3G Fundamentals

7/17/2019 3G Fundamentals

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Vodafone

Company Confidential 14 October 2015

3G Fundamentals


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Vodafone

Company Confidential

WCDMA FDD technology

Multiple access technology is wideband CDM !"CDM#

ll cells at same carrier fre$uency

%preading codes used to separate cells and users

%ignal bandwidth &'(4 M)*

Multiple carriers can be used to increase capacity

+nter,-re$uency functionality to support mobility between fre$uencies

Compatibility with .%M technology

+nter,%ystem functionality to support mobility between .%M and /M%


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Differences between WCDMA & GSM

WCDMA GSM

Carrier spacing 5 MHz 200 kHz

Frequency reuse factor 1 118

Power controlfrequency

1500 Hz 2 Hz or lower

Quality control Radio resource

management algorithms

Network planning

(frequency planning)

Frequency diversity 5 MHz bandwidth givesmultipath diversity with

Rake receiver

Frequency hopping

Packet data Load-based packetscheduling

Timeslot basedscheduling with GPRS

Downlink transmitdiversity

Supported forimproving downlink

capacity

Not supported by thestandard, but can be

applied

High bitrates

Services with

Diferentqualityrequirements

Ecientpacketdata


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Multile WCDMA carriers !ayered networ"

F1

F2

F2

F3

F3

F3

Micro BTSMacro BTS

PicoBTSs

1 - 10 km

50 - 100 m200 - 500

m


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preading Code

Spread Signal

Data

ir Interace

CDMA rincile # Chis & $its & Symbols

Bits (n t!is dra"ing# 1 $it % & C!ips SF%&'

Base$and Data

-1

1

1

1

1

1

-1

-1

-1

-1

C!ipC!ip

Despreading


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%nergy $o

req

uency

!an

d

Duration(t = 1/Rb)

Powe

r/H

z

Originating Bit Received Bit

)nerg* per $it % Eb% const

)igher spreading factor"ider fre$uency band ower power spectral density/ %ame 3nergy per it

'(Fre)uency

$and

Fre)uency

$and

Fre)uency

$and


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requency"#werdensity$%atts&H'(

)nspread narr#wbandsignal

Spread widebandsignal

!andwidth + $*+,- .chip&sec(

)ser bitrate

/

sec

84.3 Mchip

constW ==

[ ]R

WdBGp ="r#cessing

gain0

Sreading & *rocessing Gain


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Sectrum Analysis of Sreading & Disreading

%preading code

%preading code

%ignal

Combination

arrowband signal

f

!f#

roadband signal

!f#

f

+oise & ,ther Signal

!f#

f

oise6roadband signal

!f#

f

7eco8ered signal

!f#

f


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Sreading and sharing the same sace

ff

ff

-ser A-ser A

-ser $-ser $

DataData Data afterData after

sreadingsreading**

**

.ransmission.ransmission

o/er the airo/er the air

DesreadDesread

-ser A signal-ser $ signalat the recei/erat the recei/er

ff

ff

ff ff

*

*

* *


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requency $H'(

*rocessing Gain %amles

0oice user 1(22 "bit4s5

*ac"et data user 1367 "bit4s5

5owerdensity

!"9)*#

W

8

-re$uency !)*#

/nspreadnarrowband signal

%pread widebandsignal

*rocessing GainG9W4892: d$

5owerdensity

!"9)*#

W

8

/nspread

:narrowband:signal

%pread widebandsignal

*rocessing GainG9W489(; d$

;%preading se$uences ofdifferent length;rocessing gain dependent onuser data rate

1-ser data rate5 1sreading ratio59const


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Company Confidential 11

G 9 Wc4Wi

Wc= chi rate

Wi= user data rate

he more processing gain the system has< the more the power of uncorrelated

interfering signals is suppressedin the despreading process

hus< processing gain can be seen as an impro8ement factor in the %+7 !%ignal

to +nterference 7atio# of the signal after despreading %amle= Voice M7 12'2 >bps.p ? 10@log!&(40000912200#? 25 d fter despreading the signal power has to be typically few d abo8e the

interference and noise= 3b9o ? 5dA therefore the re$uired wideband signal-to-

interference ratiois 5d B .p ? #20 d'

+n other words< the signal power can be 20 d underunderthe interference and the

"CDM recei8er can still detect the signal Wideband signal-to-interference ratio isalso called carrier,to,interference ratio=

C9+ hans to spreading and despreading< C9+ can be much lowerin "CDM than

.%M !C9+ ? ,12 d#

f"i"c

*rocessing Gain


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.ransmission *ower

requency

1.H'

"#wer density

2ime

High bit rate user

3#w bit rate user


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Company Confidential 1&

Consists of 2 operations=

1' Channelisation !OV%-= Orthogonal Variable %-#

ransforms each symbol !data bit# to the number of chips !increases bandwidth# umber of chips per symbol ? %preading -actor !%-#

