gsm basic.ppt

8/10/2019 gsm basic.ppt

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Global System

for Mobiles

GSM


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TOPICS

GSM CONCEPTS

GSM SYSTEM ARCHITECTURE

IDENTITIES USED IN GSM GSM CHANNELS

GSM RADIO LINK

MOBILITY MANAGEMENT CALL MANAGEMENT

RADIO RESOURCE MANAGEMENT


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TOPICS

GSM CONCEPTS



GSM RADIO LINK

MOBILITY MANAGEMENT CALL MANAGEMENT



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Background to GSM

1G : Advanced Mobile Phone Service (AMPS)

Analog, Circuit Switched, FDMA, FDD

2G : Digital Advanced Mobile Phone Service (D-AMPS)

Digital, Circuit Switched, FDMA, FDD 2G : Global System for Mobile (GSM)

Digital, Circuit Switched, FDMA and TDMA, FDD

2G : Code Division Multiple Access (CDMA)

Digital, Circuit Switched, FDMA, SS, FDD


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GSM History


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1982: Groupe Spcial Mobile (GSM)

created

1984: Description of GSM features

1985: List of recommendations settled

1987: Initial MoU (Memorandum ofUnderstanding) aside the drafting

of technical specifications was

signed by network operators of 13

countries:

1988: Validation and trials, of the radio

interface.

1991: First system trials are

demonstrated at the Telecom 91

exhibition.

1992: Official commercial launch of

GSM service in Europe. First

Launch in Finland

1993: The GSM-MoU has 62

signatories in 39 countries

worldwide.

1995: Specifications of GSM phase 2are frozen.

1999: GSM MoU joins 3GPP (UMTS)

GPRS Trials begins

2000: 480M GSM subscribersWorldwide

First GPRS Networks roll out

End 2002: 792M GSM subscribersWorldwide

Development of the GSM Standard


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12 SERIES

OPERATION ANDMAINTENANCE

01 SERIES

GENERAL 02 SERIESSERVICE ASPECTS

03 SERIES

NETWORK ASPECTS

04 SERIESMS-BSS INTERFACE AND

PROTOCOLS

05 SERIES

PHYSICAL LAYER ON THERADIO PATH.

06 SERIESSPEECH CODINGSPECIFICATIONS

07 SERIESTERMINAL ADAPTERSFOR MOBILE STATIONS

11 SERIESEQUIPMENT AND TYPE

APPROVAL SPECIFICATIONS

10 SERIESSERVICE INTERWORKING

09 SERIESNETWORK

INTERWORKING

08 SERIES

BSS TO MSC INTERFACES

GSM Specifications


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Increasing GSM Data Rates

Transmission

Time

GPRS =GeneralPacketRadioService

HSCSD=HighSpeedCircuit SwitchedData

EDGE=Enhanced Data rate for GSM Evolution

UMTS= Universal Mobile Telecommunication System

10 sec 1 min 10 min 1 hour0

UMTS

E/GPRS

ISDN

PSTN

GSM

webe-mail photo

web photoe-mail

web photo

video

clipreportphoto

web photoe-mail

videoclipreport

video

clipreport

videoclipreport

video

clipreport


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throughputkbps

10 k

100 k64 k

1 M

2 M

1 k 1998 1999 2000 2001 2002

Time frame

UMTS

GPRS

HSCSD

9.614.4

GPRS=GeneralPacketRadioService

HSCSD=HighSpeedCircuit SwitchedData

EDGE=Enhanced Data rate for GSM Evolution

UMTS= Universal Mobile Telecommunication System

EDGE

Wireless Data Technology Options


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Circuit mode

Packet mode

AFDHCG

CG

CGCG

CG

DH

DH

AFDH

DH

AF

AF

AF

A

B

C

D

E

F

G

H

Circuit-Switched or Packet-Switched


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Multiple Access Technique

Multiple AccessAchieved by dividing the available

radio frequency spectrum, so that multiple users can

be given access at the same time.

FDMA - Frequency Division Multiple Access

( eg: GSM each Frequency channel is 200KHz)

TDMA - Time Division Multiple Access

( eg: GSM each frequency channel is divided into8 timeslots)

CDMA - Code Division Multiple Access

(eg: IS95- Each User data is coded with a unique

code)


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Duplex Technique

Duplex - How the up link and Down link of a user

is separated

FDD - Frequency Division Duplex

(eg:In GSM the up link and down link of a user is

separated by 45MHz )

TDD - Time Division Duplex

(the up link and down link of a user will be at the same

frequency but at different Time )


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What are the types in

GSM Network?

GSM-900 (Channels 125 operating band 900Mhz

carrier spacing 200khz spacing 45Mhz)

GSM -1800 (Channels 374 spacing 95Mhz)

GSM -1900(Used in USA)


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GSM Band Allocations (MHz)

Carrier frequency = ARFCN=Absolute Radio Frequency Channel Number

Frequencies are in MHz

GSM systems Uplink Downlink Band

Duplex

Spacing

Duplex

channels

GSM 450

GSM 480

GSM 850

450.4 457.6

478.8 486

824-849

460.4 467.6

488.8 496

869-894

2x7.2

2x7.2

2x25

10

10

45

35

35

124

GSM 900

E-GSM 900)

R-GSM 900)

890-915

880-915

876-880

935-960

925-960

921-925

2x25

2x35

2x04

45

45

41

124

174

40

GSM 1800

GSM 1900

1710-1785

1850-1910

1805-1880

1930-1990

2x75

2x60

95

80

374

299


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Frequency band

Uplink 890 - 915 MHz

Downlink 935 - 960MHz

Duplex Frequency Spacing 45MHz

Carrier separation 200KHzFrequency Channels 124

Time Slots /Frame(Full Rate) 8

Voice Coder Bit Rate 13Kbps

Modulation GMSKAir transmission rate 270.833333 Kbps

Access method FDMA/TDMA

Speech Coder RPE-LTP-LPC

GSM System specifications

GSM F il R di B d S


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GSM Family Radio Band Spectrum

Uplink

Downlink

880 890 915 1710 1785

925 935 960 1805 1880

MHz

P-GSM

GSM 1800 GSM 1900

1850 1910

1930 1990

R-GSM

876

921

960

960

915

915

E-GSM

Uplink

Downlink

824 849

869 894 MHz

GSM 850

478.8 486

488.8 496

450.4 457.6

460.4 467.6

GSM 450 GSM 480


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890 MHz 915 MHz 935 MHz 960 MHz

Uplink Downlink

Example:

Channel 48

0 124channel # 0 124channel #

Frequency Frequency

Duplex spacing = 45 MHz

Frequency band spectrum = 2 x 25 MHz

Channel spacing = 200 kHz

BTS

Paired Radio Channels in GSM

Case of GSM 900


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GSM Time DivisionMultiplexFrame and Physical Channels

TS TS TS TS TS TS TS TS

0 1 2 3 4 5 6 7

Time4.615 ms

TDMA frame

Physical channel # 2 = recurrence of time-slot # 2

TDMA frame

0 9.23 ms

Time-slot

(frames repeat continuously)

TS TS TS TS TS TS TS TS

0 1 2 3 4 5 6 7


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Physical Channel

MS3

//ARFCN

1 2 124FDMA

BTS

Without FH

0

TDMAs

TS7

n

n-1

n+1

MS2

MS1

timeBTS

With FH


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Radio Link Aspects

From Speech to RF SignalBlah Blah Blah...Blah... Blah... Blah...

