gprs and edge basics

8/11/2019 Gprs and Edge Basics

1/51

GB_BT03_E1_0 GPRS and EDGE Basics

Course Objectives:

Understand GPRS/EDGE conception

Understand GPRS/EDGE system architecture

State GPRS/EDGE radio frame structure and channels

Understand GPRS/EDGE key technologies


2/51

Contents

1 GPRS Technoo!"#########################################################################################################################################1

1.1 GPRS Definition..................................................................................................................................1

1.2 GPRS eatures.....................................................................................................................................1

1.! GPRS Specifications............................................................................................................................2

1." GPRS #et$ork Structure.....................................................................................................................!

1.% GPRS Protocol Platform......................................................................................................................%

1.%.1 GPRS &ransmission Protocol Platform....................................................................................%

1.%.2 GPRS Signaling Protocol Platform..........................................................................................'

$ GPRS %et&or' (rchitecture#####################################################################################################################13

2.1 (ogical Structure...............................................................................................................................1!

2.1.1 )ain #et$ork Entities...........................................................................................................1"

2.1.2 )ain #et$ork *nterfaces........................................................................................................1'

3 GPRS )ra*e Structure and Radio Channes##########################################################################################$0

!.1 Radio rame Structure.......................................................................................................................2+

!.2 Physical ,hannel...............................................................................................................................2+

!.! (ogical ,hannel.................................................................................................................................21

!.!.1 Packet ,ommon ,ontrol ,hannel -P,,,s0......................................................................21

!.!.2 Packet roadcast ,ontrol ,hannel -P,,0.......................................................................22

!.!.! Packet transport channel0........................................................................................................22

!.!." Packet dedicated control channel0..........................................................................................22

!." ,hannel ,omination........................................................................................................................22

!.% )apping et$een (ogical ,hannels and Physical ,hannels............................................................2!

!.%.1 Uplink ,hannel )apping0......................................................................................................2!


3/51

!.%.2 Do$nlink ,hannel )apping0.................................................................................................2%

+ GPRS ,e" Technoo!ies#############################################################################################################################$-

".1 3oS *mplementation..........................................................................................................................24

".2 )edia 5ccess ,ontrol -)5, (ayer................................................................................................24

".2.1 Radio lock Structure............................................................................................................!+

".2.2 ,hannel ,oding......................................................................................................................!2

".2.! lo$ ,ontrol...........................................................................................................................!%

".2." ,ell Selection and Reselection...............................................................................................!6

. EDGE Technoo!"#######################################################################################################################################+0

%.1 Definitions........................................................................................................................................."+

%.2 eatures.............................................................................................................................................."+

%.! Specifications....................................................................................................................................."1

%." 7ey &echnologies.............................................................................................................................."2

%.".1 EDGE )odulation )odes......................................................................................................"2

%.".2 EDGE Radio lock Structure................................................................................................."!

%.".! ,hannel ,oding......................................................................................................................""

%."." (ink 3uality ,ontrol.............................................................................................................."6

%.".% Dynamic 8indo$ Si9e..........................................................................................................."'


4/51

1 GPRS Technology

1.1 GPRS Definition

GPRS is a packet data ser:ice introduced in GS) Phase2;. GPRS pro:ides

suscriers the end


5/51

GPRS pro:ides solutions to implement data ser:ices in GS) technologies and

current net$orks. GPRS can sa:e in:estment and makes Auick returns.

1.3 GPRS Specifications

*n Europe= it $as suggested in 144! for GPRS to e deployed in GS) net$ork. *n

144'= great progress $as made in GPRS standardi9ation. *n @ctoer 144'= E&S* issued

GPRS Phase1 ser:ice description. GPRS phase 2 $as completed at the end of 1444.

GPRS standard goes through three phases. *n order to implement GPRS= 1B ne$

standards are made and many standards are modified three phases.

&ale 1.!


6/51

$ GPRS %et&ork 5rchitecture

Gn= G= Gr= Gp= Gs= and Gi interfaces

P&P and roaming security guarantee

,harging

@perator


7/51

GF&+!FE1F+ GPRS and EDGE asic

BSC MSC/VLR SMC

PCU

Charginggateway

function (CGF)

Billing syste

!LR

Signaling an" GPRS su#scri#er "ata

Signaling

Pac$et "atanetwor$

SGS%

Gs interface

Gn interface

SGS%

GGS%

G" interface

Gr interface

Gc interface

Gn interface

Gi interface

G# interface

Gainterface

Ga interface

ig 1."


8/51


SGS#. &he SGS# resumes the GPRS connection after recei:ing the message.

