owj200102 wcdma power control algorithm and parameters ran10 issue2.00

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

WCDMA Power Control and Relevant Parameters


Objectives

Upon completion of this course, you will be able to:

Describe the purpose and function of power control

Explain open loop power control and parameters

Explain inner loop power control and relevant

parameters

Explain outer loop power control and relevant

parameters


Contents

1. Power Control Overview

2. Open Loop Power Control

3. Closed Loop Power Control


Purpose of Uplink Power Control

Uplink Transmission Character Self-interference system

Uplink capacity is limited by interference level

Near-far effect

Fading

Uplink Power Control Function Ensure uplink quality with minimum transmission power

Decrease interference to other UE, and increase capacity

Solve the near-far effect

Save UE transmission power


Purpose of Downlink Power Control

Downlink Transmission Character Interference among different subscribers

Interference from other adjacent cells

Downlink capacity is limited by NodeB transmission power

Fading

Downlink Power Control Function Ensure downlink quality with minimum transmission power

Decrease interference to other cells, and increase capacity

Save NodeB transmission power


Effect of Power Control

Time (ms)0 200 400 600 800

-20

-15

-10

-5

0

5

10

15

20R

elat

ive

po

wer

(d

B)

Channel Fading

Transmitting power

Receiving power


Power Control Classification

Open Loop Power Control

Uplink / Downlink Open Loop Power Control

Closed Loop Power Control

Uplink / Downlink Inner Loop Power Control

Uplink / Downlink Outer Loop Power Control


Power Control For Physical Channels

Power control methods are adopted for these physical channels:

“√" – can be applied, “×" – not applied

Physical

Channel

Open Loop

Power Control

Closed Loop Power ControlNo

Power Control

Inner Loop Power Control

Outer Loop Power Control

DPDCH √ √ √ ×

DPCCH √ √ √ × 　SCH × × × √

PCCPCH × × × √

SCCPCH × × × √

PRACH √ × × ×

AICH × × × √

PICH × × × √


Common Physical Channel Power Parameters

MAXTXPOWER

Parameter name: Max transmit power of cell

The recommended value is 430, namely 43dBm

PCPICHPOWER

Parameter name: PCPICH transmit power

The recommended value is 330, namely 33dBm



PSCHPOWER or SSCHPOWER

Parameter name: PSCH / SCCH transmit power

The recommended value is -50, namely -5dB

BCHPOWER

Parameter name: BCH transmit power




MAXFACHPOWER

Parameter name: Max transmit power of FACH

The recommended value is 10, namely 1dB

PCHPOWER

Parameter name: PCH transmit power




AICHPOWEROFFSET

Parameter name: AICH power offset

The default value of this parameter is -6, namely -6dB

PICHPOWEROFFSET

Parameter name: PICH power offset

The default value of this parameter is -7, namely -7dB


Contents





Contents


2.1 Open Loop Power Control Overview

2.2 PRACH Open Loop Power Control

2.3 Downlink Dedicated Channel Open Loop Power

Control

2.4 Uplink Dedicated Channel Open Loop Power Control


Open Loop Power Control Overview

Purpose

Calculate the initial transmission power of uplink / downlink

channels

Principle

Estimates the downlink signal power loss on propagation path

Path loss of the uplink channel is related to the downlink

channel

Application

Open loop power control is applied only at the beginning of

connection setup to set the initial power value.


