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GSM FREQUENCIES

GSM systems use radio frequencies between 890-915 MHz forreceive and between 935-90 MHz for transmit!"# carriers are s$aced every %00 &Hz' a((owin) a tota( of 1%*

carriers for use!+n "# carrier is a $air of radio frequencies' one used in eac,

direction! ransmit and receive frequencies are a(ways se$arated by *5

MHz!

890 960935915

UPLINK FREQUENCIES DOWNLINK FREQUENCIES

UPLINK AND DOWNLINK FREQUENCY SEPARATED BY 45MH

INTRODUCTION TO GSM

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  From To excluding

GSM 1800

713 718

832 844

900 Domain

63 78 65,72

80 82

87 88

111 124 114,121

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GSM S./#+2S

1! Standard - /S!

%! +ccess Met,od - #4M+-4M+!

3! oice c,anne(s -8 c,n(s6carrier!

*!"# c,anne( s$acin) 7 %00 Hz!

5! oice odin) +()orit,m 7 "./-.!

!oice odin) "ate 7 13 b$s!

:! ,anne( bitrate 7 %:0!833 b$s!

8! Modu(ation Met,od- GMS!

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:

 

TS

MS! "#$

%#$

&ST'(SD'

Da)a

'e)*or+

!

-ir in)er.ace

/SS

T

S

T

S

MS! "#$

BSCBSC

+ nterface

+-bisinterface

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INTERFACE NAMES

/ac, interface s$eci;ed in GSM ,as a name associatedwit, it!

NAME INTERFACE

Um MS ----- BTS

Abis BTS ----- BSCA MSC ------ BSC

B MSC ------ VLR  

C MSC ------ HLR  

D VLR ----- HLR  

E MSC ------ MSC

F MSC ------ EIR  

G VLR ------ VLR  

H HLR ------ AUC

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BSS CONNECTIONS

MSC

XCDR 

BSC

  BTS BTSBTS

OMC

CBC

MTL

(C7 )

OML (X.25)

RSL

( LAPD)

CBL

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C"## G#$% I'"()*)+ ! CGI , -

MCCMNCLACCI

MCC MNC LAC CI

LAI

CGI

< Mobi(e ountry ode =*0*>< Mobi(e etwor& ode =:% >< ocation +rea dentity =e)?3%01>< e(( dentity =e)?3%*51>

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Physical channel  - /ac, times(ot on a carrier is referred to as a

$,ysica( c,anne(! .er carrier t,ere are 8 $,ysica( c,anne(s!

Logical channel  - ariety of information is transmitted betweent,e MS and @S! ,ere are diAerent (o)ica( c,anne(s de$endin)

on t,e information sent! ,e (o)ica( c,anne(s are of two ty$es

 raBc c,anne(

ontro( c,anne(

D$.(#*(/ 

U#*(/ 

CHANNELS

CHANNEL CONCEPT

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GSM T&2 C&(("# 

Traffic Channels

 TCH/FFull rae !!"#$%is/s 

TCH/HHalf rae &&"' $%is/s

CHANNEL CONCEPT

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GSM C$()$# C&(("#

 BCH ! @roadcast c,anne(s ,D$.(#*(/ $(#+

C$()$# C&(("#

 DCCH!4edicated ,anne(s,D$.(#*(/ U#*(/  CCCH!ommon ontro( ,an,D$.(#*(/ U#*(/ 

  S(nch"ChannelsRACH"andom

+ccess ,anne(

CBCHe(( @roadcast

 ,anne(

SDCCHS!"#!$%"& #i'!

 '%"%$ '!""&$

ACCHAss%'i!

C%"%$ C!""&$s

SACCHS$%* !ss%'i! C%"%$ C!""&$

FACCHF!s Ass%'i!

 C%"%$ C!""&$PCH/

AGCHP!+i"+,A''&ss +!"

FCCHF&&"'/

C%&'i%" '!""&$

SCHS/"'%"is!i%"

 '!""&$

BCCHB%!#'!s

'%"%$ '!""&$

CHANNEL CONCEPT

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BCH C&(("#

BCCH( Broadcast Control Channel )4own(in& on(y

@roadcasts )enera( information of t,e servin) ce(( ca((ed

System nformation

@H is transmitted on times(ot zero of @H carrier

"ead on(y by id(e mobi(e at (east once every 30 secs!SCH( Synchronisation Channel )

4own(in& on(y

arries information for frame sync,ronisation! ontains

 4M+ frame number and @S!

FCCH( Frequency Correction Channel )4own(in& on(y!

/nab(es MS to sync,ronise to t,e frequency!

+(so ,e($s mobi(es of t,e nce((s to (ocate S 0 of @H

carrier!

CHANNEL CONCEPT

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CCCH C&(("#

RACH( Random Access Channel )

C$(in& on(y

Csed by t,e MS to access t,e etwor&!

 AGCH( Access Grant Channel )4own(in& on(y

Csed by t,e networ& to assi)n a si)na((in) c,anne(

u$on successfu(( decodin) of access bursts!

PCH( Paging Channel )

4own(in& on(y!

Csed by t,e etwor& to contact t,e MS!

