gsm-bss_i_01_200909 gsm gprs edge basic principles 111

8/11/2019 Gsm-bss_i_01_200909 Gsm Gprs Edge Basic Principles 111

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ZTE GSM-BSSAfter-Sales CompetencyCertification Training Manual

GSM/GPRS/EDGE Basic Principles

Course Objectives

Learn GSM development history;

Learn and master network structure of GSM system and functions

principles of different portions;

Learn and be familiar with GSM wireless channel and protocol

Learn and be familiar with main service call process for GSM


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Contents

1 GSM Overview..............................................................................................................................................1

!"! GSM #asic Concepts"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!

!"!"! $istory of the mobile communication""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!

!"!"% GSM &efinition""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""'

!"% Services Supported by GSM System"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""(

!"%"! )elecom Services *rovided by GSM""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""(

!"%"% Supplementary Services of the GSM System""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""+

!", GSM Specification"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""+

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

%"! GSM -rea &ivision Concepts""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" """""".

%"% GSM composition""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!/

%", Mobile Switchin0 System 1MSS2""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!'

%"' #ase Station Subsystem 1#SS2""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!3

%"3 Operation Maintenance Subsystem 1OMS2"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" """"!3

%"( Mobile Station 1MS2""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!(

%"+ GSM System 4umber""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!(

%"+"! Mobile Subscriber 5S&4 4umber 1MS5S&42"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!(

%"+"% 5nternational Mobile Subscriber 5dentity 15MS52"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!+

%"+", Mobile Subscriber 6oamin0 4umber 1MS642""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" """"!+

%"+"' $andover 4umber""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" """!7

%"+"3 )emporary Mobile Subscriber 5dentification 1)MS52""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!7

%"+"( Location -rea 5dentification 1L-52""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" """!7

3 Interfaces and Protocols.............................................................................................................................19


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,"! 5nerfaces"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!.

,"% *S8&omain *rotocol Stack""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!.

,"%"! 9ser *lane *rotocol Stack at *S &omain"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""!.

,"%"% Control *lane *rotocol Stack at *S &omain""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""%%

,", CS8&omain *rotocol Stack""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""%,

,","! 9ser *lane *rotocol Stack at CS &omain""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""%,

,","% Control *lane *rotocol Stack at CS &omain""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""%'

4 GSM Radio !annel...................................................................................................................................2"

'"! GSM :orkin0 re


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3","% 5nter8#SC $andover within MSC"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" ""'3

3",", 5nter8MSC $andover""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""'3

3"' #asic Si0nalin0 *rocess"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""'+

3"'"! Location 9pdate *rocess""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""'+

3"'"% 5MS5 &etach *rocess"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" """"'.

3"'", Mobile8Ori0inated Call and Called *arty On8hook *rocess""""""""""""""""""""""""""""""""""""""""""""""""""3/

3"'"' Mobile8)erminated Call and Callin0 *arty On8hook *rocess""""""""""""""""""""""""""""""""""""""""""" """"3!

3"'"3 5nter8cell $andover low""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""3,

% &oice Processin$ and 'e( Radio )ec!nolo$(...........................................................................................""

("! ?oice *rocessin0""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""33

("!"! #asic low of ?oice *rocessin0""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" """"33

("!"% ?oice @ncodin0"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""3(

("!", Channel @ncodin0"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""3(

("!"' 5nterleavin0Adeinterleavin0"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""3+

("!"3 @ncryptionA&ecryption"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""(/

("!"( ModulationA&emodulation"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""(/

("% re


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+"! &efinition and eature"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""+3

+"!"! G*6S &efinition"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""+3

+"!"% G*6S eatures""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""+3

+"!", @&G@ &efinition""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""+(

+"!"' @&G@ eatures"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""+(

+"% 5nheritance and @volution""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""+7

+", G*6S 6adio Channel"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" """"""+.

+","! G*6S *hysical Channel"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""+.

