3 lte eran6.0 power control feature issue1.00
DESCRIPTION
This document has a brief explanation of LTE power control and also feature issue have addressed in greater detailed.The reader can find this document helpful to understand how power control works in lte.TRANSCRIPT
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LTE eRAN6.0 Power Control Feature
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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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Contents1. Power Control Overview 2. Downlink Power Allocation3. Uplink Power Control4. Feature Activate Observation
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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)
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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
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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
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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
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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
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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
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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
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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
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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
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PDSCH Power Control - Dynamic
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Contents1. Power Control Overview 2. Downlink Power Allocation3. Uplink Power Control4. Feature Activate Observation
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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
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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
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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
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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
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Closed Loop Power Control – For Semi-persistent Scheduling Service
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Closed loop Adjust TPC according to the IBLER
Uplink user dataPUSCH
Power control commandPDCCH
UE eNBeNB measures IBLER and compare with target value
UE adjusts power
according to TPC
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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
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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
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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
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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
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Inner Loop Power Control
Inner loop Adjust TPC according to the SINR
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Uplink control infoPUCCH
Power control commandPDCCH
UE eNBeNB measures SINR and compare with target value
UE adjusts power
according to TPC
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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
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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
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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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Contents1. Power Control Overview 2. Downlink Power Allocation3. Uplink Power Control4. Feature Activate Observation
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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
SIB2 via UU interface tracing
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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
SIB2 via UU interface tracing
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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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