&hus= the )S need not to estalish GPRS connection repeatedly. )ost of the

GPRS )S types in current market are type


9/51


&hrough G&P= Suscrier data and signaling et$een GPRS Support #odes

-GS# are transmitted in GPRS ackone net$ork. 5ll point


10/51


*n SS= relay transfers ((, PDUs et$een Um interface and G interface. *n

SGS#= relay transfers PDP PDUs et$een G interface and Gn interface.

SS GPRS Protocol -SSGP

&his layer transfers the information related to routing ser:ice Auality et$een

SS and SGS#. SSGP does not pro:ide error correction function. GS)+B.1B

pro:ides SSGP specifications.

#et$ork Ser:ice -#S

&his layer transfers SSGP PDUs. #S is ased on the frame relay connection

et$een SS and SGS#. *t pro:ides multi


11/51


G))/S) refers to GPRS moility management and session management. )S0

"ownlin$ &'3essage 5 &'3essage5

B4 B B, ,4 B0 B5 B- , B6 B7 B8 ,, B9 B4 B ,0

-,3ultifrae nu#er n1-:

ulin$&'>4&'>

"ownlin$&'3essage 0 &'3essage

0

B4 B B, 6 B0 B5 B- 7 B6 B7 8 B9 B4 B 9

-,3ultifrae nu#er n15:

ulin$&'>8&'>9

"ownlin$&'3essage 0 &'3essage

0

B8

"ownlin$

&'3essage &'3essage

B4 B B, 4 B0 B5 B- B6 B7 B8 , B9 B4 B 0

-,3ultifrae nu#er n:

ulin$&'>4&'>

B4 B B, 5 B0 B5 B- - B6 B7 B8 6 B9 B4 B 7


ulin$&'>,&'>0

"ownlin$&'3essage &'3essage

-,3ultifrae nu#er n1,:

ulin$&'>5&'>-

"ownlin$&'3essage , &'3essage

,

BB4 B, 8 B0 B5 B69B- B7 B8 4 B9 B4 B

B4 B B, , B0 B5 B- 0 B6 B7 B8 5 B9 B4 B -


ulin$&'>6&'>7

"ownlin$&'3essage , &'3essage

,

ig !.%


28/51


3.".2 Donlin! Channel &apping6

PD&,/D and P5,,/D mapping0

)S interprets e:ery do$nlink lock on the allocated PD, and determines

$hether the lock is its PD&,/D and P5,,/D according to &*.

& is a physical connection used y t$o RR entities to transmit ((, PDU in a

unidirectional manner on packet data radio channel.&his parameter is used in

((, frame transmission seAuence of the same timeslot in same cell to replace

)S identification in R(,/)5, layer. *t is radio resource assigned to one or

multiple PD,s. *t transmits R(,/)5, locks carrying one or multiple ((,

PDUs.&he & is temporary and only kept in data transmission -the & is

kept until there is no R(,/)5, lock to transmit= or all the R(,/)5, locks

are recei:ed successfully y the recei:er under the R(, ackno$ledgement

mode.

or each &= net$ork allocates a &*.or concurrent &s in each direction=

&* allocated is uniAue. *t is used to replace )S identifier in R(,/)5, layer.

&he same &* can e used in different directions.&* is assigned in the resource

allocation message efore transmission of ((, frame.

R(,/)5, lock related to a specific & must contain a &*. or a R(, data

lock= the & is Hointly identified y the &* and the transmission direction of

the data lock. or a R(,/)5, control message= there are transmission

direction and message type in addition to the &*. *f the header of a do$nlink

control lock contains a &*= the &* identifies to $hich )S the control message

is sentK other$ise= all )Ss $ill recei:e this message. *f the &* in the header is

inconsistent $ith that in the message= the )S accepts the &* in the header.

P,, mapping and packet system message transmission0

*n a cell= P,, is mapped to one PD, only. Specific location is roadcast

y ,,. *n a %2


29/51


of messages to e sent.

System parameter PS*1FREPE5&FPER*@D determines the position $here PS*1is sent. *n addition= ecept PS* 1= other PS*s are di:ided into t$o groups. @ne

group is sent at a high repetition rate= $hile the other is sent at a lo$ repetition

rate.Parameter PS*F,@U#&FR indicates the numer of PS*s sent at a high

repetition rate= and PS*F,@U#&F(R indicates the numer of PS*s sent at a lo$

repetition rate.

System sends PS*s according to the follo$ing rules0

PS* 1 is sent on (@,7 + $hen &, is +. -&, I -# D* %2 mod

PS*1FREPE5&FPER*@D.