+","% G*6S Lo0ic Channel"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""7/

+",", Mappin0 of Lo0ical Channel Combination in the *hysical Channel""""""""""""""""""""""""""""""""""""7%

+","' G*6S Channel Codin0"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""7+

+"' 6adio Link and Media -ccess Control low""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""./

+"'"! *a0in0 low""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""./

+"'"% )# Setup low"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""".%

+"'", G*6S SuspendA6esume low"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""".7

+"'"' )# 6elease low"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" """"!//

+"3 )erminal and -pplication"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" """"""!/'


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GSM !"er"ie#

$no#le%ge points

)his chapter mainly introduces some basic information for GSM= includin0 GSM

development history= supported service type= specification= and system features"

& GSM Basic Concepts

&& 'istory of t(e mo)ile communication

)he mobile communication was first used in military and some special fields in !.%/Es"

5n !.'/Es= it be0an to be employed for civil use" )he mobile communication really booms

in recent decade" )he development of the mobile communication comprises the

followin0 three phasesF

)he first 0eneration 1!G2 mobile communication system

)he second 0eneration 1%G2 mobile communications system

)he third 0eneration 1,G2 mobile communications system

! Startin0 from !.7/Es= the !G analo0 mobile communication system adopts cellular

networkin0 technolo0y"

$owever= the !G mobile communication system has the followin0 disadvanta0esF

)here is no common interface between systems"

5t cannot keep up with the fast di0itiin0 of the fiBed network and provide di0ital

bearer services"

5t cannot meet the demand for lar0e capacity due to low fre


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GSM G*6S @&G@ *rinciples

!2 Compared with the !G mobile communication system= the %G mobile

communication systemF

*rovides hi0h spectrum utiliation and lar0e system capacity"

*rovides diversified services 1voice services and low8rate circuit8switched data

services2"

@nables automatic roamin0"

*rovides better voice


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Chapter ! GSM Overview

system"

$i0h Speed Circuit Switched &ata 1$SCS&2 based on hi0h8speed data bit rate andcircuit switchin0

General *acket 6adio Service 1G*6S2 based on packet switched data

)hese two services are called %"3G services" -doptin0 hi0h8rate adaptive codin0 solution=

the G*6S provides the data rate up to !+! bitAs"

)he @nhanced &ata 6ates or GSM @volution 1@&G@2 developed by the @uropean

)elecommunications Standards 5nstitute 1@)S52 adopts 78*S 1*hase Shift eyin02

modulation" 5t supports the rate up to ,7' bitAs theoretically" )he @&G@ is more

advanced than the G*6S" $owever= it cannot provide the rate up to % MbitAs as the ,G

system does" )herefore= it is called %"+3G technolo0y"

)he research of ,G theory= development of ,G technolo0ies= and establishment of ,G

standards be0an in mid !.7/Is"

)he 5nternational Mobile )elecommunication %/// 15M)8%///2 released by the

5nternational )elecommunications 9nion 15)92 defines and describes ,G" 5t enables the

mobile data service and some fiBed hi0h8speed data services to use one or several radio

channels and fiBed network platform to provideF

- 0lobal standard

5M)8%/// services= which are compatible with other fiBed network services"

$i0h


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6ate up to !'' bitAs for vehicle mounted stations"

Currently= instead of driven by pure technolo0y= the communication technolo0y isdevelopin0 into the mode featurin0 the combination and interoperability of services and

technolo0y" 5t is estimated that the lar0est and the most profound chan0e in the comin0

five to ten years is the strate0ic transition from voice services to data services from the

aspect of market application and service demand" )his chan0e will deeply influence the

development trend of the communication technolo0y"

Some researchers and telecom operators describe the fourth80eneration 1'G2 mobile

communication system as a new world better than ,G= which can provide many

unima0inable applications" )he 'G system can provide over !// MbitAs data transmissionrate= which is !/=/// times of the current MSs and 3/ times of ,G MSs" )he 'G MSs can

provide hi0h8performance multi8media contents" )hrou0h 5& application= the 'G MS can

serve as a personal identification device" 5t can also receive hi0h8resolution movies and

)? pro0rams= acin0 as the brid0e of combined broadcast and new telecommunication

infrastructure" 5n addition= some services= such as 'G wireless instant connection= are less

char0ed than ,G services"

