gsm dummy neskishat

7/25/2019 Gsm Dummy Neskishat

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GSM [email protected]

Introduction

Uplink/Downlink

FDMA

Frequencies

Number Identifiers

MSISDN

IMSI

TMSI

IMEI

IMEISV

MSN

Network Architecture Mobile St!tion

"!se Tr!nscei#er St!tion

"!se St!tion $ontroller

Mobile Switc%in& $enter

'!tew!( MS$

)ome *oc!tion e&ister

Visitor *oc!tion e&ister

Equipment Identit( e&ister

Aut%entic!tion $enter

Time Division Multiple Access (TDMA)

Introduction

Time Slots

D!t! !tes

"urst Structure

Norm!l "urst

Frequenc( $orrection "urst

S(nc%roni+!tion "urst

Access "urst

D!t! T%rou&%put

Fr!me Structure

TDMA Fr!me

Multifr!mes

Superfr!mes

)(perfr!mes

Logical Channels

Si&n!lin& $%!nnels

"ro!dc!st $%!nnels ,"$$) F$$) S$) $"$)-

$ommon $ontrol $%!nnels ,.$) A$) A'$)-


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SD$$)

Associ!ted $ontrol $%!nnels ,FA$$) SA$$)-

Si&n!l $%!nnel M!ppin&

o Tr!ffic $%!nnels

o Encoded Speec%

o D!t!

o Tr!ffic $%!nnel M!ppin&

o AF$N M!ppin&

o Frequenc( )oppin&

Authentication & ncr!ption

Introduction

Aut%entic!tion .rocedures

$ip%erin& .rocedures

Timing Advances Access "urst

Dur!tion of ! "it

.rop!&!tion Del!(

M! $ell Si+e

Determinin& ! TA

Dist!nce of ! TA

"peech ncoding

Analog/Digital ConversionSeech Co!ing

"loc# Co!ingConvol$tion Co!ing%eor!ering & 'artioning

#"M vents

(MS( Attach(MS( DetachLocation U!ateMo)ile*+riginate! CallMo)ile*Terminate! Call

Cell "election & $eselection

Signal Strength%,-UALCell Selection an! %eselectionCCCell %eselection +0set

Cell %eselection 1ysteresisCell "ar Access


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Cell "ar -$ali2er

Timer

Introduction to #"M

Uplink/Downlink FDMA Frequencies Number

Identifiers MSISDN IMSI TMSI IMEI IMEISV MSN

Introduction

'SM is !n !cron(m t%!t st!nds for #lo%al "!stem or Mo%ile Communications0 T%e ori&in!l frenc%

!cron(m st!nds for Group Spcial Mobile0 It w!s ori&in!ll( de#eloped in 1234 !s ! st!nd!rd for ! mobile

telep%one s(stem t%!t could be used !cross Europe0

'SM is now !n intern!tion!l st!nd!rd for mobile ser#ice0 It offers %i&% mobilit(0 Subscribers c!n e!sil(

ro!m worldwide !nd !ccess !n( 'SM network0

'SM is ! di&it!l cellul!r network0 At t%e time t%e st!nd!rd w!s de#eloped it offered muc% %i&%er c!p!cit(

t%!n t%e current !n!lo& s(stems0 It !lso !llowed for ! more optim!l !lloc!tion of t%e r!dio spectrum5w%ic% t%erefore !llows for ! l!r&er number of subscribers0

'SM offers ! number of ser#ices includin& #oice communic!tions5 S%ort Mess!&e Ser#ice ,SMS-5 f!5

#oice m!il5 !nd ot%er supplement!l ser#ices suc% !s c!ll forw!rdin& !nd c!ller ID0

$urrentl( t%ere !re se#er!l b!nds in use in 'SM0 467 M)+5 367 M)85 277 M)+5 1377 M)+5 !nd 1277

M)+ !re t%e most common ones0

Some b!nds !lso %!#eExtended GSM (EGSM)b!nds !dded to t%em5 incre!sin& t%e !mount of spectrum

!#!il!ble for e!c% b!nd0

'SM m!kes use of Frequenc( Di#ision Multiple Access ,FDMA- !nd Time Di#ision Multiple Access,TDMA-0

9TDMA will be discussed l!ter

'plinksDownlinks & $everse orward


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'SM !llows for use of duple oper!tion0 E!c% b!nd %!s ! frequenc( r!n&e for t%e uplink ,cell p%one to

tower- !nd ! sep!r!te r!n&e for t%e downlink ,tower to t%e cell p%one-0 T%e uplink is !lso known !s

t%eReverse!nd t%e downlink is !lso known !s t%eForward0 In t%is tutori!l5 I will use t%e terms uplink

!nd downlink0

'plink and Downlink

re*uenc! Division Multiple Access (DMA)

'SM di#ides t%e !lloc!ted spectrum for e!c% b!nd up into indi#idu!l c!rrier frequencies0 $!rrier

sep!r!tion is :77 k%+0 T%is is t%e FDMA !spect of 'SM0

A%solute $adio re*uenc! Channel Num%er (A$CN)

T%e AF$N is ! number t%!t describes ! p!ir of frequencies5 one uplink !nd one downlink0 T%e uplink

!nd downlink frequencies e!c% %!#e ! b!ndwidt% of :77 k)+0 T%e uplink !nd downlink %!#e !

specific offsett%!t #!ries for e!c% b!nd0 T%e offset is t%e frequenc( sep!r!tion of t%e uplink from t%edownlink0 E#er( time t%e AF$N incre!ses5 t%e uplink will incre!se b( :77 k)+ !nd t%e downlink !lso

incre!ses b( :77 k)+0

An AF$N %!s !n !llowed b!ndwidt% of :77 k)+5 w%ic% corresponds e!ctl( to t%e c!rrier sep!r!tion0

T%e frequenc( of t%e AF$N refers to its center frequenc(0 If !n AF$N %!s ! frequenc( of 214037

M)+5 t%en it occupies t%e frequenc( sp!ce from 2140; M)+ to 21402 M)+ ,:77 k)+ tot!l-0 emember

t%!t t%is is t%e allocatedb!ndwidt%0 "ec!use of t%e n!ture of t%e modul!tion met%od ,'MS


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T%e followin& t!ble summ!ri+es t%e frequenc( r!n&es5 offsets5 !nd AF$Ns for se#er!l popul!r b!nds0

#"M +ands

T%e followin& di!&r!m illustr!tes !n AF$N wit% p!ired uplink !nd downlink frequencies for AF$N 1

in t%e 'SM 277 b!nd0

#"M,-- A$CN .


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Calculating 'plinkDownlink re*uencies

T%e followin& is ! w!( to c!lcul!te t%e uplink !nd downlink frequencies for some of t%e b!nds5 &i#en t%e

b!nd5 t%e AF$N5 !nd t%e offset0

#"M ,--

Up ? 32707 @ ,AF$N 9 0:-

Down ? Up @ 4607

e!mple>

'i#en t%e AF$N ;:5 !nd we know t%e offset is 46M)+ for t%e 'SM277 b!nd>

Up ? 32707 @ ,;: 9 0:-

Up ? 32707 @ ,1404-

Up ? 274047 M)+

Down ? Up @ ffset

Down ? 274047 @ 4607

Down ? 242047 M)+

T%e uplink/downlink p!ir for 'SM277 AF$N;: is 274047/242047 ,M)+-

Note t%!t c%!nnel 7 ,32707 M)+- is used !s ! &u!rd b!nd in 'SMB277 !nd is not us!ble for tr!ffic0

)ere !re t%e formul!s for E'SM2775 D$S13775 !nd .$S1277>

#"M,--

Up ? 32707 @ ,AF$N 9 0:- ,AF$N 7B1:4-

Up ? 32707 @ ,,AF$NB17:4-970:- ,AF$N 2;6 B 17:=-

Down ? Up @ 4607

999Notice t%!t t%e extendedportion of t%e EB'SM b!nd !ctu!ll( occurs below t%e re&ul!r b!nd in

frequenc(0 AF$N 2;4B17:= occur from 33707 M)+ to 332037 M)+ T%e re&ul!r 'SM ,7B1:4- occursfrom 32707 M)+ to 21403 M)+

AF$N 2;4 ,33707 M)8- is used !s ! &u!rd b!nd !nd so is not us!ble for tr!ffic0 AF$N 7 ,32707

M)+-5 w%ic% is used !s ! &u!rd b!nd in re&ul!r 'SMB2775 is !#!il!ble for use !s ! tr!ffic c%!nnel in EB

'SM since t%is c%!nnel %!ppens to be in t%e middle of t%is b!nd !nd ! &u!rd c%!nnel is not necess!r(


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t%ere0

DC"./--

Up ? 1;1707 @ ,,AF$N B 611- 9 0:-

Down ? Up @ 2607

0C".,--

Up ? 136707 @ ,,AF$N B 61:- 9 0:-Down ? Up @ 3707

Num%ering "!stem (Identiiers)

Mo%ile "u%scri%er I"DN (M"I"DN)

T%e MSISDN is t%e subscriberCs p%one number0 It is t%e number t%!t !not%er person would di!l in

order to re!c% t%e subscriber0 T%e MSISDN is composed of t%ree p!rts> $ountr( $ode ,$$-

N!tion!l Destin!tion $ode ,ND$-

Subscriber Number ,SN-

M"I"DN

Countr! Code (CC)B T%is is t%e intern!tion!l di!lin& code for w%ic%e#er countr( t%e MS is re&istered

to0

National Destination Code (NDC)B In 'SM5 !n ND$ is !ssi&ned to e!c% .*MN0 In m!n( c!ses5 !

