Power Control & Power Setting
Overview
Overview
Objective
Improve cell edge behaviour, reduce inter-cell interference and power consumption.
Downlink (DL)
DL ‘Semi-static’ Power Setting
• eNodeB gives fixed power density per PRB scheduled for transport.
– Total Tx power is max. when all PRBs are scheduled
– No adaptive/dynamic power control
– (O&M parameter) Cell Power Reduction level CELL_PWR_RED [0...10] dB attenuation in 0.1 dB steps
DL Power Control on PDCCH
dlCellPwrRed
Uplink (UL)
Slow Uplink Power Control
• Combination of open loop PC and closed loop PC
• Open Loop Power Control (OLPC)
– Calculated at the UE based on pathloss measurements
• Closed Loop Power Control (CLPC)
– Based on exchange of feedback data and commands between UE and eNodeB
– SW-licensed enhancement (can be switched on and off)
Reduction of DL Tx power; deducted
from max. antenna TX power.
LNCEL; 0..10; 0.1; 0 dB
ULUL-PC: Overview
UL-PC: Overview
LTE: orthogonal UL Tx, i.e. near-far-problem much less severe than WCDMA
• UL: dynamic, slow PC – Open Loop (OL) & Closed Loop (CL)
• need for PL / shadowing etc. compensation OL PC
• need for correction/ adjustments of e.g. open loop inaccuracies CL PC
Signal strength S:
Depends on PL, indoor loss etc.,
i.e. location
Low
High
Interference (I)
- main cause: inter-cell
Noise (N) = kB T ∆f + NFeNB
Power control does not control the absolute UE Tx power but the Power Spectral Density (PSD), power per Hz, for a device.
The PSDs at the eNodeB from different users have to be close to each other so the receiver doesn’t work over a large range
of powers.
Different data rates mean different Tx bandwidths so the absolute Tx power of the UE will also change. PC makes that the
PSD is constant independently of the Tx bandwidth.
Overview
Procedure for Slow UL Power Control
• UE controls the Tx power to keep the transmitted power spectral density (PSD) constant independent of
the allocated transmit bandwidth (#PRBs)
• If no feedback from eNodeB ( in the PDCCH UL PC command) the UE performs open loop PC based on path
loss measurements
• If feedback from eNodeB the UE corrects the PSD when receiving PC commands from eNodeB ( in the
PDCCH UL PC command)
PC commands (up and down) based on UL quality and signal level measurements
• Applied separately for PUSCH, PUCCH
• Scope of UL PC is UE level ( performed separately for each UE in a cell)
2) SINR measurment
3) Setting new power offset
4) TX power level
adjustment with the new
offset
1) Initial TX power level
ULUL-PC: PUSCH
UL-PC: PUSCH Equation
PPUSCH (i) :PUSCH Power in subframe i
Open Loop (OL)
Closed Loop (CL)
PPUSCH(i) = min {PCMAX ,10 log10 (M PUSCH(i)) + PO_PUSCH( j) + α ( j ) ⋅ PL + ∆TF (i) + f (i)} [dBm]
*PH = Power Headroom
UL-PC: PUSCH
PPUSCH(i) = min {PCMAX ,10 log10 (M PUSCH(i)) + PO_PUSCH( j) + α ( j ) ⋅ PL + ∆TF (i) + f (i)} [dBm]
PH (i ) = PCMAX − {10 log10 ( M PUSCH (i )) + PO_PUSCH ( j ) + α ⋅ PL + ∆ TF (i ) + f (i ) }[dB ]
PH = Power Headroom
PPUSCH (i) :PUSCH Power in subframe i
PCMAX: max. allowed UE power (23 dBm for class 3)
MPUSCH: number of scheduled RBs (The UE Tx. Power increases proportionally to # of PRBs)
PO_PUSCH(j) = PO_NOMINAL_PUSCH(j) + PO_UE_PUSCH(j)
PL: pathloss [dB] = referenceSignalPower – higher layer filtered RSRP