&&* GSM Definition

Ori0inally= the Global System for Mobile Communication 1GSM2 was the standard made

for the communication system workin0 at .// M$ in @urope" #ecause the analo0

communication system has limited capability in eBpansion= the GSM is developed on the

demand for capacity eBpansion and has achieved 0lobal success" GSM has become the

wireless communication standard widely accepted in the world"

)he development process of the GSM is as followsF

!.7%F )he Group Special Mobile 1GSM2 was set up in the Conference of

@uropean *osts and )elecommunications 1C@*)2 to develop the %G mobile

communication system"

!.7(F @i0ht proposals put forward by @uropean countries after massive research

and eBperiments were accepted in *aris= and on8site eBperiments were performed"

-fter on8site test= demonstration= and comparison= the GSM member countries

have reached an a0reement that the di0ital system adopts narrowband )ime

&ivision Multiple -ccess 1)&M-2= 6e0ular *ulse @Bcitation8Lon0 )erm

*rediction 16*@8L)*2= voice codin0= and Gaussian Minimum Shift eyin0

4


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1GMS2 modulation"

@i0hteen @uropean countries reached GSM Memorandum of 9nderstandin01MO92"

GSM took effect"

!..!F )he first GSM network was deployed in @urope"

!..%F )he GSM standard was froen"

!..,F )he major part of the GSM phase 55 standard was completed"

!..'F - new research phase 1*hase %H2 was added to further improve the GSM as

the platform of mobile data services"

5n the sta0e of GSM *hase 55H= the G*6S service is introduced to provide subscribers

with end8to8end mobile data service based on packet switchin0" )o support the G*6S= the

GSM introduces two kinds of new e


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&* Ser"ices Supporte% )y GSM System

&*& Telecom Ser"ices Pro"i%e% )y GSM

! Circuit Services

!2 ?oice service

ull8rate voice service

$alf8rate voice service

@nhanced full8rate voice service

%2 &ata Services

!'"'bitAs full8rate data service

."(bitAs full8rate data service

'"7bitAs full8rate data service

%"'bitAs full8rate data service

% SMS services 1support Chinese short messa0es2

!2 *oint8to8point short messa0e service

*oint8to8point short messa0e service with the mobile user servin0 as called

*oint8to8point short messa0e service with the mobile user servin0 as caller

%2 Cell #roadcast Short Messa0e

Cell broadcast service ori0inated from the SMS center or the OMC86"

, *acket Services

!2 G*6S service

%2 @&G@ Service

-t present= the point8to8point interactive telecom services are supported= includin0

-ccess to the databaseF -llocate service to users as needed= e"0" 5nternet= and

provide storin0 and forwardin0= as well as information processin0 for user8to8user

communications"

Session serviceF *rovide bi8directional user8to8user and port8to8port real time

information communication= e"0" 5nternet )elnet service"

6


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)ele8action serviceF -pplicable to small8volume data processin0 services= credit

card confirmations= lottery transactions= electronic monitorin0= remote meter

readin0 1water= electricity and 0as2= monitorin0 systems= and so on"

&*&* Supplementary Ser"ices of t(e GSM System

GSM supplementary services are diversified= includin0F

Call orwardin0 9nconditionalF forward all incomin0 calls to the number specified by

the subscriber"

#arrin0F barrin0 of out0oin0Acomin0 calls"

Call :aitin0F :hen a call is connected for a subscriber= indication of a new comin0 call

is 0iven to the subscriber" )he subscriber can accept= reject or i0nore the waitin0 call"

Call $oldF - subscriber can suspend the connected call to do other thin0s"

Multiparty ServiceF - simultaneous communication with up to siB parties is allowed"

Closed 9ser GroupF )he subscribers of C9G are restricted from out0oin0 and incomin0

calls= but they can normally communicate with each other"

$ot #illin0F )he network 0enerates an instant call billin0 messa0e from the billin0

mana0er" 5t is applicable to leased phone service= includin0 all kinds of call modes" #ills

are 0enerated and presented to the subscriber immediately after the call is ended"

&+ GSM Specification

GSM critieria was issued and compiled by @)S5"

@)S5 divided it into many phases= established Special Mobile Group 1SMG2 that takes

responsibility for relevant GSM criteria"

