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C!"A #owerControl $verview
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Contents
1. Power Control Overview2. open loop #ower Control
%. closed loop #ower Control
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&plin' transmission character
(el)*inter)erence
Capacity is limited +y inter)erence
ear*)ar e-ect
ading
&plin' power control
/nsure uplin' uality with minimum transmission power
!ecrease inter)erence to other &/, and increase capacity
(olve the near*)ar e-ect
(ave &/ transmission power
#urpose o) uplin' powercontrol
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!ownlin' transmission character
nter)erence among di-erent su+scri+ers since the
orthogonality is in3uenced +y transmission environment
nter)erence )rom other ad4acent cells
!ownlin' capacity is limited +y ode5 transmission power
ading
!ownlin' power control
/nsure !ownlin' uality with minimum transmission power
!ecrease inter)erence to other cells, and increase capacity
(ave ode5 transmission power
#urpose o) downlin' powercontrol
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The 7elationship +etween T8 #owerand 78 #ower
0 200 400 600 800-20
-15
-10
-5
0
5
10
15
20
Time (ms)
Relativepower
(dB)
Channel
Transmitted power
Received power
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#ower Control Classi9cation
#ower control classi9cation open loop power control
closed loop power control &plin' inner*loop power control
!ownlin' inner*loop power control &plin' outer*loop power control !ownlin' outer*loop power control
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#ower control methods adopted)or various physical channels
#ower control methods adopted )or various physicalchannels
; can +e applied, =>= > not applied
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Contents
@. #ower Control $verview2. open loop Power Control
%. closed loop #ower Control
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Contents
2. open loop #ower Control
2.1 open loop power control overview
2.2 #7ACH open loop power control
2.% !#CCH open loop power control
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$pen loop #ower Control$verview #urpose
&/ estimates the power loss o) signals on thepropagation path +y measuring the downlin' channelsignals, then calculates the transmission power o) theuplin' channel
principle #ath loss o) the uplin' channel is related to path loss
o) the downlin' channel
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$pen loop #ower Control$verview !isadvantage
This power control method is rather rough
Application scenarios n a cell, signal )ading caused +y )ast )ading is usually
more serious than that caused +y propagation loss open loop power control is applied only at the
+eginning o) connection setup, generally in setting theinitial power value
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Contents
2. open loop #ower Control
2.@ open loop power control overview
2.2 PRACH open loop power control
2.% !#CCH open loop power control
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$pen loop #ower Control o)#7ACH
AICH access
slots RX at UE
PRACH access
slots TX at UE
One access slot
p-a
p-mp-p
Pre-amble
Pre-amble
Message part
Acq.Ind.
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$pen loop #ower Control o)#7ACH
The initial value o) #7ACH power is set through open loop
power control
Preamble_Initial_Power
= PCPICH DL TX power CPICH_R!CP " #L inter$erence" Con%tant &al'e
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$pen loop power control o) #7ACH
(O. Parameter Parameter meanin)
1 Power O*%et Ppm The power o-set o) the last access pream+le and message control
part. This value plus the access pream+le power is the power o) the
control part
2 Con%tant &al'e This parameter is the correction constant used )or the &/ to estimatethe initial transmission power o) #7ACH according to the open loop
power
+ PRACH Power Ramp !tep This parameter is the ramp step o) the pream+le power when the &/
has not received the capture indication )rom ode5
, Preamble Retran% -a This parameter is the permitted ma8imum pream+le repeat times o)
the &/ within a pream+le ramp cycle
Power Ramp tep
Pp-m
!"ms#$"ms
Preable%In&t&al%
power