.*MN m!( need more t%!n one ND$0

"u%scri%er Num%er ("N)B T%is is ! number !ssi&ned to t%e subscriber b( t%e ser#ice pro#ider ,.*MN-0

T%e combin!tion of t%e ND$ !nd t%e SN is known !s t%e N!tion!l ,si&nific!nt- Mobile Number0 T%is


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number identifies ! subscriber wit%in t%e 'SM .*MN0

National (signiicant) Mo%ile Num%er

International Mo%ile "u%scri%er Identit! (IM"I)

T%e IMSI is %ow t%e subscriber is identified to t%e network0 It uniquel( identifies t%e subscriber wit%in

t%e 'SM &lob!l network0 T%e IMSI is burned into t%e SIM c!rd w%en t%e subscriber re&isters wit% .*MN

ser#ice pro#ider0 T%e IMSI is composed of t%ree p!rts>

Mobile $ountr( $ode ,M$$-

Mobile Network $ode ,MN$-

Mobile Subscriber Identific!tion Number ,MSIN-

IM"I

Mo%ile Countr! Code (MCC)B T%is number identifies w%ic% countr( t%e subscriberCs network is in0 It

%!s = di&its0

Mo%ile Network Code (MNC)B T%is number identifies t%e %ome 'SM .*MN of t%e subscriber

,$in&ul!r5 TBMobile5 etc0-0 It %!s : or = di&its0 Some networks m!( %!#e more t%!n one MN$ !lloc!ted to

it0

Mo%ile "u%scri%er Identiication Num%er (M"IN)B T%is number uniquel( identifies ! user wit%in t%e

%ome 'SM network0

International Mo%ile *uipment Identit! (IMI)

T%e IMEI uniquel( identifies t%e Mobile Equipment itself0 It is essenti!ll( ! seri!l number t%!t is

burned into t%e p%one b( t%e m!nuf!cturer0 T%e IMEI is composed of t%ree p!rts>

T(pe Alloc!tion $ode ,TA$- B 3 di&its


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Seri!l Number ,SN- B di&its

Sp!re ,S.- B 1 di&it

IMI

T!pe Allocation Code (TAC)B T%is number uniquel( identifies t%e model of ! wireless de#ice0 It is

composed of 3 di&its0 Under t%e new s(stem ,!s of April :774-5 t%e first two di&its of ! TA$ !re

t%eReporting Body dentifierof t%e 'SMA !ppro#ed &roup t%!t !lloc!ted t%is model t(pe0

"erial Num%er ("N$)B T%is number is ! m!nuf!cturer defined seri!l number for t%e model of wireless

de#ice0

"pare ("0)T%is number is ! c%eck di&it known !s !!u"n #"ec$ %igit0 It is omitted durin& tr!nsmissionwit%in t%e 'SM network0

n m!n( de#ices t%e IMEI number c!n be retrie#ed b( enterin& 97

ormer IMI "tructure

.rior to April5 :774 t%e IMEI %!d ! different structure>

T(pe Alloc!tion $ode ,TA$- B di&its

Fin!l Assembl( $ode ,FA$- B : di&its


Sp!re ,S.- B 1 di&it

ormer IMI "tructure

As of April :7745 t%e use of t%e FA$ w!s no lon&er required0 T%e current pr!ctice is for t%e TA$ for !new model to &et !ppro#ed b( n!tion!l re&ul!tin& bodies5 known !s t%eReporting Body dentifier0

International Mo%ile *uipment Identit!"otware 1ersion (IMI"1)

T%is is ! newer form of t%e IMEI t%!t omits t%e Sp!re di&it !t t%e end !nd !dds ! :Bdi&it Software &ersion

'uber (S&')!t t%e end0 T%e SVN identifies t%e softw!re #ersion t%!t t%e wireless de#ice is usin&0 T%is

results in ! 1Bdi&it IMEI0

T(pe Alloc!tion $ode ,TA$- B 3 di&its


Softw!re Version Number ,SVN- B : di&its


10/95

Net3or# Architect$re

Mo)ile Station "ase Transceiver Station "ase Station Controller Mo)ileS3itching Center Gate3ay MSC

1ome Location %egister 4isitor Location %egister E5$iment (!entity

%egister A$thentication Center

GSM Net3or# Architect$re

A GSM net3or# is ma!e $ o6 m$ltile comonents an! inter6aces that 6acilitate

sen!ing an! receiving o6 signaling an! tra7c messages. (t is a collection o6

transceivers8 controllers8 s3itches8 ro$ters8 an! registers.

A '$)lic Lan! Mo)ile Net3or# 9'LMN: is a net3or# that is o3ne! an! oerate! )y

one GSM service rovi!er or a!ministration8 3hich incl$!es all o6 the comonents

an! e5$iment as !escri)e! )elo3. For e;amle8 all o6 the e5$iment an! net3or#

reso$rces that is o3ne! an! oerate! )y Cing$lar is consi!ere! a 'LMN.

Mo)ile Station 9MS:

The Mo)ile Station 9MS: is ma!e $ o6 t3o comonentss (ME(.

Subscriber Identity Module (SIM)?

The S(M is a small smart car! that is inserte! into the hone an! carries

in6ormation seci2c to the s$)scri)er8 s$ch as IMSI, TMSI, Ki9$se! 6or encrytion:8

Service 'rovi!er Name 9S'N:8 an! Local Area Identity9LA(:. The S(M can also store

hone n$m)ers 9MS(SDN: !iale! an! receive!8 the Kc9$se! 6or encrytion:8 hone

)oo#s8 an! !ata 6or other alications. A S(M car! can )e remove! 6rom one hone8

inserte! into another GSM caa)le hone an! the s$)scri)er 3ill get the same

service as al3ays.

Each S(M car! is rotecte! )y a *!igit 'ersonal (!enti2cation N$m)er 9'(N:. (n or!er

to $nloc# a car!8 the $ser m$st enter the '(N. (6 a '(N is entere! incorrectly three

times in a ro38 the car! )loc#s itsel6 an! cannot )e $se!. (t can only )e $n)loc#e!

3ith an *!igit 'ersonal Un)loc#ing Bey 9'UB:8 3hich is also store! on the S(M car!.

"ase Transceiver Station 9"TS:


12/95

Base Transceiver Station (BTS)* The "TS is the Mo)ile Station>s access oint to

the net3or#. (t is resonsi)le 6or carrying o$t ra!io comm$nications )et3een the

net3or# an! the MS. (t han!les seech enco!ing8 encrytion8 m$ltile;ing 9TDMA:8

an! mo!$lation/!emo!$lation o6 the ra!io signals. (t is also caa)le o6 6re5$ency

hoing. A "TS 3ill have )et3een an! Transceivers 9T%,:8 !een!ing on the

geograhy an! $ser !eman! o6 an area. Each T%, reresents one A%FCN.

+ne "TS $s$ally covers a single !egree sector o6 an area. Us$ally a to3er 3ith

"TSs 3ill accommo!ate all !egrees aro$n! the to3er. 1o3ever8 !een!ing on

geograhy an! $ser !eman! o6 an area8 a cell may )e !ivi!e! $ into one or t3o

sectors8 or a cell may )e service! )y several "TSs 3ith re!$n!ant sector coverage.

A "TS is assigne! a Cell Identity. The cell i!entity is *)it n$m)er 9!o$)le octet:

that i!enti2es that cell in a artic$lar Location Area. The cell i!entity is art o6 the

Cell Glo)al (!enti2cation 9CG(:8 3hich is !isc$sse! in the section a)o$t the 4isitor

Location %egister 94L%:.

Sector

The inter6ace )et3een the MS an! the "TS is #no3n as the Um Interfaceor theAir

Interface.


13/95

Um (nter6ace

+ase "tation Controller (+"C)

+ase "tation Controller (+"C)B T%e "S$ controls multiple "TS0 It %!ndles !lloc!tion of r!dio

c%!nnels5 frequenc( !dministr!tion5 power !nd si&n!l me!surements from t%e MS5 !nd %!ndo#ers from

one "TS to !not%er ,if bot% "TSs !re controlled b( t%e s!me "S$-0 A "S$ !lso functions !s ! funneler0

It reduces t%e number of connections to t%eMobile Switc"ing #enter,MS$- !nd !llows for %i&%erc!p!cit( connections to t%e MS$0

A "S$ m!( be colloc!ted wit% ! "TS or it m!( be &eo&r!p%ic!ll( sep!r!te0 It m!( e#en be colloc!ted

wit% t%e Mobile Switc%in& $enter ,MS$-0

The interface between the BTS and the BSC is known as the Abis Interface


14/95

A)is (nter6ace

The Base Transceiver Station (BTS) and the Base Station Controller (BSC)

together make up the Base Station System(BSS).

"ase Station System

Mo)ile S3itching Center 9MSC:

Mobile Switchin !enter (MS!)* The MSC is the heart o6 the GSM net3or#. (t

han!les call ro$ting8 call set$8 an! )asic s3itching 6$nctions. An MSC han!les

m$ltile "SCs an! also inter6aces 3ith other MSC>s an! registers. (t also han!les

inter*"SC han!o0s as 3ell as coor!inates 3ith other MSC>s 6or inter*MSC han!o0s.


15/95

Mo)ile S3itching Center

T%e interf!ce between t%e "S$ !nd t%e MS$ is known !s t%e nterface

A (nter6ace

"ateway Mobile Switchin !enter ("MS!)

There is another imortant tye o6 MSC8 calle! a Gate3ay Mo)ile S3itching Center

9GMSC:. The GMSC 6$nctions as a gate3ay )et3een t3o net3or#s. (6 a mo)ile

s$)scri)er 3ants to lace a call to a reg$lar lan! line8 then the call 3o$l! have to go

thro$gh a GMSC in or!er to s3itch to the '$)lic S3itche! Telehone Net3or# 9'STN:.


16/95

Gate3ay Mo)ile S3itching Center

For e;amle8 i6 a s$)scri)er on the Cing$lar net3or# 3ants to call a s$)scri)er on a

T*Mo)ile net3or#8 the call 3o$l! have to go thro$gh a GMSC.

Connections )et3een T3o Net3or#s

The inter6ace )et3een t3o Mo)ile S3itching Centers 9MSC: is calle! the E Interface

E (nter6ace


17/95

1ome Location %egister 91L%:

#ome $ocation %eister (#$%)* The 1L% is a large !ata)ase that ermanently

stores !ata a)o$t s$)scri)ers. The 1L% maintains s$)scri)er*seci2c in6ormation

s$ch as the MS(SDN8 (MS(8 c$rrent location o6 the MS8 roaming restrictions8 an!

s$)scri)er s$lemental 6eat$res. There is logically only one 1L% in any givennet3or#8 )$t generally sea#ing each net3or# has m$ltile hysical 1L%s srea!

o$t across its net3or#.