GSM criteria only contain detailed specification for its functions and interfaces= no

re0ulations for hardware" )his is to reduce desi0n restriction and enable various operators

can buy e


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* GSM ,et#or Structure

$no#le%ge points

)his section introduces network structure of GSM system and basic functions of

various 4@s"

*& GSM Area Di"ision Concepts

5n the GSM system= due to the mobility of users= the location information is a very

crucial parameter= which can be presented in the way as shown in i0ure %"! 8%"

i0ure %"!8% 6elationship between -reas in GSM

)he smallest area in the GSM network is the area covered by a #)S 1all8direction

antenna2 or a sector antenna= and it is the cell"

Several cells can compose a location area that can be set by the network operators" -location area can be associated with one or more #SCs but belon0s to one MSC"

Location area information is stored in MSCA?L6 of the system and the L-5 is used for

location area identification"

)o confirm the position of the mobile station= the re0ion covered by each GSM *LM4 is

divided into several L-s" One L- can contain one or several cells" )he network will store

the L- of each mobile station as location information for pa0in0 the mobile station" )he

pa0in0 of the mobile station is made by pa0in0 all the cells in the location area where the

mobile station is located" 5n the plannin0 of the network= it is paramount to divide

9


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location areas" 5n the division of location areas= on the premise that no eBcessively hi0h

call load occurs= try to minimie the number of location updates"

:hen an MS moves into another location area= it will find that the received L-5 differs

from the ori0inal one stored in the S5M card and then re0isters the new one" )his process

is location update process that is initiated by the MS"

)he MSC service area is the area overlapped by all the cells under it" 5t can be one or

several location areas"

*LM4 service area is composed of one or multiple MSC service areas and each country

may have one or several of them" or eBample= the national GSM mobile communication

network code of China Mobile is represented by K//= while that of China 9nicom is

represented by K/!"

GSM service area contains the *LM4s of countries all over the world"

*&* GSM composition

)he GSM communication system consists mainly of three partsF mobile switchin0 sub8

system 1MSS2= base8station sub8system 1#SS2 and mobile station 1MS2= as shown in

i0ure %"% 8,"

IBM

IBM

#SS MSS

MS

MS

*S)4

Other

PLMN

9m

5nterfac

e

-

5nterf

ace

i0ure %"%8, GSM System Composition

Mo-ile Switc!in$ Su-s(ste /MSS0

MSS fulfills messa0e eBchan0in0= user information mana0ement= call connection and

number mana0ement functions"

10


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#ase Station Su-s(ste /#SS0

)he #SS is controlled by MSC in a certain wireless covera0e and communicates with the

MS" 5t implements channel allocation= user access and pa0in0= and information

transmission functions"

Mo-ile Station /MS0

MS which is the mobile e


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#SCn

#)S

MSCA?L6

SGS4

SMC

$L6A-9C

@56

MS

Other PLMN

GGS4GGS4

*&4 )@

*S)4MSCA?L6

-bis

#)S

MS

9m

-bis

#SC!

-

Gb

i0ure %"%8' *osition of the #SS in the GSM 4etwork

)he #SS provides a brid0e between the fiBed part and the wireless part in the *LM4

network= connects the MS for communications directly via the wireless interface and

connects the MSC of MSS"

i0ure %"% 83shows the basic GSM network structure"

12


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#SC )6-

9 MSCA?L6

SMC

GMS

C

-9

C

5:

; @56

$L

6

*S)45S&

4*&4

Signal

#)

S

MS

#)

S

MS

i0ure %"%83 GSM 4etwork Structure

)he meanin0 of each name is as followsF

MSF Mobile Station

#)SF #ase )ransceiver Station

#SCF #ase Station Controller

)6-9F )ranscodin0 and 6ate -daptation 9nit

5:F 5nterworkin0 unction

@56F @


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SMCF Short Messa0e Center

*S)4F *ublic Switched )elephone 4etwork 5S&4F 5nte0rated Services &i0ital 4etwork