Digitizing and

Source Coding

Channel Coding

Interleaving

Ciphering

Burst Formatting

Modulating Demodulating

Burst De-formatting

Deciphering

De-interleaving

Channel Decoding

Source Decoding


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GSM Delays Uplink TDMA Frames

Downlink TDMA

T T T T T T T T

R TMS1

R TMS2

Downlink

Uplink

Fixed transmit

delay of three

time-slots

R R R R R R R R

0 1 2 3 4 5 6 7

The start of the uplink TDMA

is delayed of three time-slotsBTS side

MSs side

BTS

TDMA Frame (4.615 ms)


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Timing Advance

1 - Propagation Delay

M2 M1d1>>d2d2

BTS Frame reference

MSs transmit

Propagation Delay tp

TS0 TS1 TS2 TS3 TS4 TS6TS5 TS7

Bits Overlapping

Ti i Advance


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TX BTS CAN WHAT GSM HOW WHEN WHAT

RX BTS yes the ms-isdn

RX MS1 CAN

TX MS1 yes

RX MS2 WHAT

TX MS2 the

RX MS3 GSM

TX MS3 ms-isdn

RX MS4 HOW

TX MS4

RX MS5 WHEN

TX MS5

RX MS6 WHATTX MS6

RX MS7

TX MS7

RX MS8

TX MS8

PropagationDelay

DD

+3TS

TA

TimingAdvance2 - Without Timing Advance: Collision

Ad


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CAN WHAT HOW WHEN WHAT

CAN

WHAT

HOW

WHEN

WHAT

TX BTS

RX BTS

RX MS1TX MS1

RX MS2TX MS2

RX MS3TX MS3

RX MS4TX MS4

RX MS5TX MS5

RX MS6TX MS6

RX MS7TX MS7

RX MS8TX MS8

yes

the

PropagationDelay

DD

+3TS - TA

yes the

Timing Advance = 2 * Propagation Delay

GSMms-isdn

ms-isdn

GSM

TimingAdvance3 - With Timing Advance: No Collision


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Uplink 890 MHz to 915 MHz

Down Link 935 MHz to 960 MHz

25 MHz divided into 125 channels of 200 KHzbandwidth

890.0 890.2 890.4 914.8 915.0

935.0 935.2 935.4 959.8 960.0

UP

DOWN

Access Techniques


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GSM in comparison with other

Standards GSM gives mobility without any loss in Audio quality

Encryption techniques used gives high security in the

air Interface and also use of SIM.

Bit Interleaving for high efficiency in Transmission.

Variable Power (Power budgeting- extend battery life)

Minimum Interference.

Features-CCS7 Signaling SMS (Short Message Services)

Emergency Calls

CELL Broadcast


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TOPICS

GSM CONCEPTS



GSM RADIO LINK

MOBILITY MANAGEMENT

CALL MANAGEMENT



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AuC

MS

MS

BTS

BTS

BTS

BSC

BSC

MSC

MSC

VLR

VLR

GMSC

HLR

PSTN

EIR

Um

Abis

Abis

A

A

OMC Server

Um

GSM - Network Structure

B

E

E

X.25

C

F

H

X.25


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GSM Network

OMC

AUC

HLR

MSC

EIRVLR

BSC

BTS

MS

External

PSTN &

PDN N/W

SS

BSS

Switching

System

Base StationSystem

MS Mobile Station

BTS Base transceiver System

BSC Base Station Controller

MSC Mobile Switching CenterHLR Home Location Register

VLR Visitor Location Register

EIR Equipment Identity Register

AUC Authentication Center

OMC Operation And Maintenance Center

GSM Architecture


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GSM Architecture

HLR

VLR

EIR

AUC

MSC

B

SC

B

S

C

SMSC

PSTN

VMSC

Mobile

Station

GSM

Air interface

OMCR

TRAU

Base Station System

Network and switching

subsystemA interface SS7 / speech

SS7

X.25

BTSBTS

BTS

BTS

BTSBTS

Abisinterface

Ainterface

OMCS

Fundamentals


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GSM utilizes two bands of 25 MHz. 890-915MHz band is used for uplink while the 935-960 MHz is used for downlink.

The frequency bands are divided into 200KHz wide channels called ARFCNs (AbsoluteRadio Frequency Channel Numbers) i.e.there are 125 ARFCNs out of which only 124are used.

Each ARFCN supports 8 users with each usertransmitting / receiving on a particular time

slot (TS).

Fundamentals

124

123

.

2

1

124

123

.

2

1

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

Data burst = 156.25 bit periods = 576.9s

960 MHz

959.8MHz

200KHz

935 MHz

935.2 Mhz

915 MHz

200KHz

45 MHz

Downlink (TDMA frame) = 8 TS

Uplink (TDMA frame)

Delay

TS: Time slot

914.8 MHz

890.2 MHz

890 MHz

DOWNLINK

UPLINK

Therefore 1 TDMAframe = 156.25 x 8 = 1250 bits

and has a duration of 576.92s x 8 = 4.615 msThe technology


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Channels : differentiating

between Physical and LogicalchannelsPhysical channels :The combination of an ARFCN

and a time slot defines a physical channel.

Logical channels :These are channels specified by

GSM which are mapped on physical channels.

Logical Channels on Air interface


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Logical Channels on Air interface

LOGICAL

CHANNELS

COMMON

CHANNELS

DEDICATED

CHANNELS

BROADCASTCHANNELS

COMMONCONTROL

CHANNELS

DEDICATEDCONTROL

CHANNELS

TRAFFICCHANNELS

FCCH BCCHSCH SDCCH SACCH FACCH

PCH AGCHRACH TCH/F TCH/EFRTCH/H


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FCCH

Logical channels

Logical channels

Control channels Traffic channels

BCH CCCHDCCH

Half

rate

Full

rate

SCH BCCH PCH AGCH RACH SDCCH SACCHFACCHCBCH

requency p an an mpor ance o


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requency p an an mpor ance oBCCH

B3

B2

B9

B6 B4

B1

Sectored

antennas

MS ( monitoring the

broadcast radio B1 in idle

mode )

F S B B B B .. F S .. .. I

F0 F50F2 F3 F4 F5 F10 F11F1

F,S,B exist in time slot 0 of each frame

B7

B8

B5

B10

B11

B12

BPL frequency plan:

Broadcast frequencies :

15 Broadcast channels = 48-62

15 Hopping channels = 32-46


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What information does Broadcast Control channel

(BCCH) contain?

Serves as a Beacon for the Cell

Country Code (CC) and the Network Code (NC)

Location Area Identity (LAI)

List of neighboring cells which should be monitored by MS

List of frequencies used in the cell

Cell identity

Back

Location Updates


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Location Updates

Location Updates can be classified into

two:

Periodic Location Updates:

This occurs as per the timer set by the network operator.If the MS does not perform this update the MSC marksthe MS as Detached on the VLR.

Location Update on a handover:This occurs if during a handover the MS is moved into anew Location Area Code (LAC).


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1. The MS is monitoring the BCCH and has all the decoded

information stored on the SIM ( including the LAC)2. As soon as the mobile is on a TCH it sends the signal

strength indication on the corresponding SACCH

3. The BSC monitors the signal strengths and on analysis

sends a handoff request on FACCH. The handoffprocess is completed on the FACCH.

4. After the completion of call, the MS starts monitoring the

BCCH again. On finding the LAC (stored on SIM) and that

decoded from the BCCH to be different , the MS requestsa Location Update through SDCCH.


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Mobile Station (MS)

Hand portable unit

Contains Mobile Equipment(ME) and

Subscriber Identity Module (SIM)


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Mobile Equipment(ME)

Frequency and Time Synchronization

Voice encoding and transmission

Voice encryption/decryption functions

Power measurements of adjacent cells

Display of short messages

International Mobile Equipment Identifier (IMEI)


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SIM Portable Smart Card with memory (ROM-6KB to

16KB-A3/A8 algorithm, RAM- 128KB TO 256KB,EEPROM- 3KB to 8KB )

Static Information

International Mobile Subscriber Identity(IMSI)

Personal Identification Number (PIN)

Authentication Key (Ki)

Dynamic Information

Temporary Mobile Subscriber Identity(TMSI) Location Area Identity (LAI)

Phone memories, billing information

Ability to store Short Messages received

SIM C d d GSM M bil


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SIM-Card and GSM Mobile

Equipment

G S M

Global GSM MobilityCardThe Smart Card to use

+

SIM-Card

Contains:

- IMSI

=


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The SIM-Card Functions

Microchip with storeduser information

Credit Card Size

Permanent data:- Unique mobile subscriber identitythrough IMSI number and PIMSI

for Packet Mode

- Authentication parameter Ki,

- Authentication algorithm A3,

- Generating encryption key Kcalgorithm A8,

- PIN code.

