wcdma power control overview

8/9/2019 WCDMA Power Control Overview

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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

C!"A #owerControl $verview


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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. #age2

Contents

1. Power Control Overview2. open loop #ower Control

%. closed loop #ower Control


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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. #age%

&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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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. #age

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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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. #age

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 power control overview

2.2 PRACH open loop power control

2.% !#CCH open loop power control


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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. #age@%

$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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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. #age@

$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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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. #age@:

Contents


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


open loop power

control o) +PCCH*. +ownl&n, ncron&/at&on


er2&ngR0C

+CH - 3P


RRCRRC

01AP01AP


01AP01AP$. Rad&o 4&n, et(p Req(est


tart RXdescr&pt&on

tart TXdescr&pt&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


open loop power

control o) +PCCH

*. +ownl&n, ncron&/at&on


er2&ngR0C

+CH - 3P


RRCRRC

01AP01AP


01AP01AP$. Rad&o 4&n, et(p Req(est


tart RXdescr&pt&on

tart TXdescr&pt&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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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. #age2%

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



+.+ 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


How to adjust power

=

=+=

0)(TPCif

1)(TPCif)(P

estTPC

estTPC

TPC k

kk


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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



%.% !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


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 BLER

Outer

loop

Inner loop L1

L'

10+1001(00

!ownlin' outer loop powercontrol


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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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,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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