Oma000001 Gsm Fundamentals Issue4.0

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OMA000001GSM Fundamentals

ISSUE 4.0

HUAWEI TECHNOLOGIES CO., LTD. Page 2All rights reserved

Upon completion of this course, you will be able to: Grasp basic idea of GSM system such as

frequency spectrum, frequency reuse etc. Grasp the structure of the GSM system and the

protocol used. Grasp certain numbers that refer to BSS Grasp the 4 kinds of channel combination and

understand the idea of multi-frame. Know some radio techniques Get the idea of EDGE


References

BSS Feature Description

BSS Signaling Analysis Manual

BSC Technical Manual


Chapter 1 GSM System OverviewChapter 1 GSM System Overview

Chapter 2 GSM Network StructureChapter 2 GSM Network Structure

Chapter 3 Chapter 3 Service Area and Number PlanningService Area and Number Planning

Chapter 4 Chapter 4 Channels on the Wireless InterfaceChannels on the Wireless Interface

Chapter 5 Radio TechniquesChapter 5 Radio Techniques

Chapter 6 GPRS & EDGE IntroductionChapter 6 GPRS & EDGE Introduction


GSM system overview

The GSM system is a frequency- and time-division cellular system, each physical channel is characterized by a carrier frequency and a time slot number

Cellular systems are designed to operate with groups of low-power radios spread out over the geographical service area. Each group of radios serve MSs presently located near them. The area served by each group of radios is called a CELL

Uplink and downlink signals for one user are assigned different frequencies, this kind of technique is called Frequency Division Duplex (FDD)

Data for different users is conveyed in time intervals called slots , several slots make up a frame. This kind of technique is called Time Division Multiple Access (TDMA)


GSM 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


Cell Technique

A certain radio coverage area formed by a set of transceivers that connected to a set of antennas is called a CELL.

Macro Cell

In the beginning , High-Power BTS´s are adopted to provide services. The BTS covers a wider area , but its frequency utilization is not efficient. So , it can only provide a few channels for subscribers.

Micro Cell

Later the Low-Power BTS joins the system for getting a better service area with high capacity . At the same time it adopts the frequency reuse technique to improve the efficiency of the frequency utilization and also the whole capacity of the network.

Macro Cell and Micro CellMacro Cell and Micro Cell


Multiple 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).


FDMA

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


TDMA

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


CDMA

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

Frequency



Duplex Separation: 95MHzChannel Bandwidth: 200KHz

Base Station Receive

1710 1785 1805 1880MHz

Base Station Transmit

DCS 1800DCS 1800

The Frequency Spectrum


The Frequency Spectrum

Frequency Spectrum Range (MHz) Uplink Frequency

Frequency Point

Available

Downlink Frequency

Duplex Separation

(MHz)

Channels No

GSM 450 UL 450.4~457.6DL 460.4~467.6

Fu(n)=450.6+0.2(n-259) 259<=n<=293 Fd(n)=Fu(n)+10 10 34

GSM 480 UL 478.8~486DL 488.8~496 Fu(n)=479+0.2(n-306) 306<=n<=340 Fd(n)=Fu(n)+10 10 34

GSM 850 UL 824~849DL 869~894

Fu(n)=824.2+0.2(n-128) 128<=n<=251 Fd(n)=Fu(n)+45 45 123

E-GSM 900 UL 880~915 DL 925~960

Fu(n)=890+0.2nFu(n)=890+0.2(n-1024)

0<=n<=124975<=n<=1023 Fd(n)=Fu(n)+45 45 172

R-GSM 900 UL 876~915DL 921~960

Fu(n)=890+0.2nFu(n)=890+0.2(n-1024)

0<=n<=124955<=n<=1023 Fd(n)=Fu(n)+45 45 192

DCS 1800 UL 1710~1785DL 1805~1880

Fu(n)=1710.2+0.2(n-512) 512<=n<=885 Fd(n)=Fu(n)+95 95 373

PCS 1900 UL 1850~1910DL 1930~1990

Fu(n)=1850.2+0.2(n-512) 512<=n<=810 Fd(n)=Fu(n)+80 80 298


Frequency Reuse

The frequency resource of mobile system is very limited.

