go_bt1005_e01_0 gsm gprs edge principles-86

8/21/2019 Go_bt1005_e01_0 Gsm Gprs Edge Principles-86

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GSM/GPRS/EDGE Principles

Curriculum Objective:

Learn GSM development history;

Learn and master network structure o GSM system and unctions !

principles o dierent portions;

Learn and be amiliar with GSM wireless channel and protocol

Learn and be amiliar with main service call process or GSM


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Content

1 GSMOverview...............................................................................................................................................1

"#" GSM $asic Concepts###########################################################################################################################"

"#"#" %istory o the mobile communication######################################################################################"

"#"#& GSM 'einition########################################################################################################################(

"#& Services Supported by GSM System###################################################################################################)

"#" *elecom Services +rovided by GSM########################################################################################)

"#& Supplementary Services o the GSM System##########################################################################,

"#- GSM Speciication###############################################################################################################################,

2 GSM Network Structure..............................................................................................................................9

" GSM .rea 'ivision Concepts####################################################################################################### ######/

& GSM composition##############################################################################################################################"0

- Mobile Switchin1 System 2MSS3######################################################################################################"-

( $ase Station Subsystem 2$SS3##########################################################################################################"(

Operation ! Maintenance Subsystem 2OMS3############################################################################## ####"(

) Mobile Station 2MS3##########################################################################################################################"4

, GSM System number#########################################################################################################################"4

,#" Mobile subscriber 5S'6 number 2MS5S'63##################################################################### ###"4

,#& 5nternational Mobile Subscriber 5dentity 25MS53###################################################################")

,#- Mobile subscriber roamin1 number 2MS763########################################################################",

,#( %andover number###################################################################################################################",

,#4 *emporary mobile subscriber identiication 2*MS53######################################################## #####"8

,#) Location area 5dentiication 2L.53#########################################################################################"8

3 GSM Radio Channel...................................................................................................................................19


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-#" GSM 9orkin1 reuency $and########################################################################################################"/

-#& Structure o GSM 7adio rame#########################################################################################################&"

-#- +hysical Channel and Lo1ical Channel#############################################################################################&-

-#-#" +hyC% +hysical Channel###################################################################################################### #&-

-#-#& Lo1ic channel############################################################################################################### ##########&-

-#-#- Channel Combination#############################################################################################################&)

4 Basic Service and Sinalin !rocess.........................................................................................................33

(#" Mobile subscriber state######################################################################################################################--

(#"#" MS starts< network does =.ttach= marks on it#######################################################################--

(#"#& MS shutdowns< separated rom network################################################################################-(

(#"#- MS $usy######################################################################################################################## #########-(

(#& Location >pdate#################################################################################################################################-(

(#" Location update at a MSC oice############################################################################################-(

(#& 5nteroice Location >pdate################################################################################################ ###-4

(#- *ypical Call and %andover +rocess###################################################################################################-)

(#-#" Call between Mobile Subscribers###########################################################################################-)

(#-#& 5nter?$SC %andover within MSC######################################################################################## ##-,

(#-#- 5nter?MSC %andover##############################################################################################################-8

(#( $asic Si1nalin1 +rocess#####################################################################################################################-/

(#(#" Location >pdate +rocess########################################################################################################-/

(#(#& 5MS5 'etach +rocess########################################################################################################## ####("

(#(#- Mobile?Ori1inated Call and Called +arty On?hook +rocess##################################################(&

(#(#( Mobile?*erminated Call and Callin1 +arty On?hook +rocess########################################### ####((

(#(#4 5nter?cell %andover low########################################################################################################()

" #oice !rocessin and $e% Radio &echnolo%...........................................................................................4'

4#" @oice +rocessin1################################################################################################################################(,

4#"#" $asic low o @oice +rocessin1######################################################################################### ####(,


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4#"#& @oice Ancodin1#######################################################################################################################(8

4#"#- Channel Ancodin1###################################################################################################################(8

4#"#( 5nterleavin1Bdeinterleavin1#####################################################################################################(/

4#"#4 AncryptionB'ecryption###########################################################################################################4&

4#"#) ModulationB'emodulation#####################################################################################################4-

4#& 'iversity 7eceivin1###########################################################################################################################4-

4#- 'iscontinuous *ransmission 2'*3##################################################################################################44

4#( +ower Control####################################################################################################################################44

4#(#" $asic Concepts o +ower Control############################################################################### ###########44

4#(#& GSM +ower Control +rocess##################################################################################################4)

4#(#- %i1h?speed power control######################################################################################################48

4#4 *imin1 .dvance#################################################################################################################################4/

4#) reuency %oppin1 *echnolo1y#################################################################################################### ###)0

( G!RS and )*G)........................................................................................................................................(3

)#" 'einition and eature#######################################################################################################################)-

)#"#" G+7S 'einition#####################################################################################################################)-

)#"#& G+7S eatures########################################################################################################################)-

)#"#- A'GA 'einition####################################################################################################################)(

)#"#( A'GA eatures#######################################################################################################################)(

)#& 5nheritance and Avolution##################################################################################################################))

)#- G+7S 7adio Channel################################################################################################################## ######),

)#-#" G+7S +hysical Channel#########################################################################################################),

)#-#& G+7S Lo1ic Channel#############################################################################################################)8

)#-#- Mappin1 o Lo1ical Channel Combination in the +hysical Channel####################################,0

)#-#( G+7S Channel Codin1###########################################################################################################,4

)#( *erminal and .pplication########################################################################################################### #######,8


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1 GSMOverview

Knowledge points

*his chapter mainly introduces some basic inormation or GSM< includin1 GSM

development history< supported service type< speciication< and system eatures#

1.1 GSM Basic Concepts

1.1.1 Histor o! t"e #o$ile co##%nication

*he mobile communication was irst used in military and some special ields in "/&0Ds#

