lte eran6.0 power control feature

8/12/2019 LTE eRAN6.0 Power Control Feature

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LTE eRAN6.0 Power

Control Feature




Objectives

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

Describe the object of power control in LTE

Describe the strategy and parameters of DL power control

Describe the strategy and parameters of UL power control

Monitor power control result from M2000

Page2




Purpose of Power Control

Compensate path loss , including shadow fading and multiplepath fading

Reduce interference on the edge cell

Page4




Strategy for Algorithm

Algorithm Strategy Reason

PHICH dynamic

power adjustment

Disabled PHICH carry HARQ feedback which

requires high accuracy, and default power

could guarantee it. And it is not necessary to

reduce PHICH power because it occupies

very less resource.PDCCH dynamic

power adjustment

Enabled To reduce the service drop rate and

increase the throughput for

CEUs.

PDSCH dynamic

power adjustment

Disabled Turning on this switch may waste RB

resources in multi-UE scenarios. This willbring negative gains to cell throughput and

increase overall interference on the entire

network.

All uplink power

control

Enabled Reduce UE power as low as possible

Improve performance for cell edge user

Page6




DL Power Distribution

Page8

Total DL Power

Fixed allocation Dynamic or fixed allocation

RS

PSS+SSS

PBCH

PCFICH

PDCCH (SIBs/Paging/RA response

scheduling

PDSCH (SIBs/Paging/RA rsponse)

PHICH

PDCCH (Dedicate UE scheduling)

PDSCH(Dedicated UE data)




Cell Specific RS Power Setting

EPRE: Energy Per Resource Element

The RS power setting is based on EPRE

RS power is the reference power for the other channel

Page9

x R

R x

x R

R x

x R

R x

x R

R x

R x

x R

R x

x R

R x

x R

R x

x R

R RS symbol for antenna port 0

R RS symbol for antenna port 1

Antenna Port 0 Antenna Port 1

Type A Symbol: without RS REs Type B Symbol: RS REs




Cell Specific RS Power Setting (Cont .)

RS Power＝ Total power per channel(dbm) – 10lg(total

subcarrier)+10lg(Pb + 1)

Page10

Bandwidth PB PRS ( dBm)

10M 1 18.2

15M 1 16.4

20M 1 15.2

3/4 1 1

3/4 1 1X 1 1 X

3/4 1 1

3/4 1 1

R 1 1 R

3/4 1 1

3/4 1 1

X 1 1 X

3/4 1 1

3/4 1 1

R 1 1 R

Pb=2 , 2 Antennas

compensate

compensate

Pb Symbol B/ Symbol A

1 ANT port 2 or 4 ANT ports

0 1 5/4

1 4/5 1

2 3/5 3/4

3 2/5 1/2




Synchronization Signal Power Setting

Power SCH ＝ ReferenceSignalPwr +SchPwr

Page11

Radio Frame

Slots

0 1 2 3 4 5 6

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Bandwidth

72Subcarriers

PSS (PrimarySynchronizationSequence)

Repeated inslots 0 and 10

SSS (SecondarySynchronizationSequence)

0 1 2 3 4 5

Bandwidth

Normal CP

Extended CP

62

Subcarriers




PBCH/PCFICH Power Setting

Power PBCH

＝ReferenceSignalPwr + PbchPwr

Power PCFICH＝ ReferenceSignalPwr + PcfichPwr

Page12




PDCCH/PDSCH Power Setting

In the following two status, the power for PDCCH and

PDSCH power is fixed setting

When PDCCH carry scheduling information of common control

information (RACH response /paging/SIBs indicator ) When PDSCH carry the common info (RACH

response/SIB/paging message)

Page13




Power Allocation Setting

Page14




Dynamic Power Allocation - PHICH

The PHICH occupies very few resources, which means decreasing its

transmit power cannot significantly reduce power consumption. In

addition, the PHICH carries the ACK/NACK messages for the uplinkdata, which requires high accuracy. Decreasing the transmit power of

the PHICH may reduce accuracy and uplink data rate. Therefore, the

dynamic power allocation is not recommended in commercial

network.