8hen SFP,,F(7S is higher than 1= PS* 1 is also sent on (@,7 6

$ith &, of +.

PS*s in the group sent at a high freAuency are sent in seAuence determined y

net$ork. &he seAuence starts $hen &, is +K that is= sending cycle of PS*s in this

group is PS*1FREPE5&FPER*@DN%2 frame. 8hen PS*s in this group are sent=

P,, (@,7s= $hich are not occupied y PS*s= $ill e used.

PS*s sent in the group sent at a lo$ freAuency are sent in the seAuence

determined y the net$ork= and sent repeatedly. 8hen the PS*s in this group are

sent= the P,, (@,7s= $hich are not occupied y PS*s= $ill e used.

Do$nlink P,,, mapping

Do$nlink P,,, mapping on a PD, can e descried y the follo$ing four

rules0

SFP,,F(7S locks are used in the P,, if PD, has a P,,.

SFP5GF(7SFRES locks cannot e used in the PP, in the remaining

locks. &hey can e used in the P5G,= P#,= PD&, and P5,, only.

&he remaining locks can e used in the PP,= P5G,= P#,= PD&, and

P5,,.

8hen P,, is on timeslot k= the P,,, can e located on timeslot n only=

and n must e greater than k


30/51


kno$n according to the lock seAuence -+= 6= != 4= 1= '= "= 1+= 2=

B= %= and 110

P,,s are located on + and 6.

PP, can e located on 1+= 2= B= %= and 11 only.

P5G,= P#,= PD&,= and P5,, can e located on != 4= 1= '= "=

1+= 2= B= %= and 11.

28


31/51


32/51

@n the do$nlink -for eample= the )S= )5, layer has the access reAuests Aueue and

makes an access time tale. or do$nlink= contention mechanism is unnecessary

ecause there is only one transmit end in do$nlink direction.

)5, layer assigns data to e sent $ith different priority and transmits data according

to priority. Signaling data has higher priority than suscrier data. 5fter comined=

signaling and suscrier data are sent through transmission media. )5, layer enales

se:eral )Ss to share same transmission medium. &ransmission medium can e a

physical channel or se:eral physical channels. *n &D)5= physical channels are &D)5

timeslots.

8hen se:eral physical channels ser:e as transmission media= )S sends dataconcurrently. *t can increase the data transmission capacity et$een )S and net$ork.

See the eample as sho$n elo$ in ig ".2


33/51


34/51


)ade up of one it= 5, indicates $hether the header of the do$nlink

R(,/)5, control lock contains optional &*/D field. >+? indicates &*/D field

is contained= and >1? not.

Direction -D it

)ade up of one it= D it indicates & direction. & is identified y &* field

in do$nlink R(,/)5, control header. *f D it is += & identified y &* is

uplink. *f it is 1= & is do$nlink.

4.2.2 Channel Co*ing

GPRS defines four coding modes on PD&,0 ,S

#loc$

co"e

Ra"io #loc$

no co"ing

5-6#its

ig ".2


35/51


,oding procedure is as follo$s0

1. 5dd a lock ,heck SeAuence -,S to the end of the radio lock for errordetection.

2. Perform pre!. Punch to otain desired coding rate.

Error&ale ".2

Procedure&ype

,S1 ,S2 ,S! ,S"

(ength of data

source1B" its 2'1 its !1% its "1! its

Packet coding

-1 ire coding. &he

multinomial generated

is0

-D2!;1-D1';D!;1.

&he ,S added is "+

its.

-2 5dd four tail its.

&he coding data

length is 22B its.

-1 Packet coding. &he

multinomial generated

is0

D16

;D12

;D%

;1. &headded ,S is 16 its.

-2 US preprocessing.

See&ale ".2


36/51


&ale ".2

,S


37/51


,hannel

&ype

*nput

Rate-kit/s

*nput ,ode

lock -its

,ode @utput

,ode

lock

-its

*nterlea:ing

Depth,heck it

US

Precod

ing

&ailit

,on:olutio

nal

,ode Rate

P5G,=

P#,=

P,,=

P5,,

coding= "+consecuti:e

ursts

4.2.3 Flo Control

*t controls the 3oS delay Aueue load et$een SGS# and SS to optimi9e the use of

uffer area.

SSGP layer P,U manages t$o uffers $hich are )S uffer and SSGP irtual

,onnection -, uffer. 8hen P,U recei:es a ((, packet= its SSGP protocol layer

identifies it according to &((* and places it into )S uffer. &hen= SSGP protocol

layer uses ,* as identifier and places all related information into the uffer for that

,.

