3 LTE ERAN6.0 Power Control Feature ISSUE1.00

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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

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Contents1. Power Control Overview 2. Downlink Power Allocation3. Uplink Power Control4. Feature Activate Observation

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Purpose of Power Control

Compensate path loss , including shadow fading and multiple path fading

Reduce interference on the edge cell

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Power Control Features in eNodeB Downlink power control:

There is no uplink power control command, so DL power control is more like dynamic power allocation

Uplink power control Including open loop, closed loop and inner loop power

control. 1 bit or 2 bits power control command is defined for closed loop and inner loop power control

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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 forCEUs.

PDSCH dynamic power adjustment

Disabled Turning on this switch may waste RB resources in multi-UE scenarios. This will bring negative gains to cell throughput and increase overall interference on the entire network.

All uplink power control

Enabled Reduce UE power as low as possibleImprove performance for cell edge user

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DL Power Distribution

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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 Page11

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 0R 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)

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Bandwidth

PB PRS ( dBm)

10M 1 18.215M 1 16.420M 1 15.2

3/4　 1　 1　　　　　3/4　 1　 1　　　　　X 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 A1 ANT port 2 or 4 ANT ports

0 1 5/41 4/5 12 3/5 3/43 2/5 1/2


Synchronization Signal Power Setting

PowerSCH ＝ ReferenceSignalPwr +SchPwr

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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

72 Subcarriers

PSS (Primary Synchronization Sequence)

Repeated in slots 0 and 10

SSS (Secondary Synchronization Sequence)

0 1 2 3 4 5

Bandwidth

Normal CP

Extended CP

62 Subcarriers


PBCH/PCFICH Power Setting

PowerPBCH ＝ ReferenceSignalPwr + PbchPwr

PowerPCFICH ＝ ReferenceSignalPwr + PcfichPwr

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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)

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Power Allocation Setting

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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 uplink data, 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.

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Estimate SINR_RS

Compare it with target SINR_RS

Adjust PHICH power

CQI Report

CQI report

RSRP measurementUE eNB


Dynamic Power Control - PDCCH

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PDCCH dynamic power control switch

Off

Set PDCCH with fixed power

eNB measure BLER

Target BLER+

_

On

Result>0 <0

Decrease Power Increase Power


PDSCH Power Presentation

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SymbolPPDSCH_A ＝ ρA + ReferenceSignalPwrPPDSCH_B ＝ ρB + ReferenceSignalPwr

　　　　　　　　

X 　 X 　　　　　　　　　　

R 　 R 　　　　　　　　　　

X 　 X 　　　　　　　　　　

R 　 R 　　

ρA

ρB

Sub_carriers


PDSCH Power Control Mechanism

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Switch Setting Power Control MechanismDlIcicStaticSwitch: 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 orDlIcicReuse3Switch:ON and

PdschPaAdjSwitch: OFF

PDSCH power is fixed setting


PDSCH Power Control - Dynamic

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PRACH Open Loop Power Control

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ensure the random access success rate and latency

Minimize the transmit power

Preamble APreamble 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


PRACH Power Control

The purpose of power control for the PRACH is to ensure the random access success rate while minimizing transmit power

The PRACH power is calculated using the following formula:

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})1(,min{ _ stepprepreamblepreoCMAXPRACH NPLPPP

Format 0

Format 1

Format 2

CP Zadoff Chu Sequence

6 PRB

Subframe 1ms Subframe 1ms

Format 3


Related Parameters MOD RACHCFG

MOD CELLULPCDEDIC

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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:

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)}()())(log(10,min{)( _ ifiPLPiMPiP TFPUSCHoPUSCHCMAXPUSCH


Inner Loop Power Control- Dynamic Scheduling Service

Inner loop Adjust TPC according to the transmit power density

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Uplink user dataPUSCH

Power control commandPDCCH

UE eNBeNB measures power density and compare with target value

UE adjusts power

according to TPC


Closed Loop Power Control – For Semi-persistent Scheduling Service

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Closed loop Adjust TPC according to the IBLER

Uplink user dataPUSCH


UE eNBeNB measures IBLER and compare with target value

UE adjusts power

according 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

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)()1()( PUSCHPUSCH Kiifif

)()( PUSCHPUSCH Kiif


Power Ramping OffsetTPC Command Field in

DCI format 0/3Accumulated Absolute

0 -1 -4

1 0 -1

2 1 1

3 3 4

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PUSCHPUSCH

TPC Command Field inDCI format 3A Accumulated

0 -1

1 1

PUSCH


Related Commands Algorithm Switch

Initial power setting

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Msg3 Power Control When the PUSCH carries Msg3, the transmit power of

each UE's PUSCH is calculated using the following formula:

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)}()())(log(10,min{)( 3_O_pre ifiPLPiMPiP TFMsgPREAMBLEPUSCHCMAXPUSCH


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 the following formula:

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)}()(,nh,min{)( _CQI_0 igFnPLPPiP PUCCHFHARQPUCCHCMAXPUCCH


Inner Loop Power Control

Inner loop Adjust TPC according to the SINR

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Uplink control infoPUCCH


UE eNBeNB measures SINR and compare with target value

UE adjusts power

according 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

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)()1()( mPUCCH kiifig


PUCCH Power Ramping

TPC Command Field inDCI format 1A/1B/1D/1/2A/2B/2/3 [dB]

0 -11 02 13 3

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PUCCH

TPC Command Field inDCI format 3A [dB]

0 -1

1 1

PUCCH


Related Commands Algorithm Switch

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Related Commands (Cont.) Initial power setting

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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:

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)}()log(10,min{)( _0_CMAX ifPLPPMPiP PUSCHOFFSETSRSSRSSRS

The same as PUSCH Power Control



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Contents4. Feature Activate Observation

4.1 DL power control observation

4.2 UL power control observation

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Check RS Power Setting Start UU interface trace, from SIB2 message, you

can check current RS power setting

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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.

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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

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Check PHICH/PDCCH/PDSCH 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

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Check PHICH/PDCCH/PDSCH Dynamic Power Allocation (Cont.) Step 4: Start the traffic (eg. FTP) for the UE, and obsever the value

for 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

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Contents4. Feature Activate Observation

4.1 DL power control observation 4.2 UL power control observation

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Check PRACH Power Configuration We can check all the PRACH power parameters from

SIB2 via UU interface tracing

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Check PUSCH Power Configuration We can check all the PUSCH power parameters from


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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

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Check PUCCH Configuration We can check all the PUSCH power parameters from


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PUCCH Power Control Verification As all DCI could be used for PUCCH power control, so it is difficult to

verify the PUCCH power control from DCI statistic We can monitor PUCCH SINR to verify PUCCH power control. When

UE moves, if SINR is convergence with target value (16dB), it indicate PUCCH power control works.

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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?

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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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3 LTE ERAN6.0 Power Control Feature ISSUE1.00