CHANNEL CONCEPT

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DCCH C&(("#

SDCCH( Standalone Dedicated Control Channel )

C$(in& and 4own(in&

Csed for ca(( setu$' (ocation u$date and SMS!

SACCH( Slo Associated Control Channel )

Csed on C$(in& and 4own(in& on(y in dedicated mode!C$(in& S+H messa)es - Measurement re$orts!

4own(in& S+H messa)es - contro( info!

FACCH( Fast Associated Control Channel )

C$(in& and 4own(in&!+ssociated wit, H on(y!

s used to send fast messa)es (i&e ,andover messa)es!

Dor&s by stea(in) traBc bursts!

CHANNEL CONCEPT

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NORMAL BURST

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

57 bis 57 bis24 bis

FRAME1(3.415ms) FRAME2

T!i"i"+

s&&"'&D!! D!!

T!i$

Bis

T!i$

Bis

F$!+

Bi

F$!+

Bi

G!#

P&i%#

G!#

P&i%#

0.534ms0.577ms

C!i&s !i' '!""&$ !"# '%"%$ '!""&$s BCCH6 PCH6 AGCH6 SDCCH6

SACCH !"# FACCH.

CHANNEL CONCEPT

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Data - wo b(oc&s of 5: bits eac,! arries s$eec,' data or contro(info!

 ai( bits - Csed to indicate t,e start and end of eac, burst! ,ree

bits a(ways 000!

Guard !eriod  - 8!%5 bits (on)! ,e receiver can on(y receive and

decode if t,e burst is received wit,in t,e times(ot desi)nated forit!Since t,e MS are movin)! /Eact sync,ronization of burst is not

$ossib(e $ractica((y! Hence 8!%5bits corres$ondin) to about 30us is

avai(ab(e as )uard $eriod for a sma(( mar)in of error!

Flag "its  - ,is bit is used to indicate if t,e 5: bits data b(oc& is

used as #+H!#raining Sequence - ,is is a set sequence of bits &nown by bot,

t,e transmitter and t,e receiver= @ of @S>! D,en a burst of

information is received t,e equa(iser searc,es for t,e trainin)

sequence code! ,e receiver measures and t,en mimics t,e

distortion w,ic, t,e si)na( ,as been subFected to! ,e receiver

NORMAL BURST

CHANNEL CONCEPT

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FREQUENCY CORRECTION BURST

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

132 bis

FRAME1(3.415ms) FRAME2

Fi D!!

T!i$

Bis

T!i$

Bis

G!#

P&i%#

G!#

P&i%#

0.534ms0.577ms

arries #H c,anne(!

Made u$ of 1*% consecutive zeros!

/nab(es MS to correct its (oca( osci((ator (oc&in) it to t,at of t,e

@S!

CHANNEL CONCEPT

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NEED FOR TIMESLOT OFFSET

+ & ! , ' ) - . + & ! , ' ) - .

+ & ! , ' ) - . + & ! , ' ) - .

f C$(in& and 4own(in& are a(i)ned eEact(y' t,en MS wi(( ,ave to

transmit and receive at t,e same time! o overcome t,is

$rob(em a oAset of 3 times(ots is $rovided between down(in&

and u$(in&

BSS D01nlin$ 

MS U2lin$ 

CHANNEL CONCEPT

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+ & ! , ' ) - . + & ! , ' ) - .

) - . + & ! , ' ) - . + & ! , '

+s seen t,e MS does not ,ave to transmit and receive at t,e

same time! ,is sim$(i;es t,e MS desi)n w,ic, can now

use on(y one synt,esizer!

BSS D01nlin$ 

MS U2lin$ 

)

+

, iesl00ffse

CHANNEL CONCEPTNEED FOR TIMESLOT OFFSET

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GSM TDMA STRUCTURE

•  TDMA 8 T*" S#$) : RF C&(("#

•  T*" #$) ';&)*$( 0

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BCCH

CCCH

BCCH

CCCH

BCCH

CCCH

BCCH

CCCH

CCCH

CCCH

CCCH

CCCH

CCCH

CCCH

CCCH

CCCH

+

&+

!+

,+

'+

)+ )+

'+

,+

!+

&+

+

IDLE

CCCH BLOC8 

BCCH BLOC8 SCH BLOC8 

FCCH BLOC8 

BCCH/CCCH NON7COMBINED MULTIFRAME

RACH BLOC8 

D%*"$i": U9$i":  

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+

&+

!+

,+

'+

)+ )+

'+

,+

!+

&+

+

IDLECCCH BLOC8 

BCCH BLOC8 SCH BLOC8 

FCCH BLOC8 

BCCH/CCCH COMBINED MULTIFRAME

)&

&+& &+&

)&

BCCH

CCCH

BCCH

CCCH

CCCH

BCCH

CCCH

CCCH

CCCH

SACCH

SACCH

CCCH

CCCH

CCCH

CCCHSDCCH

SDCCH

SDCCH

SDCCH

BCCH

CCCH

BCCH

CCCH

CCCH

BCCH

CCCH

CCCH

CCCH

SACCH

SACCH

CCCH

CCCH

CCCH

CCCHSDCCH

SDCCH

SDCCH

SDCCH

BCCHCCCHSDCCH

CCCHSACCH

CCCHSACCH

CCCHCCCHCCCHSDCCH

CCCHCCCHCCCHSDCCH

CCCHCCCHCCCHSDCCH

BCCHCCCHSDCCH

CCCHSACCH

CCCHSACCH

CCCHCCCHCCCHSDCCH

CCCHCCCHCCCHSDCCH

CCCHCCCHCCCHSDCCHRACH BLOC8 SDCCH/'