Contents





Control



PRACH Open Loop Power Control

5. Downlink Synchronization

UE Node BServing

RNC

DCH - FP

Allocate RNTISelect L1 and L2parameters

RRCRRC

NBAPNBAP3. Radio Link Setup Response

NBAPNBAP2. Radio Link Setup Request

RRCRRC7. CCCH: RRC Connection Set up

Start RX description

Start TX description

4. ALCAP Iub Data Transport Bearer Setup

RRCRRC9. DCCH: RRC Connection Setup Complete

6. Uplink Synchronization

NBAPNBAP8. Radio Link Restore Indication

DCH - FP

DCH - FP

DCH - FP

Open loop power control of PRACH

1. CCCH: RRC Connection Request



Initial Power Calculation for the First Preamble

When UE needs to set up a RRC connection, the initial

power of uplink PRACH can be calculated according to

the following formula:

Power Tx Initial gCalculatin For Value Constant+ceInterferen UL+

CPICH_RSCP-Power Transmit PCPICH=ernitial_PowPreamble_I


PRACH Open Loop Power Control Parameters

CONSTANTVALUE

Parameter name: Constant value for calculating initial

TX power




Timing relationship of PRACH and AICH

AICH

PRACH

1 access slot

p-a

p-m p-p

Pre-amble

Pre-amble

Message part

Acq. Ind.


PRACH Open Loop Power Control Parameters AICHTXTIMING

Parameter name: AICH transmission timing Content:

When AICHTXTIMING = 0,

p-p,min = 15360 chips, p-a = 7680 chips, p-m = 15360 chips

When AICHTXTIMING = 1,

p-p,min = 20480 chips, p-a = 12800 chips, p-m = 20480 chips

The recommended value is 1



Power Ramping for Preamble Retransmission

Power Ramp Step

Power Offset Pp-m

Preamble_Initial_Power

Message part

Pre-amblePre-

amble……

Pre-amblePre-

amble

＃ 1 ＃ 3 ＃ N＃ 2



POWERRAMPSTEP

Parameter name: Power increase step


PREAMBLERETRANSMAX

Parameter name: Max preamble retransmission

The Recommended value is 20



MMAX

Parameter name: Max preamble loop

The recommended value is 8

NB01MIN / NB01MAX

Parameter name: Random back-off lower / upper limit

The recommended value: 0 for both NB01MIN /

NB01MAX



POWEROFFSETPPM

Parameter name: Power offset

The default value:

-3dB for signalling transmission;

-2dB for service transmission.


Contents





Control



DL DPDCH Open Loop Power Control


UE Node BServing

RNC

DCH - FP


RRCRRC










DCH - FP

DCH - FP

DCH - FP





When a dedicated channel is set up, the initial power

of downlink DPDCH can be calculated according to

the following formula:

Total

CPICH

CPICHDLInitial P

)No/Ec(

P)

No

Eb(

W

RP



Data1 TPC TFCI Data2 Pilot

DownlinkTransmit

Power

DPCCHDPDCH DPDCH DPCCH

PO2PO1

PO3

1 timeslot


Downlink Power Control Restriction

The power of downlink dedicated channel is limited by

an upper and lower limit for each radio link.

The DL DPDCH power could not exceed

Maximum_DL_Power, nor could it be below

Minimum_DL_Power.

RLMAXDLPWR / RLMINDLPWR

Parameter name: RL Max / Min DL TX power

The recommended value is shown in the following table.


Downlink Power Restriction Parameters Referential configurations for typical services:

ServiceRL Max Downlink

Transmit Power (dB)

RL Min Downlink

Transmit Power (dB)

Downlink SF

CS Domain

12.2 kbps AMR -3 -18 128

28 kbps -2 -17 64

32 kbps -2 -17 64

56 kbps 0 -15 32

64 kbps 0 -15 32

PS Domain

8 kbps -8 -23 128

32 kbps -4 -19 64

64 kbps -2 -17 32

144 kbps 0 -15 16

256 kbps 2 -13 8

384 kbps 4 -11 8


Contents





Control

2.4 Uplink Dedicated Channel Open Loop Power

Control


UL DPCCH Open Loop Power Control


UE Node BServing

RNC

DCH - FP


RRCRRC










DCH - FP

DCH - FP

DCH - FP


Open Loop Power Control of UL DPCCH


UL DPCCH Open Loop Power Control

The initial power of the uplink DPCCH can be calculated according to the following formula:

Where CPICH_RSCP means the received signal code power, the

received power measured on the CPICH.