*&4F *ublic &ata 4etworks

- GSM di0ital mobile communication system is composed of the Mobile Switchin0

System 1MSS2= #ase Station Subsystem 1#SS2= Operation Maintenance Sub8system

1OMS2 and Mobile Station 1MS2" )he followin0 introduces the functions of each part"

*&+ Mo)ile S#itc(ing System .MSS4SS performs switchin0 function and database for mana0ement of user data= mobility

and security"

)he MSS consists of such entities as the mobile switchin0 center 1MSC2= home location

re0ister 1$L62= visitor location re0ister 1?L62= e


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-9CF - strictly protected database that stores subscriber authentication information

and encryption parameters" )he -9C and $L6 are inte0rated physically"

@56F Stores parameters related to the mobile station e


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*&3 Mo)ile Station .MS

-s the subscriber e


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%" $L6 identification number 1$!$%$,2

$!$% in $L6 identification number is allocated uniformly by state; $, is assi0nedby different provinces" One $L6 can contain one or more $!$%$, numbers"

," Mobile subscriber number 1-#C&2

-#C& is mobile suscriber number in each $L6= automatically assi0ned by

different $L6s"

*&4&* 5nternational Mo)ile Su)scri)er 5%entity .5MS5

5MS5 is the only one number to identify a mobile subscriber in *LM4= composed of !3

di0its"

MCC M4C MS54

5nternational mobile number

$ome mobile number

MCC N mobile country code= composed of , di0its= to uni


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$!$% in MS5S&4 number"

-#C code is ///P'.."

*&4&0 'an%o"er ,um)er

$O4 is a number temporarily assi0ned to mobile subscriber by tar0et MSCA?L6= to

select route durin0 interoffice handover"

)his number is a part of MS64 number= only used durin0 interoffice handover for

mobile subscriber" 5t can be released to and used by other subscribers after connection" 5ts

structure is !,./M!M%M,-#C" M!M%M, is MSC number= and M!M% is same as

$!$% in MS5S&4 number"

-#C code is 3//P..."

*&4&1 Temporary Mo)ile Su)scri)er 5%entification .TMS5

)MS5 is to provide security for 5MS5= which is temporarily assi0ned to visited mobile

subscriber identification number by ?L6" -s a ' bytes #C& code= it only can be used

locally and assi0ned by different MSCA?L6"

*&4&3 6ocation Area 5%entification .6A5

L-5 is used to identify location area= its structure as followsF

MCCHM4CHL-C

:hereF MCC and M4C are same as that of 5MS5"

L-C is location area code= to uni


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+ 5nterfaces an% Protocols

$no#le%ge points

G@6-4 interfaces

9ser planeAcontrol plane protocol stack at *S and CS

+& 5nerfaces

)he main interfaces in GSM system is as shown in i0ure ,"! 8!"

i0ure ,"!8! GSM interfaces

9m interface is a wireless interface"

5nterface - provides messa0es about the establishment and deletion of 5nterface -

connection= as well as upper8layer messa0es transparently forwarded between MS and

MSC" 5nterface - also transfers voice information"

Gb interface provides messa0es about the establishement and deletion of Gb interface

connection= as well as upper8layer messa0es transparently forwarded between MS and

SGS4" Gb interface also transfers G*6S data"

+&* PS-Domain Protocol Stac

+&*& 7ser Plane Protocol Stac at PS Domain

)he user plane protocol stack at *S domain is as shown in i0ure ,"% 8%"

19


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PHY

RLC

PDCP

LLC

SNDCP

PHY

RLC

PDCP

SNDCP

LLC

BSSGP

Network

Service

5u-ps

G)

7m

MS

6elay

GERAN SGSN

/Ack Unack

RLC

MACMAC

/Ack Unack

RLC

Common protocols

5u influenced protocols

Gb influenced protocols

FR

IP

L2

FR

BSSGP

Network

Service

IP

L2

L1L1L1

GP!U

L2

UDP/IP

L1

GP!U

L2

UDP/IP

s defined in

Iu Secs.

s defined in

Iu Secs.

i0ure ,"%8% 9ser plane protocol stack at *S domain

5n this fi0ure= the white sections represent the peculiar protocol stack under -AGb mode=

the li0ht 0rey sections representin0 the peculiar protocol stack under 5u mode= and the