SACCH/'

D%*"$i":  U9$i": 

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SPEECH

CODING

CHANNEL

CODING

INTERLEA9ING

BURST

ASSEMBLING

CIPHERING

MODULATION DEMODULATION

DECIPHERING

BURST

DISASSEMBLING

DEINTERLEA9ING

CHANNEL

DECODING

SPEECH

DECODING

Transissi0n

CODING4 INTERLEA9ING CIPHERING

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 ,e transmission of s$eec, is one of t,e most im$ortant serviceof a mobi(e ce((u(ar system!

 ,e GSM s$eec, codec' w,ic, wi(( transform t,e ana(o)si)na(=voice> into a di)ita( re$resentation' ,as to meet t,efo((owin) criterias

+ )ood s$eec, qua(ity' at (east as )ood as t,e one obtainedwit, $revious ce((u(ar systems!

 o reduce t,e redundancy in t,e sounds of t,e voice! ,isreduction is essentia( due to t,e (imited ca$acity oftransmission of a radio c,anne(!

 ,e s$eec, codec must not be very com$(eE becausecom$(eEity is equiva(ent to ,i), costs!

 ,e ;na( c,oice for t,e GSM s$eec, codec is a codec named "./-. ="e)u(ar .u(se /Ecitation on)-erm .rediction>!

SPEECH CODING

CODING

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 ,is codec uses t,e information from $revious sam$(es =t,isinformation does not c,an)e very quic&(y> in order to $redictt,e current sam$(e!

 ,e s$eec, si)na( is divided into b(oc&s of %0 ms! ,ese b(oc&sare t,en $assed to t,e s$eec, codec' w,ic, ,as a rate of 13

&b$s' in order to obtain b(oc&s of %0 bits!

SPEECH CODING

CODING

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S"" C&(("# C$'*(@

Class &a

)+ %is

Class &%

&,! %is

Class &a

)+ %is

Class &%

&,! %is

,.# %is

Class !

.# %is

, '

Pari(

chec$ 

Tail

%is

!-+ %is

')- %is

C0n:0lui0n c0;in<

CODING

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4

GSM SPEECH CHANNEL INTERLEAING ! D*&@& ,

1 7 3 5 6

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

4456 %*)

5456 %*)

6456 %*)

F$$ !& &"'%# s9&&' b$%':s %m ! si"+$& '%";&s!i%"

Bss

TDMA

F!m&s F!m& 1 F!m& 2 F!m& F!m& 3

INTERLEA9ING

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GSM SPEECH CHANNEL INTERLEAING

+ burst in GSM transmits two b(oc&s of 5: data bits eac,!

 ,erefore t,e *5 bits corres$ondin) to t,e out$ut of t,e c,anne(coder ;t into 8 5: data bits =8 I 5: < *5>! ,e *5 bits aredivided into ei),t b(oc&s of 5: bits!

 ,e ;rst b(oc& of 5: bits contains t,e bit numbers =0' 8'

1' !!!!!**8>' t,e second one t,e bit numbers =1' 9' 1:' !!!!!**9>'etc!

 ,e (ast b(oc& of 5: bits wi(( t,en contain t,e bit numbers =:'15' !!!!!*55>!

 ,e ;rst four b(oc&s of 5: bits are $(aced in t,e even-numbered

bits of four consecutive bursts! ,e ot,er four b(oc&s of 5: bits are $(aced in t,e odd-numbered

bits of t,e neEt four bursts!

 ,e inter(eavin) de$t, of t,e GSM inter(eavin) for s$eec,c,anne(s is ei),t!

+ new data b(oc& a(so starts every four bursts! ,e inter(eaver for

INTERLEA9ING

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CIPHERING

i$,erin) is used to $rotect si)na(in) and user data!

+ ci$,erin) &ey is com$uted usin) t,e a()orit,m A8 storedon t,e SM card'

+ 11* bit sequence is $roduced usin) t,e ci$,erin) &ey' an

a()orit,m ca((ed +5 and t,e burst numbers! ,is bit sequence is t,en J2"ed wit, t,e two 5: bit b(oc&s of

data inc(uded in a norma( burst!

n order to deci$,er correct(y' t,e receiver ,as to use t,e samea()orit,m +5 for t,e deci$,erin) $rocedure!