DPCCH_Power_Offset is provided by RNC to the UE via RRC signaling.

RSCP_CPICHOffset_Power_DPCCHPower_Initial_DPCCH


UL DPCCH Open Loop Power Control Parameter

DEFAULTCONSTANTVALUE

Parameter name: Constant value configured by default The recommended value is -22, namely -22dB.


Uplink Power Control Restriction

During the operation of uplink power control, the UE

transmit power shall not exceed the Maximum

Allowed Uplink Transmit Power.

MAXALLOWEDULTXPOWER Parameter name: Max allowed UE UL TX power The recommended value is 24, namely 24 dBm.


Uplink Power Control Restriction

In addition, there are four parameters which correspond to the

maximum allowed transmit power of four classes of services

respectively:

MAXULTXPOWERFORCONV

Parameter name: Max UL TX power of Conversational service

MAXULTXPOWERFORSTR

Parameter name: Max UL TX power of Streaming service

MAXULTXPOWERFORINT

Parameter name: Max UL TX power of Interactive service

MAXULTXPOWERFORBAC

Parameter name: Max UL TX power of Background service

The recommended value is 24, namely 24 dBm.


Contents





Contents


3.1 Closed Loop Power Control Overview

3.2 Uplink Inner Loop Power Control

3.3 Downlink Inner Loop Power Control

3.4 Outer Loop Power Control


Closed Loop Power Control Overview Why closed loop power control is needed?

Open loop power control is not accurate enough, it can only estimate the initial transmission power.

Closed loop power control can guarantee the QoS with minimum power. By decreasing the interference, the system capacity will be increased.

Inner LoopOuter Loop

SIRtar

SIRmea>SIRtar→ TPC=0

SIRmea<SIRtar→ TPC=1

UntilSIRmea=SIRtar

TPCBLERtar

BLERmea>BLERtar→SIRtar

BLERmea<BLERtar→SIRtar

Until BLERmea=BLERtar

TPC=1 Power

TPC=0 Power


Contents







Uplink Inner Loop Power Control

NodeB compares the measured SIR to the preset target SIR,

then derives TPC and sends the TPC Decision to UE.

TPC Decision( 0, 1 )

Generate TPC_cmd( -1, 0, 1 )

Adjust DPCCH Tx△DPCCH = TPC×TPC_cmd△

Single RL / Soft HOPCA1 / PCA2

Adjust DPDCH Tx( c , d )

NodeB UETransmit TPC

Inner Loop

Set SIRtar

Compare SIRmea with SIRtarSIRmea SIRtar → TPC = 0SIRmea SIRtar → TPC = 1


Uplink Inner Loop PCA1 with Single Radio Link

For single radio link and PCA1, UE derives one TPC_cmd in

each time slot as follows:

0110110110…… ……

…… ……TPC_cmd

TPC

-111-111-111-1

This control is performed in each time slot, so the power control frequency is 1500Hz


Uplink Inner Loop PCA2 with Single Radio Link

For single radio link and PCA2, UE derives one TPC_cmd in

each 5-slot group as follows:

This control is performed in each 5-slot group, so the power control frequency is 300Hz

110111111100000

TS14TS13TS12TS11TS10TS9TS8TS7TS6TS5TS4TS3TS2TS1TS0

10ms radio frame

Group 2Group 1 Group 3

…… ……

0000010000-10000

TPC

TPC_cmd

…… ……


Uplink Inner Loop with Soft Handover When UE enters soft handover state, on the NodeB

side, there are two phases :

Uplink synchronization phase

Multi-radio link phase

On UE side, UE will receive different TPCs from

different RLS in one time slot. Therefore, the UE

should combine all the TPCs to get a unique

TPC_CMD.