Removable data:- Temporary Mobile Subscriber Number,

- Location Area Identification

- Routing Area Identification (Packet mode)

SIM-Card

G S M

Global GSM MobilityCardThe Smart Card to use

25 mm

15 mm


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Subscriber Identification

NatureInternational Mobile Subscriber Identity

Conformity with E212

Mobile Station -Integrated Services DigitalNetwork Nb

Similar to ISDN,

Conformity with E164/E213

Nb. digits 3 2 max 10 1 to 3 2 to 4 total max 15

*This cod e does not identify a geographical area

but an o perator

MS - ISDN

FormatMCC MNC MSIN

H1 H2 x x x ......... x x xCC NDC SN

M1 M2 x x x x x x x x

MeaningMobile

Country

Code

Mobile

Network

Code

Mobile Subscriber

Ident. Nb

H1 H2 = Identity of HLR

within the home PLMN

Country

Code

(where

subscription

has been made)

National

Destination

Code *

Mobile Subscriber

(national definition)

M1 M2 = nbr of logical HLR

IMSI

National Significant Mobile NumberIdentify a PLMN

worldwideIdentify the subscriber

of a PLMN


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Description Stored in SIM Card

MobileCountryCode

3 digits

MobileNetworkCode

2 digits

Mobile SubscriberIdentification Number (MSIN)

H1 H2 X X X X X X

10 digits max

Location Area Code

LAC

Temporary MobileSubscriber Identity

4 octets

G S M

Global GSM MobilityCardThe Smart Card to useMCC

=

208 (France)

234 (G-B)

262 (Germany)

404,405(India)

MNC

=

71(APBSNL)

72(TNBSNL)

20 (Bytel) IMSI = 15 digits max

NMSI

LAI

MobileCountryCode

3 digits

MobileNetworkCode

2 digits

Routing Area Code

RAC

RAI


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Country

Code

3 digits max

National

Destination

Code2 or 3 digits

Subscriber Number (SN)

Roaming Number (RN)

HO-number

Must be dialed tomake a call to

mobile

subscriber

Is a PSTN-like

number to track the

MS that hands over

to another MSC

during call-in-state

Is a PSTN-likenumber used to

reach a roaming

MS

CC= 33 (France)

091(India)

001(US)

NDC= 9448(BSNL-karnataka)

9845,9880(Airtel)

9886(Hutch)

= 660, 661, 618 (Bytel)

M1 M2 X X X X X X X X X X X X X

10 digits max

Country

Code

National

Destination

Code

CountryCode

National

DestinationCode

MS-ISDN (15 digits max)

MSRN

Description Stored in the Network


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Descriptor Embodied in the Mobile

Equipment

Type Approval

Code

TAC FAC SNR SP

Final Assembly

Code

Serial NumbeR (SPare)

IMEI enables the operator to check

the Mobile Equipment Identity

at call setup and make sure

that no stolen or unauthorized MS

is used in the GSM network


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International Mobile Equipment Identity IMEI)

Type Approval

Code

TAC FAC SNR SP

Final Assembly

Code

Serial number (SPare)

IMEI:*# 0 6 #351475 60 926514 4


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MS Classmark

Revision level

RF power

Encryption algorithm

Frequency

Short message

LoCation Services

MS Positioning Method

8-PSK modulation

Multi-slot class

Multi-band

Classmark

Power classes

Class GSM400/850/900

1

2

3

45

8 W*

5 W

2 W**0.8 W

GSM1800

GSM1900

1 W**

0.25 W

4 W

1 W**

0.25 W

2 W

* Typical value for car mounted

** Typical value for handheld

Class

GSM

400/850/900

GSM

1800

GSM

1900E1

E2

E3

2 W

0.5 W

0.2 W

1 W

0.4 W

0.16 W

1 W

0.4 W

0.16 W

For GMSK modulation

For 8-PSK modulation


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Base Transceiver Station

(BTS) Handles the radio interface to the mobile station.

Consists of one or more radio terminals for

transmission and reception

Each Radio terminal represents an RF Channel

TRX and MS communicates over Um interface

Received data transcoding

Voice encryption/decryption Signal processing functions of the radio interface

Uplink Radio channel power measurements


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Base Station Controller (BSC) Provides all the control functions and physical links

between the MSC and BTS

External Interfaces

Abis interface towards the BTS

A interface towards the MSC

Monitors and controls several BTSs

Management of channels on the radio interface

Alarm Handling from the external interfaces Performs inter-cell Handover

Switching from Abis link to the A link

Interface to OMC for BSS Management


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Mobile Switching Center

(MSC) Performs call switching

Interface of the cellular network to PSTN

Routes calls between PLMN and PSTN

Queries HLR when calls come from PSTN to mobile

user

Inter-BSC Handover Paging

Billing


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Home Location Register

(HLR) Stores user data of all Subscribers related to the

GMSC

International Mobile Subscriber Identity(IMSI)

Users telephone number (MS ISDN)

Subscription information and services

VLR address

Reference to Authentication center for key (Ki) Referred when call comes from public land network


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Visitor Location Register

(VLR) Database that contains Subscriberparameters and location information for all

mobile subscribers currently located in the

geographical area controlled by that VLR

Identity of Mobile Subscriber

Copy of subscriber data from HLR

Generates and allocates a Temporary

Mobile Subscriber Identity(TMSI) Location Area Code

Provides necessary data when mobile

originates call


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Authentication Center (AuC)

Stores Subscriber authentication data called Ki, a

copy of which is also stored in in the SIM card

Generates security related parameters to authorize a

subscriber (SRES-Signed RESponse)

Generates unique data pattern called Cipher key (Kc)

for user data encryption

Provides triplets - RAND, SRES & Kc, to the HLR on

request.


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EIR (Equipment Identity

Register) EIR is a database that contains a list of all valid

mobile station equipment within the network,

where each mobile station is identified by its

International Mobile Equipment Identity(IMEI). EIR has three databases.,

White list - For all known,good IMEIs

Black list - For all bad or stolen handsets

Grey list - For handsets/IMEIs that areon observation


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Interfaces and Protocols

Um

Abis A

C

B

E

D

F

Digital

Networks

POTS

TUP

ISUP

MA P

MAP

MAP

BSSAPLAPD

LAPDm

G


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GSM Entities and Signaling

Architecture


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GSM Protocols

CM - Connection Management

MM - Mobility Management

RR - Radio resource

LAPDm - LAPD for mobile

LAPD - Link Access Procedure for D channel

BTSM - BTS Management Part BSSAP - BSS Application Part (BSC - MSC)

DTAP - Direct Transfer Application Part (MS - MSC)

MAP - Mobile Application Part

MTP - Message Transfer part of SS7

SCCP - Signalling Connection Control Part of SS7

TCAP - Transaction Capabilities Application Part

ISUP - ISDN User Part


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Functional Plane of GSM

MS BTS BSC MSC/ HLR GMSC

VLR

MS BTS BSC MSC/VLR HLR GMSC

CC

MM

RR

Trans

TOPICS


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TOPICS

GSM CONCEPTS


IDENTIFIERS USED IN GSM

GSM CHANNELS GSM RADIO LINK

MOBILITY MANAGEMENT

CALL MANAGEMENT RADIO RESOURCE MANAGEMENT


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Temporary Mobile Subscriber

Identity [TMSI] The TMSI is used for the subscribers confidentiality.

It should be combined with the LAI to uniquely

identify a MS.

Since the TMSI has only local significance (that is,

within the MSC/VLR area), the structure may be

chosen by each administration.

The TMSI should not consist of more than four

octets.


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Mobile Station Roaming

Number[MSRN] HLR knows in what Service area the subscriber is

located.

In order to provide a temporary number to be used

for routing, the HLR requests the current MSC/VLR toallocate a Mobile Station Roaming Number(MSRN) to

the called subscriber and to return it.

At reception of the MSRN, HLR sends it to the MSC,

which now can route the call to the VLR where thecalled subscriber is currently registered.


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International Mobile

Equipment Identity [IMEI] The IMEI is used for equipment identification. AnIMEI

uniquely identifies a mobile station as a piece or

assembly of equipment. IMEI = TAC + FAC + SNR + sp

TAC= Type Approval Code (6 digits),determined by GSM

body

FAC= Final Assembly Code (2 digits), identifiesthemanufacturer

SNR= Serial Number (6 digits), uniquely identifying all

equipment within each TAC and FAC

sp = Spare for future use (1 digit)


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Location Area Identity

LAI identifies a location area which is a group ofcells..

It is transmitted in the BCCH.

When the MS moves into another LA (detected by

monitoring LAI transmitted on the BCCH) it mustperform a LU.

LAI = MCC + MNC + LAC

MCC= Mobile Country Code(3 digits), identifies the country

MNC= Mobile Network Code(1-2 digits), identifies the GSM-PLMN

LAC= Location Area Code, identifies a location area within a

GSM PLMN network. The maximum length of LAC is 16

bits,enabling 65536 different location areas to be defined in

one GSM PLMN.

TOPICS


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TOPICS

GSM CONCEPTS


IDENTITIES USED IN GSM

GSM CHANNELS GSM RADIO LINK

MOBILITY MANAGEMENT



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Physical channel:One timeslot of a TDMA-frame on one carrier

is referred to as a physical channel.

There are 8 physical channels per carrier in

GSM,channel 0-7(timeslot 0-7)

Logical channel:

A great variety of information must be

transmitted between BTS and the MS,for e.g.

user data and control signaling.Depending

on the kind of information transmitted we

refer to different logical channels.These logical

channels are mapped on physical

channel.