MODULATION

Modu(ation is done usin) GMS 

MODULATION

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1

4

7

2 3

5 6

8 9

0

<  #

6325 0/0/0/

nformation istransmittedby diAerentfrequencies atdiAerent times(ot

oice

Modu(ated"# si)na(

? 1

? 7

? 3

? 4

? 1

INTRODUCTION TO FREQUENCY HOPPING

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Moile /rigina)ed !allMS

MS

@S

@S

@S

@S

@S

MS

"

GMS

H"

.S

/"

+u

R" ?$ '"'*&)"' &(("#

?$ $;(*&)*$( !RACH,

A##$ $? '"'*&)"' &(("#

!AGCH,

C# ")&%#*"() ";")

!SDCCH,

A;)"()*&)*$( ";")

!SDCCH,

A;)"()*&)*$( "$("

!SDCCH,

A;)"()*&)*$( "$("!SDCCH,

C*"*(@ $&('

!SDCCH,

C*"*(@ "$("

!SDCCH,

A*@("() $? TCH!SDCCH, C# S");

A*@("() $? TCH

!SDCCH,

C# S");

A#")*(@!TCH, A#")*(@

A#")*(@

!TCH,

C$((")"'!TCH, C$((")"'

C$((")"'

!TCH,

C$((")"'

E&(@" $? C$;(*&)*$(

E&(@" $? $;(*&)*$(!TCH,

E&(@" $? C$;(*&)*$(

C# "#"&"

C# "#"&"

!TCH,

C# "#"&"

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Moile Termina)ed !allMS

MS

@S

@S

@S

@S

@S

MS

"

GMS

H"

.S

/"

+u

L&(' )$M$%*#" #

Q;"+ ?$LR *(?$

R"#+

R$;)")$MSC

Q;"+ LR

?$ LAC &('TMSIP&@*(@)" &"&

P&@*(@

P&@*(@

DIAL 9844017345

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I()$';)*$( )$ F";"(+ H$*(@#adin)

 – auses qua(ity deterioration – s frequency de$endent

#H diversi;es t,e im$act of fadin) and im$roves qua(ity! ,e immunity to fadin) increases by eE$(oitin) its frequency

se(ectivity' because usin) diAerent frequencies t,e$robabi(ity of bein) continuous(y aAected by fadin) is

reduced' so t,e transmission (in& qua(ity is im$roved! ,is im$rovement is muc, more noticeab(e for s(ow movin)

mobi(es!

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TYPES OF HOPPING

Base Band Hopping (BBH)

 ,e radio units transmit a(ways t,e same frequency

umber of frequencies for ,o$$in) < umber of carriers

 ,e radio units are a(ways transmittin) a ;Eed frequency andfrequency ,o$$in) is $erformed by movin) t,e information for

every ca(( amon) t,e avai(ab(e radio units in a ce(( on a $erburst basis!

n rece$tion t,e ca(( is a(ways $rocessed by t,e same radio unit=t,e one w,ere t,e ca(( started>!

 ,e number of frequencies to ,o$ over is (imited by t,e number

of radio units equi$$ed in t,e ce((! ,e @H carrier can ,o$ in times(ots 1 to : =wit,out $ower

contro(64J>!

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TYPES OF HOPPING

Synthesiser Frequency Hopping (SFH)

 ,e radio units c,an)e =retune> t,e frequency every burst!

 ,e ca(( a(ways stays in t,e same radio unit!

umber of frequencies for ,o$$in) K umber of carriers!

 ,e radio units can ,o$ over a ran)e of diAerent frequencies= *

in case of Motoro(a>!Hybrid combiners are required in t,e base station =avity

ombiners can not be used wit, S#H>!

 ,e @H carrier can never ,o$!

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H$*(@ P&&")"

#or frequency ,o$$in) o$erabi(ity' GSM de;nes t,e fo((owin) setof $arameters?

$o"ile Allocation ($A)% Set of frequencies t,e mobi(e is a((owed to,o$ over! M+ is a subset of a(( t,e frequencies a((ocated by t,esystem o$erator to t,e ce(( =ce(( a((ocation> a(t,ou), it can bet,e same! /)?- f t,e o$erator ,as frequencies from 1 -3%' t,en,e can use 1-15 for @H and 1:-3% for ,o$$in) = M+>!

Ho!!ing Sequence &um"er (HS&)% 4etermines t,e ,o$$in) orderused in t,e ce((! * diAerent HSs can be assi)ned' w,ere HS< 0 $rovides a cyc(ic ,o$$in) sequence and HS < 1 to 3$rovide various $seudorandom ,o$$in) sequences!

$o"ile Allocation 'nde *set ($A')%  4etermines inside t,e

,o$$in) sequence w,ic, frequency t,e mobi(e starts totransmit on!

Frequency Ho!!ing 'ndicator (FH')%  4e;nes a ,o$$in) systemmade u$ by an associated set of frequencies =M+> to ,o$ overand a ,o$$in) sequence =HS>!

BASIC DEFINITIONS

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BASIC DEFINITIONSdBm

d@m < 10 (o) =.> =1000 mD6watt>w,ere d@m < .ower in d@ referenced to 1 mi((iwatt. < .ower in watts

f $ower (eve( is 1 mi((iwatt?.ower=d@m> < 10 (o) =0!001 watt> =1000 mD6watt>

< 10 (o) =1>

< 10 =0>< 0

 ,us a $ower (eve( of 1 mi((iwatt is 0 d@m!f t,e $ower (eve( is 1 watt

1 watt .ower in d@m < 10 (o) =1 watt> =1000 mD6watt>

  < 10 =3>

< 30 

BASIC DEFINITIONS

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BASIC DEFINITIONSdBm

d@m < 10 (o) =.> =1000 mD6watt> ,e d@m can a(so be ne)ative va(ue!f $ower (eve( is 1 microwatt

.ower in d@m < 10 (o) =1 E 10/- watt> =1000 mD6watt>

< -30 d@m

Since t,e d@m ,as a de;ned reference it can be converted bac& towatts if desired!Since it is in (o)arit,mic form it may a(so be convenient(y

combined wit, ot,er d@ terms!