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$pen loop power control o)#7ACH$pen loop power control o)#7ACH
!. CCCH' RRC Connect&on Req(est
open loop powercontrol o) PRACH
*. +ownl&n, ncron&/at&on
UE 0ode 1Serving RNS
er2&ngR0C
+CH - 3P
Allocate R0TIelect 4! and 4$parameters
RRCRRC
01AP01AP
5. Rad&o 4&n, et(p Response
01AP01AP
$. Rad&o 4&n, et(p Req(est
RRCRRC6. CCCH' RRC Connect&on et (p
tart RXdescr&pt&on
tart TXdescr&pt&on
7. A4CAP I(b +ata Transport 1earer et(p
RRCRRC8. DCCH' RRC Connect&on et(p Complete
9. Upl&n, ncron&/at&on
01AP01AP:. Rad&o 4&n, Restore Ind&cat&on
+CH - 3P
+CH - 3P
+CH - 3P
Application scenarios
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Contents
2. open loop #ower Control
2.@ open loop power control overview
2.2 #7ACH open loop power control
2.+ DPCCH open loop power control
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$pen loop power control o) !L !#CCH
The !L !#CCH open loop power control can +ecalculated +y the )ollowing )ormulaB
P=/0cIoRe3CPICH_0cIo " CPICH_Power
#arameters e8planation /cDoEre is the reuired /cDo, which should ensure
that &/ can receive
the message )rom the dedicated channel correctly
C#CHF/cDo is measured +y &/, then it is sent to&T7A +y 7ACH
C#CHF#oweris the transmission power o) C#CH
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$pen loop power control o) !L!#CCH$pen loop power control o) !L!#CCH
Application scenarios
!. CCCH' RRC Connect&on Req(est
open loop power
control o) +PCCH*. +ownl&n, ncron&/at&on
UE 0ode 1Serving RNS
er2&ngR0C
+CH - 3P
Allocate R0TIelect 4! and 4$parameters
RRCRRC
01AP01AP
5. Rad&o 4&n, et(p Response
01AP01AP$. Rad&o 4&n, et(p Req(est
RRCRRC6. CCCH' RRC Connect&on et (p
tart RXdescr&pt&on
tart TXdescr&pt&on
7. A4CAP I(b +ata Transport 1earer et(p
RRCRRC8. DCCH' RRC Connect&on et(p Complete
9. Upl&n, ncron&/at&on
01AP01AP:. Rad&o 4&n, Restore Ind&cat&on
+CH - 3P
+CH - 3P
+CH - 3P
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$pen loop power control o) &L!#CCH
The &L !#CCH open loop power control can +e
calculated +y the )ollowing )ormulaB
DPCCH_Initial_Power = DPCCH_Power_O*%et CPICH_R!CP
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open loop power control o) &L !#CCHopen loop power control o) &L !#CCHApplication scenarios
!. CCCH' RRC Connect&on Req(est
open loop power
control o) +PCCH
*. +ownl&n, ncron&/at&on
UE 0ode 1Serving RNS
er2&ngR0C
+CH - 3P
Allocate R0TIelect 4! and 4$parameters
RRCRRC
01AP01AP
5. Rad&o 4&n, et(p Response
01AP01AP$. Rad&o 4&n, et(p Req(est
RRCRRC6. CCCH' RRC Connect&on et (p
tart RXdescr&pt&on
tart TXdescr&pt&on
7. A4CAP I(b +ata Transport 1earer et(p
RRCRRC8. DCCH' RRC Connect&on et(p Complete
9. Upl&n, ncron&/at&on
01AP01AP:. Rad&o 4&n, Restore Ind&cat&on
+CH - 3P
+CH - 3P
+CH - 3P
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Contents
@. #ower Control $verview2. open loop #ower Control
+. clo%e4 loop Power Control
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Contents
%. closed loop #ower Control+.1 clo%e4 loop power control overview
%.2 &plin' inner loop power control
%.% !ownlin' inner loop power control%.1 $uter loop power control
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Closed loop power controloverview
The characteristics o) open loop power control The results )rom open loop power control are not
accurate enough
open loop power control can only decide the initial
power
The advantages o) closed loop power control
Guarantee the o(
!ecrease the inter)erence
ncrease the system capacity
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Closed loop power controloverview
Inner loopOuter loop
BLERmea>BLERtarSIRtar
BLERmeaSIRtar
TPC=0
SIRmea
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Contents
%. closed loop #ower Control%.@ closed loop power control overview
+.2 #plin5 inner loop power control
%.% !ownlin' inner loop power control%.1 $uter loop power control
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&/ gets one T#C in each time slot
) T#CI0, T#CFcmdI *@
) T#CI@, T#CFcmdI @
T7i% control i% 4one in eac7 time %lot
Power control $re3'enc8 i% 19::H;
: 1 1 : 1 1 : 1 1 :FF FF
FF FFTPC%CM+
TPC
1 1 1 1 1 1 1 1 1 1
&plin' inner*loop #CA@ without so)t handover
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: 1 1 : 1 1 : 1 1 :"" ""
R4!-TPC ;G! T!? T!1
:
T!1
1
T!1
2
T!1
+
T!1
,
RL!
1: : : : : : : : : 1 : : : : :
RL!