Channel concept

L i l h l


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75

FCCH

Logical channelsLogical channels

Control channels Traffic channels

BCH CCCHDCCH

Half

rate

Full

rate

SCH BCCH PCH AGCH RACH SDCCH SACCHFACCHCBCH


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76

Broadcast channels BCH Broadcast Channel-BCH

Alloted one ARFCN & is ON all the time in every cell.

Present in TS0 and other 7 TS used by TCH.

Frequency correction channel-FCCH

To make sure this is the BCCH carrier. Allow the MS to synchronize to the frequency.

Carries a 142 bit zero sequence and repeats once in every

10 frames on the BCH.

Synchronization Channel-SCH

This is used by the MS to synchronize to the TDMA frame

structure within the particular cell.

Listening to the SCH the MS receives the TDMA frame

number and also the BSIC ( in the coded part- 39 bits).

Repeats once in every 10 frames.


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77

Broadcast channels BCH ... BCH

The last information the MS must receive in order to receive

calls or make calls is some information concerning the cell.

This is BCCH.

This include the information of Max power allowed in the cell.

List of channels in use in the cell.

BCCH carriers for the neighboring cells,Location Area

Identity etc.

BCCH occupies 4 frames (normal bursts) on BCH and

repeats once every Multiframe. This is transmitted Downlink point to multipoint.

Cell Broadcast Channel - CBCH

Used for the Transmission of generally accessible

information like Short Message Services(SMS)


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78

Common Control Channels

CCCH CCCH- Shares TS-0 with BCH on a Multiframe.

Random access channel-RACH:

Used by Mobile Station for requesting for a channel. When

the mobile realizes it is paged it answers by requesting a

signaling channel (SDCCH) on RACH. RACH is also used

by the MS if it wants to originate a call.

Initially MS doesnt know the path delay (timing advance),

hence uses a short burst (with a large guard period = 68.25

bits).

MS sends normal burst only after getting the timing advance

info on the SACCH.

It is transmitted in Uplink point to point.


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79

Common Control Channels

CCCH .. Access Grant Channel-AGCH

On request for a signaling channel by MS the network

assigns a signaling channel(SDCCH) through AGCH. AGCH

is transmitted on the downlink point to point. Paging Channel-PCH

The information on this channel is a paging message

including the MSs identity(IMSI/TMSI).This is transmitted on

Downlink, point-to-multipoint.


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80

Dedicated Control Channels-

DCCH Stand alone dedicated control channel(SDCCH)

AGCH assigns SDCCH as signaling channel on

request by MS.The MS is informed about which

frequency(ARFCN) & timeslot to use for traffic. Used for location update, subscriber authentication,

ciphering information, equipment validation and

assignment of TCH.

This is used both sides, up and Downlink point-point.

C C


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81

Dedicated Control Channels-

DCCH Slow associated control channel-SACCH

Transmission of radio link signal measurement, power

control etc.

Average signal strengths(RXLev) and quality of service(RXQual) of the serving base station and of the neighboring

cells is sent on SACCH (on uplink).

Mobile receives information like what TX power it has to

transmit and the timing advance. It is associated with TCH

or SDCCH Fast associated control channel-FACCH

Used for Hand over commands and during call setup and

release. FACCH data is sent over TCH with stealing flag set


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82

Traffic Channels-TCH

TCH carries the voice data.

Two blocks of 57 bits contain voice data in the normal

burst.

One TCH is allocated for every active call.

Full rate traffic channel occupies one physical

channel(one TS on a carrier) and carries voice data

at 13kbps

Two half rate (6.5kbps) TCHs can share one physicalchannel.

GSMChannels


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83

GSM Channels

Control ChannelsTraffic Channels(TCHs)

Full

rate

Half

rate

Dedicated Control

Channels

(DCCHs)

SlowFast

Downlink

Broadcast

Channels

(BCHs)

Common Control

Channels

(CCCHs)

Downlink Uplink

TCH /F TCH /H FCCH SCH BCCH PCH CBCH RACHAGCH SDCCH SACCHFACCH

Traffic Multiframing Signaling Multiframing Traffic Multiframing

(down uplink)

The Logical Channels on Radio Interface


81/175

84FACCH

BTS

0 1 2 3 4 5 6 7TS

MS

FCCH

SCH

BCCH

PCH

AGCH

CBCH

SDCCH

SACCH

TCH

TCH

FACCH

SDCCHSACCH

FCCH

SCH

BCCH

RACH

PCH

AGCH

RACH

CBCH

Synchronization

Frequency correction

Broadcast control

Access request

Subscriber paging

Answer to Access request

Broadcast info

Dedicated Signaling

Sys InFo 5, 6 + SMS

Traffic (speech data)

Associated Signaling

Associated Signaling

Traffic (speech-data)

Radio Measurement + SMS

Dedicated Signaling

Broadcast info

M.S. Pre-synchronization

Access request

Subscriber paging

Answer to Access request

e og ca C a e s o ad o e ace

Logical Channel Description


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85

FACCH MESSAGES

Connection establishment from

SDCCH to TCH

End validation of a SDCCH-TCH

commutation

Characteristics of the future used BS

after handover

Connection establishment to BS after

handover

Validation of an handover

SACCH MESSAGES

Measures:

-power level of the communication-quality level of the communication

- level on the beacon frequency ofthe neighboring cells

Timing Advance

Power Control

SMS

TCH MESSAGES

Speech Data

Handover Access message (uplink)

SDCCH MESSAGES

Request for a SDCCH assignment

Request for the end of channelassignment

Order of commutation from SDCCH to

TCH

SMS


(1/2)



83/175

86

FCCH MESSAGES

no message is sent (all bits 0)

BCCH MESSAGES

System Information type 1, 2, 2bis,

2ter, 3, 4, 7, 8

(idle mode)

SCH MESSAGES

Frame Number

Base Station Identity Code (BSIC)

AGCH MESSAGES

For dedicated channel assignment:

-frequency number

-slot number-frequency hopping description-Timing Advance (1stestimation)-MS identification

PCH MESSAGES

messages containing a mobile

identity for a call, a short message

or an authentication

RACH MESSAGES

Service request:

-emergency call-answer to an incoming call-outgoing call-short message-call re-establishment- inscription

CBCH MESSAGES

Specific information

(weather, road information


(2/2)

GPRS Ch l


84/175

87

GPRS

CORE

NETWORK

BSC

PCUSN

PDCH = Packet DataCHannel

PPCH

PAGCH

PNCH

PDTCH

PACCH

PTCCH

PDTCH

PACCH

PTCCH

PBCCH

PRACH

DL

UL

PacketCommonControl

CHannels

PacketTraffic

CHannels

PBCCH

GPRS Channels


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88

RACH Control parameters

- maxNumberRetransmiss ion

- n umberOfSlotsSpreadTrans

- cel lBarred

- cal lReestabl ishm ent

- emergen cyCallRestr icted

- notA l lowedAc cessClasses

- Acc essClassCongest ion

BCCH allocation - Neighboring cells BCCHfrequencies in the same band

Extended BCCH allocation

- Neighboring cells BCCH frequencies inthe same band (complementary list)

- Neighboring cells BCCH frequencies inthe other band

- 2 ter indicator

- 5 ter indicator

LAI- loc ationA reaCode

- mo bi leCoun tryCode

- mob i leNetwork Code

- cel l Identi ty

SYS INFO 1-4

SYS INFO 2/5

SYS INFO 2bis/5b

SYS INFO 2ter/5te

SYS INFO 3-4/6

V10

System Information

SYS INFO: Parameters (1/2)

SYS INFO 3

SYS INFO 6

Cell Identity SYS INFO 3/6

System Information


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89

Control Channel description- IMSIAt tachDetach

- noOfBloc ksForAc cessGrant

- noOfMult i f ramesBetweenPaging

Cell Options

- upl inkPow erContro l

- dtxMode (UL)

- CellDtxDown link (DL)- radioLinkTimeOut

Cell Selection Parameters- cel lReselectHysteresis

- msTxPw rMaxCCH

- rxLevAc cessMin

Cell Reselection Parameters

- cellRes elInd

- cel lBarQuali fy

- c ellReselectOffset

- temporaryOffs et

- penaltyTime

- ear lyClassm arkSending

- power offset

SYS INFO 3

SYS INFO 3-4

SYS INFO 3-4or 7-8

SYS INFO 3

System Information

SYS INFO: Parameters (2/2)

V10

Traffic and Control Multiframing
http://localhost/var/www/apps/conversion/tmp/Notes%20for%20Training/systemInformation.ppthttp://localhost/var/www/apps/conversion/tmp/Notes%20for%20Training/systemInformation.ppt


