad OMC

GSM Fundamentals


Contents Contents



Terrestrial InterfaceTerrestrial Interface



Radio Techniques


GSM Fundamentals


HLR

VLR

MSC

EIR

AUC

EC IWF

TC

VLR

MSC

IWF EC

BTS BSCMS

B

H

F

G

A

E

C

D

Um Abis

GSM InterfaceGSM Interface

GSM Fundamentals


CM: Call ManagementMM: Mobility ManagementRR: Radio Resource Management

LAPDm: LAPD modifiedLAPD: Link Access Procedure on D ChannelBTSM: BTS Site Management

MTP: Message Transfer PartSCCP: Signaling Connection Control PartBSSMAP: BSS Management Application Part

GSM Protocol StackGSM Protocol Stack

GSM Fundamentals


OSI Layers

7. Application

6. Presentation

5. Session

4. Transport

3. Network

2. Link

1 Physical

CCS7 Levels

MTP Level 1 2 Mb/s Trunk

MTP Level 3

TUP

SCCP

BSSAP(DTAP+BSSMAP)ISUP

MAP

TCAP

MTP Level 2

ITU Signaling System CCS7 ITU Signaling System CCS7

GSM Fundamentals


Abbreviation of CCS7Abbreviation of CCS7

MTP Message Transfer Part TCAP Transaction Capabilities Application Part SCCP Signaling Connection Control Part TUP Telephone User Part ISUP ISDN User Part MAP Mobile Application Part BSSAP Base Station System Application Part BSSMAP BSS Management Application Part DTAP Direct Transfer Application Part

MTP Message Transfer Part TCAP Transaction Capabilities Application Part SCCP Signaling Connection Control Part TUP Telephone User Part ISUP ISDN User Part MAP Mobile Application Part BSSAP Base Station System Application Part BSSMAP BSS Management Application Part DTAP Direct Transfer Application Part

GSM Fundamentals


Typical Configuration

TS 0 TS 1-15 TS16 TS 17-31

TS = Time slot

TS# Used for

0

1-15

16

17-31

Synchronization / Clock

Traffic

CCS7 Signaling (Other TS may also the used)

Traffic

2MBps Trunks2MBps Trunks

GSM Fundamentals


HLR

MSC/VLR

EIRAUC

EC

OMC

MSC/VLR

TC

IWF

EC

BSC PSTN

BTSBTS BTS

SigL1: 2MBps TrunksSigL1: 2MBps Trunks

GSM Fundamentals


CCS7 InterfaceCCS7 Interface

GSM Fundamentals


LAPD InterfaceLAPD Interface

GSM Fundamentals


Contents Contents




Service Area and Number PlanningService Area and Number Planning


Radio Techniques


GSM Fundamentals


Service AreaService Area

PLMN service area

......

System area PLMN service area

MSC service area...

Location area...

Base station area...

Radio cell

...... ......

MSC service area...

Location area...

Base station area...

Radio cell

PLMN service area

GSM Fundamentals


MSC/VLR NumberMSC/VLR Number

The format is CC+NDC+LSPCC ： Country Code. For example: The CC of Iraq is “964".

NDC ： National Destination Code. For example: The NDC of AsiaCell is 770.

LSP (locally significant part): is defined by Telecom operator.

For example: 964-770-1144002

CC NDC LSP

MSC/VLR number

GSM Fundamentals


HLR NumberHLR Number

The format is ： CC + NDC + LSP.CC ： Country Code. For example: The CC of Iraq is “964".

NDC ： National Destination Code. For example: The NDC of Asiacell is 770


For example: 964-770-1144001.

The format is ： CC + NDC + LSP.CC ： Country Code. For example: The CC of Iraq is “964".

NDC ： National Destination Code. For example: The NDC of Asiacell is 770


For example: 964-770-1144001.

GSM Fundamentals


LAILAI

Location Area Identification

The LAI is the international code for a location area.