∆TF (i) = 10 log 10 (2MPR Ks – 1) for Ks = 1.25 else 0, MPR = TBS/NRE, NRE : number of RE
Ks defined by deltaMCS-Enabled, UE specific
f(i): TPC (Closed Loop adjustment)
j : This can be 0 or 1, j = 0, 1 come from higher layer
Semi-persistant: j=0 / dynamic scheduling: j=1
PO_NOMINAL_PUSCH(0,1): cell specific (SysInfo)
PO_UE_PUSCH(0,1): UE specific (RRC)
α (0,1) = 0.0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 (partial PL compensation by open loop)
Random access grant: j=2
PO_NOMINAL_PUSCH(2): PO_PRE + ∆Preamble_Msg3
α (2) = 1.0 (i.e. full PL compensation)
PO_UE_PUSCH(2) = 0
Open Loop PC vs. Closed Loop PC
Open Loop Power Control
Target: provide a basic operating point for a suitable PSD for an average
MCS (average SINR):
Basic _ Operating _ Po int = PO_PUSCH ( j ) + α ( j ) ⋅ PL
• Open Loop Power Control takes into account effects like inter-cell
interference and shadowing
• Based on PL (Pathloss)
Closed Loop Power Control
f(i) adjustments
Target: Fine tuning around the basic operating point
• Adapt dynamically to the channel conditions (take into account e.g. fast fading)
• Correct the estimations of power from the open loop PC
ulpcEnable
enable UL closed loop PC
LNCEL; true, false; false
Open Loop PC
PPUSCH(i) = min {PCMAX,10 log10 (M PUSCH(i)) + PO_PUSCH( j ) + α ( j) ⋅ PL + ∆TF (i) + f (i)} [dBm]
PO_PUSCH(j) = PO_NOMINAL_PUSCH(j) + PO_UE_PUSCH(j)
j=0 -> PUSCH transmission with semi-persistent grant
j=1 -> PUSCH transmission with dynamic scheduling
j=2 -> PUSCH transmission for random access grant
PO_NOMINAL_PUSCH(j) -> cell specific component signaled from system information for j=0, 1
This term is a common power level for all mobiles in the cell (used to control SINR)
p0NomPusch
Nominal Power for UE PUSCH Tx
Power Calculation
LNCEL; -126..24dbm; 1; -100 dBm
PO_UE_PUSCH(j)
-> UE specific component provided by higher layers (RRC) for j=0,1
This term is a UE specific offset used to correct the errors from the estimation of the pathloss
PUSCH Formula
PPUSCH(i) = min {PCMAX ,10 log10 (M PUSCH(i)) + PO_PUSCH( j) + α ( j ) ⋅ PL + ∆TF (i) + f (i)} [dBm]
PL: pathloss [dB] = referenceSignalPower –
higher layer filtered RSRP
This path loss compensation factor a is adjustable by
Alpha
O&M. α is a cell - specific parameter (broadcasted on
BCH).
α ∈ [0.0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0]
α = 0 , no compensation
α = 1 , full compensation
ulpcAlpha
LNCEL; 0, 0.4..1.0; 0.1; 1.0
α ≠ { 0 ,1 } , fractional compensation
Conventional & Fractional PC
• Conventional PC schemes:
– Attempt to maintain a constant SINR at the receiver
– UE increases the Tx power to fully compensate for increases in the path loss
• Fractional PC schemes:
– Allow the received SINR to decrease as the path loss increases.
– UE Tx power increases at a reduced rate as the path loss increases. Increases in path loss are only partially compensated.
– [+]: Improve air interface efficiency & increase average cell throughputs by reducing Inter-cell interference
• 3GPP specifies fractional power control for the PUSCH with the option to disable it & revert to conventional based on α
UL
SINR
Conventional Power
Control: α=1
If Path Loss
increases by 10 dB
the UE Tx power
increases by 10 dB
UE Tx
Power
UL
SINR
UE Tx
Power
Fractional
Power Control: α
≠ { 0 ,1}
If Path Loss