5n "/(0Ds< it be1an to be employed or civil use# *he mobile communication really booms

in recent decade# *he development o the mobile communication comprises the

ollowin1 three phases:

*he irst 1eneration 2"G3 mobile communication system

*he second 1eneration 2&G3 mobile communications system

*he third 1eneration 2-G3 mobile communications system

"# Startin1 rom "/80Ds< the "G analo1 mobile communication system adopts cellular

networkin1 technolo1y#

%owever< the "G mobile communication system has the ollowin1 disadvanta1es:

*here is no common interace between systems#

5t cannot keep up with the ast di1itiEin1 o the iFed network and provide di1ital

bearer services#

5t cannot meet the demand or lar1e capacity due to low reuency utiliEation#

5t eatures poor security# *he inormation bein1 eFchan1ed on the radio path may

be easily eavesdropped< and the subscriber account may be easily embeEEled#

'ue to the deects o analo1 systems< the di1ital mobile communication system

characteriEed by di1ital transmission< *ime 'ivision Multiple .ccess 2*'M.3*7.

9C'M.

5M*?&000

&G G -G

A'GA

>9C?"-)

,4G

i1ure "#"?" Avolution rom &G to -G

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) G+7S and A'GA

5n +hase& and +hase&H< two hi1h?rate data service models are put orward or the GSM

system#

%i1h Speed Circuit Switched 'ata 2%SCS'3 based on hi1h?speed data bit rate and

circuit switchin1

General +acket 7adio Service 2G+7S3 based on packet switched data

*hese two services are called G services# .doptin1 hi1h?rate adaptive codin1 solutionnicom is

represented by K0"#

GSM service area contains the +LM6s o countries all over the world#

&.& GSM co#position

*he GSM communication system consists mainly o three parts: mobile switchin1 sub?

system 2MSS3< base?station sub?system 2$SS3 and mobile station 2MS3< as shown in

i1ure & ?-#

IBM

IBM

$SS MSS

MS

MS

+S*6

+LM6

>m .

i1ure &?- GSM System Composition

Moile Switchin Sus%ste /MSS

ulills messa1e eFchan1in1< user inormation mana1ement< call connection and number

mana1ement unctions#

Base Station Sus%ste /BSS

*he $SS is controlled by MSC in a certain wireless covera1e and communicates with the

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) G+7S and A'GA

MS# 5t implements channel allocation< user access and pa1in1< and inormation

transmission unctions#

Moile Station /MS

MS which is the mobile euipment o the GSM system consists o two parts: mobile

terminal and customer 5' card 2S5M card3# *he mobile terminal is nothin1 but a

Khandset< which perorms such unctions as voice codin1< channel codin1< inormation

encryption< inormation modulation and demodulation< inormation transmission and

receivin1#

Oeration 5 Maintenance Sus%ste /OMS

.lso includin1 the operation and maintenance subsystem 2OMS3< the GSM system

mana1es and monitors the entire GSM network# 5t implements the unctions like

monitorin1< status reportin1 and ault dia1nosis o all the component unctions within the

GSM network#

+osition o GSM di1ital mobile communication network in $SS is as shown in i1ure

& ?(#

$SCn

$*S

MSCB@L7

SGS6

SMC

%L7B.>C

A57

MS

+LM6

GGS6GGS6

+'6 *A

+S*6MSCB@L7

.bis

$*S

MS

>m

.bis

6

$SC"6

.

Gb

i1ure &?( +osition o the $SS in the GSM 6etwork

*he $SS provides a brid1e between the iFed part and the wireless part in the +LM6

network< connects the MS or communications directly via the wireless interace and

connects the MSC o MSS#

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G+7S A'GA +rinciples

i1ure & ?4shows the basic GSM network structure#

$SC *7.> MSCB@L7

SMC

GMSC

.>C

59: A57

%L7

+S*6

5S'6

+'6

$*S

MS

$*S

MS

i1ure &?4 GSM 6etwork Structure

*he meanin1 o each name is as ollows:

MS: Mobile Station

$*S: $ase *ransceiver Station

$SC: $ase Station Controller

*7.>: *ranscodin1 and 7ate .daptation >nit

59: 5nterworkin1 unction

A57: Auipment 5dentity 7e1ister

MSC: Mobile Switchin1 Center

@L7: @isitor Location 7e1ister

GMSC: Gateway MSC

%L7: %OMA Location 7e1ister

.>C: .uthentication Center

SMC: Short Messa1e Center

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) G+7S and A'GA

+S*6: +ublic Switched *elephone 6etwork

5S'6: 5nte1rated Services 'i1ital 6etwork

+'6: +ublic 'ata 6etworks

. GSM di1ital mobile communication system is composed o the Mobile Switchin1

System 2MSS3< $ase Station Subsystem 2$SS3< Operation Maintenance Sub?system

2OMS3 and Mobile Station 2MS3# *he ollowin1 introduces the unctions o each part#

&.( Mo$ile Switc"ing Sste# ,MSS-

6SS perorms switchin1 unction and database or mana1ement o user data < mobilityand security#

*he MSS consists o such entities as the mobile switchin1 center 2MSC3< home location

re1ister 2%L73< visitor location re1ister 2@L73< euipment identity re1ister 2A573C3 and short messa1e center 2SMC3#