The different Subscribers can use the same frequency in different places.

The quality of communication must be ensured.


R

4/12


Cell Types

Omni

1

120degree

12

3

Omni-directional Cell

120 Degree Cell









GSM-GPRS Network Component

GSM /GPRS BSS

BTS

BSC

BTS

BSC

PCU

SS7

SMS system

PSTNISDN

Internet,Intranet

MSC/VLR GMSC

HLR/AUC

SGSN

CG BG

GGSN

GPRS Backbone

Other PLMN

MS

MS

OMC


Interface Between Different Entities

GSM /GPRS BSS

BTS

BSC

BTS

BSC

PCU

SS7

SMS system

PSTNISDN

Internet,Intranet

MSC/VLR GMSC

HLR/AUC

SGSN

CG BG

GGSN

GPRS backbone

Other PLMN

A

Gb

Gi

Gp

C/D/Gs

Gr/Gs/Gd/Ge Gc

Ga

Abis

Um

MS

MS

OMC

B


Interfaces GSM/GPRS

INTERFACE ENTITIES RELATED

SIGNALING AND PROTOCOL

Um MS - BTS DTAP (Direct Transfer Application Part)

Abis BTS – BSC Internal Protocol (LAPD)

A BSC – MSC BSAP (Base Station Application Part)

B MSC – VLR Internal Protocol

C MSC – HLR MAP (Mobile Application Part)

D VLR – HLR MAP (Mobile Application Part)

Ga GGSN - CG GTP (GPRS Tunneling Protocol)

Gb BSS – SGSN SNDCP (SubNetwork Dependent Convergence Protocol), BSSGP (BSS GPRS Protocol)

Gd SGSN - SMS MAP (Mobile Application Part)

Ge SGSN – GSMSCF CAP (CAMEL Application Part)

Gi GGSN – PDN IP (Internet Protocol)

Gn (misma PLMN) SGSN – SGSN GTP (GPRS Tunneling Protocol)

Gp (diferente PLMN) SGSN - SGSN GTP (GPRS Tunneling Protocol)

Gr SGSN – HLR MAP (Mobile Application Part)

Gs SGSN - MSC BSSAP+ (Base Station Subsystem Application Part)


Mobile Station—MS

International Mobile Equipment Identity (IMEI)

– Mobile Equipment

MS=ME+SIM

International Mobile Subscriber Identity (IMSI)

– Subscriber Identity Module


Subscriber Identity Module – SIM

International Mobile Subscriber Identity

(IMSI)

Temporary Mobile Subscriber Identity

(TMSI)

Location Area Identity (LAI)

Subscriber Authentication Key (Ki)

SIM



BTS

BSC

TC/SMBSS

MSC

Base Station Subsystem – BSS

The Base Station Controller – BSC

The Base Transceiver Station – BTS

The Trans-coder – TC and Sub multiplexer (SM)


BTS

BSC

TC/SMBSS

MSC

Packet Control Unit-----PCU

Packet data switching

Bridge between SGSN and BSC

Provide Pb and Gb interface

GPRS Backbone

PCU SGSN

GbPb


Mobile-service Switching Center – MSC Home Location Register – HLR Visitor Location Register – VLR Equipment Identity Register – EIR Authentication Center – AUC Echo Cancellor – EC

AUCHLR

MSC/VLR

PSTN

NSSEIROMC

BSS

EC

The Network Switching System


Mobile-service Switching Center – MSC

Call Processing Operations and Maintenance Support Interface management Inter-network & Inter-working Billing


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


Visitor Location Register – VLR

Mobile Status (IMSI attached / detached / busy / idle etc.)

Location Area Identity (LAI)

Temporary Mobile Subscriber Identity (TMSI)

Allocating the Roaming Number (MSRN)


IMEI is Checked In White List

IMEI is Checked in Black/Grey List

If NOT found, checked against Grey/Black List

EIR focus on the equipment , not the subscriber!!

Equipment Identity Register – EIR

White List Black List Grey List




OMC Functional Architecture

OSMMI

DB

Event/AlarmManagement

SecurityManagement

ConfigurationManagement

Performance Management

Fault Management









Service Area

PLMN service area

......

