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3G Fundamentals
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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$uences ofdifferent length;rocessing gain dependent onuser data rate
1-ser data rate5 1sreading ratio59const
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G 9 Wc4Wi
Wc= chi rate
Wi= user data rate
he more processing gain the system has< the more the power of uncorrelated
interfering signals is suppressedin the despreading process
hus< processing gain can be seen as an impro8ement factor in the %+7 !%ignal
to +nterference 7atio# of the signal after despreading %amle= Voice M7 12'2 >bps.p ? 10@log!&(40000912200#? 25 d fter despreading the signal power has to be typically few d abo8e the
interference and noise= 3b9o ? 5dA therefore the re$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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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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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 $eample < path channel(
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Maimal8atio Combining of Symbols
/eceived signal$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+
8F Analysis Aroaches Cell Dominance
8F Analysis Aroaches Cell Dominance
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8F Analysis Aroaches Cell Dominance
8F Analysis Aroaches C*@C> Co/erage
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8F Analysis Aroaches C*@C> Co/erage
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+
8F Analysis Aroaches C*@C> Co/erage
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8F Analysis Aroaches C*@C> Co/erage
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