Uplink Inner Loop PCA1 with Soft Handover

For each slot, combine TPC from the same RLS, then get Wi

CELL1 CELL2

CELL4CELL3

RL1-1 RL1-2

RLS1

RLS2 RLS3Get TPC_cmd based on

TPC_cmd = (W1, W2, … WN)

0110110110…… ……RLS1-TPC (W1)

…… ……RLS2-TPC (W2) 1010101101

…… ……

…… ……TPC_cmd

1101100100

-1-1-1-11-1-11-1-1

RLS3-TPC (W3)



Combine TPC from same RLS

in each time slot

Calculate TPC_cmd If any TPC_tempi = -1, TPC_cmd = -1

If , TPC_cmd = 1

Otherwise, TPC_cmd = 0

Calculate TPC_tempi for each RLSi

5.0_1

1

N

iitempTPC

N

CELL1 CELL2

CELL4CELL3

RL1-1 RL1-2RLS1

RLS2 RLS3



RLS3

RLS2

RLS1 100100000000100

100110000011111

111110000011111


…… ……

10ms/frame

Group 1 Group 2 Group 3

RLS3

RLS2

RLS1 00000-1000000000

00000-1000010000

10000-1000010000


…… ……

TPC

TPC_tempi

00000-1000010000


…… ……

TPC_cmd


Uplink Inner Loop Power Control Parameters

PWRCTRLALG

Parameter name: Power control algorithm selection

The recommended value is ALGORITHM1

ULTPCSTEPSIZE

Parameter name: UL closed loop power control step

size



Contents







Downlink Inner Loop Power Control

UE L1 compares the measured SIR to the preset target SIR, then

derives TPC and sends the TPC Decision to NodeB.

Derive TPCest(k) ( 0, 1 )

Generate PTPC(k)

Calculate P(k)

Adjust DPCH Tx Power

DPC_MODE

NodeB

L3 Set SIRtar

Derive and transmit TPC based on DPC_MODE

Inner Loop

UE

L1 compare SIRmea with

SIRtar


Downlink Inner Loop Power Control Mode Two DPC_MODE (Downlink Power Control Mode) could

be used: If DPC_MODE = 0, UE sends a unique TPC in each slot, UTRAN

shall derive TPCest to be 0 or 1, and update the power every slot;

If DPC_MODE = 1, UE repeats the same TPC over 3 slots, UTRAN shall derive TPCest over three slots to be 0 or 1, and update the power every three slots.


Downlink Inner Loop Power Control Parameters

DPCMODE

Parameter name: Downlink power control mode

The recommended value is SINGLE_TPC, namely

DPC_MODE = 0



After estimating the TPC, the UTRAN shall set the downlink power to P(k) for k:th slot according to the following formula:

Where P(k-1) is downlink transmission power in (k-1):th slot

PTPC(k) is the adjustment of downlink power in k:th slot

Pbal (k) is correction value according to the downlink power balance procedure. For a single radio link, Pbal (k) equals 0.

)k(P)k(P)1k(P)k(P balTPC



PTPC(k) is calculated according to the following:

If the value of “Limited Power Increase Used”

parameter is “Not Used” , then:

Where

TPCest (k) is uplink received TPC of the k:th slot

TPC is downlink power adjustment step size

0)k(TPC if

1)k(TPC if )k(P

estTPC

estTPCTPC



If the value of “Limited Power Increase Used”

parameter is “Used” , then:

Where

1k

Size_Window_Average_Power_DLkiTPCsum )i(P)k(

0)k(TPC if

Limit_Raise_Power)k( and 1)k(TPC if 0

Limit_Raise_Power)k( and 1)k(TPC if

)k(P

estTPC

TPCsumest

TPCsumestTPC

TPC


Downlink Inner Loop Power Control Parameters

INNER_LOOP_DL_LMTED_PWR_INC_SWITCH

This is one switch in PCSWITCH (Power control

algorithm switch) parameter.

The default value is 1, namely ON.

FDDTPCDLSTEPSIZE

Parameter name: FDD DL power control step size

The recommended value is STEPSIZE_1DB, namely 1dB


Downlink Power Balance

Purpose The purpose of this procedure is

to balance the DL transmission

powers of more than one Radio

Links.