2' %crambling !does not affect the signal bandwidth# %crambling code is applied ! codes#

scramblingchanneli*ation

Datas*m$ol

4hips aterspreading

Sreading in WCDMA


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WCDMA Codes

+n "CDM two separate codes are used in the spreading operation

' Channelisation code' %crambling code

' Channelisation codeD= separates physical channels of different users and common channels

*ilot

8adio frame 9 (: time slots

.ime

-ser 3

3

8F carrier

&'(4 M)* bandwidth

C>A++%!@SA.@,+ codes=

*#C*@C>

*#CC*C>

D*C>(

D*C>2

D*C>3


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-! Sreading for D*CC> and D*DC>s

+

E

cd


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D! & -! Channelisation Codes

"alsh,)adamard codes= orthogonal 8ariable spreading factor codes !OV%- codes# %- for the D transmission in -DD mode ? H4< (< 1G< &2< G4< 12(< 25G< 512I %- for the / transmission in -DD mode ? H4< (< 1G< &2< G4< 12(< 25GI

.ood orthogonality properties= cross correlation 8alue for each code pair in the code

set e$uals 0+n theoretical en8ironment users of same cell do not interfere each other in D+n practical multipath en8ironment orthogonality is partly lost+nterference

between users of same cell Orthogonal codes are suited for channel separation< where synchronisation

between different channels can be guaranteed

Downlin channels under one cell

/plin channels from a single user Orthogonal codes ha8e bad auto correlation properties and thus not suited in an

asynchronous en8ironment%crambling code re$uired to separate signals between cells in D and users in /


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Channelisation Code .ree

45$5(6789

4:$8(678;89

4:$5(67889

4-$5(67888

89

4-$8(6788;8;

89

4-$:(678;88;89

4-$*(678;8;889

4,$5(67888888

889

4,$8(678888;8;8;8;89

4,$:(6788;8;888;8;89

4,$*(6788;8;8;8;8889

4,$5(678;88;88;88;89

4,$1(678;88;8;88;889

4,$


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WCDMA Channeliation Code

%- ? chip rate 9 symbol rate

; )igh data rates J low %- code; ow data rates J high %- code

8adio bearer SF 8adio bearer SF

Seech (2


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,al rate speec

F.ll rate speec!

12& k$ps

3&/ k$ps

2 M$ps

Symbolphyb RR = 2_SF

WRSymbol=

!F%> modulation#

*hysical !ayer $it 8ates 1D!5

Rb_phy includes= DDC) !/ser data !DC)# 6 & control !DCC)## 6 3rror protection 6

DCC) !1 control#


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D! *rimary Scrambling Code Grou

"rimaryscramblingc#des #rd#wnlink

physicalchannels

?r#up 5

@

"rimary

scrambling c#de5

@@

"rimaryscrambling c#de,


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D! & -! Scrambling Codes

DL Scrambling Codes

; seudo noise codes used for cell separation; 512 rimary %crambling Codes

UL Scrambling Codes

; wo different types of / scrambling codes are generated

; ong scrambling codes of length of &( 400 chips ? 10 ms radio frame; %hort scrambling codes of length of 25G chips are periodically repeated toget the scrambling code of the frame length

; %hort codes enable ad8anced recei8er structures in future


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Code Multileing

;Downlin ransmission on a Cell e8el

%crambling code%crambling code

Channeli*ation code 1Channeli*ation code 1

Channeli*ation code 2Channeli*ation code 2

Channeli*ation code &Channeli*ation code &

/ser 1 signal

/ser 2 signal

/ser & signal

ode


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Code Multileing

; /plin ransmission on a Cell e8el

ode

%crambling code &

/ser & signal

Channeli*ation code

%crambling code 2

/ser 2 signal

Channeli*ation code

%crambling code 1

/ser 1 signal

Channeli*ation code


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Channelisation and Scrambling Codes


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*hysical !ayer $it 8ates 1-!5 # >S-*A

&. 7elease G standards introduced enhanced / bit rates with )igh %peed /plin acet

ccess !)%/# technology

-ast allocation of a8ailable / capacity for users B )igh pea bit rates

%imultaneous usage of up to 262 / channelisation codes !+n )%/ %-?2 B 4#

Coding rateCoding rate

192192

&94&94

494494

1 L %-41 L %-4 2 L %-42 L %-4 2 L %-22 L %-22 L %-2 62 L %-4

2 L %-2 62 L %-4

4(0 bps4(0 bps G0 bpsG0 bps 1'2 Mbps1'2 Mbps 2'(( Mbps2'(( Mbps

K20 bpsK20 bps 1'4G Mbps1'4G Mbps 2'(( Mbps2'(( Mbps 4'&2 Mbps4'&2 Mbps

G0 bpsG0 bps 1'2 Mbps1'2 Mbps &'(4 Mbps&'(4 Mbps 5'KG Mbps5'KG Mbps


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Wireless *roagation

7ecei8ed

%ignal

ransmitted

%ignal

ransmission oss=

ath oss 6 Multi,path -ading

ime

mplitude


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*roagation of 8adio Signal

%ignal at ransmitter

%ignal at 7ecei8er

;-5

;*1

;*5

;:1

;:5;81

;85

;1

d!