Service Area

MSC service area...

Location area...

cell

PLMN service area PLMN service areaMSC service area...

Location area...

cell



HLR Number

CC NDC H0H1H2H3


LAI (Location Area Identity)

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 China is "460"MNC: Mobile Network Code， It consists of 2 digits . For example: The MNC of China Mobile is "00"LAC: Location Area Code， It is a two bytes hex code. The value 0000 and FFFF is invalid.For example: 460-00-0011

MCC MNC LAC


CGI (Cell Global Identity)

The CGI is a unique international identification for a cellThe format is LAI+CILAI: Location Area IdentificationCI: Cell Identity. This code uses two bytes hex code to

identify the cells within an LAI.For example : 460-00-0011-0001


BSIC (Base Station Identity Code)

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, used to

distinguish different cells assigned the same frequency!

NCC BCC

BSIC


CC: Country Code. For example: The CC of China is "86".NDC: National Destination Code. For example: The NDC of

China Telecom is 139, 138, 137, 136, 135.SN: Subscriber Number. Format:H0 H1 H2 H3 ABCDExample: 86-139-0666-1234

MSISDN

CC NDC SNNational (significant)

Mobile number

Mobile station internationalISDN number


MCC: Mobile Country Code， It consists of 3 digits . For example: The MCC of China is "460"。MNC: Mobile Network Code， It consists of 2 digits . For example: The MNC of China Telecom is "00"。MSIN: Mobile Subscriber Identification Number. H1H2H3 S ABCDEF For example: 666-9777001NMSI: National Mobile Subscriber Identification ， MNC and MSIN

form it together. For Example of IMSI : 460-00-666-9777001

Not more than 15 digits

3 digits 2 digits

IMSI

MCC MNC MSINNMSI

IMSI


TMSI (Temporary Mobile Subscriber Identity)

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 operator.


IMEI (International Mobile Station Equipment Identity)

TAC FAC SNR SP

IMEI

TAC: Type approval code, 6 bit, determined by the type approval centerFAC: Final assembly code, 2 bit, It is determined by the manufacturer.SNR: Serial number, 6 bits, It is issued by the manufacturer of the MS. SP: 1 bit , Not used. Check the IMEI in your MS : *#06#










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

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

Physical Channel and Logical Channel

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

TDMA FRAME


Two 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.


Traffic Channel (TCH)

TCHTraffic Channels

Speech

TCH/FS

Data

TCH/HSTCH/9.6 TCH/2.4

TCH/4.8

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


FCCHSCH

CCH (Control Channels)

DCCH

SDCCH

BCH

BCCH Synch. CH.ACCH

SACCHFACCH CCCH

RACH CBCH

PCH/AGCH

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

Control Channel (CCH)


CCH

BCH

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

Broadcast Control Channel – BCCH


CCH

CCCH

RACHuplink

CBCH downlink

PCH/AGCHdownlink

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

RACH: Random Access Channel

PCH: Paging Channel

AGCH: Access Granted Channel

CBCH: Cell Broadcast Channel

Common Control Channel – CCCH


CCH

DCCH

SDCCH

FACCH SACCH

DCCH is assigned to a single wireless connection for measurement and handover purpose.SDCCH: Stand-alone Dedicated

Control Channel ACCH: Associated Control Channel SACCH: Slow Associated

Control Channel FACCH: Fast Associated Control

Channel

ACCH

Dedicated Control Channel – DCCH


RACH CCCHCCH

SDCCH

SACCHFACCH

TCH/F

TCH/H

DCCH

TCH

DCH

Uplink Logical channel


FCCHSCHBCCH

PCH

AGCH

BCCH

CCCH

CCH

SDCCHSACCHFACCH

TCH/F

TCH/H

DCCH

TCH

DCH

Downlink Logical channel


Allocate signaling channel

FCCHSCHBCCH

PCHRACHAGCHSDCCHSDCCHTCHFACCH

Power-off

Idle mode

Dedicated mode

Idle mode

How to use these channels?

