mobile mangment

7/25/2019 mobile mangment

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GSM Mobility Management

Originals by: Rashmi Nigalye, Mouloud Rahmani, Aruna Vegesana, Garima Mittal, Fall 2001

ro!" M" Veeraragha#an, olyte$hni$ %ni#ersity, Ne& 'or(

) GSM ar$hite$ture o#er#ie&* Net&or( layout

* roto$ols* Addresses + identi!iers

) o$ation management* -all deli#ery . lo$ation u/date* Se$urity

) ando#er management


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GSM net&or( layout

GSM Network

(PLMN)

MSC region

MSC region

MSC region

Location area

BSCBSC

Location

area

BTS BTS

PLMN: Public Land Mobile Network

MSC: Mobile Switching Center

BTS: Base Transceiver Station

BSC: Base Station Controller


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GSM net&or( layout

BSC

MSC

BSC

BTS

EIRLR

!"C#LR

BTS

BTS

"$

!!bisE

B%C

&MC

'MSC

PSTN

ISDN


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GSM MA /roto$ol

) GSM MA similar to S1 MA) MA uses 3ransa$tions -a/abilities

art 43-A5 o! the SS6 sta$() MA !un$tions:* %/dating o! lo$ation in!ormation in VRs* Storing routing in!ormation in Rs

* %/dating and su//lementing user /ro!ilesin Rs

* ando!! o! $onne$tions bet&een MS-s


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7hat is a lo$ation area 4A58

) A /o&ered9on mobile is in!ormed o! an in$oming$all by a /aging message sent o#er the AG-$hannel o! a $ell

) One etreme is to /age e#ery $ell in the net&or(!or ea$h $all 9 a &aste o! radio band&idth

) Other etreme is to ha#e a mobile send lo$ationu/dates at the $ell le#el" aging $ut to 1 $ell, but

large number o! lo$ation u/dating messages") en$e, in GSM, $ells are grou/ed into o$ationAreas * u/dates sent only &hen A is $hanged;/aging message sent to all $ells in last (no&n A


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Addresses and denti!iers

) nternational Mobile Station MS- !rom the MS"


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) Mobile Subs$riber S?N 4MSS?N5* 3he @real tele/hone number: assigned to

the SM

* 3he SM $an ha#e se#eral MSS?Nnumbers !or sele$tion o! di!!erentser#i$es li(e #oi$e, data, !a

CC N(C SN

N?-: National ?estination -ode 4N?- identi!ies o/erator5;SN: Subs$riber Number; --: -ountry -ode;?igits !ollo&ing N?- identi!ies the R


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) Mobile Station Roaming Number4MSRN5

* t is tem/orary lo$ation de/endentS?N number

* t is assigned by lo$al VR to ea$h MS inits area"

CC N(C SN


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Addresses and identi!iers

) 3em/orary Mobile Subs$riberdentity 43MS5* t is an alias o! the MS and is used in its /la$e !or

/ri#a$y"* t is used to a#oid sending MS on the radio /ath"

* t is an tem/orary identity that is allo$ated to an MS bythe VR at inter9VR registration, and $an be $hanged bythe VR

* 3MS is stored in MS SM $ard and in VR"


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3MS, MS, MSRN and MSS?N

) %nli(e MSS?N, MS is not (no&n to the GSM user" 3he-- o! MSS?N translates to an M-- o! MS as !ollo&s,e"g, ?enmar( --: B M--: 2CD

) 3MS is used instead o! MS during lo$ation u/date to/rote$t /ri#a$y" As user mo#es, 3MS is used to sendlo$ation u/date" 3hus a third /arty snoo/ing on the &irelesslin( $annot tra$( a user as he>she mo#es"

) MSRN is the routing number that identi!ies the $urrentlo$ation o! the $alled MS"* MSRN is tem/orary net&or( identity assigned to a

mobile subs$riber"* MSRN identi!ies the ser#ing MS->VR"* MSRN is used !or $all deli#ery 4$alls in$oming to an MS5"

) MSS?N is the dialed number to rea$h a GSM user


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) o$ation Area ? 4A5* --: -ountry -ode, MN-:Mobile Net&or(

-ode, A-: o$ation Area -ode

* A is broad$ast regularly by EaseStation on E--

*


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o$ation management

) Set o! /ro$edures to:* tra$( a mobile user

* !ind the mobile user to deli#er it $alls) -urrent lo$ation o! MS maintained by

29le#el hierar$hi$al strategy &ith

Rs and VRs"


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7ays to obtain MSRN

1" Obtaining at lo$ation u/date * MSRN !or the MSis assigned at the time o! ea$h lo$ation u/date,and is stored in the R" 3his &ay the R is in a/osition to immediately su//ly the routing in!o

4MSRN5 needed to s&it$h a $all through to thelo$al MS-"