5

5d!m

;:5;81

;85

;1

1

85

81

:5

-ading


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Fading Categories

-ading Categories

%low -ading

-ast -ading


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Di/ersity .echni)ue

Di8ersity techni$ue is used to obtain uncorrelated signalsfor combining

7educe the effects of fading= -ast fading caused by multi,path

%low fading caused by shadowing

+mpro8e the reliability of communication

+ncrease the co8erage and capacity


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Di/ersity

ime di8ersityChannel coding< loc interlea8ing

-re$uency di8ersityhe user signal is distributed on the whole bandwidth fre$uency

spectrum

%pace di8ersity

olari*ation di8ersity


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8A% 8ecei/er

Combination or multipath components and signal from different cells

Delay8

Code usedfor the

connection

8

,utut

Finger

t

Cell#(

Cell#(

Cell#(

Cell#2

8

8

8

Finger

Finger

Finger

Delay:

Delay*


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*rincile of 8A% 8ecei/er

/eceive set

4#rrelat#r 8

4#rrelat#r :

4#rrelat#r *

Searc!ercorrelator

4alculate thetime delay andsignal strength

4#mbiner

2he c#mbinedsignal

tt

s$t( s$t(

/ACE receiver help t# #verc#me #n the multi;path ading and enhance thereceive per#rmance # the system


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&5

Definition= channel is defined wide when its bandwidth !w# is greater than the Coherence

andwidth= w EEfc

S

fc

2

1=

Wide $and Channel


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VodafoneCompany Confidential &G

4hannel impulse resp#nse $p#wer delay pr#le( and delay spread

D#minant "ath

1

Wide $and Channel Delay Sread


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&K

Wide $and Channel +arrow4Wide $and System


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&(

WCDMA and GSM in .-3 Channel


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&

8a"e 8ecei/er # Combining

4#mbined signal with#ut and with phase estimati#n andc#rrecti#n $eample < path channel(


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VodafoneCompany Confidential 40

Maimal8atio Combining of Symbols

/eceived signal$Bn#ise(

ingern+8

inger n+:

inger n+*

2ime andphase

adFustment

4#mbinedsignal $B

residual n#ise(

2ransmittedsignal

+BTS

)


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42

WCDMA in .- Channel

G,ig! leel o m.ltipat! diersit*

time

Corr 1Corr 2Corr 3Corr / Corr 5Corr Corr


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4&

WCDMA in @ndoor Channel

/ake inger /ES3)2I 6 5+:


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8F ,timiation Flow Chart

Dri8e est

+dentify any 7- +ssues

+dentify candidate

cells for changes

+dentify nature of

re$uired changes

Determine amount

of changes

+mplement changes

7epeat Dri8e est

-inish

roblem 7esol8edN

8F , ti i ti S l ti


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8F ,timiation # Solutions

Antenna d#wn tilt $.;tiltK E;tilt(

Antenna a'imuth Antenna l#cati#n !ack;l#beK Side;l#be suppressi#n Antenna height Antenna type

";4"I4H p#wer Site l#cati#n ew site


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8F Analysis Aroaches Cell Dominance

4ells with n# d#minance at all0

A site was n#t radiating during the drive survey Lery p##r d#minance can als# be caused by bl#cking # theantennaK there#re a site visit must be made t# veriy theantenna clearance+

4ells with either ecessive #r p##r d#minance2his c#uld be due t# a high site #r n#n;#ptimum antenna d#wn

tilts+ 4ells with t## large d#minance will be causing intererence t#

adFacent cells resulting in p##rer quality and capacity+


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Areas # n#n;d#minance0

Areas where there is n#t a single clear d#minant celland where the best server changes t## requently+

/esult0 ecessive number # s#t hand #f eventsreducing the system eciency and increasing thepr#bability # call dr#ps+

)E vs+ Scanner !est Serving 4ells0 4#mparis#n between the )E and scanner S4 pl#tsKsignicant diferences between the pl#ts may indicatea missing neighb#r #r ailed s#t hand#f pr#blem+




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8F Analysis Aroaches C*@C> Co/erage


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4heck areas # p##r c#verageK suggesti#n value as bel#w0 ?##d0 /S4" M ;,1 d!m air0 ;>1 d!m N /S4" O ;,1 d!m "##r0 /S4" O ; >1 d!m Eamine the /S4" c#verage #n per cell bases in #rder

t# highlight any cells that have t## large a ##tprint+



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8F Analysis Aroaches @nterference


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8F Analysis Aroaches @nterference

4"I4H Ec&I# "l#t ?##d0 Ec&I# M ;, d! air0 ;8- d! N Ec&I# O ;, d! "##r0 Ec&I# O ; 8- d!

.he #6 d$ threshold ta"es into account the eected future interference

increase as a result of increased traffic

Documents

3G Fundamentals