Search for frequency correction burst

Search for synchronous burst

Extract system information

Monitor paging message

Send access burst

Set up the call

Allocate voice channel

Conversation

Release the call


Packet data channel (PDCH)

Comprising packet service channel and packet control channel

Packet service channel (PDTCH)

Combined into the single-directional service channel

Packet control channel

Broadcast control channel: PBCCH

Public control channel: PPCH, PRACH, PAGCH

Private control channel: PACCH, PTCCH

TCH

BCCH

SACCH

Packet logic channel

CCCH

TCH


GSM Logical Channel Combination

Main BCCH combination – FCCH + SCH + BCCH + CCCH

SDCCH combination – SDCCH/8 + SACCH/8

Combined BCCH – BCCH + CCCH +SDCCH/4 + SACCH/4

TCH/FR combination – TCH/F + FACCH/F + SACCH/F

TCH/HR combination – TCH/H + FACCH/H + SACCH/H


Packet logic channels (PDCH) can be combined via the following three modes

Mode 1: PBCCH+PCCCH+PDTCH+PACCH+PTCCH;

Mode 2: PCCCH+PDTCH+PACCH+PTCCH;

Mode 3: PDTCH+PACCH+PTCCH

In case of small GPRS traffic, GPRS and circuit services use the same BCCH and CCCH in the cell. In this case, only combination mode 3 is needed in the cell

With the increase of traffic, the packet public channel should be configured in the cell. Channel combination mode 1 and mode 2 should be adopted

Combination of packet logic channel


TDMA Frames

0 1

0 1 2 43 46 47 48 5049

51 – Frame Multi-frames

0 1 10

CONTROL CHANNELS

2 3 4 5 6 7 2 3 5 764

GSM Multi-frames


GSM Multi-frames

TDMA Frames

0 1

0 1 2 43 21 22 23 2524

26 – Frame Multi-frames

0 1 10

TRAFFIC CHANNELS

2 3 4 5 6 7 2 3 5 764









Power Control

Saves battery powerReduces co-channel andadjacent channel interference

8W

0.8W

5WBoth Uplink and Downlink power settings can be controlled independently and individually.

BCCH -------Does not attend Power control


DTX and VAD

Voice Activity Detection – VAD

Discontinuous Transmission – DTX

Battery SavingInterference reduction


Timing Advance (TA)

Transmission delay t

Transmission delay t

TA

The mobile phone should send the signal in advance!


Multi-path Fading

Diversity

Frequency Hopping

Time Dispersion


Diversity – What’s Diversity?

Receive diversity provides an effective technique for both overcoming the impact of fading across the radio channel and increasing the received signal to interference ratio.

The former is achieved by ensuring “uncorrelated” (i.e. low enough correlated) fading between antenna branches i.e. not all antennas experience fades at the same time.


Kinds of DiversityTime diversity

Coding, interleaving

Frequency diversity Frequency hopping

Space diversity Multiple antennas

Polarization diversity

Dual-polarized antennas

Multi-path diversity Equalizer

t

f


Frequency HoppingFrequency

f 0

Frame

f 1

f 2

f 3

f 4

Time









57.6 kbps

115 kbps

384 kbps

2 Mbps

GSM

HSCSD

GPRS

EDGE

IMT-2000

9.6 kbps

2G

2.5G

3G

GSM Development Evolution


Data rate of EDGE and GPRS

8PSKGMSK

9.013.4

15.6

21.4

8.811.2

14.817.6

22.4

29.6

44.8

54.4

59.2

0.0

10.0

20.0

30.0

40.0

50.0

60.0

CS-1 CS-2 CS-3 CS-4 MCS-1 MCS-2 MCS-3 MCS-4 MCS-5 MCS-6 MCS-7 MCS-8 MCS-9

Kbps

GPRSEGPRS


Downlink, 4 TS, MCS-9：

Huawei EDGE Test Result


The basic idea of GSM

The frequency spectrum used in GSM

The structure of GSM

Certain service area and numbers

Some radio techniques used in GSM

Evolution of GSM

SummarySummary

www.huawei.com

Thank You

Oma000001 Gsm Fundamentals Issue4.0

Documents

gsm system huawei technologies

effect gsm system

gsm system overview

rights reserved page

basic idea of gsm system

frequency reuse technique

gsm development

global system