MSC: .s the core o the GSM< the MSC implements the switchin1 unction< that

is< accomplishes the communication connection between the +LM6 subscribers

and the subscribers in other networks# 5t implements the unctions such as the

pa1in1 access o +LM6 subscribers< channel assi1nment< call connection< traic

control< billin1< and base station mana1ement# 5t provides interaces to other

unctional entities< interaces with other networks< and interaces or connectin1

with other MSCs#

%L7: *he central database o the system# 5t stores all subscriber?related

inormation< includin1 roamin1 authority< basic services< supplementary services

and current location inormation# 5t provides routin1 inormation or MSC or the

purpose o call setup# .n %L7 may cover multiple MSCs or even the whole

mobile network#

@L7: @L7 stores inormation o all subscribers in the covera1e< and provides

conditions or establishin1 call connections or the re1istered mobile subscribers#

.s a dynamic database< the @L7 must eFchan1e lar1e volume o data with the

%L7 to ensure data validity# 9hen a subscriber leaves the controllin1 area o a

@L7< it re1isters in another @L7# *he ori1inal @L7 deletes the temporary records

o that subscriber# *he @L7 is always inte1rated with the MSC physically#

.>C: . strictly protected database that stores subscriber authentication

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inormation and encryption parameters# *he .>C and %L7 are inte1rated

physically#

A57: Stores parameters related to the mobile station euipment# 5t can identiym interace#

5n addition< the $SS also comprises the *7.># Located between the $SC and the MSC perorms the conversion between ") bitBs 7+A?L*+ codes and )( bitBs .

law +CM codes#

&. Operation 0 Maintenance S%$sste# ,OMS-

*he OMS reers to the operation ! maintenance part o the GSM system# .ll unctional

units in the GSM system can be connected to the OMS via respective networks# *he

OMS perorms such unctions as monitorin1 various unctional units in the GSM

network< issuin1 status report< and dia1nosin1 aults#

*he OMS consists o two parts: Operation ! Maintenance Center System 2OMC?S3

and OMC?7adio 2OMC?73# *he OMC?S serves the 6SS< while the OMC?7 serves the

$SS#

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) G+7S and A'GA

&. Mo$ile Station ,MS-

.s the subscriber euipment in the GSM< the MS can be vehicle installed or handportable# *he MS consists o mobile terminals and Subscriber 5dentity Module 2S5M3

card#

*he mobile terminal is in char1e o voice si1nal processin1 and radio transceivin1#

*he S5M stores all inormation reuired or identiyin1 a subscriber and security

inormation< preventin1 unauthoriEed user access# . mobile terminal can not 1ain

access to the GSM network without an S5M card#

&.2 GSM S%ste nuer

&.2.1 Mo$ile s%$scri$er 3SD) n%#$er ,MS3SD)-

MS5S'6 number is the number dialed by caller while callin1 certain subscriber in

di1ital public terrain celluar mobile communication network# 5ts number

comprises o:

State 6o# %ome valid 5S'6 number

%ome Mobile 5S'6 number

China code number is 8)#

*he structure or valide 5S'6 number in China is:

6"6&6-

Mobile service number

%"%&%-

%L7 5'

.$C'

Mobile number

%ome valid 5S'6 number

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'omestic valid 5S'6 number is a number with "0 di1its#

"# Mobile service access number 26"6&6-3

*o identiy dierent mobile systems< mobile service access number is "-4?"-/ or

current post and telecom; "-0 or China >nicom#

%L7 identiication number 2%"%&%-3

%"%& in %L7 identiication number is allocated uniormly by state; %- is

assi1ned by dierent provinces# One %L7 can contain one or more %"%&%-numbers#

-# Mobile subscriber number 2.$C'3

.$C' is mobile suscriber number in each %L7< automatically assi1ned by

dierent %L7s#

&.2.& 3nternational Mo$ile S%$scri$er 3dentit ,3MS3-

5MS5 is the only one number to identiy a mobile subscriber in +LM6< composed o "4

di1its#

MCC M6C MS56

5nternational mobile number

%ome mobile number

MCC N mobile country code< composed o - di1its< to uniuely identiy the country or

mobile subscriber# China is ()0#

M6C N mobile network code< composed o & di1its< to uniuely identiy the mobile

network or mobile subscriber# GSM +LM6 network is 00 or post and telecom ministrynicom is 0"#

MS56Mobile subscriber identiication number< a number with "0 di1its< such as

%"%&%-/# 9here< %"%&%- is same as %"%&%- in MS5S'6; / represents

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) G+7S and A'GA

GSM/00M%; is subscriber number#

5MS5 is used to all si1nalin1 in GSM mobile communication network< saved in %L7plink and 'ownlink Oset o *C%

rom the above description< it can be concluded that on 0:

*S0: a lo1ical control channel< with repeat cycle o 4" timeslots#

*S": a lo1ical control channel< with repeat cycle o "0& timeslots#

*S&: a lo1ical service channel< with repeat cycle o &) timeslots#

*S- to *S,: lo1ical traic channels< with repeat cycle o &) timeslots#

*he *S0 to *S, o other 0 P 6 are all traic channels#

*he channel coni1uration adopted by *A or common cells is as ollows:

6umber o carrier reuencies " & - ( 4 ) ,

6umber o control channels " & & & - - -

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6umber o service channels , "( && -0 -, (4 4-

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Basic Service and Signaling Process

Knowledge points

*his section introduces GSM terminal start< position re1isterBupdate< service call and

handover service implementation and si1nalin1 interaction process#

.1 Mo$ile s%$scri$er state

.1.1 MS starts8 networ* does 9+ttac"9 #ar*s on it

*hat is< commonly used 5MS5 attachment< divided into the ollowin1 three cases:

"# 5 MS is started irstly: no L.5 in S5M card< MS transmits =location update

reuest= messa1e to MSC< inorm GSM system this is a new subscriber in this

location area# MSC transmits =location update reuest= to %L7 based on 5MS5

number sent by this subscriber< %L7 records MSC number that sends reuest< and

correspondin1 @L7 number< and send MSC =location update acceptance=

messa1e# >p to now< MSC considers the MS is activated< do attachement mark on

correspondin1 5MS5 or this subscriber< then send =location update validation=

messa1e to MS< and S5M card o this MS records this location area identiication#

5 MS is not irstly started< but start ater shutdown< L.5 accepted by MS is not

consistent with ori1inal L.5 in its S5M card< MS immediately sends =location

update reuest= to MSC< @L7 shall jud1e whether ori1inal L.5 is the ori1inal

location in service area#

5 jud1ement is airmative< MSC only reuires chan1e ori1inal L.5 code in userS5M card to new L.5 code#

5 it is ne1ative< MSC sends =location update reuest= to %L7 based on the

inormation in 5MS5 number or this subscriber< %L7 records the MSC number to

send reuest into database< then return =location update acceptance=# MSC does

=attachment= mark or user 5MS5< and send =location update acknowled1ement=

messa1e to MS< and MS chan1es ori1inal L.5 code in S5M card to new L.5 code#

9hen MS starts a1ain< the received L.5 is consistent with that saved in ori1inal

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S5M card: at this time< @L7 does =attachment= mark or this subscriber#

.1.& MS s"%tdowns8 separated !ro# networ*.

.ter MS powers o< MS sends separation processin1 reuest to MSC< MSC inorms

@L7 to do =separation= marks or this MS on correspondin1 5MS5 ater receivin1 the

reuest# .t this time< %L7 doesnDt 1et the notiication that this subscriber has detach rom

the network# 9hen this subscriber is pa1ed< %L7 reuests MS76 rom visitor

MSCB@L7< and then @L7 inorms %L7 this subscriberDs MS power o#

.1.( MS B%s

.t this time< assi1n a service channel to transmit voice or data or this MS< and label this

subscriber as =busy= on subscriber 5S'6#

.& 4ocation :pdate

9hen an MS moves into another location area< it will ind that the received L.5 diers

rom the ori1inal one stored in the S5M card and then re1isters the new one# *his process

is location update process that is initiated by the MS# *here are two cases or location

update:

"# Location area o MS is chan1ed< but still at same MSC oice;

MS transers rom one MSC oice to the other MSC oice#

.&.1 4ocation %pdate at a MSC o!!ice

5 location is updated at a MSC oice< %L7 doesnDt participate in location update

process# Location update at same oice is as shown in :

$SC

&

"

- (

MSCB@L7

L.5

"

L.5

&

M

S

M

S

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) G+7S and A'GA

i1ure (#&?/ Location >pdate at Same MSC Oice

Location update at same MSC oice is simple< allin1 into the ollowin1 our steps:

9hen MS roams to a new location area< it is ound received L.5 is not consistent with

that saved in S5M card throu1h analysis< then a location update reuest is sent to current

base station controller 2$SC3#

5 $SC receives location update reuest rom MS< it sends a location update reuest to

MSCB@L7#

@L7 modiies the data or this MS< chan1es the L.5 to current L.5< then sends a

response messa1e to $SC#

$SC sends a response messa1e to MS< and MS chan1es L.5 saved in its S5M card to

current L.5# So the location update process at same MSC oice is completed#

.&.& 3ntero!!ice 4ocation :pdate

9hen mobile subscriber roams rom a MSC oice to the other< you shall do interoice

location update# .t this time< %L7 shall participate in location update process< as shown

in i1ure (#& ?"0:

"# Location update between dierent MSCs is more complicated than that at same

MSC# *o more conveinient description< ori1inal MSC oice or subscriber is

MSC"< roamed MSC oice is MSC 5n the i1ure< $SC is omitted< but it also will

be mentioned durin1 description< $SC and MSC are called as $SC" and $SC&+' 7ATAS* 56'

>.

S.$M

5MM .SS5MM .SS CM'

C% .C* .C

C% .C*

C% 7T'C% 7AT

MS $*S $SC MSC

'*.+LOC >+' .CCA+*

i1ure (#(?"- Location >pdate +rocess o MS

*he MS sends a C% 7AT 2Channel 7euest3 messa1e throu1h the 7.C% to the $*S#

>pon receivin1 the C% 7T' 2Channel reuired3 messa1e< the $*S processes it and then

sends it to the $SC#

.ter receivin1 the C% 7AT messa1e< the $SC sends a C% .C* messa1e to the $*S to

activate the S'CC%# .ter activatin1 the channel< the $*S returns a C% .C* .C

messa1e#

*he $SC sends the 5MM .SS CM' to the $*S# >pon receivin1 the messa1e< the $*S

sends the 5MM .SS throu1h the .GC% to the MS# 9hen receivin1 the messa1e< the MS

sends the S.$M# *he $*S sends the >. to the MS#

.t the same time< the $*S sends a channel establishment indication 2AS* 56'3 to the

$SC< containin1 a reuest to update the mobile phone location# *he $SC orwards the

location update reuest to the MSC 2LOC >+' 7AT3 via C7# .s receivin1 the reuestp to now< the S'CC% has been established between the mobile phone and the $*S#

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) G+7S and A'GA

*he location update messa1e is transmitted to the MSC over S'CC%< and the MSC

sends a location update acceptance messa1e 2LOC >+' .CCA+*3 to the mobile phone

ater perormin1 an optional encryption#

*he MSC sends a Clear CM' messa1e to the $SC# *he $SC returns a Clear COM

messa1e to the MSC# Meanwhile< the $SC sends the $*S a C% 7AL messa1e to release

the S'CC% and a 'A.C* S.CC% messa1e to deactivate the S.CC%#

*he $*S sends a C% 7AL messa1e to the MS# *he MS reuests the $*S to release radio

link 2'5SC3# *he $*S returns the >. and reports the channel release indication to the

$SC#

*he $SC sends a 7 C%L 7AL messa1e to the $*S# *he $*S returns a 7 C%L 7AL

.C messa1e# *he radio channel is released#

..& 3MS3 Detac" Process

i1ure (#( ?"( shows the 5MS5 detach procedure#

7: C% 7AL .C

7: C% 7AL

7AL 56'>.