See ig ".2


38/51


39/51


4.2.4.2 Cell Reselection

GPRS net$ork or )S control ,ell reselection process. *n net$ork controlled cell

reselection process utili9es cell load= status= le:el and other information in optimi9ed

manner.

#et$ork


40/51


41/51


cell= and sends the cell reselection indication to the RP. )ean$hile= it sends the

cell reselection indication to the RP $here the target cell is located. &hus= after

the cell reselection of the )S= the ne$ cell can perform cell reselection control

o:er it rapidly.

Send cell reselection command.

5fter recei:ing the cell reselection indication= the RP sends the cell reselection

command to the )S. Under the packet idle status= if P,,, is configured= the

cell reselection command is sent to the )S on P,,,. *f there is no P,,,= a

do$nlink lock is assigned on ,,, :ia the immediate assignment message.

&he cell reselection command is sent in the do$nlink lock assigned. Under thepacket transmission status= the cell reselection command is sent to the )S on

P5,,. ,!1 and ,!2 are used to select the optimal cell= and the last selection is

not made here in the pre


42/51


" 'DG' Technology

".1 Definitions

Enhanced Data for GS) E:olution -EDGE includes Enhanced General Packet Radio

Ser:ice -EGPRS and Enhanced ,ircuit S$itched Data -E,SD. EDGE is a method

used to impro:e the data transmission rate during GS) radio connection.

Essentially= EDGE is only a ne$ modulating and channel encoding technology= $hich

can e used to transmit Packet s$itching -PS and ,ircuit S$itching -,S data/:oice.

5s an e:ol:ed GPRS


43/51


communication control layer= and communication connection layer. &he

interface et$een layers is standard. &he hierarchical architecture makes the call

control and communication connection mutually independent. *t also fully uses

ad:antages of the packet s$itching net$ork= making the and$idth allocation

closely related to the traffic. *t especially suits the o*P ser:ice.

)edia Gate$ay -)G8 is adopted in EDGE. )G8 has the same functions as

Signaling &ransfer Point -S&P= and can reali9e the signaling net$ork

estalishment in *P net$ork. )oreo:er= )G8 is not only the interface et$een

GS) circuit s$itching ser:ice and PS ut also the interface et$een Radio

5ccess #et$ork -R5# and !G core net$ork.

EDGE supports t$o data transmission modes0 packet s$itching and circuit

s$itching. 8ith the packet data ser:ice= a rate of 11.2 kps 64.2 kps per

timeslot can e reali9ed. EDGE supports the circuit s$itching ser:ice $ith a rate

of 2B.B kps. EDGE also supports symmetric/asymmetric data transmission=

$hich is :ery important for the moile eAuipment to access net$ork. or

eample= in EDGE system= the user can ha:e a higher rate in do$nlink than in

uplink.

".3 Specifications

&he EDGE standardi9ation in:ol:es the follo$ing three aspects0

Standardi9es the rele:ant change in physical layer -the definition of modulation

and coding method

Standardi9es the change in E,SD protocol

Standardi9e the change in EGPRS protocol

&$o Hos are done in the ao:e aspects0

EDGE #SS= $hich is related to the change in net$ork susystem

EDGE SS= $hich is related to the change in ase station susystem

EDGE is reali9ed in t$o phases0

Phase 10 pro:ides the single/multiple


44/51


Phase 20 pro:ides real


45/51


46/51


data lock. *n EGPRS= the radio lock transferring data is composed of one )5,/R(,

header and one or t$o R(, data locks. &he ,S is used for the error check of the

head and the ,S is used for the error check of the data.

,ompared $ith GPRS radio data lock= the EGPRS radio data lock has the follo$ing

features0

Phase 10 pro:ides single


47/51


e added after the payload.

amily 0 &he payload of family code has 2B ytes. *t corresponds to ),S


48/51


22."

24.6

"".B

%"."

%4.2

G)S7

B

1'.6

G)S7

,S

under G)S7 modulation mode at lo$ rate is more suitale at the edge of a cell to

compensate the poor link Auality. *n the central area of a cell $ith good transmission

conditions= an ),S $ith high rate can e used.

".4.4 %in! 8uality Control

".4.4.1 %in! $*aptation

EGPRS allo$s re


49/51


has more po$erful anti


50/51


-see GS)+".6+.

&hat the $indo$ si9e can change $ith the multi


51/51


8indo$ Si9e ,oding&imeslots 5llocated -)ulti

gprs and edge basics

Documents