2 : : : : 1 : : : : 1 : : : : :RL!
+: : : : 1 : : : : : : : : : 1
FF FF
TPC
TPC%temp&
T!
:
T!1 T!2 T!+ T!, T!9 T!< T! T!> T!? T!1
:
T!1
1
T!1
2
T!1
+
T!1
,
: : : : 1 : : : : 1 : : : : :
FF FF
TPC%CM+
Power &s controlled &n eac * t&me slots
Te power control )req(enc &s 5""HJ
&plin' inner*loop #CA2 with so)thandover
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Comparison +etween #CA@ and#CA2
The control )reuency T#C@, the power control )reuency is @00HJ
T#C2, the power control )reuency is %00HJ
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Contents
%. closed loop #ower Control%.@ closed loop power control overview
%.2 &plin' inner loop power control
+.+ Downlin5 inner loop power control
%.1 $uter loop power control
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,o-eB
set SIRtar
Transmit TPC
.easure an- /ompare SIR
.easure an- /ompare BLER
Outer loop
Inner loop L1
L'
10+1001(00
!ownlin' closed loop powercontrol
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!ownlin' nner loop powercontrol
0ode1
et IRtar
Transm&t TPC &n eac T
Meas(re IR and compare
&t w&t IRtar
Ad>(st T? power
w&t ".*= != ! or $d1
!*""H/ 45
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The transmission power can not higher than
"a8imumF!LF#ower, and not less than
"inimumF!LF#ower neither.
!ownlin' power ad4ustmentB
(k) = P(k1) + PTPC(k) + Pbal(k)
here #'*@E is power o) previous
#T#C'E is the ad4ustment
#+al'E is correction value
!ownlin' inner*loop powercontrol
How to adjust power
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here
#T#C'E is the ad4ustment value
T#Cest'E is uplin' T#C value
KT#C is downlin' power ad4ustment step0., @,
@. or 2d5E
PTPC/5
ithout ;Limited #ower 7aise &sed
!ownlin' inner*loop powercontrol
How to adjust power
=
=+=
0)(TPCif
1)(TPCif)(P
estTPC
estTPC
TPC k
kk
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here
PTPC/5
ith ;Limited #ower 7aise &sed
!ownlin' inner*loop powercontrol
=
+=
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!ownlin' inner*loop powercontrol
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!ownlin' #ower 5alance
!ownlin' power +alance process
(7C can monitor every single
ode5Ms transmission. ) (7C
)ound the power o-set in so)t
handover is e8cessive, it will
initiate the !#5 process
The initiation and stop o) !#5
The power o-set o) two 7Ls is
greater than the !#5 initial
threshold, the !#5 process isinitiated
The power o-set o) two 7Ls is
less than the !#5 stop threshold,
the !#5 process is stopped
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Contents
%. closed loop #ower Control%.@ closed loop power control overview
%.2 &plin' inner loop power control
%.% !ownlin' inner loop power control
+., O'ter loop power control
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$uter loop power control
The character o) outer loop power control The o( which A( provides to C is 5L/7, not (7
The relationship +etween inner loop power control and
outer loop power control (7tar should +e satis9ed with the reuirement o)
decoding correctly. 5ut di-erent multi*path radioenvironments reuest di-erent (7
There)ore, the outer loop power control can ad4ust the (7to get a sta+le 5L/7 in the changea+le radio environment
& li ' l
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&plin' outer loop powercontrol
,o-eB UE
Transmit TPC
.easure an- /ompare SIR
Inner+loop
Set SIRtar
Out loop
R,C
.easure re/ei2e- -ata an-/ompare BLER in te TrC
Set BLERtar
10+100
! li ' l
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,o-eB
set SIRtar
Transmit TPC
.easure an- /ompare SIR
.easure an- /ompare BLER
Outer
loop
Inner loop L1
L'
10+1001(00
!ownlin' outer loop powercontrol
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$uter loop power control
SIR target adjustmentstep
=
etBLERt
etBLERtBLERmeastepSRAd!ustSoe""i#ientSRAd!ust#SRtar
arg
arg**
here
(irAd4ust(tepB $uter loop power control ad4ustment
step
(irAd4ustactorB CoeNcient )or outer loop power
control
5L/7estB /stimated 5L/7
5L/7tarB Target 5L/7
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$uter loop power control
,o-e B SR,C
F
F
O(ter loop power control
&plin' outer loop power control command transmit toode5 through !CH*# o) u+ inter)ace
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