The start and stop of DPB The power offset of two RLs is greate

r than the DPB start threshold, the DPB process is started

The power offset of two RLs is less than the DPB stop threshold, the DPB process is stopped

NodeB NodeB

Monitor the Tx power of NodeBs and start the DPB

process

DPB process


Downlink Power Balance Parameters

DOWNLINK_POWER_BALANCE_SWITCH

This is one switch in PCSWITCH (Power control algorithm

switch) parameter.

The default value is 1, namely ON.

DPBSTARTTHD / DPBSTOPTHD

Parameter name: DPB start threshold / DPB stop threshold

The recommended value:

DPB start threshold 8, namely 4dB;

DPB stop threshold 4, namely 2dB.


Contents







Outer Loop Power Control

Why we need outer loop power control?

SIR

BLER

Different curves correspond to different multi-path environment


Uplink Outer Loop Power Control

NodeB UE

Transmit TPC

Measure SIR and compare with SIRtar

Inner loop

Set SIRtar

Out loop

RNC

Measure BLER of received data and compare with the BLERtar

Set BLERtar


Initial SIR Setting

The initial SIR target value is provided by the RNC to the NodeB through the SIR_init_target_value which is service-dependent.

For the same SRB or TRB, the values of SIR_init_target_value, Maximum_SIR_target, and Minimum_SIR_target must fulfill the following requirement: Minimum_SIR_target ≤ SIR_init_target_value ≤ Maximum_SIR_target..


Adjusting the SIR Target

SIRtar Adjustment

Where i is the i:th transport channel. n is the n:th adjustment period.

FactorStep

BLER

BLER)1n(BLER)1n(SIRMAX)n(SIR i

i,tar

i,tari,meastartar


SIR Target Adjustment Limitation

The parameters MaxSirStepUp and MaxSirStepDown limit the adjustment range of the SIRtar , and the algorithm is:

If SIRtar 0 and SIRtar “MaxSirStepUp” ,

then SIRtar (n+1) = SIRtar (n) + MaxSirStepUp If SIRtar 0 and ABS(SIRtar ) “MaxSirStepDown” ,

then SIRtar (n+1) = SIRtar (n) – MaxSirStepDown


Parameters of BLER-based outer-loop powercontrol on RAB basis

ServiceSRB 3.4k

SRB 13.6

k

AMR 12.2

k

CSD 64k

PS I/B 8k

PS I/B 16k

PS I/B 32k

PS I/B 64k

PS I/B

128k

PS I/B

144k

PS I/B

256k

PS I/B

384k

SIR init target value

102 122 102 122 102 102 102 102 102 107 122 142

OLPC adjustmen

t period4 2 2 2 4 2 2 2 2 2 2 2

Service DCH_BLER

target value

-20 -20 -20 -27 -20 -20 -20 -20 -20 -20 -20 -20

SIR adjustmen

t step4 10 5 2 4 4 4 4 4 4 4 4

MaxSirStepUp 400 500 500 1000 400 400 400 400 400 400 400 400

MaxSirStepDown 200 200 200 100 200 200 200 200 200 200 200 200

Maximum SIR target

132 132 132 152 132 132 132 132 132 137 152 172

Minimum SIR target

62 62 62 62 62 62 62 62 62 62 62 62


Uplink Outer Loop Power Control Parameters

OLPC_SWITCH

This is one switch in PCSWITCH (Power control

algorithm switch) parameter.

The default value is 1, namely ON


Downlink Outer Loop Power Control

NodeB

set SIRtar

Transmit TPC

Measure SIR and compare with SIRtar

Measure BLER of received data and compare with the

BLERtar

Outer loop

Inner loop

L1

L3

UE


Summary

In this course, we have discussed function, principle

and common parameters of the following power

control algorithm:

Open loop power control

Inner loop power control

Outer loop power control

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owj200102 wcdma power control algorithm and parameters ran10 issue2.00

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