4isitor Location %egister 94L%:

&isitor $ocation %eister (&$%)* The 4L% is a !ata)ase that contains a s$)set o6

the in6ormation locate! on the 1L%. (t contains similar in6ormation as the 1L%8 )$tonly 6or s$)scri)ers c$rrently in its Location Area. There is a 4L% 6or every Location

Area. The 4L% re!$ces the overall n$m)er o6 5$eries to the 1L% an! th$s re!$ces

net3or# tra7c. 4L%s are o6ten i!enti2e! )y the Location Area Co!e 9LAC: 6or the

area they service.

4isitor Location %egister

$ocation Area !ode ($A!)

A LAC is a 2;e!*length co!e 9t3o octets: that i!enti2es a location area 3ithin the

net3or#. Each Location Area is service! )y a 4L%8 so 3e can thin# o6 a Location Area

Co!e 9LAC: )eing assigne! to a 4L%.

$ocation Area Identity ($AI)

An LA( is a glo)ally $ni5$e n$m)er that i!enti2es the co$ntry8 net3or# rovi!er8 an!


18/95

LAC o6 any given Location Area8 3hich coinci!es 3ith a 4L%. (t is comose! o6 the

Mo)ile Co$ntry Co!e 9MCC:8 the Mo)ile Net3or# Co!e 9MNC:8 an! the Location Area

Co!e 9LAC:. The MCC an! the MNC are the same n$m)ers $se! 3hen 6orming the

(MS(.

$ocation Area Identity ($AI)

!ell "lobal Identi'cation (!"I)

The CG( is a n$m)er that $ni5$ely i!enti2es a seci2c cell 3ithin its location area8

net3or#8 an! co$ntry. The CG( is comose! o6 the MCC8 MNC8 LA(8 an! Cell (!entity

9C(:

Cell Glo)al (!entity

The 4L% also has one other very imortant 6$nction< the assignment o6 a Temorary

Mo)ile S$)scri)er (!entity 9TMS(:. TMS(s are assigne! )y the 4L% to a MS as it

comes into its Location Area. TMS(s are only allocate! 3hen in ciher mo!e.

The inter6ace )et3een the MSC an! the 4L% is #no3n as the B Interfacean! the

inter6ace )et3een the 4L% an! the 1L% is #no3n as the D Interface. The inter6ace

)et3een t3o 4L%s is calle! the Interface

GSM (nter6aces

Equipment Identity %eister (EI%) ?

The E(% is a !ata)ase that #ees trac#s o6 han!sets on the net3or# $sing the (ME(.

There is only one E(% er net3or#. (t is comose! o6 three lists. The 3hite list8 the

gray list8 an! the )lac# list.


19/95

The )lac# list is a list i6 (ME(s that are to )e !enie! service )y the net3or# 6or some

reason. %easons incl$!e the (ME( )eing liste! as stolen or clone! or i6 the han!set is

mal6$nctioning or !oesnt have the technical caa)ilities to oerate on the net3or#.

The gray list is a list o6 (ME(s that are to )e monitore! 6or s$sicio$s activity. This

co$l! incl$!e han!sets that are )ehaving o!!ly or not er6orming as the net3or#e;ects it to.

The 3hite list is an $no$late! list. That means i6 an (ME( is not on the )lac# list or

on the gray list8 then it is consi!ere! goo! an! is on the 3hite list.

The inter6ace )et3een the MSC an! the E(% is calle! the ! Interface.

E5$iment (!entity %egister

Authentication !enter (Au!) ?

The A$C is resonsi)le 6or generating the necessary cryto varia)les6or a$thentication an! encrytion on the net3or#. These varia)les are the %AND8

S%ES8 an! Bc. The A$c also stores the Bi 6or each (MS( on the net3or#. Altho$gh it is

not re5$ire!8 the A$c is normally hysically collocate! 3ith the 1L%.


20/95

A$thentication Center

There is one last inter6ace that 3e haven>t !isc$sse!. The inter6ace )et3een the

1L% an! a GMSC is calle! the C Interface. Ho$ 3ill see it in the 6$ll net3or# !iagram

)elo3.This comletes the intro!$ction to the net3or# architect$re o6 a GSMnet3or#. "elo3 yo$ 3ill 2n! a net3or# !iagram 3ith all o6 the comonents as 3ell

as the names o6 all o6 the inter6aces.


21/95

Time Division Multiple Access (TDMA)

Introduction Time Slots D!t! !tes "urst Structure Norm!l "urst Frequenc( $orrection

"urst S(nc%roni+!tion "urst

Access "urst D!t! T%rou&%put Fr!me Structure TDMA

Fr!me Multifr!mes Superfr!mes )(perfr!mes

Time Division Multiple Access

Introduction

'SM uses Time Di#ision Multiple Acces ,TDMA- !s its !ccess sc%eme0 T%is is %ow t%e MS interf!ces

wit% t%e network0 TDMA is t%e protocol used on t%e Air ,Um- *ink0 'SM uses '!ussi!n MinimumBS%ift


22/95

n ! side note5 !lso remember t%!t 'SM c!rrier frequencies !re sep!r!ted b( :77k)+ !nd t%!t 'SMoper!tes in duple0 A c%!nnel number !ssi&ned to ! p!ir of frequencies5 one uplink !nd one downlink5 is

known !s !n Absolute !dio Frequenc( $%!nnel Number ,AF$N-0

E!c% time slot l!sts 6;02 Gs0 A time slot is t%e b!sic r!dio resource used to f!cilit!te communic!tion

between t%e MS !nd t%e "TS0

Time "lot Duration

Data $ates

As st!ted e!rlier5 'SM uses '!ussi!n MinimumBS%ift

:;703== kb/s H 1777 ? :;753== bits/sec ,$on#ertin& from kilobits to bits-

:;753== b/sec 157775777 ? 0:7;3== b/Gs ,$!lcul!tin& bits per miscrosecond-

0:7;3== b/Gs H 6;02 Gs ? 160:6 bits ,$!lcul!tin& number of bits per time slot-

So5 160:6 bits c!n be tr!nsmitted in ! sin&le time slot

+its per Time "lot


23/95

Data +urst

T%e d!t! tr!nsmitted durin& ! sin&le time slot is known !s ! burst0 E!c% burst !llows 30:6 bits for guard

tiewit%in ! time slot0 T%is is to pre#ent bursts from o#erl!ppin& !nd interferin& wit% tr!nsmissions in

ot%er time slots0 Subtr!ctin& t%is from t%e 160:6 bits5 t%ere !re 143 bits us!ble for e!c% burst0

T%ere !re four m!in t(pes of bursts in TDMA>

Normal +urst (N+)

re*uenc! Correction +urst (+)

"!nchroni2ation +urst ("+)

Access +urst (A+)

Normal +urst

T%e d!t! tr!nsmitted durin& ! sin&le time slot is known !s ! burst0 E!c% burst !llows 30:6 bits for guardtie0 T%is is to pre#ent bursts from o#erl!ppin& !nd interferin& wit% tr!nsmissions in ot%er time slots0

ut of 160:65 t%is le!#es 143 bits us!ble for e!c% burst0

)ere is t%e structure of ! norm!l burst>

+urst

Tail +itsB E!c% burst le!#es = bits on e!c% end in w%ic% no d!t! is tr!nsmitted0 T%is is desi&ned to

compens!te for t%e time it t!kes for t%e power to rise up to its pe!k durin& ! tr!nsmission0 T%e bits !t t%e

end compens!te for t%e powerin& down !t t%e end of t%e tr!nsmission0

Data +itsB T%ere !re two d!t! p!(lo!ds of 6; bits e!c%0

"tealing lags B Indic!tes w%et%er t%e burst is bein& used for #oice/d!t! ,set to 7- or if t%e burst is bein&
http://www.gsmfordummies.com/tdma/tdma.shtml#sbursthttp://www.gsmfordummies.com/tdma/tdma.shtml#sburst


24/95

stolen b( t%eF##*to be used for sin&!llin& ,set to 1-0 9T%e FA$$) is discussed in t%e *o&ic!l

$%!nnels

Training "e*uenceB T%e tr!inin& sequence bits !re used to o#ercome multiBp!t% f!din& !nd prop!&!tion

effects t%rou&% ! met%od c!lled e+uali,ation0

9Note> ='.. TS 460771 St!nd!rd does not describe ste!lin& bits5 !nd inste!d !llows for two 63Bbit d!t!p!(lo!ds in ! burst0 )owe#er5 it is common pr!ctice in 'SM networks to use 6;Bbit p!(lo!ds !nd ste!lin&

bits0

T%is di!&r!m illustr!tes ! sin&le burst inside ! time slot0 emember t%!t 30:6 bits !re not used in order to

!llow for ! &u!rd time0

+urst within a Time "lot

Since e!c% burst %!s two 6;Bbit d!t! se&ments5 we c!n see t%!t ! sin&le burst %!s ! d!t! p!(lo!d of 114

bits0

re*uenc! Correction +urst

T%is burst is used for frequenc( s(nc%roni+!tion of t%e mobile st!tion0 It is !n unmodul!ted c!rrier t%!t

s%ifts in frequenc(0 It %!s t%e s!me &u!rd time !s ! norm!l bit ,30:6 bits-0 T%e bro!dc!st of t%e F" usu!ll(

occurs on t%e lo&ic!l c%!nnelF##*0

9T%e F$$) is discussed in t%e *o&ic!l $%!nnels

re*uenc! Correction +urst

"!nchroni2ation +urst


25/95

T%is burst is used for time s(nc%roni+!tion of t%e mobile0 T%e d!t! p!(lo!d c!rries t%e TDMAFrae