'5SC'A.C* S.CC%

'7C% 7ALC% 7AL

C7A:

C75MS5 'A*.C%AS* 56'

>.

S.$M

5MM .SS5MM .SS CM'

C% .C* .C

C% .C*

C% 7T'C% 7AT

MS $*S $SC MSC

i1ure (#(?"( 5MS5 'etach +rocess

*o power o a mobile phone< an S'CC% channel should be established irst# *hen a

power?o messa1e is sent to the MSC over S'CC% 25MS5 'A*.C%3# >pon receivin1

the messa1e< the MSC releases the S'CC%#

..( Mo$ile;Originated Call and Called Part On;"oo* Process

i1ure (#( ?"4 shows the mobile?ori1inated call and the called party on?hook process#

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9hen a mobile subscriber ori1inates a call< the S'CC% is established irst< and then a

reuest or the *C% is sent throu1h the S'CC% to the MSC#

7 C% 7AL .C

7 C% 7AL

7LC

7LS'

C% 7AL

'5SC

>.7 C% 7AL

7 C% 7AL .C

7AL 56'

'A.C* S.CC%

'7C% 7AL

AS* 56'

.SS COM'*".SS COM

'*":.SS 7AT

'*"C5+% MO'A CM'

C% .C* .C

C% .C*

+% CO6* CO6

>.

S.$M

+% CO6* 7AT

'7.SS CM'.SS CM'

'*"Clear COM

'*"Clear CM'

'*"C5+% MO'A COM'5C5+% MO'A COM

C5+% MO'A COM

C5+% MO'A CM'A6C7 CM'

CC

C7CM SA7@ 7ATAS* 56'

>.

S.$M

5MM .SS5MM .SS CM'

C% .C* .C

C% .C*

C% 7T'C% 7AT

MS $*S $SC MSC

'*.+:SA*>+

'*.+:C.LL +7OC

'5.SS COM

'*.+.lertin1

'*.+Connect

'*.+Connect .C

'*.+'isconnect

'*.+7elease

'*.+7elease COM

'*.+:CM SA7@ .CC+

i1ure (#(?"4 Mobile?Ori1inated Call and Called +arty On?hook +rocess

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) G+7S and A'GA

*he MSC sends an .ssi1nment 7euest messa1e to the $SC# .ter receivin1 the

messa1e< the $SC sends an 5MM .SS CM' messa1e to the MS# *he MS establishes a

*C% with the $*S# *he $*S sends a channel establishment indication< completes

immediate assi1nment< and release the S'CC%#

*he MSC sends a rin1?back tone to the mobile phone over the established *C%# . call

session is set up by connection establishment and connection conirmation#

9hen the called hooks on< the MSC sends a disconnection messa1e to the mobile phone#

*hen the mobile phone releases the *C% and the MSC replies with a release

acknowled1ement to complete the *C% release process#

.. Mo$ile;'er#inated Call and Calling Part On;"oo* Process

i1ure (#( ?") shows the mobile?terminated call and the callin1 party on?hook process#

*o call a mobile phone< the MSC initiates a pa1in1 messa1e to the mobile phone< which

establishes an S'CC% upon receivin1 the pa1in1 messa1e# *hen the S'CC% is released

ater a *C% has been established# *he call setup is accomplished over the *C%#

9hen the call is ended< the *C% is to be released#

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>'*+.G+.G CM'+.G 7AT

7 C% 7AL .C

7 C% 7AL

7LC

7LS'

C% 7AL

'5SC

>.7 C% 7AL

7 C% 7AL .C

7AL 56'

'A.C* S.CC%

'7C% 7AL

AS* 56'

.SS COM'*".SS COM

'*":.SS 7AT

'*"C5+% MO'A CM'

C% .C* .C

C% .C*

+% CO6* CO6

>.

S.$M

+% CO6* 7AT

'7.SS CM'.SS CM'

'*"Clear COM

'*"Clear CM'

'*"C5+% MO'A COM'5C5+% MO'A COM

C5+% MO'A COM

C5+% MO'A CM'A6C7 CM'

CC

C7+.G 7ASAS* 56'

>.

S.$M

5MM .SS5MM .SS CM'

C% .C* .C

C% .C*

C% 7T'C% 7AT

'*.+:SA*>+

'*.+:C.LL CO6

'5.SS COM

'*.+.lertin1

'*.+Connect

'*.+Connect .C

'*.+'isconnect

'*.+7elease

'*.+7elease COM

$SC MSC$*SMS

i1ure (#(?") Mobile?*erminated Call and Callin1 +arty On?hook +rocess

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) G+7S and A'GA

.. 3nter;cell Handover 6low

i1ure (#( ?", illustrates the inter?cell handover low#$ased on the measurement reports ori1inated rom the mobile phone continuously< the

$SC jud1es whether it is necessary to perorm handover#

9hen intra?cell handover is necessary< the mobile phone is located in the source cell

$*S"# *he $SC activates a *C% in the tar1et cell $*S&< and sends a handover command

to the mobile phone# *he mobile phone is switched to the *C% in $*S& and completes

the handover process#

.s the intra?cell handover is completed< the $SC inorms the MSC o the event and

releases the *C% in the source cell#

'*"%O +A7:

%O CM'

C% .C*

MA.S 7A+

7: C% 7AL .C

7: C% 7AL

'5%O COM

AS* 56'

%O 'A*

C% .C* .C

MS $*S" $*S& $SC MSC

MA.S 7AS

'7%O CM'

%O .CCASS

+% 56:O

S.$M

>.