increases by 10
dB the UE Tx
power increases
by < 10 dB
MCS dependent component
PPUSCH(i) = min {PCMAX,10 log10 (M PUSCH(i)) + PO_PUSCH( j ) + α ( j ) ⋅ PL + ∆TF (i) + f (i)} [dBm]
∆ TF (i ) = 10 log10 (2 MPR∗K s − 1)
0
for
K S = 1.25
Otherwise
deltaTfEnabled
Enabled TB size (MCS) impact to
UE PUSCH power calculation
LNCEL; Yes/No; -
MPR = TBS/NRE with NRE : number of RE, TBS = Transport Block Size
•
•
•
•
•
TF = Transport Format
Ks - Enabling/disabling of the transport format dependent offset on a per UE basis
If this parameter is enabled, PUSCH power calculation in UE uplink power control equation takes the
Transport Block size in account during the power calculation
Could be seen as dynamic offset of the TX power: when the BTS changes the MCS for the UE then the UE
indirectly may adapt the power
Increase the power if the Transport Format (MCS, TBS size, Number of Resource Blocks) it is so selected
to increase the number of bits per Resource Element
UL PUSCH Power Control - Parameter
PPUSCH (i ) = min{ PCMAX ,10 log( M PUSCH (i )) + Po _ PUSCH + α ⋅ PL + ∆ TF (i ) + f (i )}
Category
Parameter
P0 PUSCH
Huawei
CellUlpcComm.P0
NominalPUSCH
α
CellUlpcComm.Pa
ssLossCoeff
ΔTF (i)
CellUlpcDedic.Del
taMcsEnabled
f(i) - Close Loop CellAlgoSwitch.Ul
PUSCH Power
Switch
PcAlgoSwitch Control
InnerLoopPuschS
witch
Value
Nokia
Value
Ericssons
-80 dBm [LNCEL]
-80 dBm [EUtranCellFDD]
p0NomPusch
pZeroNominalPusch
5 (0.8) [LNCEL]
7 (alpha 1) [EUtranCellFDD] alpha
ulpcAlpha
0 (off) [LNCEL]
0
deltaTfEnabled
on
[LNCEL]
3
actUlpcMethod (PuschCLPucc
[LNCEL]
hCL)
ulpcLowlevSch
-103 dBm
[LNCEL]
-98 dBm
ulpcUplevSch
18
[LNCEL]
10
ulpcLowqualSch
[LNCEL]
ulpcUpqualSch
Value
ZTE
Value
-80 dBm [PowerControlUL]
-75
p0NominalPUSCH
dBm
8 (0.8) [PowerControlUL]
5 (0.8)
alpha
[PowerControlUL] ks
0
[PowerControlUL]
switchForCLPCofPUS
CH
1
UL PUSCH Messge 3 Power Control - Parameter
When LTE PUSCH carry Message 3, transmit power of Ue’s PUSCH is calculated as follow:
PPUSCH (i ) = min{PCMAX ,10 log( M PUSCH (i )) + PO_pre + ∆ PREAMBLE _ Msg 3 + PL + ∆ TF (i ) + f (i )}
Category
Parameter
Huawei
PUSCH Msg3 Δ preamble_msg3 [CellUlpcComm]
Power Control
DeltaPreambleMsg3
Value
Nokia
2 (4 dB) [LNCEL]
deltaPreMsg3
Value
1 (2 dB)
Ericssons
Value
ZTE
[PowerControlUL]
deltaPreambleMsg3
Value
0
ULUL-PC: PUCCH
UL-PC: PUCCH
PPUCCH (i ) = min{ PMAX , P0_PUCCH ( j ) + PL + h(nCQI , nHARQ ) + ∆ F_PUCCH ( F ) + g (i)} [dBm]
PPUCCH: PUCCH Power in subframe i
p0NomPucch
Pmax: max. allowed power
Nominal Power for UE
PUCCH Tx Power Calculation
LNCEL; -126..-96; 1; -100 dB
P0_PUCCH(j) = P0_NOMINAL_PUCCH(j) + P0_UE_PUCCH(j)
P0_NOMINAL_PUCCH : cell specific (SysInfo)
P0_UE_PUCCH : UE specific (RRC)
PL: pathloss [dB] = referenceSignalPower – higher layer filtered RSRP
H(nCQI, nHARQ )
• PUCCH format 1, 1a, 1b: h(n) = 0
* For PUCCH higher degree of
orthogonality could be assumed due
to the usage of the orthogonal
codes so alpha=1 (full
compensation)
• PUCCH format 2, 2a, 2b and :
h(n) = 0 if nCQI < 4
h(n) = 10log10 (nCQI/4) otherwise
(here: normal CP, for extented CP also nHARQ to be considered, n:number of information bits)
∆F_PUCCH (F) : dFListPUCCH
(see next slide)
g(i): TPC (closed loop adjustment)
Compensation Factor for different
PUCCH formats
For example if format 1a (1ACK) is