MCC ： Mobile Country Code ， It consists of 3 digits . For example: The MCC of Iraq is “418"MNC ： Mobile Network Code ， It consists of 2 digits . For example: The MNC of Asiacell is "05"LAC ： Location Area Code ， It is a two bytes BCD

code(hex). The value 0000 and FFFF is invalid.For example: 418-05-12AB

MCC ： Mobile Country Code ， It consists of 3 digits . For example: The MCC of Iraq is “418"MNC ： Mobile Network Code ， It consists of 2 digits . For example: The MNC of Asiacell is "05"LAC ： Location Area Code ， It is a two bytes BCD

code(hex). The value 0000 and FFFF is invalid.For example: 418-05-12AB

MCC MNC LAC

E.164 = CC + NDC + … (MSC/VLR, HLR, MSISDN)E.212 = MCC + MNC + … (IMSI)

GSM Fundamentals


CGICGI

The CGI is a unique international identification for a

cell

The format is LAI+CI

LAI: Location Area Identification

CI ： Cell Identity. This code uses two bytes BCD

code(hex) to identify the radio cells within an LAI.

For example : 418-05-12AB-CD98

The CGI is a unique international identification for a

cell

The format is LAI+CI

LAI: Location Area Identification

CI ： Cell Identity. This code uses two bytes BCD

code(hex) to identify the radio cells within an LAI.

For example : 418-05-12AB-CD98

CGI: Cell Global Identification

GSM Fundamentals


BSICBSIC

NCC ： PLMN network color code. It comprises 3 bit. It allows various neighboring PLMNs to be distinguished.

BCC ： BTS color code. It comprises 3 bit. It allows distinction between different radio frequency channels using the same frequency in neighboring cells.

NCC ： PLMN network color code. It comprises 3 bit. It allows various neighboring PLMNs to be distinguished.

BCC ： BTS color code. It comprises 3 bit. It allows distinction between different radio frequency channels using the same frequency in neighboring cells.

NCC BCC

BSIC

BSIC （ Base Station Identification Color Code)

GSM Fundamentals


CC ： Country Code. For example: The CC of Iraq is “964".NDC ： National Destination Code. For example: The NDC of

Asiacell is 770.SN ： Subscriber Number. Format:H0 H1 H2 ABCDExample: 964-770-110-5246

CC ： Country Code. For example: The CC of Iraq is “964".NDC ： National Destination Code. For example: The NDC of

Asiacell is 770.SN ： Subscriber Number. Format:H0 H1 H2 ABCDExample: 964-770-110-5246

MSISDNMSISDN

CC NDC SN

National (significant)Mobile number

Mobile station internationalISDN number

GSM Fundamentals


MCC ： Mobile Country Code ， It consists of 3 digits . For example: The MCC of Iraq is “418" 。MNC ： Mobile Network Code ， It consists of 2 digits . For example: The MNC of Asiacell is "05" 。MSIN ： Mobile Subscriber Identification Number. H1H2H3

ABCDEFG For example: 000-1600123NMSI ： National Mobile Subscriber Identification ， MNC and MSIN

form it together. For Example of IMSI : 418-05-000-1600123

MCC ： Mobile Country Code ， It consists of 3 digits . For example: The MCC of Iraq is “418" 。MNC ： Mobile Network Code ， It consists of 2 digits . For example: The MNC of Asiacell is "05" 。MSIN ： Mobile Subscriber Identification Number. H1H2H3

ABCDEFG For example: 000-1600123NMSI ： National Mobile Subscriber Identification ， MNC and MSIN

form it together. For Example of IMSI : 418-05-000-1600123

Not more than 15 digits

3 digits 2 digits

IMSI

MCC MNC MSIN

NMSI

IMSI IMSI

GSM Fundamentals


The TMSI is assigned only after successful subscriber authentication.

The VLR controls the allocation of new TMSI numbers and notifies them to the HLR.

TMSI is used to ensure that the identity of the mobile subscriber on the air interface is kept secret.

The TMSI consists of 4 bytes( 8 HEX numbers) and determined by the telecom operator.