%O COM

i1ure (#(?", 5nter?cell %andover +rocess

45


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52/84

assembled into a (4)?bit messa1e# *hen come the steps o channel decodin1< checkin1

and correctin1 errors in the transmission# inally< the bitstreams 1enerated by the decoder

are decoded< and converted to analo1 voices#

.1.&


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) G+7S and A'GA

so that they are suitable or transmission in a serial port manner# $esides they also show

very little delay# *he coded n code elements are not only related to k inormation code

elements o this packet< but also to inormation code elements in the precedin1 26?"3plink and 'ownlink Oset o *C%

Supposin1 an MS occupies *S&< and call si1nals tend to shit away rom the $S< a

messa1e rom the $S will delay in reachin1 the MS# Meanwhile< the response messa1e

ori1inated rom the SM will also delay in reachin1 the $S# 5 nothin1 is done to iF the

problem< the messa1e sent rom *S& in the MS will eventually overlap with another

callin1 messa1e received in *S- in the $S# 5t is important to monitor the time when a call

reaches the $S# .s the distance between the MS and the $S chan1es< the system issues

instructions to the MS notiyin1 it o the transmission time lead# *his process is called

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adjustment o time lead#

.ter a speciic connection has been established< the $*S measures the time shitbetween the pulse *Ss and the received MS *Ss# 5t calculates the appropriate time lead

based on the measured time shit< and notiies the MS o it on S.CC% at certain

reuency#

. 6re7%enc Hopping 'ec"nolog

Spread spectrum techniues< includin1 direct spread 2'S3 and reuency hoppin1 2%3sually< the % number should be 1reaterthan three# 5 reuency diversity is also available or the % system and the messa1e is

decided more eectively via a lar1e number decision law ater several 1roups o %s

simultaneously transmit one messa1e< more subscribers can work at the same time with

least mutual intererence#

*he reuency hoppin1 comprises baseband hoppin1 and 7 hoppin1#

$ase band % keeps the transmittin1 and receivin1 reuencies o each carrier unit

unchan1ed< but sends the rame unit transmittin1 data to dierent carrier units at

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dierent 6 2rame 6umber3 moments#

%owever< radio reuency hoppin1 is to control the reuency synthesiEer o eachtransceiver< makin1 it hop in each time slot accordin1 to dierent schemes#

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GPRS and EDGE

Knowledge points

*his section describes evolution o GSM technolo1ies: basic concept< network

structure< radio channel< and basic application o G+7S and A'GA#

.1 De!inition and 6eat%re

.1.1 GPRS De!inition

G+7S: General +acket 7adio Service#

*he General +acket 7adio Service 2G+7S3 is the packet data service introduced in GSM

+hase&H# 5t provides subscribers with the end?to?end mobile data services based on

packet switchin1 and transmission technolo1ies# *he G+7S can eectively utiliEe the

radio resources and network terrestrial resources and is suitable or lon1?time small?

volume burst data services#

.1.& GPRS 6eat%res

*he G+7S has the ollowin1 eatures:

Seamless connection with 5+ network

5+ technolo1y is adopted in the core network o the G+7S< and many transmission

technolo1ies are employed in the bottom layer o the G+7S# *hus< it is easy to

implement the seamless connection with the hi1hly developed 5+ network#

%i1h rate

9ith the help o multi?slot bindin1 and hi1h?speed codin1 scheme< the G+7S

phase 5 adopts CS" and CS& codin1 schemes< and provides the access rate up to

""4 bitBs# *he G+7S phase 55 adopts CS- and CS( codin1 schemes< and provides

up the rate up to "," bitBs#

.lways online and low char1in1

*he G+7S provides the =availability or connection everywhere and the

perormance o always online=< oerin1 new means or mobile subscribers to

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access the 5nternet and 5ntranet rapidly# Once a G+7S terminal is powered on and

connected with the G+7S network< it can maintain the online status all the way#

*he subscriber can receive and send inormation at any time without the dial?up

process reuired in circuit switchin1# .s lon1 as the G+7S terminal does not

transmit data< it will not occupy network and radio resources# *hus< the mobile

subscribers can beneit rom the low char1in1# *hat is< the mobile subscribers can

stay online as lon1 as possible without botherin1 the prohibitive bill#

Mature technolo1y

*he G+7S provides solutions to implement data services in the mature GSM

technolo1ies and current networks# 5t can save investment and make uick return#

.1.( EDGE De!inition

A'GA: Anhanced 'ata 7ate or GSM Avolution#

Anhanced 'ata 7ate or GSM Avolution 2A'GA3 is a kind o technolo1y or transition o

GSM to -G# 5t mainly adopts a new modulation mode in the GSM system includin1 most

advanced multislot operation and 8+S modulation technolo1y# 8+S technolo1y makes

the si1nal space o GMS modulation technolo1y in eFistin1 GSM network eFtend rom

& to 8 so that each symbol contains ( times o previous messa1es#

*he reason why A'GA is called the solution or transition o G+7S to -G mainly lies in

such technolo1y can ully utiliEe eFistin1 GSM resources includin1 eFistin1 GSM

reuency and most o eFistin1 GSM euipment# *his technolo1y only makes small

chan1es to the network sotware and hardware part# 5n this way< operators can provide

mobile subscribers with such wireless multimedia services as 5nternet browsin1< video

teleconerence and hi1h?speed email transer< that is< individual multimedia

communication services can be oered to subscribers beore the -G mobile network is

put into commercial use# .s A'GA is the transition technolo1y between eFistin1 &G

mobile network and -G network< it is also called G 2,4 1eneration3 technolo1y#

.1. EDGE 6eat%res

5n terms o protocol< the A'GA technolo1y mainly aects the $SS 2i#e# $*S and $SC#3

o the wireless access part in the GSM system< but does not aect eFistin1 GSM core

network and network applications< and the interaces between the $SS and the MSC and