Page15

Estimate SINR_RS

Compare it with target SINR_RS

Adjust PHICH power

CQI Report

CQI report

RSRP measurement

UE eNB




Dynamic Power Control - PDCCH

Page16

PDCCH dynamic power

control switch

Off

Set PDCCH with fixedpower

eNB measure BLER

Target BLER +

_

On

Result>0 <0

Decrease Power Increase Power




PDSCH Power Presentation

Page17

Symbol

PPDSCH_A ＝ ρ A + ReferenceSignalPwr

PPDSCH_B ＝ ρB + ReferenceSignalPwr

X X

R R

X X

R R

ρ A

ρB

S u b _ c ar r i er s




PDSCH Power Control Mechanism

Page18

Switch Setting Power Control Mechanism

DlIcicStaticSwitch: ON: or

DlIcicDynamicSwitch:ON

Dynamic power control is disabled. PDSCH

power is fixed setting respectively for the

Center User (CCU) and Cell Edge User (CEU).

DlIcicSwitch: OFF or

DlIcicReuse3Switch:ON

and

PdschPaAdjSwitch: ON

Dynamic Power control is applicable for

PDSCH

DlIcicSwitch_OFF_ENUM or

DlIcicReuse3Switch:ON and

PdschPaAdjSwitch: OFF

PDSCH power is fixed setting




PDSCH Power Control - Dynamic

Page19




PRACH Open Loop Power Control

Page21

ensure the randomaccess success

rate and latency

Minimize the

transmit power

Preamble A

Preamble B

Preamble C

eNB Initially sets PRACH preamble

expected received power

UE estimates downlink path loss

UE sets the PRACH transmit

power according eNB parameter

and path loss

If the random access preamble

attempt fails ,UE can increase the

transmit power for the next RA

preamble attempt




Related Parameters

MOD RACHCFG

MOD CELLULPCDEDIC

Page23




PUSCH Power Control Overview

The purposes of power control for the PUSCH are as

follows:

Lower interference to neighboring cells and increasing cell

throughput

Ensure services rates for users on cell edges

the transmit power for the PUSCH is calculated using the

following formula:

Page24

)}()())(log(10,min{)( _ i f i PL P i M P i P TF PUSCH o PUSCH CMAX PUSCH




Inner Loop Power Control- Dynamic

Scheduling Service

Inner loop

Adjust TPC according to the transmit power density

Page26

Uplink user dataPUSCH

Power control commandPDCCH

UE eNB

eNB measures

power density

and compare

with targetvalue

UE adjusts

poweraccording to

TPC




Closed Loop Power Control – For Semi-

persistent Scheduling Service

Page27

Closed loop

Adjust TPC according to the IBLER

Uplink user dataPUSCH


UE eNB

eNB measures

IBLER and

compare with

target value

UE adjusts

poweraccording to

TPC




PUSCH Power Adjustment

Mechanism

DCI format for power control

2 bits TPC:DCI0/DCI3/

1 bit TPC: DCI 3A

Two mechanisms for TPC, configured by RRC

Accumulated mode: For all DCI formats

For FDD, KPUSCH=4

Absolute mode: Only for DCI0,

For FDD, KPUSCH=4

Page28

)()1()( PUSCH PUSCH K ii f i f

)()( PUSCHPUSCH K ii f




Power Ramping Offset

TPC Command Field in

DCI format 0/3

AccumulatedAbsolute

0 -1 -4

1 0 -1

2 1 1

3 3 4

Page29

PUSCH PUSCH

TPC Command Field in

DCI format 3AAccumulated

0 -1

1 1

PUSCH




Related Commands

Algorithm Switch

Initial power setting

Page30




Msg3 Power Control

When the PUSCH carries Msg3, the transmit power of each

UE's PUSCH is calculated using the following formula:

Page31

)}()())(log(10,min{)( 3 _ O_pre i f i PL P i M P i P TF Msg PREAM BLE PUSCH CMAX PUSCH




PUCCH Power Control

The PUCCH carries the ACK/NACK information, CQIs, and

schedule request (SR) information related to downlink data. When

the probability of incorrect demodulation on the PUCCH is high,

user throughput is severely affected.