The TMSI is assigned only after successful subscriber authentication.

The VLR controls the allocation of new TMSI numbers and notifies them to the HLR.

TMSI is used to ensure that the identity of the mobile subscriber on the air interface is kept secret.

The TMSI consists of 4 bytes( 8 HEX numbers) and determined by the telecom operator.

TMSITMSI

TMSI: Temporary Mobile Subscriber Identification)

GSM Fundamentals


IMEIIMEI

TAC FAC SNR SP

IMEI

TAC ： Type approval code, 6 bit. It is administered by the type approval center.

FAC ： Final assembly code, 2 bit. It is administered by the manufacturer.

SNR ： Serial number, 6 bits. It is issued by the manufacturer of the MS.

SP ： 1 bit, Not used.

TAC ： Type approval code, 6 bit. It is administered by the type approval center.

FAC ： Final assembly code, 2 bit. It is administered by the manufacturer.

SNR ： Serial number, 6 bits. It is issued by the manufacturer of the MS.

SP ： 1 bit, Not used.

IMEI: International Mobile Station Equipment Identification

Check IMEI by *#06#

GSM Fundamentals


MSRN/HONMSRN/HON

The MSRN is used to route the call to the MSC which MS is currently located.

The HON is used by the MSC-A to set up a connection to the MSC-B during handover process

Usually, MSRN and HON share the same numbering plan. The format is CC+NDC+individual number. CC and NDC

is the same as that of MSISDN. The individual number is taken from a pool of numbers specially reserved for MSRN.

The MSRN is used to route the call to the MSC which MS is currently located.

The HON is used by the MSC-A to set up a connection to the MSC-B during handover process

Usually, MSRN and HON share the same numbering plan. The format is CC+NDC+individual number. CC and NDC

is the same as that of MSISDN. The individual number is taken from a pool of numbers specially reserved for MSRN.

MSRN: Mobile Subscriber Roaming Number

HON: Hand-over Number

GSM Fundamentals


Contents Contents





Channels on The Air InterfaceChannels on The Air Interface

Radio Techniques


GSM Fundamentals


Multiple Access TechniqueMultiple Access Technique

Multiple Access Technique allows many subscribers to

use the same communication medium.

There are three kinds of basic Multiple Access Technique

: FDMA , TDMA and CDMA.

GSM system adopt FDD-TDMA (FDMA and TDMA

together).

GSM Fundamentals


FDMAFDMA

FDMA uses different frequency

channels to accomplish

communication.

The whole frequency spectrum

available is divided into many

individual channels (for

transmitting and

receiving) ， every channel can

support the traffic for one

subscriber or some control

information.

Frequency

Time

GSM Fundamentals


TDMATDMA

TDMA accomplishes the

communication in different

timeslot.

A carrier is divided into channels

based on time. Different signals

occupy different timeslots in

certain sequence , that is , many

signals are transmitted on the

same frequency in different time.

Time

Frequency

GSM Fundamentals


CDMACDMA

CDMA accomplishes the

communication in different

code sequences.

Special coding is adopted

before transmission, then

different information will lose

nothing after being mixed

and transmitted together on

the same frequency and at

the same time.Time

FrequencyCode

GSM Fundamentals


Physical Channel and Logical ChannelsPhysical Channel and Logical Channels

2 30 16 74 52 3

The physical channel is the medium over which the information is carried: 200KHz and 0.577ms

0 1

TDMA FRAME

TimeslotThe information carried in one time

slot is called a “burst”

The information carried in one time slot is called a “burst”

The logical channel consists of the information carried over the physical channels

TDMA FRAME

GSM Fundamentals


Two types of Logical ChannelTwo types of Logical Channel

Traffic Channel (TCH) :Transmits traffic information, include data and speech.

Control Channel (CCH) :Or Signaling Channel, transmits all kinds of control information.