FREE SPACE PROPAGATION

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FREE SPACE PROPAGATION

Friis Formula

.r < .t GtGrλ%

  =*πd>%

Pro!agation Loss$ < 10(o) L*πd 6 λ

%

 ,e square term is t,e $ro$a)ation eE$onent! t is )reatert,an % w,en obstructions eEist!

 Pro!agation Loss in dB% $ < 3%!** N %0o)=d> N%0o)=f>

f < MHzd < &m

 

P)

G) G

PL

'

vers y n enna

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vers y n ennaSystems

&++D F D',+RS'#- 

B;*#'*(@

B;*#'*(@

B;*#'*(@

Diversity Antenna

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Diversity AntennaSystems

$ulti!ath Pro!agationMu(ti$at, $ro$a)ation causes (ar)e and ra$id Ouctuations in a

si)na( ,ese Ouctuations are not t,e same as t,e $ro$a)ation $at,

(oss!

$ulti!ath causes three ma.or things

"a$id c,an)es in si)na( stren)t, over a s,ort distance or time!"andom frequency modu(ation due to 4o$$(er S,ifts on diAerent

mu(ti$at, si)na(s! ime dis$ersion caused by mu(ti$at, de(ays ,ese are ca((ed Pfadin) eAects

Mu(ti$at, $ro$a)ation resu(ts in sma((-sca(e fadin)! 

vers y n enna

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vers y n ennaSystems

D',+RS'#- #+CH&'/0+

4iversity tec,niques ,ave been reco)nised as an eAectivemeans w,ic, en,ances t,e immunity of t,e communicationsystem to t,e ;#)*&) ?&'*(@! GSM t,ereforeeEtensive(y ado$ts diversity tec,niques t,at inc(ude

Di:ersi( echni=uesInerlea:in<

In ie ;0ain

Fre=uenc( H022in<

In Fre=uenc( ;0ain

S2aial ;i:ersi(

In s2aial ;0ain

P0larisai0n ;i:ersi(

In 20larisai0n ;0ain

Diversity Antenna

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Diversity AntennaSystems

#-P'CAL SPA#'AL A+&&A D',+RS'#- C&F'G0RA#'&S

H$*$() S"&&)*$( ")* S"&&)*$(

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vers y n enna

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vers y n ennaSystems

D0AL PLAR'S+D A+&&AS+ dua(-$o(arisation antenna consists of two sets of radiatin)

e(ements w,ic, radiate or' in reci$roca(' receive twoort,o)ona( $o(arised ;e(ds!

 ,e antenna ,as two in$ut connectors w,ic, se$arate(yconnects to eac, set of t,e e(ements!

 ,e antenna ,as t,erefore t,e abi(ity to simu(taneous(y

transmit and receive two ort,o)ona((y $o(arised ;e(ds!

H : S#&() 45 

Diversity Antenna

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Diversity AntennaSystems

 AD,AAG+S F D0AL PLAR'S+D A+&&AS

 ,e best advanta)e of usin) t,e dua( $o(arisation antenna is t,ereduction in t,e number of antennas $er sector!

"educed size of t,e ,eadframe of t,e su$$ortin) structure"educed wind(oad and wei),t!"educed diBcu(ty in site acquisition and insta((ation!ost savin)

 – Requiring slim toer  – Requiring less installation time2 – Cost o3 one dual !olarisation antenna is generally loer

than that o3 to single !olarised antennas

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T&S /F ('T$F$'!  ,ere are two ty$es of system )enerated interference

 – o-c,anne( interference – +dFacent c,anne( interference

Co4Channel 'nter3erence

 ,is ty$e of interference is t,e due to frequency reuse ' i!e!

severa( ce((s use t,e same set of frequency!

 ,ese ce((s are ca((ed co-c,anne( ce((s!

o-c,anne( interference cannot be combated by increasin) t,e

$ower of t,e transmitter! ,is is because an increase in carrier

transmit $ower increases t,e interference to nei),borin) co-

c,anne( ce((s!

 o reduce co-c,anne( interference' co-c,anne( ce((s must be

$,ysica((y se$arated by a minimum distance to $rovide

suBcient iso(ation due to $ro$a)ation or reduce t,e foot$rint

of t,e ce((!

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Co4Channel 'nter3erence

Some factors ot,er t,en reuse distance t,at inOuence co-c,anne(interference are antenna ty$e' directiona(ity' ,ei),t' site

$osition etc'

GSM s$eci;es 6 K 9d@!

arrier f1 nterferer f1

d@

4istance

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 Ad.acent4Channel 'nter3erence

nterference resu(tin) from si)na(s w,ic, are adFacent infrequency to t,e desired si)na( is ca((ed adFacent c,anne(

interference!