SGS6 in the eFistin1 system will be kept# *hus< network operators can utiliEe eFistin1

wireless network euipment to maFimum eFtent to provide subscribers with individual

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) G+7S and A'GA

multimedia communication services beore the -G mobile network is put into

commercial use# A'GA has the ollowin1 eatures:

A'GA neither chan1es GSM or G+7S network structure nor introduces new

network element< but only up1rades the $SS#

5n terms o wireless interaces< A'GA does not chan1e the GSM channel structure.LCOM< and

orean Samsun1 ! LG always canDt 1et more commercial opportunity#

rom evolution mode< due to GSM scale advanta1es< it enables more countries preer

9C'M. or *'?SC'M. evolution scheme# G transitional technolo1y or this

evolution scheme is G+7S< so G+7S technolo1y is outstandin1# Currently< there are over

"00 operators that open G+7S commerce system< trial commerce system< or

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) G+7S and A'GA

eFperimental system 1lobally# G+7S technolo1y has been eFtensively deployed in 1lobal

GSM network# Some amous telecom euipment manuacturers< such as 6okia< Siemensnder the packet switchin1 mode< the +'*C% bears subscriber data# 5t is

allocated temporarily to a speciic MS or a 1roup o MSs 2under the +*M?M

mode3# >nder multi?slot mode< an MS can use several +'*C%s concurrently#

$ecause dierent lo1ical channels can be multipleFed on a physical channel< a

+'*C% can bear 0 to &"#( bitBs pure data rate 2includin1 7LC header3# 'ierent

rom the CS service< all the +'*C%s are unidirectional# *he MS uses the

+'*C%B> to send packet data to the network and uses the +'*C%B' to receive

packet data rom the network#

(# +acket dedicated control channel

*he +.CC% transmits si1nalin1 inormation< such as conirmation and power

control# 5t also carries resource allocation and reallocation messa1es< which can be

used to allocate +'*C% capacity or add new +.CC% in the uture# 'urin1 packet

transmission< the MS can enter the CS mode throu1h +.CC% pa1in1# *he +.CC%

is dynamically allocated to the physical channel which carries +'*C%# 5t is a

bidirectional channel#

+*CC%B> serves to transer random access burst pulse and estimate the time lead

o an MS in packet transmission mode#

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+*CC%B' is used to correct the time lead o several MSs# One +*CC%B'

corresponds to several +*CC%B>#

.(.( Mapping o! 4ogical C"annel Co#$ination in t"e P"sical C"annel

.ter G+7S is added< three lo1ical channel combinations will be added:

+$CC% H +CCC% H +'*C% H +.CC% H +*CC%

+CCC% H +'*C% H +.CC% H +*CC%

+'*C% H +.CC% H +*CC%

9here< +CCC% N ++C% H +7.C% H +.GC% H +6C%#

'ierent lo1ical channels may appear on the same +'C%# *he physical channel is

shared in unit o blocks# *hat is< on a +'C%< the type o the lo1ic channel that the block

belon1s to varies rom one block to another# Channel type is the messa1e type 5'

contained in the head o a block 2eFcept or +7.C%3#

.(.(.1 Mapping o! :plin* C"annel

"# Mappin1 o the +'*C%B> and +.CC%B>

or each +'C% allocated to the MS< the MS will be allocated with an >S2>plink State la13# *he network uses the >S to control the multipleFin1 o radio

blocks o dierent MSs in the uplink +'C%# *he >S controls the timeslot use o

the MS# 5t is used in the dynamic and eFtended dynamic medium access modes#

*he three?bit >S is located on the header o each downlink radio block< and can

orm ei1ht states used or uplink transmission multipleFin1# 5n the +CCC%< one

>S value is used to mark the +7.C% 2>S N idle3< and other values are reserved

or use by seven dierent MSs 2>S N 7"B7& R 7,3# 9hen a +'C% is not the

+CCC%< the ei1ht >S values are all used to reserve uplinks or ei1ht dierent

MSs# 9hen an MS without a >S uses the uplink< a >S value can be used to

prevent conlict o the uplink channel# *he >S is directed to the neFt uplink radio

block#

9hen the MS inds its own >S on the header o a $ 2$F N $0R$""3 downlink

block o a +'C%< the MS will be able to use $H" 2]N ""3 or $0 2when N""3

uplink block on this +'C% # 5 the network permits< the MS can also use three

consecutive blocks 2there are our blocks in total3#

*he +.CC%B> correspondin1 to the +'*C%B' will be determined by the network

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) G+7S and A'GA

in the pollin1 mode#

Mappin1 o the +*CC%B>

9hen the MS obtains +'*C% allocation rom a certain +'C%< it will also obtain

+*CC%B> allocation rom the +'C%# *he cycle o the +*CC%B> is ei1ht 4&?

multirames< includin1 ") +*CC%B> sub?channels 20R"43# *he +*CC%B> sub?