'uber (F')!nd t%eBase Station dentity #ode (BS#)0

"!nchroni2ation +urst

It is bro!dc!st wit% t%e frequenc( correction burst0 T%e S(nc%roni+!tion "urst is bro!dc!st on

t%e Sync"roni,ation #"annel (S#*)0

Access +urst

T%is burst is used t%e b( mobile st!tion for r!ndom !ccess0 It %!s ! muc% lon&er &u!rd period ,30:6 bits

comp!red to t%e 30:6 bits in ! norm!l burst-0 It is desi&ned to compens!te for t%e unknown dist!nce of t%e

mobile st!tion from t%e tower5 w%en t%e MS w!nts !ccess to ! new "TS5 it will not know t%e

correct -iing dvance0

9T%e A$) is discussed in t%e *o&ic!l $%!nnels Tutori!l

Access +urst

Calculating the Data Throughput

Since e!c% burst %!s two 6;Bbit d!t! se&ments5 we c!n see t%!t ! sin&le burst %!s ! d!t! p!(lo!d of 114

bits0E!c% burst l!sts 6;02 Gs5 so we c!n c!lcul!te t%e t%eoretic!l bit r!te of ! sin&le time slot>

114 bits 6;02 Gs ? 012; bits/Gs ,$!lcul!tin& bits per Gs-7 012; bits/Gs H 157775777 ? 12;57; bits/sec nbspJ ,$on#ertin& Gs to sec-

Since t%ere !re 3 time slots per c!rrier frequenc(5 e!c% time slot would onl( &et 1/3 of t%is bit r!te5 so000

12;57; bits 3 ? :45;77 bits ,$!lcul!tin& bit r!te for one of ei&%t time slots0-

:45;77 bits 1777 ? :40; kbits/sec ,$on#ertin& bits to kilobits-

So5 usin& 'MS< modul!tion t%ere is ! m!imum bit r!te of :40; kb/s for ! sin&le time slot0 Note t%!t t%is

bit r!te does not !ccount for !n( error correction bits0 An( bits used for error correction would %!#e to be


26/95

stolen from t%e 114Bbit d!t! p!(lo!d of e!c% burst0

TDMA rame "tructure & 3ierarch!

TDMA rame

E!c% sequence of 3 time slots is known !s ! TDMA fr!me0 T%e dur!tion of ! TDMA fr!me is 4016

milliseconds ,ms- ,6;02 Gs H 3-0

9 emember t%!t ! TDMA fr!me is 3 time slots !nd t%!t no one resource will be &i#en !n entire TDMA

fr!me5 t%e resources must s%!re t%em0

A TDMA rame

Multirame

A Multifr!me is composed of multiple TDMA fr!mes0

T%ere !re two t(pes of multifr!mes>

Control Channel Multirames Traic Channel Multirames

9$ontrol $%!nnels !nd Tr!ffic $%!nnels !re epl!ined in *o&ic!l $%!nnels

Control Channel Multirame

composed of 61 TDMA fr!mes dur!tion ? :=604 ms


27/95

Control Channel Multirame

Traic Channel Multirame

composed of : TDMA fr!mes dur!tion ? 1:7 ms


28/95

Traic Channel Multirame

)ere is ! di!&r!m comp!rin& t%e $ontrol $%!nnel multifr!me !nd ! tr!ffic c%!nnel multifr!me0

Traic Channel and Control Channel Multirames

T%e net di!&r!m s%ows ! Tr!ffic $%!nnel ,T$)- Multifr!me wit% TS: ,&reen- bein& !lloc!ted to !Mobile St!tion ,MS-0 T%e red !rrow indic!tes t%e sequence of tr!nsmission0 T%e sequence st!rts in

TDMA fr!me 7 !t TS75 proceeds t%rou&% !ll ei&%t time slots5 t%en st!rts !&!in wit% TDMA fr!me 10

In t%is e!mple5 t%e MS %!s been !lloc!ted ! Tr!ffic $%!nnel in TS:0 T%erefore t%e MS will onl(

tr!nsmit/recei#e durin& TS: of e!c% TDMA fr!me0


29/95

"ingle Time "lot Allocated

"uperrame

A Superfr!me is composed of multiple Multifr!mes0

A&!in5 t%ere is ! superfr!me for $ontrol $%!nnels !nd one for Tr!ffic $%!nnels0

Control Channel "uperrame

composed of : $ontrol $%!nnel ,$$)- multifr!mes ,e!c% $$) multifr!me %!s 61 TDMA fr!mes- dur!tion ? 01: seconds

Traic Channel "uperrame

composed of 61 Tr!ffic $%!nnel ,T$)- multifr!mes ,e!c% T$)- multifr!me %!s : TDMA fr!mes- dur!tion ? 01: seconds

E!c% superfr!me5 w%et%er it is ! $$) or T$) fr!me5 consists of 1=: TDMA fr!mes ,61 9 :-

9Note> T%e $$) !nd T$) fr!me sequences will s(nc%roni+e e#er( superfr!me0

3!per rame

A %(perfr!me is composed of :743 super fr!mes0

dur!tion ? =% :3m 6=s ;ms ,1:56==0; seconds-

consists of :5;16543 TDMA fr!mes

E!c% TDMA fr!me is numbered !ccordin& to its sequence wit%in t%e %(perfr!me5 st!rtin& from 7 !nd

endin& !t :5;1654;0

T%e TDMA fr!me number wit%in ! %(perfr!me is !bbre#i!ted FN0 T%e FN is one of t%e #!ri!bles used in

'SM encr(ption !l&orit%ms0


30/95

T%e followin& di!&r!m s%ows t%e rel!tions%ip between !ll of t%e #!rious time se&ments introduced in t%is

tutori!l0

$elationship o All Time "egments


31/95

Logical Channels

Si&n!lin& $%!nnels "ro!dc!st $%!nnels ,"$$) F$$) S$) $"$)- $ommon $ontrol

$%!nnels ,.$) A$) A'$)-

SD$$) Associ!ted $ontrol $%!nnels ,FA$$) SA$$)- Si&n!l $%!nnel M!ppin&

Tr!ffic $%!nnels Encoded Speec% D!t! Tr!ffic $%!nnel M!ppin& AF$N

M!ppin& Frequenc( )oppin&

Introduction

'SM di#ides up e!c% AF$N into 3 time slots0

T%ese 3 timeslots !re furt%er broken up into lo&ic!l c%!nnels0

*o&ic!l c%!nnels c!n be t%ou&%t of !s Kust different t(pes of d!t! t%!t is tr!nsmitted onl( on cert!in fr!mes

in ! cert!in timeslot0

Different time slots will c!rr( different lo&ic!l c%!nnels5 dependin& on t%e structure t%e "SS uses0

T%ere !re two m!in c!te&ories of lo&ic!l c%!nnels in 'SM>

.4 "ignaling Channels

54 Traic Channels (TC3)

"ignaling Channels

T%ese !re t%e m!in t(pes of si&n!lin& $%!nnels>+roadcast Channels (+C3)B Tr!nsmitted b( t%e "TS to

t%e MS0 T%is c%!nnel c!rries s(stem p!r!meters needed to identif( t%e network5 s(nc%roni+e time !nd

frequenc( wit% t%e network5 !nd &!in !ccess to t%e network0

Common Control Channels (CC3)B Used for si&n!lin& between t%e "TS !nd t%e MS !nd to request

!nd &r!nt !ccess to t%e network0

"tandalone Dedicated Control Channels ("DCC3)B Used for c!ll setup0

Associated Control Channels (ACC3)B Used for si&n!lin& !ssoci!ted wit% c!lls !nd c!llBsetup0 An

A$$) is !lw!(s !lloc!ted in conKunction wit% ! T$) or ! SD$$)0

9keep in mind5 t%ese !re onl( c!te&ories of lo&ic!l c%!nnels5 t%e( !re not lo&ic!l c%!nnels t%emsel#es0
http://www.gsmfordummies.com/tdma/logical.shtml#schhttp://www.gsmfordummies.com/tdma/logical.shtml#cbchhttp://www.gsmfordummies.com/tdma/logical.shtml#ccchhttp://www.gsmfordummies.com/tdma/logical.shtml#ccchhttp://www.gsmfordummies.com/tdma/logical.shtml#schhttp://www.gsmfordummies.com/tdma/logical.shtml#cbchhttp://www.gsmfordummies.com/tdma/logical.shtml#ccchhttp://www.gsmfordummies.com/tdma/logical.shtml#ccch


32/95

T%e !bo#e c!te&ories c!n be di#ided into t%e followin& lo&ic!l c%!nnels>

+roadcast Channels (+C3)

"ro!dc!st $ontrol $%!nnel ,"$$)-

Frequenc( $orrection $%!nnel ,F$$)- S(nc%roni+!tion $%!nnel ,S$)-

$ell "ro!dc!st $%!nnel ,$"$)-

Common Control Channels (CCC3)

.!&in& $%!nnel ,.$)-

!ndom Access $%!nnel ,A$)-

Access 'r!nt $%!nnel ,A'$)-

Dedicated Control Channel (DCC3)

St!nd!lone Dedic!ted $ontrol $%!nnel ,SD$$)-

F!st Associ!ted $ontrol $%!nnel ,FA$$)-

Slow Associ!ted $ontrol $%!nnel ,SA$$)-

+roadcast Channels (+C3)

+roadcast Control Channel (+CC3)B DLN*IN< B T%is c%!nnel cont!ins s(stem p!r!meters needed

to identif( t%e network !nd &!in !ccess0 T%ese p!r!meters include t%e *oc!tion Are! $ode ,*A$-5 t%e

Mobile Network $ode ,MN$-5 t%e frequencies of nei&%borin& cells5 !nd !ccess p!r!meters0

re*uenc! Correction Channel (CC3)B DLN*IN< B T%is c%!nnel is used b( t%e MS !s !frequenc( reference0 T%is c%!nnel cont!ins frequenc( correction bursts0

"!nchroni2ation Channel ("C3)B DLN*IN< B T%is c%!nnel is used b( t%e MS to le!rn t%e "!se