+dFacent c,anne( interference resu(ts from im$erfect receiver

;(ters w,ic, a((ow nearby frequencies to (ea& into t,e

$assband!+dFacent c,anne( interference can be minimized t,rou), carefu(

;(terin) and c,anne( assi)nments!

@y &ee$in) t,e frequency se$aration between eac, c,anne( in a

)iven ce(( as (ar)e as $ossib(e ' t,e adFacent interference may

be reduced considerab(y!

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 Ad.acent4Channel 'nter3erence

arrier f1 nterferer f%

d@

+

4istanceGSM s$eci;es 6 K -9d@!

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TIMING ADANCE- 0 )$ 63 >TA %*) ") *( )" SACCH "&'"35/< $ 733*$"(' The BTS calculates the frst TA when receiving a A!H andreports the value to the BS!" TA can ta#e any value $etween%and &' which relates to a distance $etween % #m and ' #m"The steps are a$out % m (' #m*&' + % m)" ,ith respect to

time the di-erent valueso. TA re.er to the interval % msthrough /'/ ms in steps o. 01*2' ms" 3t is important to note

GPRS N").$/ O"*".

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361061

SGSN GGSN

(MAP)

Gr (MAP)Gb

 A

Gp (IP)

Gs

Gn

Gi (IP)

MSC:LR

G% I()"?&" %").""( SGSN &(' BSC!F&" R"#&+,G* R"?""(" $*() %").""( GPRS

&(' ")"( &/") '&)& (").$/ G I()"?&" %").""( SGSN &('MSCG I()"?&" %").""( SGSN &(' HLRG' I()"?&" %").""( SGSN &(' SMSCG( I()"?&" %").""( ).$ GSN.*)*()" &" PLMNG I()"?&" %").""( ).$ GSN *(

'*""() PLMN

G% I()"?&" %").""( SGSN &(' BSC!F&" R"#&+,G* R"?""(" $*() %").""( GPRS&(' ")"( &/") '&)& (").$/ 

G I()"?&" %").""( SGSN &('MSCG I()"?&" %").""( SGSN &(' HLRG' I()"?&" %").""( SGSN &(' SMSCG( I()"?&" %").""( ).$ GSN.*)*()" &" PLMNG I()"?&" %").""( ).$ GSN *('*""() PLMN

Gn

SMSGMSCSMSIWMSCGd 

(MAP)

IPN").$/ 

IPN").$/ 

O)"PLMN

O)"PLMN

B&/%$("

N").$/ 

B&/%$("

N").$/ 

BTS Abis

HLRBSC

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etwor& arc,itecture 7 ew interfaces

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PSPDN

MSC

A

VLR

PSTN/ISDN

Agprs

Gr

Gs

Note: Gc & Gsinter3aces are optional

Gc

Gn

GGSN

Gb

Ater

BTSSMSC

Gd

Gp

SGSN of other PLMN

HLR

EIR

Gf

BSC

TCU

Gi

SGSNPCUSN

GaGa

CGF

Th GPRSb kb t k it itt itGPRS ll

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• The GPRS backbone network permits point-to-point GPRS calls,interworking with the BSS, HLR, MSC, SMSC, and the Internet.

• These services are supported via the following interfaces:

 –Ga• Between SGSN or GGSN and a CGF.

 –Gb• between PCUSN and SGSN, using Frame Relay.

 –Gr• between SGSN and HLR, extension of MAP.

 –Gn• between SGSN and GGSN using GTP protocol (tunnel).

 –Gi• between GGSN and PDNs (IP and X.25).

 –Gs

• between SGSN and MSC/VLR, for some simultaneous GPRS and GSM operation(same as BSSMAP but optional).

 –Gd• between SGSN and SMS-C to deliver SMS messages via GPRS (same as MAP).

 –Gc• between GGSN and HLR (same as MAP but optional)

SGS functions

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HLRDNS

PCUSN

GGSN

SGSN

G%F&""#&+

G(G T  P  T  ; ( ( " #  *  (  @ 

G

CGFG&

SGS= F"'i%"!$i/

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/

D=S SGS= HLR 

PCUS= GGS=

R%i"+

R&s%$i%"

M%bi$i/

M!"!+&m&"

Ci9&i"+ >

C%m9&ssi%"

F!m&

R&$!/

GTP T""&$i"+

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DHCP

GGS=

C!+i"+ G!&*!/

SGS=

I=TER=ET

IP A##&ss

M!"!+&m&"Bi$$i"+

R&'%#s

GTP T""&$i"+

VP= T""&$i"+

GGS= F"'i%"!$i/

!arging Ga)e*a Func)ion

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!arging Ga)e*a Func)ion

Corenetwork

SGSN

Aggregator&

Distributor

CGF

Billing FilesTransfer

Billing

Center

Get / Push billing files

G-CDR

GGSN

S-CDR and M-CDR

Collector

GTP’

GTP

Billing Records:• PDP session duration• GPRS QoS Negotiated• Input Octets• Output Octets• Hot Billing

orte( etwor&s im$(ementation =16%>NortelNetworksimplementation(1/2)

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 ATM Ethernet

Internet

A

PSTN/ISDN

Agprs

GrGs

SGSN

Gn GGSN

PCUSN

Gb

Ater

BTS

HLRSMSC

Gd

SS7/IPgateway

DHCP& DNS

OMC-R

OMC-D

ChargingGateway

Intranet B

Nortel Networks implementation (1/2)

SIG

Gn

BSCs

TCU

Gi

Gi

Gi

VLR

MSC-VLR

Intranet A

PP 7K

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MS

/ 4/#+2

SDH 2

.M S//2

/ S//2

"/GS"+2

4++ "+S#/"

+ttac, .rocedure

.4. onteEt activation!