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90

0 1 2 3 4 21 22 23 24 25 0 1 2 3 4 46 47 48 49 50

26 traffic frames = 120 ms

1 Hyperframe = 2,715,648 frames= 3h 28 min. 53 s 760 ms

0 1 2 3 5 2042 2043 2044 2045 2046 20474

1326

frames

0 1 2 3

46 47 48 49 500 1 3 42

22 23 2524

TS

0

TS

1

TS

2

TS

3

TS

5

TS

6

TS

7

TS

0

TS

1

TS

2

TS

3

TS

4

TS

5

TS

6

TS

7

TS

0

TS

1

TS

2

TS

3

TS

4

TS

5

TS

6

TS

7

TS

4

TS

0

TS

1

TS

2

TS

3

TS

4

TS

5

TS

6

TS

7

TS

0

TS

1

TS

2

TS

3

TS

4

TS

5

TS

6

TS

7

Frame

4.615 ms

Control channelTraffic channel

51 x 26 traffic frames = 6.12 s

26 x 51 control frames = 6.12 s


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91

Logical Channel Mapping1 T ffi Ch l C bi i


89/175

93

Full Rate - Downlink & Uplink

T : TCH A : SACCH : IDLETi: TCHsub-channel no. i

Ai: SACCHsub-channel no. i

time

26 frames = 120 ms

T0 A0T0 T0 T0 T0 T0 T0 T0 T0 T0 T0 T0T1 T1 T1 T1 T1 T1 T1 T1 T1 T1 T1 T1 A1 time

Half Rate - Downlink & Uplink

T AT T T T T T T T T T TT T T T T T T T T T T T

T

26 frames = 120 ms

1 - Traffic Channel Combination


90/175

Logical ChannelMapping3 C Ch l C bi ti


91/175

95

51 frames = 235.38 ms

Downlink

time

51 frames = 235.38 ms

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

Uplink

time

B : BCCHS : SCHF : FCCH : IDLE: PCH /

AGCHC R : RACH

BTS MSPhysical Channel

ARFCN (n) TS (s)

FCCH

SCH BCCH

PCH/AGCH

Frames repeat continuously

Multiframe

m+1

Multiframe

m-1

Multiframe m

C CF SC CF SC CF SC CCBF S F S BF SC

3 - Common Channel Combination

Logical ChannelMapping


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96

A3A2

A1D3D2

D3D2

D1

D1

D0

D0 F SF SF SC CC F SBF S

F SF SF SC CC F SBF S

51 frames = 235 ms

A0

time

Downlink

R R

R R D2

D2

D1

D1

D0

D0A1

A3

A0

A2R

R

R

R

D3

D3

51 frames = 235 ms

time

Uplink

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

A : SACCH D : SDCCH : IDLEB : BCCHS : SCHF : FCCH: AGCH

/PCHC R : RACH

4 - Common Channel Combination


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97

Why 26 and 51

Frames

per Multiframe?


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98

Downlink

message

Uplink

message

Neighboring BTS

(downlink)

Measurement Windows

C CF SC CF SC CF SC CCBF S F S F S

0 1 12 25 0 1 12 25

0 1 10 20 30 40 50 0 1

T AT T T T T T T T T T TT T T T T T T T T T T T T AT T T T T T T T T T TT T T T T T T T T T T T

Mobile

activityRx Rx Tx Rx Rx Tx Rx Rx Tx

(n) (n) (n)

TOPICS


95/175

99

GSM CONCEPTS



GSM CHANNELS

GSM RADIO LINK

MOBILITY MANAGEMENT


Speech

From Speech to Radio Transmission


96/175

100

Speech

Source

decoding

Channeldecoding

De-interleaving

Burst deformatting

Deciphering

Demodulation

equalization

Digitizing and

source coding

Channel

coding

Modulation

Ciphering

Burst formatting

Interleaving

Step 1

Step 2

Step 3

Step 4

Transmission

Step 5

Step 6 Diversity

GSM R di Li k


97/175

101

GSM Radio Link

Speech Coding -Done at Transcoder of BSC and MS

The Linear Predictive Coder uses RPE-LTP(Regular Pulse

Excitation- Long Term Prediction)

Converts 64kbps voice to 13kbps(260 bits every 20ms) Channel Coding - Done at BTS and MS

Uses Convolution Coding and CRC (Cyclic Redundancy

Check)

Converts 13 kbps to 22.8 kbps (456 bits per 20ms)


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102

GSM Radio Link

Bit Interleaving - Done at BTS and MS

Encryption - Done at BTS and MS

EX OR data with cipher block, which is generated by

applying A5 Algorithm to the Ciphering Key(Kc) Multiplexing - Done at BTS

Modulation - Done at BTS and MS

GMSK(Gaussian filtered Minimum Shift Keying)

Phase change of +90 for 0 and -90 for 1

Speech Coding


99/175

105

BP A/DSPEECH

ENCODER

CHANNEL

CODING

LP D/ASPEECH

DECODER

CHANNEL

DECODING

BAND

PASS

300 Hz -

3.4 kHZ

Every 125

s value is

sampled from analog

signal and quantised by

13 bit word

Data rate = 13/125*10 -6

= 104 kbps

Every 20ms 160 samples

taken

Data rate = 160 * 13/20ms

= 104 kbps

Linear Predictive Coding & Regular

Pulse Excitation Analysis1. Generates 160 filter coeff2. These blocks sorted in 4 sequence

1,5,9,37 / 2,6,10----38/

3,7,1139/8,12,1640

3. Selects the sequence with most

energy

So data rate = 104/4 = 26 kbps

Long term prediction analysis1. Previous sequences stored in memory

2. Find out the correlation between the

present seq. And previous sequences

3. Select the highest correlation sequence

4. Find a value representing the difference

between the two sequences.

Reduces data rate = 26 kbps/2 = 13 kbps

ie 260 bits in 20ms

50 132 78

1A 1B 2

1A = Filter Coeff

block ampl, LTP

params

1B = RPE pointers &pulses

2 = RPE pulse & filter

params

50 3 132 4

3 crc bitsFour 0 bits for codec

378 coded bits

Conv coding rate = 1/2 delay = 4

78

456 bits in 20 ms = 22.8 kbps

57 x 8 = 456

To modulator

Channel Processing in GSM


100/175

106

C

20 ms20 ms

A

A8

A7

A6

A5

B4

B3

B2

B1

B8

B7

B6

B5

C4

C3

C2

C1

57 bits

Information

1 1

CRL CRL

3 3

Tail Tail

26 bits

Training

8 Bursts

8 Sub blocks

of 57 bits

Source coding

Channel coding

Interleaving

Normalburst

20 ms

B

456 bitsA 456 bitsB 456 bitsC

57 bits

Information

A8B4A7B3A6B2A5B1 B8C4B7C3B6C2B5C1

Speech blocks

Codec dependent Codec dependentCodec dependent

Overview for Full Rate


101/175

107

Channel Processing in GSM


102/175

108

C

20 ms20 ms

A

A4

A3

A2

A1

B2

B1

B4

B3

C4

C3

C2

C1

4 Bursts

4 Sub blocks

of 57 bits

Source coding

Channel coding

Interleaving

20 ms

B

228 bitsA 228 bitsB 228 bitsC

A4B2

A3B1

B4C2

B3C1

Speech blocks

Codec dependent Codec dependentCodec dependent

Normalburst 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

Overview for Half Rate

456

Interleaving: TCH Full Rate


103/175

109

0 1 2 3 4 5 6 7 8 ... ... 452 453 454 455

0 1 2 3 4 5 6 78 9 10 11 12 13 14 15

448 449 450 451 452 453 454 455

57Rows

Divide 456 bits in 8 sub-blocks

765432107654 0 1 2 3

reordering&

partitioningout

diagonalinterleaving

456coded bits

burst

b0 b1 b56 b1 b56b0

bitinterleaving

Burst Formatting


104/175

110

1 frame:4.615 ms

0 1 2 3 4 5 6 7

Guard

157 126 57

DATA

156.25 bits duration

(0.577 ms)

Training

sequence

33

DATA

8.25

S SGuard

Band

Burst

148 bits

Normal Burst


105/175

Normal Burst

Burst Formats


106/175

112

Access Burst

Tail TrainingSequence Guard PeriodTail

156.25 bits (0.577 ms)

8 bits 36 encrypted bits 68.25 bits3 bits41 synch bits

Data

Dummy Burst

Tail Dummy Sequence Training Sequence Dummy Sequence Tail

3 bits 58 mixed bits 26 midamble bits 58 mixed bits 3 bits 8.25 bits

Guard

Period

156.25 bits (0.577 ms)

156.25 bits (0.577 ms)

13 bits 57 encrypted bits 1 26 bits 57 encrypted bits 3 bits 8.25 bits

Tail Data Training Sequence Data Tail Guard

Period

Normal Burst

Burst to be

Ciphering


107/175

113

Plain data: 0 1 1 1 0 0 1 0.....