St!tion Inform!tion $ode ,"SI$- !s well !s t%e TDMA fr!me number ,FN-0 T%is lets t%e MS know w%!tTDMA fr!me t%e( !re on wit%in t%e %(perfr!me0

9 T%e "SI$ w!s co#ered in t%e Introduction to 'SM Tutori!l0 ou c!n !lso re!d !bout

t%e numberin& sc%emes used in 'SM0

Cell +roadcast Channel (C+C3)B DLN*IN< B T%is c%!nnel is not trul( its own t(pe of lo&ic!l

c%!nnel0 T%e $"$) is forpoint.to.onipointmess!&es0 It is used to bro!dc!st specific inform!tion to

network subscribersJ suc% !s we!t%er5 tr!ffic5 sports5 stocks5 etc0 Mess!&es c!n be of !n( n!ture dependin&

on w%!t ser#ice is pro#ided0 Mess!&es !re norm!ll( public ser#ice t(pe mess!&es or !nnouncements0 T%e

$"$) isnt !lloc!ted ! slot for itself5 it is !ssi&ned to !n SD$$)0 It onl( occurs on t%e downlink0 T%e

$"$) usu!ll( occupies t%e second subslot of t%e SD$$)0 T%e mobile will not !cknowled&e !n( of t%e

mess!&es0


33/95

Common Control Channels (CCC3)

0aging Channel (0C3)B DLN*IN< B T%is c%!nnel is used to inform t%e MS t%!t it %!s incomin&

tr!ffic0 T%e tr!ffic could be ! #oice c!ll5 SMS5 or some ot%er form of tr!ffic0

$andom Access Channel ($AC3)B U.*IN< T%is c%!nnel is used b( ! MS to request !n initi!l

dedic!ted c%!nnel from t%e "TS0 T%is would be t%e first tr!nsmission m!de b( ! MS to !ccess t%e

network !nd request r!dio resources0 T%e MS sends !n ccess Burston t%is c%!nnel in order to request

!ccess0

Access #rant Channel (A#C3)B DLN*IN< B T%is c%!nnel is used b( ! "TS to notif( t%e MS of t%e!ssi&nement of !n initi!l SD$$) for initi!l si&n!lin&0

Dedicated Control Channels (DCC3)

"tandalone Dedicated Control Channel ("DCC3)B U.*IN


34/95

CC3 6 "C3 6 +CC3 6 CCC3

Downlink

'plink

+CC3 6 CCC3

Downlink

'plink


35/95

CC3 6 "C3 6 +CC3 6 CCC3 6 "DCC37(-448) 6 "ACC3C7(-448)

T%e SA$$) t%!t is !ssoci!ted wit% e!c% SD$$) is onl( tr!nsmitted e#er( ot%er multifr!me0 E!c%

SA$$) onl( &ets %!lf of t%e tr!nsmit time !s t%e SD$$) t%!t it is !ssoci!ted wit%0 So5 in one

multifr!me5 SA$$)7 !nd SA$$)1 would be tr!nsmitted5 !nd in t%e net multifr!me5 SA$$): !nd

SA$$)= would be tr!nsmitted0 T%e two sequenti!l multifr!mes would look like t%is>

Downlink

'plink

ou will !lso notice t%!t t%e downlink !nd uplink multifr!mes do not !li&n wit% e!c% ot%er0 T%is is done

so t%!t if t%e "TS sends !n inform!tion request to t%e MS5 it does not %!#e to w!it !n entire multifr!mes

to recei#e t%e needed inform!tion0 T%e uplink is tr!nsmitted 16 TDMA fr!mes be%ind t%e downlink0 For

e!mple5 t%e "TS mi&%t send !n !ut%entic!tion request to t%e MS on SD$$)7 ,downlink- w%ic%corresponds to TDMA fr!mes ::B:60 T%e MS t%en %!s enou&% time to process t%e request !nd repl( on

SD$$)7 ,uplink- w%ic% immedi!tel( follows it on TDMA fr!mes =;B470


36/95

"DCC3/(- 49) 6 "ACC3C/ (-4 9)

nce !&!in5 t%e SA$$) t%!t is !ssoci!ted wit% !n SD$$) is onl( tr!nsmitted e#er( ot%er multifr!me0

Two consecuti#e multifr!mes would look like t%is>

Downlink

'plink

Traic Channels (TC3)

Tr!ffic $%!nnels !re used to c!rr( two t(pes of inform!tion to !nd from t%e user>

ncoded "peech

Data

T%ere !re two b!sic t(pes of Encoded Speec% c%!nnels>

ncoded "peechB Encoded speec% is #oice !udio t%!t is con#erted into di&it!l form !nd compressed0 See

t%e Speec% Encodin& tutori!l to see t%e process0

ull $ate "peech TC3 (TC3")B 1= kb/s

3al $ate "peech TC3 (TC33")B 60 kb/s

DataB D!t! refers to user d!t! suc% !s tet mess!&es5 picture mess!&es5 internet browsin&5 etc0 It includes

prett( muc% e#er(t%in& ecept speec%0

ull rate Data TC3 (TC3.74.)B 1404 kb/s

ull rate Data TC3 (TC3,4:)B 20 kb/s

ull rate Data TC3 (TC374/)B 403 kb/s

3al rate Data TC3 (TC374/)B 403 kb/s

ull rate Data TC3 (TC3547)B O:04 kb/s


37/95

3al rate Data TC3 (TC33547)B O:04 kb/s

Traic Channel Mapping

Time slots : t%rou&% ; !re norm!ll( used for Tr!ffic $%!nnels ,T$)-

Tr!ffic $%!nnel Multifr!mes !re composed of onl( : TDMA fr!mes0 n e!c% multifr!me5 t%ere !re :4

fr!mes for Tr!ffic $%!nnels5 1 fr!me for ! SA$$)5 !nd t%e l!st fr!me is Idle0 emember t%!t ! MS ,or

ot%er de#ice- onl( &ets one time slot per TDMA fr!me to tr!nsmit5 so in t%e followin& di!&r!ms we !re

lookin& !t ! sin&le time slot0

ull $ate Traic Channel (TC3")

L%en usin& )!lfB!te Speec% Encodin& ,T$)/)S-5 t%e speec% encodin& bit r!te is 60 kb/s5 so one time

slot c!n %!ndle two %!lfBr!te c%!nnels0 In t%is c!se5 one c%!nnel will tr!nsmit e#er( ot%er TDMA fr!me5

!nd t%e ot%er c%!nnel would be tr!nsmitted on t%e ot%er fr!mes0 T%e fin!l fr!me ,:6-5 w%ic% is norm!ll(

used !s !n Idle fr!me5 is now used !s ! SA$$) for t%e second %!lfBr!te c%!nnel0

3al $ate Traic Channel (TC33")


38/95

A$CN Mapping

T%is di!&r!m s%ows ! s!mple Multifr!me wit% lo&ic!l c%!nnels m!pped to time slots !nd TDMA fr!mes0

T%is is Kust one possible confi&ur!tion for !n AF$N0

9For illustr!ti#e purposes5 %!lf of t%e tr!ffic c%!nnels !re fullBr!te !nd t%e ot%er %!lf !re %!lfBr!te

Si&n!lin& time slot 7 P 1 M!ppin&B

TS7

TS1

em!inin& T$) time slot m!ppin&B

TS:

TS=

TS4

TS6


39/95

TS

TS;

9emember t%!t $$) Multifr!mes %!#e 61 fr!mes !nd T$) Multifr!mes onl( %!#e :0 T%eir sequences

will s(nc%roni+e e#er( super fr!me0

;set

E#en t%ou&% 'SM uses ! full duple r!dio c%!nnel5 t%e MS !nd t%e "TS do not tr!nsmit !t t%e e!ct s!me

time0 If ! MS is !ssi&ned ! &i#en time slot5 bot% t%e MS !nd t%e "TS will tr!nsmit durin& t%!t &i#en time

slot5 but t%eir timin& is offset0 T%e uplink is e!ctl( = time slots be%ind t%e downlink0 For e!mple5 if t%e

MS w!s !lloc!ted ! T$) on TS=5 t%e "TS would tr!nsmit w%en t%e downlink is on TS= !nd t%e MS is set

to recei#e on TS=0 At t%is point5 t%e uplink is onl( on TS70 nce t%e uplink re!c%es TS=5 t%e MS would

be&in to tr!nsmit5 !nd t%e "TS is set to recei#e on TS=0 At t%is point5 t%e downlink would be !t TS0

L%en t%e MS is not tr!nsmittin& or recei#in&5 it switc%es frequencies to monitor t%e "$$) of !dK!cent

cells0

"peech Data Throughput

L%en lookin& !t ! Time slot !lloc!ted to ! T$)5 (ou will notice t%!t T$) does not occur on e#er( sin&lefr!me wit%in ! time slot0 T%ere is one reser#ed for ! SA$$) !nd one t%!t is Idle0 So5 in ! T$)

Multifr!me5 onl( :4 of t%e : fr!mes !re used for tr!ffic ,#oice/d!t!-0 T%is le!#es us wit% ! d!t!


40/95

t%rou&%put of ::03 kb/s0

T%e m!t%>

.4 Calculate %its per TC3 Multirames. The MS is c$rrently sitting on "TS* in Location Area . As the MS

moves to3ar!s the e!ge o6 the location area8 it meas$res "TS* as )eing strongeran! !eci!es to s3itch to that "TS. Since "TS* is in another location area8 it 3ill

nee! to !o a location $!ate.

Stes (nvolve!*

. Channel %e5$est

. Gaining 4L% re5$ests !ata 6rom Losing 4L%

. Location U!ate

. U!ating the %egisters

. Channel %e5$est


73/95

$st li#e the (MS( Attach8 an! every other time the MS re5$ests access8 it goes

thro$gh the same roce!$res.

. The MS re5$ests a channel )y sen!ing a C"annel (eque#t9C1AN%E-: message

on the %AC1.

. The "TS reson!s )y sen!ing an Immediate A##i%nment Commandmessage9(MMASSCMD: on the AGC1.