0rey sections representin0 the common protocol stack under both modes" rom the

fi0ure= we can see that both operatin0 modes are separated above the M-C layer"*rotocols at all layers under 5u mode are very similar to those of 9)6-4 in terms of

architecture and hierarchy= and most protocols= such as *&C*= G)*89= and 9&*A5*= are

identical" )heir difference lies in the protocol at the radio link layerF 6LCAM-C= which is


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M-C controls the access si0nalin0 process on radio channel= makes decision

when a lar0e number of MS access shared media= and maps LLC frame onto

GSM physical channels"

Compared with the M-C function under -AGb mode= G@6-4 M-C features the

followin0 two major differencesF

5t supports one M-C entity and multiple )#s"

5t supports M-C8layer encryption"

,! LLC Layer

LLC is a radio link protocol based on hi0h8speed data link procedure $&LC" 5tprovides hi0hly reliable encrypted lo0ic links" )he LLC layer 0enerates LLC

addresses and frame fields from the S4&C data unit of the S4&C layer to create

complete LLC frames" LLC also supports point8to8multipoint addressin0 and

control of data frame resendin0" LLC is independent of the bottom8layer radio

interface protocol to minimie network subsystem 14SS2 modifications when

introducin0 other optional G6*S radio solutions" GSM/'"(' provides LLC

speficications"

'! S4&C*

-s the transition between the network layer and the link layer= S4&C* protocol is

mainly used for packetin0 and packa0in0 data= sendin0 data to the LLC layer for

transmission= and determinin0 )C*A5* address and encryption mode"

-t the S4&C layer= the data tranmitted between mobile station and SGS4 is

divided into one or more S4&C packet units= which are then placed in LLC frame"

3! 6elay

5t is used for the relay and forwardin0 of LLC *&9 between the 9m interface andthe Gb interface"

% Gb 5nterface

!! L! 8 *hysical transmission layer

L! can use % MbitAs @! cable or C-)3 network cable"

%! 4S 14etwork Service2

)he 4S layer is based on frame relay= and is used to tranmit upper8layer #SSG*

21


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*&9"

,!

#SSG*

)his protocol is used to provide a connectionless link between #SS and SGS4 for

unacknowled0ed data transmission on transmission platforms"

'! 5*

5* refers to the 5nternet *rotocol defined in 6C +.!= and is used for routin0 user

data and control si0nalin0" 5* is used at the data link layer of the Gb interface

when @ transmission is used between #SC and SGS4"

3! 6

6 provides permanent virtual circuit and transmits user data and si0nalin0 at the

Gb interface" )he 6 protocol is used at the data link layer of the Gb interface

when @! tranmission is used between #SC and SGS4"

+&*&* Control Plane Protocol Stac at PS Domain

)he control plane protocol stack at *S domain is as shown in u0ure ,"% 8,"

RR

PHY

RLC

LLC

GMM/SM

PHY

RLC

RRC

GMM/SM

LLC

BSSGP

NetworkService

5u-ps

G)

7m

MS

6elay

GERAN SGSN

Ack/Unack

RLC

MACMAC

Ack/Unack

RLC

Common protocols



FR

IP

L2FR

BSSGP

NetworkService

IP

L2

L1L1

LAPD" LAPD"

RRRRC

RR

PHY

RLC

LLC

GMM/SM

PHY

RLC

RRC

GMM/SM

LLC

BSSGP

NetworkService

5u-ps

G)

7m

MS

6elay

GERAN SGSN

Ack/Unack

RLC

MACMAC

Ack/Unack

RLC

Common protocols



FR

IP

L2FR

BSSGP

NetworkService

IP

L2

L1L1

LAPD" LAPD"

RRRRC

L2

L1

RANAP

SCCP

As Define%

in 5u Specs#

L$

L2

L1

RANAP

SCCP

As Define%

in 5u Specs&

L$

u0ure ,"%8, Control plane protocol stack at *S domain



0rey sections representin0 the common protocol stack under both modes" )he functions

22


28/107


of such protocols as 6-4-* and SCC* are identical with those of the correspondin0