Ciphering sequence: 0 0 0 1 1 0 1 0.....

XOR:

Ciphered data (transmitted): 0 1 1 0 1 0 0 0.....

Ciphered sequence: 0 0 0 1 1 0 1 0.....XOR:

Recovered data: 0 1 1 1 0 0 1 0.....

Data S S DataBurst to be

transmitted

Data S STraining

sequenceData

Received

burst

Interleaving


108/175

114

57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57

57 57 57 57

57 57 57 57

57 57 57 57

57 57 57 5757 57 57 57

57 57 57 57 57 57 57 57

57 57 57 57

Encoded speech blocks - Diagonal Interleaving

Even bits

Odd bits

Tb

3

Coded Data

57

F

1

Training Sequence

26

F

1

Coded Data

57

Tb

3

Gp

8.25

Bn-4 Bn-3 Bn-2 Bn-1 Bn Bn+1 Bn+2 Bn+3

57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57 57

57 57 57 57

57 57 57 57

57 57 57 57

57 57 57 5757 57 57 57

57 57 57 57

Encoded control channel blocks - Rectangul ar Interleaving

Even bits

Odd bits

Bn-4 Bn-3 Bn-2 Bn-1 Bn Bn+1 Bn+2 Bn+3


109/175

115

Burst The information format transmitted during one

timeslot in the TDMA frame is called a burst.

Different Types of Bursts

Normal Burst

Random Access Burst Frequency Correction Burst

Synchronization Burst


110/175

116

Normal Bu rst

T

3

Coded Data

57

S

1

T. Seq.

26

S

1

Coded Data

57

T

3

GP

8.25

Tail Bit(T) :Used as Guard Time

Coded Data :It is the Data part associated with the burst

Stealing Flag :This indicates whether the burst is carrying

Signaling data (FACCH) or user info (TCH).

Training Seq. :This is a fixed bit sequence known both to

the BTS & the MS.This takes care of the

signal deterioration.

156.25 bits 0.577 ms

T Training Sequence Coded Data T GP

156.25 bits 0.577 ms


111/175

117

T

3

Training Sequence

41

Coded Data

36

T

3

GP

68.25

Random Access Burst

T

3

Fixed Bit Sequence

142

T

3

GP

8.25

T

3

Coded Data

39

Training Sequence

64

Coded

Data 39

T

3

GP

8.25

Freq. Correc. Burst

Synchronization Burst

156.25 bits 0.577 ms

156.25 bits 0.577 ms

Transmission on the

di h l


112/175

118

radio channels A timeslot has a duration of .577 m seconds (148 Bits)

8 timeslots(8 x 0.577 = 4.62 ms) form a TDMA frame

If a mobile is assigned one TS it transmits only in this time

slot

and stays idle for the other 7 with its transmitter off, called

burst ing

The start on the uplink is delayed from downlink by 3 TSperiods

One TS = duration of 156.25 bits, and its physical contents is

called a burs t

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

DownlinkBTS > MS

UplinkMS > BTS

Offset


113/175

119

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

MS1

near

MS2

far

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

At

BTS

0 1 2 3 4 5 6 7MS1

near

0 1 2 3 4 5 6 7MS2

far

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

At

BTS

Timing Advance

Frames Types On Um


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120

Interface TDMA Frame

8 Time slots (Burst Period)

Length is 4.62 ms(8 * 0.577ms)

26-TDMA Multiframe

26 TDMA Frames (24 TCH, SACCH, Idle)

120 ms (26 * 4.62ms)

51-TDMA Multiframe

26 TDMA Frames (FCCH, SCH, BCCH, SDCCH, CCCH)

235.6 ms (51 * 4.62ms)

Frames Types On Um


115/175

121

Frames Types On Um

Interface Super Frame 51* 26 TDMA Frames

6.12 S

Hyper Frame 2048 * 51* 26 TDMA Frames

3 Hours, 28 Minutes, 53 Secs and 760 ms

TOPICS


116/175

122

GSM CONCEPTS



GSM CHANNELS

GSM RADIO LINK

MOBILITY MANAGEMENT


M bili M


117/175

123

Mobility Management

Mobility Management (MM)

Location updating- normal,periodic, IMSI attach

Paging

Security Management Preventing unauthorized users- authentication

Maintaining Privacy of users- ciphering

Providing roaming facility

MM functionality mainly handled by MS, HLR,MSC/VLR.

Network Attachment


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124

Cell Identification

MS scans complete GSM frequency band for

highest power

Tunes to highest powered frequency and looks

for FCCH. Synchronizes in frequency domain

Get training sequence from SCH which followsFCCH. Synchronizes in time domain.

Accesses BCCH for network id, location area and

frequencies of the neighboring cells.

Stores a list of 30 BCCH channels

N t k Att h t


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125

Network Attachment..

PLMN Selection

Get the operator information from SIM.

Cell Selection

Selected cell should be a cell of the selected

PLMN

Signal strength should be above the threshold.

Cell should not be barred

Location Update

Register with the network by means of locationupdation procedures.


120/175

S it A th ti ti


121/175

127

Security - Authentication

Authentication center

provides RAND to Mobile

AuC generates SRES using

Ki of subscriber and RANDMobile generates SRES

using Ki and RAND

Mobile transmits SRES to

BTS

BTS compares receivedSRES with one generated

by AuC

MSKi RAND

A3

SRES

RAND

SRES

SRES

Auth Result

AuCBTSMS

S it Ci h i


122/175

128

Security - Ciphering

Data sent on air

interface ciphered

for securityA5 and A8

algorithms used to

cipher data

Ciphering Key isnever transmitted

on air

MSKi RAND

A8

Kc

MS Network

Um interface

A5 A5

Kc Kc

Data DataCipheredData

TOPICS


123/175

129

GSM CONCEPTS



GSM CHANNELS

GSM RADIO LINK

MOBILITY MANAGEMENT


Communication Management


124/175

130

Communication Management

(CM) Setup of calls between users on request

Routing function i.e. Choice of transmission

segments linking users

Point to Point Short message services

PLMN Selection


125/175

132

No

automaticmode

The MS selects the firstPLMN from the preferredPLMNs list (if it is not in

the forbidden PLMNs list)

The user selects aPLMN from the

displayed PLMNs

manualmode

YesYes

Creation of a foundPLMN list

Is there an up to datefound PLMNs list?

End of PLMNselection

YesNo (automatic)

Cell Selectionsucceed?

Selection of thenext preferredpossible PLMN

No (manual)

PLMN Selection Constitution of the "Found PLMN list"


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133

Listen to all the

frequencies of the GSMspectrum:power level measurement

and average on thesemeasurements

Select the best

frequenciesaccording to the

power level

(124 channels in GSM

900, 374 in GSM 1800

and 299 in GSM 1900

(30 in GSM 900 and 40 in GSM 1800)

Memorize thebeacon

frequencies in the

precedentselection

=> Create theFound PLMN list

Constitution of the "Found PLMN list"


127/175

CellSelection


128/175

135

BTS-2

BTS-1

This cell

BTS-3

BTS-4

BTS-5

1

1

1

1

2

3

45

Purpose: get synchronization

with the GSM network

prior establishing any communication.

1

Immediate Assignment

MS BSC MSCBTS


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136

MS BSC MSC

CM SERVICE REQUEST

SDCCH or TCH6

CHANNEL REQUEST

RACH1

BTS

CHANNEL REQUIRED2

CHANNEL ACTIVATION3

IMMEDIATE ASSIGNMENTAGCH

5

IMMEDIATE ASSIGNMENT

COMMAND 5

CHANNEL ACTIVATION

ACK.4

Immediate

Assignment

LOCATION UPDAT. REQU.