. The MS s3itches to the assigne! SDCC1 an! relies 3ith a Location Update

(eque#t9L+CU'D%E-:. (ncl$!e! in the L+CU'D%E- is the TMS( the MS is

c$rrently $sing as 3ell as the Location Area Identi$er9LA(: o6 the 4L% it is leaving.

. The "TS ac#no3le!ges receit o6 the message.

. Gaining 4L% re5$ests !ata 6rom Losing 4L%

K. The "SS 6or3ar!s the Location U!ate %e5$est to the gaining MSC/4L%.

. The gaining MSC/4L% !oes not recogniJe the TMS(/(MS( o6 the MS8 so it contacts

the losing MSC/4L% that correson!s to the LA( that 3as rovi!e! )y the MS. The

ne3 MSC/4L% re5$ests the s$)scri)er !ata 6or the given TMS(.O. The gaining MSC/4L% 3ill then a$thenticate the MS. There are t3o 3ays this

co$l! occ$r. First8 the losing MSC/4L% may have 6or3ar!e! any sets o6 trilets that it

3as retaining 6or the MS. The gaining MSC/4L% 3o$l! then $st $se the ne;t set o6

trilets. Secon!8 the gaining MSC/4L% co$l! contact the 1L% an! re5$est

a$thentication trilets 6rom the A$C an! rocee! 3ith a$thentication that 3ay.

The a$thentication an! encrytion rocess is not sho3n here. (t occ$rs the same

3ay as in the (MS( Attach. For more in6ormation8 see the Encrytion an!

A$thentication T$torial.


74/95

. Location U!ate

. +nce the MS has )een a$thenticate! an! is in Ciher Mo!e8 the MSC/4L% sen!s a

Location U!ate Accet message 9L+CU'DACC: thro$gh the "SS to the MS. The

L+CU'DACC may have a TMS( assignment in it8 other3ise the TMS( 3ill )e

assigne! in a TMS(%EALCMD message.

P. The MS 3ill reson! 3ith a TMS( %eallocation Comlete message

9TMS(%EALC+M: in!icating it has receive! the TMS(.

. The "SS then sen!s the MS a Channel %elease message 9C1AN%EL: instr$cting

it to go into i!le mo!e. The "SS then $nassigns the SDCC1. As 6ar as the MS is

concerne!8 the location $!ate has )een comlete!.


75/95

. U!ating the %egisters

The Gaining MSC/4L% sen!s an Update Locationmessage to the 1L%. The 1L%

$!ates its recor!s to oint to the gaining MSC/4L% 3hen it is as#e! 6or its location.

(t also asses on s$)scri)er in6ormation 6or the MS to the gaining MSC/4L%.

The 1L% sen!s a Cancel Locationmessage to the losing MSC/4L%. The losingMSC/4L% !eletes the MS>s recor! an! also releases the TMS( 6or reassignment. The

losing MSC/4L% sen!s a Cancel Location (e#ultmessage )ac# to the 1L%8

con2rming the cancellation.


76/95

Mo%ile ;riginated Call

A Mo%ile ;riginated Call is a call that is initiated %! the M"4 The ollowing e@ample is a mo%ile=

originated call that terminates outside the 0LMN4

"teps Involved-

.4 $e*uest Access

54 Authentication

84 Initial Call "etup

74 Call "etup

?4 Call sta%lishment

:4 Call Termination

.4 $e*uest Access

. The MS sen!s a C"annel (eque#t9C1AN%E-: message on the %AC1.

. The "SS reson!s 3ith a ra!io reso$rce assignment 9(MMASSCMD: on the

AGC1.

. The MS sen!s a Ser'ice (eque#t9CMSE%4%E-: message to the "SS on the

SDCC1.

54 Authentication

. "e6ore the net3or# 3ill rovi!e any services to the MS8 the net3or# 3ill re5$ire

the MS to a$thenticate itsel6. The "SS sen!s anAut"entication (eque#t9AUT1%E-:

message to the MS. The %AND serves as the challenge 6or a$thentication.

K. The MS calc$lates the roer S%ES )ase! on the %AND that 3as given an! sen!sthe S%ES to the "SS in anAut"entication (e#pon#e9AUT1%ES': message.

. The "SS veri2es the S%ES. (6 the S%ES is correct then the MS is a$thenticate! an!

allo3e! access to the net3or#. The "SS 3ill sen! a Ser'ice Accept9CMSE%4ACC:

message letting the MS #no3 that the service re5$est 3as receive! an! rocesse!.

O. +nce a$thenticate!8 the "SS or!ers the MS to s3itch to ciher mo!e 3ith the

C('1M+DCMD message.


77/95


78/95

1:0 T%e MS$ sends !nnitial ddress Message ,IAM- to t%e 'MS$0 T%e IAM cont!ins t%e MSISDN of

t%e c!lled p!rt( !s t%e MS di!led it0

T%e MS$ will !lso send ! $!ll .roceedin& ,$A**R.$- mess!&e down to t%e "SS !nd t%is is w%en t%e

"SS would !ssi&n ! T$) to t%e MS5 !s described in step 17 !bo#e0

1=0 "!sed on t%e di!led number5 t%e 'MS$ decides w%ere to route t%e IAM wit%in t%e .STN0140 T%e .STN will continue to route t%e IAM until it re!c%es t%e correct Switc%in& $enter !nd t%e c!ll

routin& is complete0 T%e .STN will t%en est!blis% t%e c!ll circuit !nd send !n ddress #oplete

Message,A$M- b!ck to t%e 'MS$0

160 T%e 'MS$ t%en forw!rds t%e A$M b!ck to t%e responsible MS$ indic!tin& t%!t t%e c!ll circuit %!s

been est!blis%ed0

?4 Call sta%lishment

10 nce t%e MS$ recei#es t%e A$M5 it sends !n A*ET mess!&e to t%e MS indic!tin& t%!t t%e c!ll is

&oin& t%rou&%0 T%e "SS sends t%e A*ET mess!&e on t%e FA$$)0 nce t%e MS recei#es t%e A*ET5 it

will &ener!te t%e rin&in& sound in t%e e!rpiece0 T%e "SS sends !n !lertin& mess!&e t%e subscriber will

%e!r t%e line rin&in&01;0 nce t%e c!lled p!rt( !nswers t%e p%one5 t%e .STN will send !n Answer mess!&e to t%e MS$0 T%e

MS$ forw!rds t%is to t%e MS in ! #onnection,$N- mess!&e0

130 nce t%e MS recei#es t%e $N mess!&e5 it switc%es o#er to #oice !nd be&ins t%e c!ll0 All #oice tr!ffic

occurs on t%e !ssi&ned T$)0

:4 Call Termination


79/95

120 L%en eit%er t%e c!ller or t%e c!lled p!rt( %!n&s up5 t%e c!ll will be disconnected0 Eit%er p!rt( c!n

initi!te t%e disconnect0 In t%is e!mple5 t%e MS initi!tes t%e disconnect0 T%e MS sends

!%isconnect,DIS$- mess!&e to t%e "TS on t%e FA$$)0

:70 T%e "SS forw!rds t%e DIS$ to t%e MS$0 nce t%e MS$ recei#es t%e DIS$ mess!&e5 it sends

!Release,E*- mess!&e t%rou&% t%e 'MS$ to t%e .STN !s well !s down t%rou&% t%e "SS to t%e MS0

:10 T%e MS responds b( sendin& ! ele!se $omplete ,E*R$M- mess!&e to t%e "SS on t%e FA$$)0

T%e "SS forw!rds t%e E*R$M mess!&e up to t%e MS$0 nce t%e MS$ recei#es t%e E*R$M

mess!&e t%e c!ll is considered ended from t%e call controlperspecti#e0

:10 Alt%ou&% t%e c!ll %!s ended5 t%e "SS still %!s ! T$) !lloc!ted to t%e MS0 T%e MS$ sends ! #"annel

Release,$)ANRE*- mess!&e to t%e "SS0 T%e "SS forw!rds t%e $)ANRE* mess!&e to t%e MS0

::0 T%e MS responds wit% ! DIS$ ,*A.Dm- mess!&e !nd returns to !n idle mode0 T%e "SS de!lloc!tes

t%e c%!nnel !nd rele!ses t%e TQ0

Mo%ile Terminated Call


80/95

The termMobile Terminated Callreers to when the M" is the receiver o a call4 In this e@ampleB the

call is originating rom outside the 0LMN4

"teps Involved=

.4 $oute sta%lishment

54 0aging the Mo%ile "tation

84 Initial "etup

74 Authentication

?4 sta%lishing a Channel

:4 Call "etup

94 sta%lishing the Call

/4 Disconnecting the Call

.4 $oute sta%lishment

10 T%e c!llin& p!rt( di!ls t%e MSISDN for t%e mobile subscriber0 T%e .STN identifies t%e network

,.*MN- t%!t t%e di!led MSISDN belon&s to !nd will loc!te ! 'MS$ for t%!t network0 T%e .STN sends

!nnitial ddressmess!&e to t%e 'MS$0

:0 T%e 'MS$ forw!rds t%e MSISDN to t%e )* !nd requests routin& inform!tion for it0 T%e )* looks

up t%e MSISDN !nd determines t%e IMSI !nd t%e SS0!ddress for t%e MS$/V* t%!t is ser#icin& t%e

MS0

=0 T%e )* t%en cont!cts t%e ser#icin& MS$/V* !nd !sks it to !ssi&n ! Mobile St!tion outin& Number

,MSN- to t%e c!ll0

40 T%e MS$/V* !lloc!tes t%e MSN !nd forw!rds it to t%e )*0

9Note> It is import!nt to remember t%!t t%e MS$/V* !ssi&ns ! MSN to t%e callnot to t%e MS itself0

