ebook4u.vn-00_OMA000001 GSM Fundamentals ISSUE4.0_2 pot

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 sys

Inte rnal

OMA000001 GSM Fundamentals

ISSUE 4.0

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

 BSS Feature Description

 BSS Signaling Analysis Manual

 BSC Technical Manual

Chapter 1 GSM System Overview

Chapter 2 GSM Network Structure

Chapter 3 Service Area and Number Planning

Chapter 4 Channels on the Wireless Interface

Chapter 5 Radio Techniques

Chapter 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 ,

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

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 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).

transmitting and receiving) ， every channel can support the traffic for one

subscriber or some control information.

Frequency

Time

 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 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

GSM 900

Duplex Separation: 45MHz Channel Bandwidth: 200KHz

The Frequency Spectrum

Uplink

890 915 935 960MHz

Downlink

Duplex Separation: 95MHz Channel Bandwidth: 200KHz

Base Station Receive

The Frequency Spectrum

Frequency

Spectrum

Range (MHz) Uplink Frequency

Frequency Point

Available

Downlink Frequency

GSM 450 450.4~457.6

460.4~467.6

Fu(n)=450.6+0.2(n-259) 259<=n<=293 Fd(n)=Fu(n)+10GSM 480 478.8~486488.8~496 Fu(n)=479+0.2(n-306) 306<=n<=340 Fd(n)=Fu(n)+10 GSM 850 824~849869~894 Fu(n)=824.2+0.2(n-128) 128<=n<=251 Fd(n)=Fu(n)+45

E-GSM

900

880~915 925~960

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

0<=n<=124 975<=n<=102

3 Fd(n)=Fu(n)+45R-GSM 876~915 Fu(n)=890+0.2n 0<=n<=124

955<=n<=102 Fd(n)=Fu(n)+45

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.

Frequency Reuse

7(Site)X 1(Cell) reuse

2 1

2

3

4 5

6 7

4 site X 3 cells reuse

Cell Types

Omni1

120 degree

1

2 3

Omni-directional Cell

120 Degree Cell

Chapter 1 GSM System Overview

Chapter 2 GSM Network Structure

Chapter 3 Service Area and Number Planning

Chapter 4 Channels on the Wireless Interface

Chapter 5 Radio Techniques

Chapter 6 GPRS & EDGE Introduction

Internet, Intranet

Interface Between Different Entities

Internet, Intranet

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/SM

BSS

MSC

Base Station Subsystem – BSS

 The Base Station Controller –

BSC TC/SM

PCU SGSN

Mobile-service Switching Center – MSC

Home Location Register – HLR

Visitor Location Register – VLR

AUC HLR

Mobile-service Switching Center – MSC

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

IMEI is Checked In White List

IMEI is Checked in Black/Grey List

If NOT found

EIR focus on the

equipment , not the

OMC Functional Architecture

OS

MMI

DB

Event/Alarm Management

Security Management

Configuration Management

Performance Management Fault

Management

Chapter 1 GSM System Overview

Chapter 2 GSM Network Structure

Chapter 3 Service Area and Number Planning

Chapter 4 Channels on the Wireless Interface

Chapter 5 Radio Techniques

Chapter 6 GPRS & EDGE Introduction

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 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 hex code to identify the cells within an LAI.

For example : 460-00-0011-0001

CGI: Cell Global Identification

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

BSIC

BSIC （ Base Station Identification Color Code)

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

NDC: National Destination Code For example: The NDC of

ISDN 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: 666-9777001

NMSI: National Mobile Subscriber Identification ， MNC and MSIN

Not more than 15 digits

 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.

TMSI: Temporary Mobile Subscriber Identification)

IMEI

IMEI: International Mobile Station Equipment Identification

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#

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#

Chapter 1 GSM System Overview

Chapter 2 GSM Network Structure

Chapter 3 Service Area and Number Planning

Chapter 4 Channels on the Wireless Interface

Chapter 5 Radio Techniques

Chapter 6 GPRS & EDGE Introduction

The information carried in one time

slot is called a “burst”

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

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)

TCH Traffic Channels

TCH/FS Full rate Speech Channel

TCH/HS Half rate Speech Channel

FCCH SCH

CCH (Control Channels) DCCH

SDCCH

BCH

BCCH Synch CH. ACCH

SACCH

Broadcast Control Channel – BCCH

Common Control Channel – CCCH

Control Channel (CCH)

periodically when it is in idle mode

BCCH: Broadcast Control Channel

FCCH: Frequency Correction Channel

SCH: Synchronization Channel

Broadcast Control Channel – BCCH

CCCH

RACH uplink downlink CBCH

The CCCH is responsible for

transferring control information

between all mobiles and the

CBCH: Cell Broadcast Channel

Common Control Channel – CCCH

DCCH

SDCCH

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

RACH CCCH CCH

SDCCH SACCH FACCH

FCCH SCH BCCH

PCH AGCH

BCCH

CCCH

CCH

SDCCH SACCH FACCH

Allocate signaling channel

FCCHSCHBCCH

PCHRACHAGCHSDCCHSDCCHTCH

Power-off

Idle mode

Dedicated 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

 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

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

Chapter 1 GSM System Overview

Chapter 2 GSM Network Structure

Chapter 3 Service Area and Number Planning

Chapter 4 Channels on the Wireless Interface

Chapter 5 Radio Techniques

Chapter 6 GPRS & EDGE Introduction

Power Control

Saves battery power

Reduces co-channel and

adjacent channel interference

8W

0.8W

5W

Both Uplink and Downlink

power settings can be

controlled independently

and individually.

BCCH

-DTX and VAD

Voice Activity Detection – VAD Discontinuous Transmission – DTX

Battery Saving Interference reduction

Timing Advance (TA)

Multi-path Fading

 Diversity

 Frequency Hopping

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

Chapter 1 GSM System Overview

Chapter 2 GSM Network Structure

Chapter 3 Service Area and Number Planning

Chapter 4 Channels on the Wireless Interface

Chapter 5 Radio Techniques

Chapter 6 GPRS & EDGE Introduction

Data rate of EDGE and GPRS

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

Summary

Thank You