SDCCH or TCH6

OR

Registration: the Very First Location

Update


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LAI HLR

IMSI

VLR id

TMSI

IMSI

TMSI

Release

VLR

IMSI

TMSI

LAI

MSC

BTS

BSS

BSC

2

4

5

2

6

1

2

4

5

6

3

4TMSI

5

Intra VLR Location Update


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138

Intra VLR Location Update

VLR

IMSI

TMSI

LAI

1

2

3

4

new TMSI

TMSI + old LAI 2

3

4

2

3TMSI

New TMSI

New LAI

MSC

BTS

BSS

BSC

IMSI not Required

BSS1

Inter VLR Location Update


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139

New LAI

newTMSI

TMSI + old LAI

TMSI New TMSI

MSC

BSS

BTS

BSC

1

2

5

7

2

5

7

2

IMSI,TMSI

LAI

New VLR

IMSI, TMSI

Old LAI

Old VLR

RAND, SRES,Kc

HLR

new

VLR id

subscriber

data

3

4

6

6

5

IMSI not Required

RAND, SRES,Kc

IMSI Attach


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MSCBTS

BSS

BSC

VLR

3

4

5

4

6

1 CHANNELREQUEST

2IMMEDIATEASSIGNMENT

LOCATION UPDATING

REQUEST (IMSI Attach )3

5LOCATION UPDATING

ACCEPT (LAC, TMSI)

4Authentication

Procedure

IMSI Detach


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MSC

BTS

BSS

BSC

VLR

1 CHANNELREQUEST

2IMMEDIATE

ASSIGNMENT

IMSI DETach

INDication3

4CHANNEL

RELEASE

IMSI DETach

INDication3

MS BSS MSC PSTN

Mobile Originating Call


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ACM= Address Complete Message

ANM= ANswer Message

IAM=Initial Address Message

MS BSS MSC

CHANNEL REQUEST1

PSTN

CM SERVICE REQUEST2 CM SERVICE REQUEST2

CALL PROCEEDING7CALL PROCEEDING

7

Assignmentprocedure7

IAM6

IMMEDIATE ASSIGNMENT2

ACM8

VLR

Ring

ANM10

ALERTING9

SETUP (basic) or

EMERGENCY4 SETUP4

CONNECT11

CONNECT ACKnowledge11

Authent icat ionprocedure3

Cipheringprocedure3

5

Dialing

Ringing

Path

Established

Ringing

SendingNumber

Mobile Terminating Call


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PSTN

LA1

LA2

BTS11

BTS21

BTS22

BTS31

BTS12

BTS23

HLR

4

3

5

1

2

5

6

6

BSC1

BSC2

BSC3

MSC/

VLRGMSC

1 - Paging Principle


2 - Detailed Procedure


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145

VMSCBSS

VLR

Visitor PLMN

GMSC

HLR

Home PLMN

RoutingInformation

(MSRN)

6

IAM : Initial Address Message

MSISDN : Mobile Station Integrated Services Digital

network Number

MSRN : Mobile Station Roaming Number

IMSI : International Mobile Subscriber Identity

GMSC : Gateway MSC

VMSC : Visitor MSC

TMSI : Temporary Mobile Subscriber Identity

PN

InternationalSS7

ISDNIAM (MSRN)

7IAM

(MSISDN)2

Send

RoutingInformation

(MSISDN)

3

Provide Roaming Number

(IMSI)4

PAGE

(TMSI + LA)

9

Send infoto I/C

(MSRN)

8

Roaming Number

(MSRN)5

PAGINGREQUEST

(TMSI + LA)10

PAGING

REQUEST

(TMSI)

11

MSISDN

1


3 - End to End Procedure


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146

MS BSS VMSC

CHANNEL REQUEST

(LAC, Cell ID)5

PSTN

IMMEDIATE ASSIGNMENT

(SDCCH or TCH)

6

PAGING REQUEST4

PAGING REQUEST

(TMSI or IMSI, LA)3

GMSC

IAM

(MSISDN)1IAM

(MSRN)2

CM SERVICE REQUEST

(Paging Response)7 PAGING RESPONSE

(TMSI or IMSI, LA)7

Authent icat ionprocedure8

Cipheringprocedure9

Address Complete Message11

ANswer Message12

Setup, Ass ignment, Alert ing10

CONNECT12

Dialing

Ringing

Path

Established

Call Release

1 - Mobile Initiated


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MS BSS MSC

Call in progress1

RELEASE COMPLETE4

PSTN

DISCONNECT2 DISCONNECT

2

RELEASE3RELEASE

3

RF Channel Releaseprocedure 8

Release5

RELEASE INDICATION7

CHANNEL RELEASE6

Release

tone9

Call Release

2 - PSTN Initiated


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PSTN

On hook

Purpose:

informs the mobile

then releases radio

and network resources.

REL

RLC

MSC

BTS

BSS

BSC

1

1 1

12

33

4

55

4

6

2

Mobile Originated Call


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149

Mobile Originated Call

Request for Service

Authentication

Ciphering

Equipment Validation

Call Setup

Handovers

Call Release

Mobile Terminated Call


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150


Paging

Authentication

Ciphering

Equipment Validation

Call Setup

Handovers

Call Release


MS


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151

MS

BTS

BTS

BTS

BSC

BSC

MSC

VLR

GMSC

HLR

PSTN

EIR

AuC

Land to

Mobile call

(MSISDN)

Query for

VLR info

Reply

(MSRN)

Route

to MSC

Query VLR

for LAC and

TMSIPaging

the area

(+TMSI)

TMSI Pagedon PCH

Paging

Ch. REQ

over RACH

Allocate SDCCH

over AGCH

Page RESP onSDCCH

( TMSI + LAI)Page RESPage RES

Authentication and Ciphering procedure done as seen in Location Updation

Assign. REQ

Assignment CMD(=TCH) on SDCCH

* MS tunes

* Assgn CMP

* Phone rings

Connect traffic Ch.to trunk

frees SDCCH

Assgn CMP

Network Alerting

TOPICS

GSM CONCEPTS


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GSM CONCEPTS



GSM CHANNELS

GSM RADIO LINK

MOBILITY MANAGEMENT



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Radio Resource Management


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154

Radio Resource Management

Power Control

Hand over Control

Discontinuous Transmission

Frequency Hopping

P C t l


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155

BTS commands MS at different

distances to use different power levels

so that the power arriving at the BTSs Rx is

approximately the same for each TS

- Reduce interference

- Longer battery life

Power Control

Handover


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Handover

Means to continue a call even a mobile crossesthe border of one cell to another

Procedure which made the mobile station really

roam

Handover causesRxLev (Signal strength , uplink or downlink)

RxQual (BER on data)

O & M intervention

Timing AdvanceTraffic or Load balancing

Handover Types


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Handover Types

Internal Handover (Intra-BSS)

Within same base station - intra cell

Between different base stations - inter cell

External Handover (Inter-BSS)

Within same MSC -intra MSC

Between different MSCs - inter-MSC


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HO required

Activate TCH(facch)

with HoRef#

Acknowledges and

HO performed

BSC

Intra BSC handover


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159

Periodic Measurement

Reports (SACCH)


Reports

if

1. Check for HO pass ed

2. Chann el avai l in new BTS

alloctes TCH (facch)

HO cmd with HoRef#Receives new BTS data(FACCH)

MS tunes into new frequency

and TS and sends HO message to

new BTS (facch)


Reports (SACCH)

Release TCH

Cell 1

Cell 2

BTS 1

BTS 2

Discontinuous


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Transmission

Discontinuous Transmission(DTX) allows the

radio transmitter to be switched off most of the

time during speech pauses.

A Silence Indicator Block is transmitted at500bps, which generates a comfort noise

Down Link interference is decreased.

Up link battery is saved

Frequency Hopping


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Frequency Hopping Frequency Hopping permits the dynamic switching of

radio links from one carrier frequency to another.

Base Band Hopping

At the BTS each the timeslot is shifted to another

transceiver, which is transmitting at the hop

frequency. User will be connected to different

Transceivers depending on hop sequence.

Synthesis Hopping

At the BTS transceiver changes the frequencies used.The user will be connected to only one transceiver.

Decreases the probability of interference

Suppresses the effect of Rayleigh fading

Wireless Data

Add-on to GSM network :

PCU; Packet Segmentation/re-assembly and scheduling

Radio channel access control and management

Transmission error detection and retransmission.

Power control

S f th I t t hil th

Enhanced Data rate for GSM Evolution

EDGE is an enhancement of GPRS and CSD technologies.

Based on the current GSM technology - same TDMA frame structure,

same bandwidth (200 kHz).

Uses 8 PSK modulation instead of GMSK

Universal Mobile Telecommunication Standards

Innovative Service Architecture : VHE Concept - providing the us

the same look and feel of its personalized services independent of


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162

Wireless Data

98 99 2000 2001

GSM

DATA

HSCSD

GPRS

EDGE

UMTS

SIM

Toolkit

WAP

Data Application

Time

Circuit Switched technology

Packet Switched technology

Technology for Applications

SMS Data: 160 -numeric characters

User Data Rate : 9.6kbps

One time slot over the air interface

High Speed Circuit Switched Data

User Data Rate:14.5kbps

Use multiple timeslots (max=8),hence max rate = 115.2kbps.