2" Obtaining on a /er $all basis * 3his $ase re=uiresthat the R has at least an identi!i$ation !orthe $urrently res/onsible VR" 7hen routing in!ois re=uested !rom the R, it !irst has to obtainthe MSRN !rom the VR" 3his MSRN is assignedon a /er $all basis, i"e" ea$h $all in#ol#es a ne&MSRN assignment


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Routing in!ormation: $ase &hen MSRNis sele$ted /er $all by VR>MS-

) ! MSRN is allo$ated to ea$h subs$riber #isiting at an MS-, then thenumber o! MSRNs re=uired is large" ! instead, an MSRN is allo$atedonly &hen a $all is to be established, then the number o! MSRNs isroughly e=ual to number o! $ir$uits at MS- * a mu$h smaller number *

hen$e MSRNs ty/i$ally allo$ated /er $all by VR>MS-

MSIS(N

'MSC

LR

MSIS(N

MSC)#LR

MSR

N

IMSI

MSRN

MSIS(NIMSI% #LR nu$ber

MSRN


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-all routing to a mobile station:$ase &hen R returns MSRN

'MSC

BSC

BSC

EIR

LR

!"C#LR

MSCBTS

BTS

BTS

L! *

L! +

IS(N

*

MS

*

MSIS(N

,

TMSI

-

MSRN

.

MSRN

+

MSIS(N

/

TMSI

/TMSI

/

TMSI

0

TMSI

1

MSRN

MSC


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Messages e$hanged: $all deli#ery

PSTN'MSC

LR#LR

Target

MSC

Originating

Switch

GMSC HLRVLR

Target

MSC

*2 IS"P I!M+2 M!P3SEN(3R&"TIN'3IN4&

.2 M!P3PRI(E3R&!MIN'3N"MBER

-2 M!P3PRI(E3R&!MIN'3N"MBER3ack

12 M!P3SEN(3R&"TIN'3IN4&3ack

,2 IS"P I!M

*

+ .

-1

,


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Find o/eration in GSM

) S?N s&it$h re$ognies !rom the MSS?N that the$all subs$riber is a mobile subs$riber" 3here!ore,!or&ard the $all to the GMS- o! the home MN4ubli$ and Mobile Net&or(5

) GMS- re=uests the $urrent routing address 4MSRN5!rom the R using MA

) Ey &ay o! MSRN the $all is !or&arded to the lo$alMS-

) o$al MS- determines the 3MS o! the MS 4by=uerying VR5 and initiates the /aging /ro$edure inthe rele#ant A

) A!ter MS res/onds to the /age the $onne$tion $anbe s&it$hed through"


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GSM se$urity

) Authenti$ation) 7hat signed res/onse 4SR


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GSM se$urity

)


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ey management

) -i/hering (ey $ is generated using algorithm AD in the samemanner as SR


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o$ation registration

) MS has to register &ith the MN to get $ommuni$ation ser#i$es) Registration is re=uired !or a $hange o! MN) MS has to re/ort to $urrent MN &ith its MS and re$ei#e ne&

3MS by ee$uting o$ation Registration /ro$ess") 3he 3MS is stored in SM, so that e#en a!ter /o&er on or o!!,

there is only normal o$ation %/date") ! the MS re$ognies by reading the A broad$ast on E-- that

it is in ne& A, it /er!orms o$ation %/date to u/date the Rre$ords"

) o$ation u/date /ro$edure $ould also be /er!ormed /eriodi$ally,inde/endent o! the MS mo#ement"

) 3he di!!eren$e in o$ation Registration and o$ation %/date isthat in lo$ation u/date the MS has already been assigned a 3MS"


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o$ation registrationMS BSS)MSC #LR LR !"C

IMSI 9i

!. < !0

=

'enerate

TMSI

Loc2";d2Re57IMSI%L!I8

";d Loc2!rea

7IMSI%L!I8!ut2Par2Re5 !uth2Ino2Re5

7IMSI8

7R!N(8

!uthenticate7IMSI%9c%

R!N(%SRES8

!ut2 Ino2

7IMSI8

7R!N(8

!uthentic2 Re5 7IMSI%9c%

R!N(%SRES8

!uth2Ino

!uth2Res;27SRES8

7SRES8

!uth2Res;

";date

Location

7IMSI%MSRN8

SRES

R!N(9i

9c SRES

Contd222


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4I$ontd5 o$ation registration"

MS BSS)MSC #LR LR !"C

!1

'enerateTMSI

79c8

Start Ci;h2

Ci;h2Mod2Co$2

Message M9c

9c7M8

Ins2Subsc2(ata

7IMSI8

4orw2 New TMSI

7TMSI8

Subs2(at2Ins2!ck

Loc2";d2!cce;t

7IMSI8Loc2";d2!cce;t

Ci;h2Mod29c7M8

!19c7M89c

M

TMSI Realloc2!ck

TMSI Realloc2C$d2

TMSI2!ck

Loc2";d2!cce;t can be co$bined

New TMSI is receie! "# MS

(TMSI Reallocation) in ci$hering %o!e&


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o$ation u/dateMS BSS)MSC #LR LR !"C