9)6-4 protocols" )he 66C protocol plays a key role in the fusion of GSMA@&G@

network and 9)6-4" 5t inte0rates the characteristics of %G and ,G networks and

represents the most important evolution from G@6-4 to 9M)S"

GMMASM performs the followin0 mobilityAsession mana0ement functionsF G*6S

mobility mana0ement= session mana0ement protocol processin0 1such as attachAdetach2=

security mana0ement= routin0 area update= location area update= and *&* conteBt

activationAdeactivation"

+&+ CS-Domain Protocol Stac

+&+& 7ser Plane Protocol Stac at CS Domain

)he user plane protocol stack at CS domain is as shown in i0ure ,", 8'"

RLC RLC

G#%11/F&

5u-cs

A7m

MS

6elay

GERAN 2G!MSC

MACMAC

Common protocols

5uinfluenced protocols- influenced protocols

L1L1

AAL2/AM

--L8%S-6 SSCS

Fra"in'Protoco()2*#+1*,

L1

AAL2/AM

--L8%S-6 SSCS

Fra"in'Protoco()2*#+1*,

RLP

AMR

L1PHY

AMR/FR/EFR/HR

AMR

PHY

ran-co.in' /RAU 0Re(a0

$G!MSC

RLPRLP

i0ure ,",8' 9ser plane protocol stack at CS domain




fi0ure= we can see that no user plane protocol processin0 eBists under 5nterface - mode"

5n fact= voice data only needs code conversion and rate adaption under 5nterface - mode"

23


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9nder 5u mode= the user plane protocol stack of voice data is relatively simple" 5ts radio

interface protocol stack is the same as that of *S domain= with 5u interface protocol usin0

* 1ramin0 *rotocol2"

+&+&* Control Plane Protocol Stac at CS Domain

)he control plane protocol stack at CS domain is as shown in i0ure ,", 83"

MP A-I

L1

L2 )AAL*,

MP$!B

SSCF!NNI

SSC&P

RANAP

SCCP

L1

L2 )AAL*,

SSC&P

RANAP

SCCP

5u-cs

MS

6elay

GERAN MSC

Common protocols


- influenced protocols

SCCPSCCP

BSSAP BSSAP

A

5u-cs

MS

6elay

GERAN MSC

Common protocols


- influenced protocols

SCCPSCCP

BSSAP BSSAP

L1 AL1

L2 )AAL*,

MP$!B

SSCF!NNI

SSC&P

RANAP

SCCP

L1

L2 )AAL*,

SSC&P

RANAP

SCCP

MP

L1

RR

RLC RLC

RRC

7m

LAPD" LAPD"

RRRRC

RR

PHY

MM/UMM/CC/SS

PHY

RRC

7m

MACMAC

LAPD" LAPD"

RRRRC

RLC RLC

MM/UMM/CC/SS

A-I

i0ure ,",83 Control plane protocol stack at CS domain




fi0ure= we can see that the control plane protocol stack at both CS domain and *S domain

is identical under 5u mode" *rotocols at all layers are as described previously= and will not

be further discussed here"

24


30/107

0 GSM Ra%io C(annel

$no#le%ge points

)his section introduces GSM radio frame= channel concept= division function for

different channels= mappin0 combination mechanism between channels"

0& GSM 8oring 9re:uency Ban%

! :orkin0 fre


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&ownlinin0 1transmitted by #S and received by MS2 fre


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d 1n2Nu 1n2 H .3 1M$2

3!% n 773

'2 !=.//M$ fre


33/107


to )C$= S-CC$= and -CC$"

1%2 Multiframe composed of 3! )&M- frames" )his kind of multiframe is usedto #CC$= CCC$ and S&CC$"

' Super frame is a continous 3!D%( )&M- frame= composed of 3! multiframes

with %( frames or %( multiframes with 3! frames"