channel 6o# possessed by an MS is determined by the time advance indeF 2*.53

obtained by the MS in resource allocation< 5t is as shown in i1ure )#- ?&)#

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$0P$""N7adio blocks

5dle rames are numbered rom " to -" ^odd numbers_

+*CC% rames are numbered rom 0 to -0 even numbers_

4&?multirame number nH,:

uplink *.5N"( *.5N"4

downlink *.?messa1e ( *.?messa1e (

$0 $" $& $- $( $4 $) $, $8 $/ $"0 $"" -"-0&/&8

$0 $" $& &( $- $( $4 &4 $) $, $8 &) $/ $"0 $"" &,

4&?multirame number nH):

uplink *.5N"& *.5N"-

downlink *.?messa1e ( *.?messa1e (

$0 $" $& &0 $- $( $4 &" $) $, $8 && $/ $"0 $"" &-

4&?multirame number nH4:

uplink *.5N"0 *.5N""

downlink *.?messa1e - *.?messa1e -

$0 $" $& ") $- $( $4 ", $) $, "8 $/ $"0 $"" "/

4&?multirame number nH(:

uplink *.5N8 *.5N/

downlink *.?messa1e - *.?messa1e -

$8

downlink *.?messa1e " *.?messa1e "

$0 $" $& 0 $- $( $4 " $) $, $8 & $/ $"0 $"" -

4&?multirame number n:

uplink *.5N0 *.5N"

$0 $" $& ( $- $( $4 4 $) $, $8 ) $/ $"0 $"" ,

4&?multirame number nH":

uplink *.5N& *.5N-

downlink *.?messa1e " *.?messa1e "

4&?multirame number nH&:

uplink *.5N( *.5N4

downlink *.?messa1e & *.?messa1e &

$"$0 $& 8 $- $( $)/$4 $, $8 "0 $/ $"0 $"" ""

$0 $" $& "& $- $( $4 "- $) $, $8 "( $/ $"0 $"" "4

4&?multirame number nH-:

uplink *.5N) *.5N,

downlink *.?messa1e & *.?messa1e &

i1ure )#-?&) Mappin1 o +*CC% on the +hysical Channel

-# >plink +CCC%: mappin1 o +7.C%

.s described above< on the +'C% with +CCC%< i the >S is marked as idle< it

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) G+7S and A'GA

indicates that the correspondin1 downlink block is the +7.C%# *he +7.C% can

be mapped in a iFed manner# *he number o +7.C% blocks iFedly allocated on

a +CCC% is determined by the system broadcastin1 parameter

K$S[+7.C%[$LS# 5ts relationship with the speciic blocks is determined by

the block occupyin1 order described above#

.(.(.& Mapping o! Downlin* C"annel

"# Mappin1 o the +'*C%B' and +.CC%B'

*he MS interprets every downlink block on the allocated +'C%< and determines i

the block is its +'*C%B' and +.CC%B' accordin1 to the *5#

*he *$ is a physical connection used by two 77 entities to transmit LLC +'>

in a unidirectional manner on the packet data wireless channel# *his parameter is

used in the LLC rame transmission seuence o the same timeslot in the same cell

to replace the MS identiication in the 7LCBM.C layer# 5t is a wireless resource

assi1ned to one or multiple +'C%s# 5t transmits some 7LCBM.C blocks carryin1

one or multiple LLC +'>s# One *$ is temporary and only kept in the data

transmission period 2that is< until there are no 7LCBM.C blocks or transmission

or< in the 7LC acknowled1ement mode< all 7LCBM.C blocks are acknowled1ed

to be received by the receiver3#

or each *$< the network allocates a *5# or concurrent *$s in each direction< other packet control channels adopt CS?"# or the packet access

pulse on +7.C% and +*CC%B>< there are 8?bit and ""?bit codin1 schemes# i1ure )#-

?&,andi1ure )#- ?&8shows the codin1 process o our dierent codin1 schemes#

>S: $CS

7adio block

rate "B& convolutional codin1

puncturin1

(4) bits

i1ure )#-?&, Codin1 +rocess o CS?" to CS?-

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>S: $CS

block

code

7adio block

no codin1

(4) bits

i1ure )#-?&8 Codin1 +rocess o CS?(

.s shown in the i1ure above< the irst step o the encodin1 is to append a $lock Check

Seuence 2$CS3 to the radio block< which is used or error detection# or the CS"PCS-

codin1 schemes< the second step is to pre?encode the >S 2not or CS"3< then append (

tail bits< and perorm hal?rate convolutional encodin1< which is used or error correction#

*he last step is puncturin1 to obtain desired encodin1 rate# Arror?correction codin1 is not

perormed in CS?(#

*able )#- ?(shows the speciic codin1 process o the our channel codin1 schemes#

*able )#-?( Channel Codin1 +rocess o +'*C%*ype

%andlin1 low

CS" CS& CS- CS(

Len1th o data

source

"8( bits &," bits -"4 bits ("- bits

+acket codin1 "3 ire codin1# *he

multinomial 1enerated

is:

2'&-"3 2'",'-"3S preprocessin1< as

shown in *able "?(#-3 .dd our tail bits# *he

codin1 data len1th is &/(

bits#

"3 +acket codin1#

*he multinomial

1enerated is:

'")'"&'4"S

preprocessin1 is thesame as CS

-3 .dd tail bits# *he

codin1 data len1th is

--8 bits#

"3 +acket codin1# *he

multinomial

1enerated is:

'")'"&'4"S

preprocessin1< asshown in *able "?4#

-3 .dd tail bits# *he

codin1 data len1th is

(4) bits#

Convolutional

code

"3 Convolutional codin1

with a "B& code rate# *he

multinomial 1enerated is

G0"'-'(< G"

"''-'(

&3 6o hole

"3 Convolutional codin1

with a "B& code rate# *he

multinomial 1enerated is

G0"'-'(< G""

''-'(

&3 Cut a code o "-& bits

"3 Convolutional

codin1 with a "B&

code rate# *he

multinomial

1enerated is: G0"

'-'(< G""

6one

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) G+7S and A'GA

*ype

%andlin1 low

CS" CS& CS- CS(

with the hole# *he positiono the hole:

C 2-H(Fk3< kN-< R< "()

and k/< &"< --< (4< 4,< )/

go_bt1005_e01_0 gsm gprs edge principles-86

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