4/+H

GPRS T 2

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GPRS T&2

• .rocedures t,at ,and(e mobi(ity ofuser are ca((ed GPRS M$%*#*)+M&(&@""()!GMM,<

• .rocedures t,at ,and(e userconnection to eEterna( networ&s are

ca((ed S"*$( M&(&@""()!SM,<

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GS$ $$ States 56s G$$ States

IDLE

READ?

STA=DB?

GMM 5GPRS6 SaesGSM MM Saes

ACTIVE

IDLE

DETACHED

IMSI ATTACH

P%ss&ssi%" %#i'! &s%'&s

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GPRS T 2

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GPRS T&2

•  ,ere are two $,ases in connectin) aG."S termina( to t,e networ&?

 - onnection to t,e G."S=SGS>

networ&?  GPRS attach

- onnection to t,e eEterna( networ&?

  PDP contet acti5ation

GPRS M$%*#*)+M&(&@""()

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GPRS M$%*#*)+M&(&@""()

• GPRS &))& $rocedure is oneeEam$(e!

• D,en G."S termina( is $owered on '

it sends an attac, messa)e to t,enetwor&!

• SGS aut,enticates before attac,in)to G."S networ&!

• 2nce sub! ,as attac,ed to networ&'(o)ica( connection is estab(is,ed b6nMS'SGS and H"!

G."S +ttac,

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G."S +ttac,

GPRS Attach Request

Update Location

Insert Sub Data

Insert Sub data Ack 

Update Location Ack GPRS Attach Accept 

%#$

MS $-D

&!S'  SGS'MS

(MS( or &TMS( old $-( :

-))ac );e

Mul)iSlo) ca;aili)

re ;arame)er

&TMS(

'ego)ia)ed read )imer =alue

&eriodic $- )imer

Securi) Func)ion

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PDP C$()") &)*&)*$( "(&*$

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SGS 4S 4H.

GGS

G#

MS

+. 2.

ntranet

PDP $()") &)*&)*$(

1

DNS ;"+%

GGSN T$ %" U"'3

C"&)" PDP $()")

*A" M$'" &(' IP &''" #$&)*$(

5

=

S)&) B*##*(@ "$'

C"&)" PDP $()") &")

8

9

PDP $()") &)*&)*$(

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PDP ) ) )* )*

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PDP $()") &)*&)*$(

• +fter a successfu( G."S attac, ' MS,as to eEc,an)e data $ac&ets wit,eEterna( .4s!

t must )et an . address to be ab(eto connect to eEterna( .4s!

  ,is is .4. conteEt activation!

•  t is an . a((ocation to MS!

.4. conteEt activation

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.4. conteEt activation

  t contains?• .4. ty$es=.v*>

• .4. address assi)ned to MS

• "equested RoS• +ddress of a GGS t,at serves as

access $oint to .4!

•  ,is conteEt is stored in 7MS' SGSand GGS!

M$%*#*)+ M&(&@""()

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+ @)&)"

• + G."S MS ,as one of t,ree mobi(itymana)ement states?

•  ,e I'#" state is used w,en MS is$assive=not G."S attac,ed>

•  .erformin) a G."S attac,' MS )ets intoR"&'+ state!

• S)&('%+ state is entered w,en sub! ,asended an active $,ase but is sti(( attac,edto networ&!

Mobility Management State

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y g

(dle

S)and

$ead

&ac+e)

T>?$>ST-'DTimer x;ir

G&$S-))ac ? De)ac

$-DTimer x;ir

MS loca)ion +no*n )o

SGS' le=el@MS i ca;ale o. recei=ing&oin)A)oAMul)i;oin) da)aand eing ;aged .or&oin)A)oA&oin) da)a

MS loca)ionno) +no*n@Sucrier i no)reacale )e

G&$S 'B@

MS loca)ion +no*n )ocell le=el@

MS i )ranmi))ing or a Cu) een )ranmi))ing@MS i ca;ale o. recei=ing&oin)A)oA&oin) da)a and&oin)A)oAMul)i;oin) da)a@

Mobi(ity Mana)ement StateMode(

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Mode(

!ell ;da)e 'o need .or ;aging

R#AD$ 

IDL# 

S%A!D&$ 

G&$S-))ac

G&$SDe)ac

Da)a &D:)ranmiion

Read'   )imerex;ir

/nl $- ;da)e &aging i re

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BSC P&/") C$()$# U(*) PCU&(' G% *()"?&"