3 $yper frame is composed of %/'7 super frames"

i0ure '"% 8(lists the schematic dia0ram of hierarchical frame structure in GSM system"

i0ure '"%8( $ierarchical frame structure in GSM system

)&M- frame is compiled cycly with the period of ,hrs %7mins 3,s +(/ms

1%/'73!%(7#* or %/'73!%( )&M- frames2" - hyper frame contains %/'73!%(

)&M- frames" @ach hyper frame can be divided into %/'7 super frames= each super

frame is 3!%( )&M- frames se


34/107


0&+ P(ysical C(annel an% 6ogical C(annel

0&+& P(yC' P(ysical C(annel

)&M- indicates it is divided into 7 time se0ements by time on each carrier for GSM.//=

each timeslot se0ement is called as a timeslot")his kind of timeslot is called as channel=

or physical channel" - )&M- frame comprises of successive 7 timeslots on a carrier= that

is= one carrier can provide 7 physical channels on a carrier for GSM"

GSM uses )&M- and &M- technolo0ies= as shown in the fi0ure below"

i0ure '",8( &M-

i0ure '",8+ )&M-

29


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0&+&* 6ogic c(annel

5f you consider each timeslot of )&M- frame as physical channel= the content

transmitted in physical channel is lo0ical channel" Lo0ic channel indicates the control

lo0ic channel or voice= data lo0ic channel assi0ned in 7 timeslots for )&M- for different

control si0nals and voice or data services"

)he transmitted information on physical channel in GSM di0ital system is the pulse

strin0 composed of about !// modulated bits= called as burst pulse se


36/107


comprisesF

re


37/107


)he &CC$s are point8to8point bi8directional channels between the base station

and the MS" )he &CC$s includeF

Stand8alone dedicated control channel 1S&CC$2F )ransmits the si0nalin0 and

channel information between the base station and the MS= such as the

authentication and re0istration si0nalin0 messa0es" &urin0 the establishment of a

call= the S&CC$ supports bi8directional data transmission and the transfer of short

messa0es"

Slow associated control channel 1S-CC$2F )hrou0h this channel= the base station

sends the power control messa0e and frame adjustment messa0e to the MS= and

receives si0nal stren0th report and link


38/107


1/= R = +2;

3

Main broadcast control channel 1Main#CC$2F CC$ H SC$ H #CC$ H CCC$;

( Combined broadcast control channel 1#CC$Combined2F CC$ H SC$ H #CC$

H CCC$ H S&CC$A' 1/= R =,2 H S-CC$AC' 1/= R = ,2;

+ #roadcast channel 1#C$2F CC$ H SC$ H #CC$;

7 Cell broadcast channel 1#CC$withC#C$2F CC$ H SC$ H #CC$ H CCC$ H

S&CC$A' 1/= R = ,2 H S-CC$AC' 1/= R = ,2 H C#C$;

. Slow dedicated control channel 1S&CC$withC#C$2F S&CC$ H S-CC$ H

C#C$"

-mon0 the above channel combinations= CCC$ N *C$ H 6-C$ H -GC$" C#C$F Only

downlink channels are aC#C$F Only downlink channels are available= carryin0 cell

broadcast information and sharin0 the physical channel with S&CC$"

@ach cell broadcasts an CC$ and an SC$" )he basic combination in downlink includes

an CC$= an SC$= a #CC$ and a CCC$ 1*C$H-GC$2= allocated strictly to )4/ of

#CC$ carrier confi0ured for a cell= as shown in i0ure '", 87"

SF B C

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

*134

SF C C SF C C SF C C I

R R R R R R R R R R

D5 D1 D2 D$ D+ D* D6 D% A5 A1 A2 A$

SF C C

R R R R R R R R R R

III

D5 D1 D2 D$ D+ D* D6 D% A+ A* A6 A% III

A1 A2 A$ III

A* A6 A% III

D5 D1 D2 D$ D+ D* D6 D% A5

D5 D1 D2 D$ D+ D* D6 D% A+

SF B C SF C C SF D5 D1 SF D2 D$ ISF A5 A1

SF B C SF C C SF D5 D1 SF D2 D$ ISF A2 A$

D$

D$

R R

R R

A2 A$

A5 A1

D2

D2

SF

SF

D5 D1

D5 D1

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

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

F78FCCH S78SCHB 78 BC CH C 78 CC CH 79 CC CH :P CH ;A GC H; RA CH 7??7

gsm-bss_i_01_200909 gsm gprs edge basic principles 111

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