Needs a duplexor in MS for

simultaneous Tx and Rx

SGSN: GPRS mobility

Encryption

ChargingGGSN : Interface to the PDN, Internet

Max user data rate : 21.4 kbps

Dynamic rate adaptation to suit the radio conditions at

that time ( 9.05 kbps, 13.4 kbps, 15.6 kbps 21.4 kbps)

W@P Gateway W@P ServiceW

@

P

F

o

n

e

InternetMobile Network

Surf the Internet while on the move

W@P Gateway :

Adaptation of the information to the mobile

Compression of the data

Buffering of the information

Uses 8-PSK modulation instead of GMSK.

Requires good propagation conditions.

Allows upto 48 kbps (EGPRS) and upto 28.8 kbps (ECSD) on every

radio channelEDGE helps GSM-Only operators to compete with UMTS.

the same look and feel of its personalized services independent of

network and terminal.

Global Convergence : Fixed/Mobile, Telecom/Datacom, public/private

Mobile Multimedia driven market.Wideband bearers - 2GHz band ( 5 MHz per carrier), -max. 2Mbps

References


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163

References

Wireless and Personal Communication Systems.Vijay.K.Garg and Wilkes

Overview of the GSM System and Protocol

Architecture, IEEE Comm. Magazine, Moe Rahnema.

The GSM System for Mobile Communications-Michel Mouly & Marie-Bernadette Pautet

Overview of the GSM Comm- John Scourias.

Coverage or Traffic LimitationsTRAFFIC-

LIMITEDCOVERAGE


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AREA

(10000

subscribersper km2)

COVERAGE-

LIMITED

AREA

(-75 dBmat cell edge)

COVERAGE-LIMITED

AREA

(-70 dBm

at cell edge)

Erlang is the unit of statistical resource use

Erlang Concept


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165

Average number of busy channels

during the period of observation

(usually, the peak hour).

Erlang B

At any time, more than 1 user may request the same resource simultaneously. The use of such a

resource is associated with a blocking rate.

Erlang C

When more than 1 user request at the same time, instead of rejecting the extra calls, there is aqueuing system.

Different Types of CellsEXTENDED-CELL:

macro cell with system coverage

CONCENTRIC-CELL:

macro cell with system coverage
http://localhost/var/www/apps/conversion/tmp/SIVAPRESENTATION/Erlang%20Concept.ppt


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High sensitivity tointerference

Requires "secured"Frequency reuse pattern

High isolation frominterferences

A few Frequenciesintensively reused

MACRO-CELL:antenna radiating above roofs

---> Wide Coverage (

35 km)

MICRO-CELL:

Antenna below the roofs

---> small coverage

PICO-CELL:

Antenna inside building

---> Very small coverage

y g

extension (

120 km) for coasts...

y g

limitation inside another macro

Cell Patterns


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Cell Sectorization


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168

TRI OMNI BI

Omnidirectional Site Antennas


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169

Bi and Trisectorial Site Antennas


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170

Link Budgeting


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171

Calculation of the maximum coverage range of each cell in a specific environment.

Definition of planning tools parameters.

Based on the path loss calculation between the MS and the BS in both ways.

This calculation considers:

RF parameters of MS and BS,

system parameters (diversity gains...),

propagation parameters (shadowing), physical installation parameters (antenna height),

environment classification.


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- What is the maximum EIRP?

- What are the losses intransmission and reception?

- Is diversity used? - What is the minimumequivalent sensitivity?

- What is the maximumequivalent output power?

- What are the body losses?

- Beyond which distance the

communication will cut off?- Is indoor coverage

guaranteed?

- Is frequency hopping used?

EIRP:Equivalent Isotropic Radiated Power

Link Budget Parameters Overview


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Duplexer

Combiner

Power Amplifier

DLNA:Diversity Low Noise Amplifier

Specific Tx Cable

Losses

Tx PA Output

Power

Combiner losses

Rx Sensitivity

Rx Diversity Gain

DLNA conf.Standard conf.

Base Station

Tx PA Output Power

Other factors for MSBody LossesCommon cable losses

Propagation Parameters:

- Incar, Indoor penetration factors- Frequency 900, 1800, 1900 MHz

- Antenna Height

- Environment

Design Parameters:

Overlapping margin

Rx Sensitivity

Antenna Gain

MS

Rx Sensitivity

Common cable Losses

Antenna Gain

Radio Link

Link Budget Parameters BTS TX Power Amplifier
http://localhost/var/www/apps/conversion/tmp/SIVAPRESENTATION/Path%20Loss%20Statistical%20Methods.ppthttp://localhost/var/www/apps/conversion/tmp/SIVAPRESENTATION/Path%20Loss%20Statistical%20Methods.ppt


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2.5W PA 25W PA 35W PA 20W PA 30W PA

GSM 900 S2000LS2000E

S4000 Indoor

S4000 Outdoor

S4000 Indoor S2000HS8000 Indoor

S8000 Outdoor

DCS 1800 S2000L S4000 IndoorS2000E

S2000H

S4000 Outdoor

S4000 Indoor

S8000 Indoor

S8000 Outdoor

PCS 1900 S2000L

S2000E

S2000H

S4000 Indoor

S4000 Outdoor

S8000 Outdoor

Link Budget Parameters Combiners


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D

H2D

Hy/2

2-Way Hybrid Combiner with Duplexer

4.5 dB Loss

allows Synthesized Frequency Hopping

4-Way Cavity Combiner withDuplexer

allows Baseband Frequency Hopping

4.9 dB Loss

C C C C

D

TX TX TX TXTXTX

Link Budget Parameters Cable Losses


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At the BS, for a 7/8 foam dielectric coaxial cable:

4 dB/100 m (900 MHz),

6 dB/100 m (1800 MHz),

Common cable losses for 40 meters: 2.5 dB (900 MHz) and 3.5 dB (1800 MHz).

Jumpers (up and down the feeder)

0.5 dB (800 MHz),

1 dB (1800 MHz).

Link Budget Parameters BTS Antenna Gain


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Omnidirectional antenna

Default 6.5 V with 11 dBi gain

Directional antenna for trisectorial site

Default 65 H / 6.5 V with 18 dBi gain

Link Budget Parameters Mobile Station Parameters


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900 MHz 1800/1900 MHz

TX PA Output

Power33 dBm (2W) 30 dBm (1W)

RX Sensitivity -102 dBm

-2 dBi for Handheld

2 dBi for Car Kit

Body Loss

Antenna Gain

Common CableLoss

-100 dBm

0 dB for Handheld2 dB for Car Kit

3 dB for Handheld

0 dB for Car Kit

Link Budget PresentationParameters

Frequency 1800 MHzAntenna Gain (65 )

18 dBi


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Base Height 40.0 m

Mobile Height 1.5 m

Environment Urban

RX TX

Mobile

Antenna Gain-2 dB

Cable Loss0 dB

Output Power

Sensitivity

-100 dBm

30 dBm

Jumper Loss

Feeder Loss

Sensitivity

-110 dBm

3 dB

Options

Rx Diversity Gain: 5 dB

Overlapping Margin: 0 dB

Penetration Factor

Body Loss 3 dB

15 dB

Outdoor Minimum Field

95%: -80 dBm

Coverage Range

95%: 810 m

0.5 dB

Base Station

Max TX Output Power

RXm RXd

44.8 dBm

Coupling system

Tx loss4.5 dB

Link Budget Calculation: S8000 INDOOR: OPERATING FREQUENCY 1800 MHz


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BTS MS

TX OUTPUT POWER

30.00 W 44.8

dBm)

1.00 W 30.0

dBm)

COMBINER LOSSES

5.0 dB

None

RX SENSITIVITY

-110.0 dBm

-102.0 dBm

RX SENSITIVITY +

DIVERSITY -115.0 dBm None

COMMON CABLE

LOSSES 3.0 dB 0.0 dB

ANTENNA GAIN

18.0 dBm

-2.0 dBm

BODY LOSSES

3.0 dB

OVERLAPPING MARGIN 0.0 dB

INDOOR PENETRATION

FACTOR 18.0 dB

Exercise 1: S8000 INDOOR: OPERATING FREQUENCY 1800 MHz

FadingExample of Field Strength Variation for GSM 1800


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-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Distance (m)

FieldStrength

(dBm)

Measurement

Free Space

Zoom on

Short Term Fading

Long Term Fading

2 m

/2

Clutters


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