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G% *()"?&" F&" R"#&+%&"' *()"?&" )$.&' SGSN

A##$&)*$( $? PDCH *( "##

H&('#*(@ $? GPRS P&@*(@

B$&'&) GPRS *(?$&)*$(

SGSN GGSN

MSC:LR HLR

=$

=i (35)

 =n

=r (4A5)=s

4A5

 =n

 A

IPN").$/ 

B&/%$("N").$/ 

IP

BSC:PCU

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GGS'Gn

Gi (IP)

Ser=ing G&$S Su;;or) 'ode E SGS'

 !i;ering, au)en)ica)ion

 Moili) managemen)

 Seion managemen)

 #ogical lin+ managemen) )o*ard )e MS

 !arging da)a

 &ac+e) rou)ing )ran.er 

 !onnec)ion A %#$, MS!, S! and SMSAMS!

SGS'

(&

'e)*or+

MS

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MS

Gi (IP)

Ga)e*a G&$S Su;;or) 'ode E GGS'

 x)ernal in)er.ace Moile (& a;;lica)ion, (n)erne)?(n)rane):

 -cce .unc)ionali)

  Tradi)ionalH ga)e*a .unc)ionali)

 Sucrier addree ;uli   $ou)ing

 !arging da)a(&

'e)*or+

GGS'

+ut,entication

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• etwor& Switc,in) Subsystem =+C>   Te -! or -u)en)ica)ion !en)er inide )e %#$ i re;onile .or ma+ing

ure )a) )e S(M card in )e moile ;one i no) a .a+e or co;@

  Te -! genera)e a Signed $e;one S$S: mixing a random

numer $-'D:, an iden)i) +e Ii:, and an algori)m -3:@

  Te Moile ma+e )e ame calcula)ion and )e SGS' com;are )e an*er@

SGS=

A@i

HLR,AUC

RA=D

SRES

Ma)cJ

RA=D > SRES

A@i   C  o  p  y  r   i  g   h  t    ©   1   9   9   6   N  o  r  t   h  e  r  n   T  e   l  e  c  o  m   R

     A     =

     D

+ut,entication

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 Authentication Request 

SS

SGS'

Send Authentication Ino

%#$MS

Send Authentication Ino Ack 

 Authentication Response

GGS! 

(IMSI)

(SR#S RA!D *c)(RA!D)

(SR#S)

-3

$-'D   Ii

-3

Ii

SR#S 

+

 Authenticated Subscriber 

no ,orbiddenSubscriber 

'es

G&$S Moile S)a)ion !a;aili)ie

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•   !la - – Simultaneous ee!ution o" !i#!uit s$it!%e& an& '()S o*e#ation is

*ossible

•   !la

 – Simultaneous ee!ution o" signaling "o# bot% !i#!uit s$it!%e& an&

'()S o*e#ation is *ossible

 – '()S t#a""i! $ill be sus*en&e& &u#ing a *en&ing o# an establis%e&

!i#!uit s$it!%e& !onne!tion

•   !la !

 –  Alte#nate use o" !i#!uit s$it!%e& an& '()S o*e#ation

$ulti!le Access !eration

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•  GPRS  Multislot  O9&!i%"

0 70 7 Non-BCCH 

TDMA

 Hence, 1 MS :: 1-8 TS 

•  GSM Si"+$& R!#i%-TS O9&!i%"

0 4 7

< Subject to QoS profiles

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Multislot Class Downlink Slots Uplink Slots Active Slots

1 1 1 2

2 2 1 3

3 2 2 3

4 3 1 4

5 2 2 4

6 3 2 4

7 3 3 4

8 4 1 5

9 3 2 5

10 4 2 5

11 4 3 5

12 4 4 5

•   Te numer o. )imelo) a G&$S moile can ue *en ending u;lin+: or recei=ingdo*nlin+: i communica)ed )o )e ne)*or+ in )e .orm o. a Mul)ilo) cla@

•   !lae exi) all )e *a )o 8 8 !la 29: u) )ee re

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• M$i9$& MSs %" ! si"+$& R!#i%-TS

0 7 70

&s RLC

Bl0c$ 

!n; RLC

Bl0c$ 

0 7 0 7

,r; RLC

Bl0c$ 

'h RLC

Bl0c$ 

7 7 7 7 7 7 7 77 7 7 7

 Hence, 1 TS :: 1-8 MS 

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G."S 5%-Mu(tiframes

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I'#" ?&"

R&'*$ B#$/

Multi Frame   0 1 2 3 4 5 6 7 8 9 1 0 11 1 2 1 3 14 1 5 16 1 7 18 1 9 2 0 21 2 2 23 2 4 25 2 6 2 7 28 2 9 30 3 1 32 3 3 3 4 35 3 6 37 3 8 39 4 0 4 1 42 4 3 44 4 5 46 4 7 48 4 9 5 0 51

B#$/ B 0 B 1 B 7 1 B 3 B 4 B 5 7 B 6 B = B 8 3 B 9 B 10 B 114

0 1 7 3 4 5 6 = 0 1 7 3 4 5 6 = 0 1 7 3 4 5 6 =

GPRS T*" S#$)TDMA F&" > 4

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