GSM Fundamentals


Traffic Channel (TCH)Traffic Channel (TCH)

TCHTraffic Channels

Speech

TCH/FS

Data

TCH/HSTCH/9.6 TCH/2.4

TCH/4.8

Normal Burst

TCH Traffic ChannelTCH/FS Full rate Speech Channel TCH/HS Half rate Speech Channel TCH/9.6 Data Channel 9.6kb/sTCH/4.8 Data Channel 4.8kb/sTCH/2.4 Data Channel 2.4Kb/s

GSM Fundamentals


FCCHSCH

CCH Control Channels

DCCH

SDCCH

BCCH

BCCH Synch. CH.ACCH

SACCHFACCH CCCH

RACHCBCH

PCH/AGCH

Broadcast Control Channel – BCCHCommon Control Channel – CCCHDedicated Control Channel – DCCHAssociated Control Channel – ACCH

Control Channel (CCH)Control Channel (CCH)

GSM Fundamentals


CCH

BCCH downlink only

BCCH Synch.

Channels

SCH FCCH

The information carried on the BCCH

is monitored by the MS periodically

when it is in idle mode

BCCH: Broadcast Control Channel

FCCH: Frequency Correction Channel

SCH: Synchronization Channel

The information carried on the BCCH

is monitored by the MS periodically

when it is in idle mode

BCCH: Broadcast Control Channel

FCCH: Frequency Correction Channel

SCH: Synchronization Channel

Broadcast Control Channel – BCCHBroadcast Control Channel – BCCH

GSM Fundamentals


CCH

CCCH

RACHuplink

CBCH downlink

PCH/AGCHdownlink

The CCCH is responsible for transferring control information between all mobiles and the network.

RACH: Random Access Control Channel

PCH: Paging Channel

AGCH: Access Grant Control Channel

CBCH: Cell Broadcast Channel

The CCCH is responsible for transferring control information between all mobiles and the network.

RACH: Random Access Control Channel

PCH: Paging Channel

AGCH: Access Grant Control Channel

CBCH: Cell Broadcast Channel

Common Control Channel – CCCHCommon Control Channel – CCCH

GSM Fundamentals


CCH

DCCH

SDCCH

FACCH SACCH

DCCH is assigned to a single mobile connection for call setup or for measurement and handover purpose.SDCCH: Standalone Dedicated Control Channel ACCH: Associated Control Channel SACCH: Slow Associated Control Channel FACCH: Fast Associated Control Channel

DCCH is assigned to a single mobile connection for call setup or for measurement and handover purpose.SDCCH: Standalone Dedicated Control Channel ACCH: Associated Control Channel SACCH: Slow Associated Control Channel FACCH: Fast Associated Control Channel

ACCH

Dedicated Control Channel – DCCH Dedicated Control Channel – DCCH

GSM Fundamentals


Uplink Logical channelUplink Logical channel

RACHCCCH CCH

SDCCHSACCH

FACCH

TCH/FTCH/H

DCCH

TCH

DCH

GSM Fundamentals


Downlink Logical channelDownlink Logical channel

FCCHSCH

BCCH

PCHAGCH

BCCH

CCCH

CCH

SDCCHSACCH

FACCH

TCH/FTCH/H

DCCH

TCH

DCH

GSM Fundamentals


Search for frequency correction pulse

Search for synchronous pulse

Unscramble system information

Snoop into paging message

Send access pulse

Allocate signaling channel

Set up the call

Allocate voice channel

Conversation

Release the call

FCCH

SCH

BCCH

PCH

RACH

AGCH

SDCCH

FACCH

TCH

FACCH

Power-off state

Idle state

Dedicated mode

Idle state

How to use these channel?How to use these channel?

GSM Fundamentals


GSM Logical ChannelGSM Logical Channel

Channel CombinationMain BCCH combination – BCCH + CCCH

SDCCH combination – SDCCH8 + SACCH8

Combined BCCH – BCCH + CCCH +SDCCH4 +

SACCH4

TCH combination – TCH/FACCH + SACCH

GSM Fundamentals


TDMA Frames

0 1

0 1 2 43 46 47 48 5049

51 – Frame Multiframes

0 1 10

CONTROL CHANNELS

2 3 4 5 6 7 2 3 5 764

GSM MultiframeGSM Multiframe

GSM Fundamentals


BCCH/CCCH MultiframeBCCH/CCCH Multiframe

F SB B B B

C C C C F F S C C C C C C C CI

Downlink

0 10 20 30 40 50

S C C .. F S C C .. F S C C ..