The purposes of power control for the PUCCH are to ensure the

PUCCH performance and reduce the interference to neighboring

cells.

The transmit power for the PUCCH is calculated using thefollowing formula:

Page32

)}()(,nh,min{)( _ CQI _ 0 i g F n PL P P i P PUCCH F HARQ PUCCH CMAX PUCCH




Inner Loop Power Control

Inner loop

Adjust TPC according to the SINR

Page33

Uplink control infoPUCCH


UE eNB

eNB measures

SINR and

compare with

target value

UE adjusts

poweraccording to

TPC




PUCCH Power Adjustment

Mechanism

DCI format for power control

2 bits TPC: DCI1A/1B/1D/2A/2B/2/3

1 bit TPC: DCI 3A

Only accumulated mode is used

For FDD, km=4

Page34

)()1()( m PUCCH k ii f i g




Related Commands

Algorithm Switch

Page36




Related Commands (Cont.)

Initial power setting

Page37




Sounding RS Power Control

The SRS is used for uplink channel estimation and uplink

timing. Power control for the SRS improves the precision in

uplink channel estimation and uplink timing.

The SRS power is calculated using the following formula:

Page38

)}()log(10,min{)( _ 0 _ CMAX i f PL P P M P i P PUSCH OFFSET SRS SRS SRS

The same as PUSCH Power Control




Contents

4. Feature Activate Observation

4.1 DL power control observation

4.2 UL power control observation

Page40




Check RS Power Setting

Start UU interface trace, from SIB2 message, you can

check current RS power setting

Page41




Check the Other Channel’s Power

For the other DL channel

which power must be fixed

can be checked by eNdoeB

configuration. You can use

either CME or MML to check

these values.

Page42




Check PHICH/PDCCH/PDSCH

Dynamic Power Allocation

We can observe PHICH power offset in real time from

M2000 UE monitoring function

Step 1: Prepare a test UE, start S1 interface trace in M2000

Step 2: Power on UE, obtain the S-TMIS from S1 message,

shown as below

Page43





Dynamic Power Allocation (Cont .)

Step 3: Start UE performance trace, and select DL power

control monitoring function, and input the S-TMIS to activate

the task

Page44





Dynamic Power Allocation (Cont .)

Step 4: Start the traffic (eg. FTP) for the UE, and obsever the valuefor each channels.

If dynamic power allocation is disabled, the value should be constant all

the time

If dynamic power allocation is enable, during the movement of UE, you

will see the variable values of power offset

Page45




Contents

4. Feature Activate Observation

4.1 DL power control observation

4.2 UL power control observation

Page46




Check PRACH Power Configuration

We can check all the PRACH power parameters from SIB2

via UU interface tracing

Page47




PUSCH Power Control Verification

Step 1: Turn on the PUSCH power control switch

Step 2: Start uplink traffic for test UE

Step 3: Monitoring DCI statistic from M2000, if you can find the

result for DCI0, DCI3 or DCI3A, that means PUSCH power control

works

Page49




Check PUCCH Configuration

We can check all the PUSCH power parameters from SIB2

via UU interface tracing

Page50




Summary

What is purpose of power control?

What is the strategy for power control deployment?

How to set downlink channel power?

What is detailed algorithm for open loop, closed loop and

inner loop power control?

How to check common power control parameters?

How to verify power control effect?

Page52




Abbreviations

PBCH: Physical Broadcast Channel PCFICH: Physical Control Format Indicator Channel

PDCCH: Physical Downlink Control Channel

PDSCH: Physical Downlink Shared Channel

PHICH: Physical HARQ Indicator Channel

PRACH: Physical Random Access Channel

PUCCH: Physical Uplink Control Channel

PUSCH: Physical Uplink Shared Channel SS: Synchronized Signal

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lte eran6.0 power control feature

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