IMSI% TMSI

9i% 9c% L!I

Start ci;hering2

!uthentication

Loc2";d2Re5

7TMSI%L!I8";date Loc2!rea

7TMSI%L!I8

";date Location

7IMSI%MSRN8

'enerate

TMSI

Start ci;hering

79c8 IMSI

Insert Subscriber2 data

Subs2 (ata Insert !ck7contd228


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4""$ontd5 o$ation u/date"

MS BSS)MSC #LR LR !"C

7IMSI8

!uth2Ino2Re5

7IMSI%9c% R!N(%SRES8

!uth2Ino

Start ci;hering2

4orward new TMSI

!uth2 Para2 Re5

Loc2 ";d2 !ce;t

Loc2 ";d2 !ce;t

TMSI !ckTMSI Reallocation

Co$;lete

TMSI Realloc2 C$d2

7TMSI8

!uth2 Ino2

7IMSI%9c% R!N(%SRES8

7IMSI8

7IMSI8

Loc2 ";d2 !ce;t


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3y/es o! hando#er4same as @hando!!5

) 3here are !our di!!erent ty/es o!hando#er in the GSM system" ando#erin#ol#es trans!erring a $all bet&een:

* -hannels 4time slots5 in the same $ell* -ells 4Ease 3rans$ei#er Stations5 under the

$ontrol o! the same Ease Station -ontroller4ES-5,

* -ells under the $ontrol o! di!!erent ES-s, butbelonging to the same Mobile ser#i$esS&it$hing -enter 4MS-5, and

* -ells under the $ontrol o! di!!erent MS-s"


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Attributes o! radio9lin( hando#er

) ard hando#er

) MAO

) Ea$(&ard) -OS sele$tion s$heme: stati$

* -ross9o#er s&it$h: an$hor s&it$h


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ando#er 4MAO5

) ando#ers are initiated by the ESS>MS-4as a means o! tra!!i$ load balan$ing5"

) ?uring its idle time slots, the mobile s$ans

the Eroad$ast -ontrol -hannel o! u/ to 1Jneighboring $ells, and !orms a list o! thesi best $andidates !or /ossible hando#er,based on the re$ei#ed signal strength"

) 3his in!ormation is /assed to the ES- andMS-, at least on$e /er se$ond, and is usedby the hando#er algorithm"


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ando#er /ro$edures in GSM

BSC

MSC>!

BSC

MSC>B

BTS *

BTS .

BTS +

BSC

MSC>C

BTS .

Connection route

*

+

.-

1

,

/

0

0

?


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nter MS- basi$ hando#erMS)BSS * MSC>!

andover re5uired

! Indication

MSC>B #LR>B

Radio chan2 !ckandover re;ort

MS)BSS +

!llocate andover nu$ber

RLC

!NS

REL

End Signal

B Indication

B Conir$

andover re;ort

Peror$ andover

I!M

!CM

Send End Signal

End o Call


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Subse=uent hando#er !rom MS-9E to MS-9A

MS)BSS * MSC>!

B Indication

B Conir$

MSC>B

#LR>B

Subse52 andover

!cknowledge

MS)BSS +

RLC

REL

End Signal

! Re5uired

! Indication

andover re;ort

Peror$ subse5uent

andover

End o Call


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Subse=uent hando#er !rom MS-9E to MS-9-

MSC>!

MSC>C

Peror$ andover

Radio chan2 !ck2

MSC>B

!llocate andover

Nu$ber

MS

I!M

!CM

! Re5uestPeror$ subse5uent

andover

#LR>C

Send andover re;ort

B Indication

7Contd@8


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4I$ontd5 Subse=uent hando#er !rom MS-9E to MS-9-

MSC>!

MSC>C

Send End Signal

ando Re;ort

MSC>B MS

REL

RLC

! IndicationPeror$ subse5uent

!cknowledge

B Conir$

!NS

MSC>B #LR>B

End Signal


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Abbre#iations

) S-: nternational s&it$hing $enter) OM-: O/erations and maintenan$e $enter) GMS-: Gate&ay s&it$hing $enter) MS-: Mobile s&it$hing $enter

) VR: Visitor lo$ation register) R: ome o$ation register)


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Re!eren$es

) 3he GSM Sytem !or Mobile$ommuni$ations by Mouly + autet

) 7ireless and Mobile Net&or(

Ar$hite$tures by 'i9Eing in + mri$h-hlamta$

) 7ireless ersonal -ommuni$ations Systems

by ?r" Goodman) GSM S&it$hing, Ser#i$es and roto$ols byKorg

mobile mangment

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