R R R R R R R R R R R R R R R R R R R R R R

Uplink

R R R .. R R R ..R R R ..

0 10 20 30 40 50

F = FCCH (Frequency) S = SCH (Sync.)C = CCCH (Common)I = Idle R = RACH (Random)

GSM Fundamentals


D0 D1 D7 A0 A3 I I I

D0 D1 D6 D7 A4 A7 I I I

A5 A6 D0 D7 A0A7 I I I

A1 A2 D0 D7 A4A3 I I I

Downlink

0 7 24 32 44 50

0 7 12 15 44 50

Uplink

D = SDCCH/8 (Dedicated) A = SACCH/C8 (Associated) I = Idle

D6

SDCCH MultiframeSDCCH Multiframe

GSM Fundamentals


Timeslots and TDMA FramesTimeslots and TDMA Frames

Higher Capacity Cell

Broadcast TrafficDedicated

Traffic00 1 2 3 4 5 6 7

00 1 2 3 4 5 6 7

Low Capacity Cell

Combined Traffic00 1 2 3 4 5 6 7

GSM Fundamentals


Combined MultiframeCombined Multiframe

BSF C CSF C D0SF D1 D2SF D3 A0S A1F I

BSF C CSF C D0SF D1 D2SF D3 A2S A3F I

0 2 6 10 20 30 40 50

Downlink

D3 RR A2 A3 RR R D0 D1 RR D2R

0 4 6 10 20 30 40 50

D3 RR A2 A3 RR R D0 D1 RR D2R

Uplink

R = RACH (Random) B = BCCH (Broadcast)F = FCCH (Frequency) S = SCH (Sync.)C = CCCH (Common) D = SDCCH/4 (Dedicated)A = SACCH/4 (Associated) I = Idle

GSM Fundamentals


GSM MultiframeGSM Multiframe

TDMA Frames

0 1

0 1 2 43 21 22 23 2524

26 – Frame Multiframes

0 1 10

TRAFFIC CHANNELS

2 3 4 5 6 7 2 3 5 764

GSM Fundamentals


TCH MultiframeTCH MultiframeIDLE

SACCH

IDLE

SACCH

25

12

0

This is used to transmit a Traffic Channel Combination (TCH/ SACCH/FACCH). The FACCH is not showed in the diagram as it does not receive its own time allocation. The FACCH steals a time period from the TCH is required.

The 13th frame is used by the SACCH which carriers link control information to and from the mobile and BTS.

The 26th frame is idle.

This is used to transmit a Traffic Channel Combination (TCH/ SACCH/FACCH). The FACCH is not showed in the diagram as it does not receive its own time allocation. The FACCH steals a time period from the TCH is required.

The 13th frame is used by the SACCH which carriers link control information to and from the mobile and BTS.

The 26th frame is idle.

Downlink Uplink

25

12

0

GSM Fundamentals


Superframe and HyperframeSuperframe and Hyperframe

GSM Fundamentals


Contents Contents






Radio TechniquesRadio Techniques


GSM Fundamentals


Modulation TechniquesModulation Techniques

– phase modulation can be implemented easily for digital signals, this is the method which is used for the GSM air interfaces. Phase Modulation is known as Phase Shift Keying when applied to digital signals

– phase modulation can be implemented easily for digital signals, this is the method which is used for the GSM air interfaces. Phase Modulation is known as Phase Shift Keying when applied to digital signals

Amplitude Modulation (AM)

Frequency Modulation (FM)

Phase Modulation (PM)

GSM Fundamentals


1 0 0 1 1 GaussianDigital Filter

Phase Modulator

Gaussian Minimum Shift Keying (GMSK) Gaussian Minimum Shift Keying (GMSK)

GSM Fundamentals


Power ControlPower Control

Saves radio battery powerReduces co-channel andadjacent channel interference

8W

0.8W

5W

Both Uplink and Downlink power settings can be controlled independently and individually.