60 T%e )* forw!rds t%e MSN !s well !s routin& inform!tion for t%e ser#icin& MS$/V* to t%e

'MS$0


81/95

0 T%e 'MS$ sends !n Initi!l Addressin& mess!&e to t%e ser#icin& MS$/V* !nd uses t%e MSN to

route t%e c!ll to t%e MS$/V*0 nce t%e ser#icin& MS$/V* recei#es t%e c!ll5 t%e MSN c!n be

rele!sed !nd m!( be m!de !#!il!ble for re!ssi&nment0

9Note> T%is is implement!tion dependent0

54 0aging the Mo%ile "tation

;0 T%e MS$/V* t%en orders !ll of its "S$s !nd "TSs to p!&e t%e MS0 Since t%e MS$/V* does not

know e!ctl( w%ic% "S$ !nd "TS t%e MS is monitorin&5 t%e p!&e will be sent out !cross t%e entire

*oc!tion Are!0

84 Initial "etup

30 T%e MS recei#es t%e/age Re+uest,.A'RE- on t%e .$)0 T%e MS reco&ni+es t%!t t%e p!&e is

intended for it5 b!sed on ! TMSI or !n IMSI0

20 T%e MS sends ! #"annel Re+uest,$)ANRE- mess!&e on t%e A$)0

170 T%e "SS responds on t%e A'$) b( sendin& !nediate ssignent,IMM ASS- mess!&e w%ic%

!ssi&ns !n SD$$) to t%e MS0


82/95

At t%is point5 t%e network does not know t%!t t%e MS is t%e one t%!t it is p!&in&J it onl( knows t%!t t%is

MS w!nts !ccess to t%e network0

110 T%e MS immedi!tel( switc%es to t%e !ssi&ned SD$$) !nd sends !/aging Response,.A'RES-

mess!&e on t%e SD$$)0 T%is lets t%e network know t%!t t%e MS is respondin& to its p!&e0

74 Authentication

1:0 "efore t%e network will pro#ide !n( ser#ices to t%e MS5 t%e network will require t%e MS to

!ut%entic!te itself0 T%e "SS sends !nut"entication Re+uest,AUT)RE- mess!&e to t%e MS0 T%e

AND ser#es !s t%e c%!llen&e for !ut%entic!tion0

1=0 T%e MS c!lcul!tes t%e proper SES b!sed on t%e AND t%!t w!s &i#en !nd sends t%e SES to t%e

"SS in !nut"entication Response,AUT)RES.- mess!&e0

140 T%e "SS #erifies t%e SES0 If t%e SES is correct t%en t%e MS is !ut%entic!ted !nd !llowed !ccess to

t%e network0

160 nce t%e MS$/V* %!s !ut%entic!ted t%e MS5 it will order t%e "SS !nd MS to switc% to cip%er mode

usin& t%e $I.)RMDR$MD mess!&e0 nce t%e MS in in encr(ption mode5 t%e V* will norm!ll(

!ssi&n ! new TMSI to t%e MS0

?4 sta%lishing a Channel


83/95

10 nce t%e MS is !ut%entic!ted !nd in encr(ption mode5 T%e MS$ sends ! Setup Mess!&e to t%e "SS5

t%e "SS forw!rds t%e SETU. mess!&e to t%e MS on t%e !ssi&ned SD$$)0t%e !ssi&ned SD$$)0 T%e

SETU. mess!&e m!( include t%e#alling !ine dentification /resentation,$*I.-5 w%ic% is essenti!ll(

c!ller ID0

1;0 T%e MS responds b( sendin& ! #all #onfired,$A**R$N- mess!&eJ w%ic% indic!tes t%!t t%e MSis !ble to est!blis% t%e requested connection0 T%e "SS rel!(s t%e mess!&e up to t%e MS$0

:4 Call "etup

130 T%e "SS t%en sends !nssignent #oand,ASSR$MD- mess!&e to t%e MS on t%e !ssi&ned

SD$$)0 T%e ASSR$MD mess!&e !ssi&ns ! Tr!ffic $%!nnel ,T$)- to t%e MS0

120 T%e MS immedi!tel( switc%es to t%e T$) !nd responds wit% !n ssignent #oplete,ASSR$M-

mess!&e on t%e FA$$)0 T%e MS be&ins rin&in& once it %!s est!blis%ed t%e T$)0

9emember t%!t !ll si&n!lin& t%!t occurs on t%e tr!ffic c%!nnel !ctu!ll( occurs on ! FA$$)5 w%ic% is !

time slot t%!t is stolen from t%e T$) !nd used for si&n!lin&0

:70 T%e MS sends !n A*ET mess!&e to t%e MS$ on t%e FA$$)0 T%e "SS forw!rds t%e A*ET

mess!&e t%rou&% t%e .STN to t%e c!llin& p!rt( !nd t%e c!ller %e!rs t%e line rin&in&0

94 sta%lishing the Call


84/95

:10 nce t%e user !nswers t%e c!ll ,b( pressin& t%e send button-5 t%e MS will send ! #onnect$N

mess!&e to t%e MS$0 T%e $onnect mess!&e is forw!rded b!ck to t%e c!llerCs switc% to !cti#!te t%e c!ll0

::0 T%e MS$ sends ! #onnect c$nowledge$NRA$< mess!&e to t%e MS !nd t%e c!ll is est!blis%ed0

/4 Disconnecting the Call

:=0 A disconnect %!ppens t%e s!me w!( !s for !n( ot%er c!ll0 In t%is e!mple5 t%e c!llin& p!rt( initi!tes

t%e disconnect0

:40 L%en t%e c!llin& p!rt( %!n&s up5 t%e c!llin& p!rt(Cs switc% initi!tes !Release,E*- mess!&e0 T%e

mess!&e is forw!rded to t%e ser#in& MS$5 w%ic% is t%en forw!rded to t%e "SS0

:60 T%e "SS will send !%isconnect,DIS$- mess!&e to t%e MS on t%e FA$$)0

:0 T%e MS confirms rele!se of t%e c!ll b( sendin& !Release,E*- mess!&e on t%e FA$$)5 w%ic% is

forw!rded to t%e MS$0

:;0 T%e MS$ sends eRelease #oplete,E*R$M- mess!&e t%rou&% t%e "SS to t%e MS0 As f!r !s c!ll

control ,$$- is concerned5 t%e connection %!s been termin!ted0

:30 T%e MS still %!s ! T$) !ssi&ned to it5 so t%e "SS sends ! #"annel Release,$)ANRE*- mess!&e to

t%e MS0 T%is rele!ses t%e r!dio resource on t%e Air Interf!ce0

:20 T%e MS responds be sendin& ! fin!l %isconnectmess!&e !nd returns to idle0

Cell Selection an! %eselection


85/95

Signal Strength %,-UAL Cell Selection an! %eselection C C Cell %eselection

+0set Cell %eselection 1ysteresis Cell "ar Access Cell "ar -$ali2er

T%ere !re m!n( f!ctors in#ol#ed in m!int!inin& t%e r!dio link ,Um interf!ce- between t%e Mobile St!tion

,MS- !nd t%e "!se Tr!nscei#er St!tion ,"TS-0 As t%e MS mo#es t%rou&%out t%e network t%e si&n!lstren&t% of t%e "TS will incre!se !nd decre!se !nd t%e MS will %!#e to continuousl( monitor t%e si&n!l

stren&t%s of ne!rb( towers !nd upd!te w%ic% "TSCs it c!mps on0 T%is p!&e co#ers !ll of t%e p!r!meters

t%!t t%e MS !nd network will use in order to ensure t%e t%e MS c%ooses t%e stron&est tower to monitor

!nd ot%er network consider!tions0

Signal Strength

T%e first !nd !r&u!bl( most import!nt consider!tion in r!dio link m!n!&ement is si&n!l stren&t%0 In 'SM

,!nd most ot%er F communic!tions- t%e st!nd!rd me!sure of si&n!l stren&t% is d"m ,decibels in

milliw!tts-0 T%e termreceived signal strengt" indicator,SSI- is often used but in 'SM t%e

term received.signal level ,Q*EV- is preferred0 T%e distinction is t%!t t%e term SSI w!s &ener!ll( used

on !n!lo& networks !nd Q*EV is used on di&it!l networks0 n t%is website SSI will be used for

&ener!l reference to si&n!l stren&t% !nd Q*EV for t%e !ctu!l #!lue t%!t is p!ssed o#er t%e network0

%,LE4

Q*EV is ! number from 7 to = t%!t corresponds to ! d"m #!lue r!n&e0 7 represents t%e we!kest si&n!l

!nd = t%e stron&est0

SSI below B117 d"m !re &ener!ll( considered unre!d!ble in 'SM0 SSI in t%e !re! of B67 d"m !re

r!rel( seen !nd would indic!te t%!t t%e MS is ri&%t net to t%e "TS0 T%e m!in f!ctor t%!t !ffects SSI is

dist!nce from t%e tower0 )owe#er5 ot%er f!ctors suc% !s terr!in5 ele#!tion5 !nd l!r&e obKects suc% !sbuildin&s c!n d!mpen si&n!l stren&t%0

%,-UAL

Alt%ou&% ! stron& SSI is desir!ble5 it does not &u!r!ntee ! qu!lit( si&n!l0 QUA* is ! #!lue t%!t

represents t%e qu!lit( of t%e recei#ed si&n!l0 T%e MS determines t%e "it Error !te ,"E- of t%e si&n!l

!nd reports it b!ck to t%e network0 T%e "E is simpl( ! percent!&e of t%e number of bits it recei#es t%!t

did not p!ss error c%eckin&0 T%e bits m!( %!#e been &!rbled !lon& t%e F p!t% or lost due to f!din& or

interference0 T%e %i&%er t%e "E t%e lower t%e si&n!l qu!lit(0 QUA* is &i#en !s ! number from 7 to ;

!nd represents ! percent!&e r!n&e of "E0


86/95

Cell Selection an! %eselection

$ell selection refers to t%e initialre&istr!tion t%!t ! MS will m!ke wit% ! network0 T%is norm!ll( onl(

occurs w%en t%e p%one powers up or w%en t%e MS ro!ms from one network to !not%er0

$ell reselection refers to t%e process of ! MS c%oosin& ! new cell to monitor once it %!s !lre!d( re&istered

!nd is c!mped on ! cell0 It is import!nt to distin&uis% t%!t selection !nd reselection !re done b( t%e MS

itself !nd not &o#erned b( t%e network0 T%e network would onl( be responsible for t%is function w%en t%e