GSM Fundamentals


VAD and DTXVAD and DTX

Voice Activity Detection – VAD

Discontinuous Transmission – DTX

Battery SavingInterference reduction

GSM Fundamentals


Multipath FadingMultipath Fading

•Diversity

•Frequency Hopping

Time Dispersion

GSM Fundamentals


DiversityDiversity

When diversity is implemented two antennas are situated at the receiver. These antennas are placed several wavelengths apart to ensure minimum correlation between the two receive paths.

The two signals are then combined, this ensures that a low signal strength is less likely to occur.

Compare oradd signals

Resultant Signal

Approx. 10 wavelengths

GSM Fundamentals


Frequency HoppingFrequency Hopping

Synthesizer Hopping:each timeslot on a given transceiver can transmit at a different frequency

Baseband Hopping: each transceiver stays at the same frequency and the data is switched to the appropriate transceiver.

Each time the BTS or mobile transmits a burst, it does so on a different RF carrier frequency.

time

frequency

GSM Fundamentals


Contents Contents






Radio Technologies

The Future DevelopmentThe Future Development

GSM Fundamentals


GSM User World WideGSM User World WideM

illio

ns

0

200

400

600

800

1000

1200

1400

1600

1800

1999 2000 2001 2002 2003 2004 2005

Fixed line (dial-up)subscribers

Mobilesubscribers

PC/NC Internetusers

Mobile Internetusers

Mobile Internet accessovertakes fixed

500m Mobileusers

Mobile usageovertakes fixed

Mobile will be the most prolific form of access to internet-basedinformation, content and services

Source: Ericsson Business Consulting

GSM Fundamentals


Number of Wireless Subscribers*Number of Wireless Subscribers*

*Update Q1, 2009 from www.wirelessintelligence.com

Iraq

Asiacell 6,686,140

Zain 10,111,000

Korek Telecom 665,361

Sanatel 361,431

Thailand

AIS 27,581,800

DTAC 18,945,227

TRUE 15,004,000

ChinaChina Mobile 477,160,000

China Unicom 133,365,000

World 4,153,784,344

GSM Fundamentals


Technology RoadmapTechnology Roadmap

1992 1999 2000 2002

9.6 38.4

TEC

HN

OLO

GY

TEC

HN

OLO

GY

DA

TA

SP

EED

DA

TA

SP

EED

Kb

it/s

Kb

it/s 64-115 384 Up to 2Mb/s?

DEV

ICES

DEV

ICES

GSM (2G)WAPHSCSD

GPRS (2.5G)EDGE (2.75G)

UMTS (3G)

GSM Fundamentals


Mobile Service EvolutionMobile Service Evolution

Basic text messaging

Hi, I’ll see you at 6 PM Regards, Bob

MessagingMessaging

Black and white screens,simple graphics

BrowsingBrowsing

Instant connectivity,color screen,WAP Push

xHTML for WAP and web integration, animated content

Ringing tones, icons,screensavers,business cards

DownloadingDownloading

Downloadable applications,MIDI sounds

Video content(MMS, streaming)

Multimedia messaging with video

Dial-up connections

Accelerated connections,voice and data multitasking

Corporate accessCorporate access

Always-on,performance and securityenhancements

Multimedia messaging with pictures and audio

GSM Fundamentals







Radio Techniques


SummarySummary

GSM Fundamentals


By [email protected] [Technical Trainer]

Thank You

GSM Fundamentals Asiacell Telecom Platform Course 1 GSM Fundamentals.

Documents

gsm system arfcn

cell bts bsc bts ms

bsc bts bsc bts bsc

degree slide

sulymaniyah slide

cell frequency arfcn

bts bsc alarm

frequency reuse