MS is in ! Tr!ffic $%!nnel ,T$)-0 L%en t%e MS reselects ! new cell it will not inform t%e network t%!t it

%!s done so unless t%!t new cell is in ! new *oc!tion Are! ,*A-0

T%ere !re m!n( p!r!meters in#ol#ed in selection !nd reselection of ! new cell0 T%e MS must ensure it is

&ettin& t%e best si&n!l !nd t%e network must ensure t%!t t%e MS does not c!use unneeded str!in on t%e

network b( switc%in& cells w%en unnecess!r( or undesired0

C1

C1 is the path-loss parameter that is used to determine the strongest cell for selection. The MS will

calculate a C1 for each tower it can see and select the cell tower with the highest C1. The C1 uses the

following parameters for calculation:

T%e formul! for c!lcul!tin& $1 is &i#en !s>

$1 ? ,A- B M!,"57-

w%ere>

A ? ,Q*EV B *AM-

" ? MS Tr!nsmit .ower M! $$) BM! F utput of MS

At first t%is m!( seem complic!ted but if we e!mine t%e #!rious p!r!meters !nd %ow t%e( !ffect t%e $1

score t%en it becomes more cle!r0

A B T%is #!lue is merel( ! d" #!lue for t%e difference between w%!t SSI is required to select t%!t cell

!nd w%!t si&n!l stren&t% t%e MS sees t%e tower !t0 If t%e *AM is B117d" !nd t%e MS sees t%e tower !tB27d" t%en t%e #!lue of A is :7d"0 T%e %i&%er t%e #!lue of A t%e %i&%er t%e $1 !nd t%e more !ttr!cti#e

t%is tower will be to t%e MS0

" B ust bec!use ! MS c!n recei#e ! towerCs si&n!l does not me!n t%!t t%e MS %!s enou&% power to re!c%

t%!t tower0 T%e tower tells t%e MS w%!t m!imum power le#el t%!t t%e MS m!( use to tr!nsmit to t%!t

tower0 If t%e p%one is c!p!ble of tr!nsmittin& !t t%is power t%!n t%ere is no problem0 )owe#er5 w%!t if t%e

p%one c!nnot tr!nsmit !t t%!t power le#el T%e si&n!l from t%e MS m!( not %!#e enou&% power to re!c%


87/95


88/95

) ? 1 if t%e MS %!s been monitorin& ! p!rticul!r cell for less t%!n t%epenalty tie1

) ? 7 if t%e MS %!s been monitorin& t%e p!rticul!r cell for lon&er t%!n t%e pen!lt( time0

) ? 7 if t%e p!rticul!r cell is t%e ser#in& cell ,t%e one t%e MS is currentl( c!mped on-0

*etCs look !t !n e!mple to see %ow t%e tempor!r( offset works0 T%e followin& c%!rt s%ows two e!mple

cell towers !nd #!lues for $1 !nd $: p!r!meters0

T%e time pro&resses !s t%e MS mo#es !w!( from cell A !nd tow!rds cell "0 For s!ke of simplicit(5 we !re

!ssumin& t%!t t%e MS c!n tr!nsmit !t t%e m! power !llowed !nd t%!t neit%er cell is usin& $0

7 seconds B T%e MS is c!mped on cell A0 T%e MS c!lcul!tes t%e $: #!lue !s =30 Since t%e Q*EV for

cell " is not !bo#e t%e *AM t%e $1 ,!nd $:- !re below 70 A MS will not select ! cell wit% ! $1 below 7

!nd it will not reselect ! cell wit% ! $: below 70

17 seconds B T%e Q*EV for cell " meets t%e minimum t%res%old ,*AM-0 T%e MS st!rts ! timer !s

soon !s it puts it on its stron&est nei&%bor list0 T%e pen!lt( time for cell " is 47 seconds5 so for t%e first 47seconds t%!t cell " is on t%e stron&est nei&%bor list it will !ppl( t%e tempor!r( offset to t%e $: #!lue0

After includin& t%e offset5 t%e $: for cell " is B:7 d"m0

:7 seconds B T%e $: for cell A continues to drop !s t%e $: for cell " continues to rise0 Lit% ! $: of :65

cell A is still t%e most !ttr!cti#e0

=7 seconds B $ell A drops to ! $: of :1 !nd cell " %!s ! $: of B60

47 seconds B $ell A drops to ! $: of 130 $ell " rises to ! $: of =0 Notice %ere t%!t if it were not for t%e

tempor!r( offset5 t%e $: for cell " would be !t :=0 At t%is point t%e MS would norm!ll( reselect cell "0

)owe#er5 due to t%e tempor!r( offset5 cell A is still t%e most !ttr!cti#e0

67 seconds B At t%is point t%e pen!lt( time for cell " %!s epired !nd t%e tempor!r( offset is no lon&er

!pplied0 T%e $: for cell " r!ises from = to :;0 T%e $: for cell " wins o#er t%e $: for cell A !nd t%e MS

reselects cell "0


89/95

T%e tempor!r( offset would be used if t%e network w!nted to discour!&e mobile st!tions from reselectin&

! cell !s soon !s t%e MS s!w it0 T%is is commonl( found in picoBcells0 T%is forces ! MS to be in t%e !re!

of t%e cell for ! cert!in period before reselectin& it0 It pre#ents mobile st!tions t%!t Kust %!ppen to be

p!ssin& b( from reselectin& t%e cell0 In order to reselect t%e cell5 t%e MS must be in t%e !re! for ! cert!in

period of time or be close enou&% t%!t t%e Q*EV o#ercomes t%e ne&!ti#e offset #!lue0

Cell $eselection ;set (C$;)

$ is ! #!lue from 7 to =0 E!c% step represents ! : d"m step ,7 to 1: d"m-0 T%is #!lue is !dded to

$10 A %i&%er $ #!lue will m!ke t%e cell tower more !ttr!cti#e to t%e MS0 T%e %i&%er t%e $5 t%e

more !ttr!cti#e t%e cell will be0 T%e network mi&%t !ssi&n ! $ #!lue to ! cell if t%e network w!nted to

encour!&e mobile st!tions to utili+e t%!t cell0 T%e network mi&%t w!nt to do t%is in order to reduce t%e

lo!d on ot%er cells durin& times of %i&% tr!ffic #olume or to force MSCs to ! cert!in b!nd0

Neigh%or List

T%e nei&%bor list is ! list of t%e stron&est cells t%!t t%e MS c!n see0 T%e Q*EV for t%ese cells is

tr!nsmitted in ! me!surement report from t%e MS to t%e "TS on t%e SA$$) w%ene#er t%e MS %!s been

!lloc!ted !n SD$$) or ! T$)0 T%e "S$ !nd MS$ use t%ese me!surements to determine if t%e MS needs

to mo#e to ! different cell0 L%ene#er ! cell is in !n !cti#e SD$$) or T$) t%e network will !lw!(s

m!n!&e t%e %!ndoff0 T%e MS will onl( mo#e from one cell to !not%er b( itself w%en it is in idle mode0

Cell $eselection 3!steresis (C$3)

L%en ! MS reselects ! new cell it does not need to notif( t%e network unless t%!t new cell is in !

different *oc!tion Are!0 L%en ! MS mo#es into ! new loc!tion !re! it must do ! loc!tion upd!te w%ic%

&ener!tes si&n!l mess!&in& between t%e "TS5 "S$5 MS$5 V*5 !nd )*0 If ! MS is loc!ted !lon& t%e

border of two loc!tion !re!s t%en it will see cells in bot% loc!tion !re!s0 A MS !lon& t%e borderline mi&%t

reselect ! cell in one loc!tion !re! !nd t%en ! few minutes l!ter reselect ! cell in t%e ot%er loc!tion !re!

!nd continuousl( bounce b!ck !nd fort% between loc!tion !re!s &ener!tin& too muc% si&n!lin& o#er%e!d

!nd puttin& str!in on t%e network0

In order to miti&!te t%is problem t%e $) is used0 It is ! #!lue t%!t is simil!r to t%e tempor!r( offset #!lue

of $:0 $) is !pplied to $: w%en t%e desired cell is in ! different loc!tion !re!0 T%is results in m!kin&t%e cell in t%is different loc!tion !re! less desir!ble to t%e MS0 T%e MS must mo#e close enou&% to t%e

new loc!tion !re! to o#ercome t%e offset t%us ensurin& t%e MS is trul( close enou&% to t%e new loc!tion

!re! to w!rr!nt ! loc!tion upd!te0 nce t%e MS reselects t%e cell in t%e new loc!tion !re! it will perform !

loc!tion upd!te0 T%e MS will t%en !ppl( t%e $) #!lue to !ll cells it sees in t%e old loc!tion !re! w%ic%

will m!ke t%em less !ttr!cti#e to t%e MS !nd ensure t%e MS does not continu!ll( bounce b!ck !nd fort%

between two loc!tion !re!s0


90/95

Cell +ar Access (C+A)

$ell "!r Access is ! sin&le bit ,7 or 1- #!lue sent down on t%e "$$)0 If $"A is set to 1 t%en MSCs !re not

!llowed to select t%!t cell0 If t%e #!lue is set to 7 t%en MSCs m!( select it0 $"A would be used on umbrell!

cells in order to pre#ent MSCs from selectin& it0 T%e umbrell! cell would be reser#ed for w%en t%e network

needs to m!n!&e %i&% le#els of tr!ffic0 T%is &i#es t%e network tot!l control of !ccess to t%e umbrell! cell0

Cell +ar ualiier (C+)

T%is #!lue is simil!r to t%e $"A but it !pplies to reselection0 A cell t%!t %!s $" set to 1 does not !llow

MSCs to reselect it0 $" set to 7 !llows norm!l !ccess to t%!t cell0

B

#"M TIM$

#"M $esource Timer=


91/95

#"M Mo%ilit! Timer=


92/95

#"M +""A0 Timers=


93/95

#"M A+I" Timers=


94/95

#"M M"C Timers=


95/95

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