having offset 0 then format 1b
(2ACK) could have offset 3dB
deltaFListPUCCH Parameters
Name
Object
Abbreviation
Range
Description
Default
DeltaF PUCCH
List
LNCEL
dFListPucch
n/a
dFListPucch: SEQUENCE (see values below)
n/a
DeltaF PUCCH
Format 1
LNCEL
dFpucchF1
-2, 0, 2 dB
Used to define the PUCCH format 1
0 dB
DeltaF PUCCH
Format 1b
LNCEL
dFpucchF1b
1, 3, 5 dB
Used to define the PUCCH format 1b
1 dB
DeltaF PUCCH
Format 2
LNCE
dFpucchF2
-2, 0, 1, 2 dB
Used to define the PUCCH format 2
0 dB
DeltaF PUCCH
Format 2a
LNCE
dFpucchF2a
-2, 0, 2 dB
Used to define the PUCCH format 2a
0 dB
DeltaF PUCCH
Format 2b
LNCEL
dFpucchF2b
-2, 0, 2 dB
Used to define the PUCCH format 2b
0 dB
UL PUCCH Power Control - Parameter
PPUCCH(i) = min{PCMAX, P0 _ PUCCH + PL+ h(nCQI, nHARQ) + ∆F _ PUCCH(F) + g(i)}
Category
PUCCH Power
Control
Parameter
Huawei
Value
P0 nominal PUCCH [CellUlpcComm]
-105 dBm
P0NominalPUCCH
Close Loop Switch [CellPcAlgo]
0
PucchCloseLoopPcType (NOT_USE_P0N
OMINALPUCCH)
1 (0 dB)
ΔF_PUCCH
[CellUlpcComm]
DeltaFPUCCHFormat1
1 (3 dB)
[CellUlpcComm]
DeltaFPUCCHFormat1b
[CellUlpcComm]
2 (1 dB)
DeltaFPUCCHFormat2
[CellUlpcComm]
2 (2 dB)
DeltaFPUCCHFormat2a
[CellUlpcComm]
2 (2 dB)
DeltaFPUCCHFormat2b
On
g(i) - Close Loop [CellAlgoSwitch]
Switch
UlPcAlgoSwitch –
InnerLoopPucchSwitch
Period of Power
control
PUCCH Outer Loop
Power Control
[CellPcAlgo]
PucchPcPeriod
[CellAlgoSwitch]
UlPcAlgoSwitch OuterLoopPucchSwitch
Value
Ericssons
Value
[LNCEL] p0NomPucch
Nokia
-100 dBm
[EUtranCellFDD]
pZeroNominalPucch
-96 dBm
[LNCEL] dFpucchF1
[LNCEL] dFpucchF1b
[LNCEL] dFpucchF2
[LNCEL] dFpucchF2a
[LNCEL] dFpucchF2b
1 (0 dB)
0 (1 dB)
1 (0 dB)
1 (0 dB)
1 (0 dB)
ZTE
[PowerControlUL]
poNominalPUCCH
[PowerControlUL]
deltaFPucchFormat1
[PowerControlUL]
deltaFPucchFormat1b
[PowerControlUL]
deltaFPucchFormat2
[PowerControlUL]
deltaFPucchFormat2a
[PowerControlUL]
deltaFPucchFormat2b
[PowerControlUL]
switchForCLPCofPUCCH
[LNCEL] actUlpcMethod 3 (PuschCLPucchCL)
[LNCEL] ulpcLowlevCch
-103 dBm
-98 dBm
[LNCEL] ulpcUplevCch
[LNCEL] ulpcLowqualCch
1
4
[LNCEL] ulpcUpqualCch
10 (200 ms)
1 (on)
N/A
N/A
N/A
Value
-105 dBm
2 (2 dB)
1 (3 dB)
2 (1 dB)
2 (2 dB)
2 (2 dB)
1
ULUL-PC: Control Scheme
UL-PC: Control Scheme
Open loop: level based
Interference: considered by P0 values
not need for explicit signaling
RRC-BCCH:
P0_NOMINAL_PUSCH, P0_NOMINAL_PUCCH, ALPHA, deltaFListPUCCH, deltaPreambleMsg3
PDCCH: DELTA_PUSCH, DELTA_PUCCH
MPUSCH taken from scheduling grant
Data
RRC-DCCH: P0_UE_PUSCH, P0_UE_PUCCH,
DELTA_TF_ENABLED,
ACCUMULATION_ENABLED,
P_SRS_OFFSET, filterCoefficient
UE: PL
SIB1, UE class: PCMAX
ULUL-PC: Closed Loop
UL-PC: Closed loop - PUSCH (example)
ulpcEnable
enable UL closed loop PC
LNCEL; true, false; false
Closed loop adjustments:
f(i) = f(i-1) + δPUSCH (i - KPUSCH)
i.e. recursive determination
or
ulpcAccuEnable
f(i) = δPUSCH (i - KPUSCH) i.e. absolute setting
where δPUSCH is the signaled TPC in subframe i-KPUSCH
PUSCH/PUCCH TPC commands
accumulation enabled
Vendor Specific
For FDD: KPUSCH = 4
whether the recursive or absolute method is used
parameter Accumulation-enabled
P (closed loop)
t
UL-PC: Closed Loop - Process
SIB/RRC parameters:
P0_NOMINAL_PUSCH, P0_UE_PUSCH, P0_NOMINAL_PUCCH,
P0_UE_PUCCH, ALPHA, deltaFListPUCCH, DELTA_TF_ENABLED,
ACCUMULATION_ENABLED, deltaPreambleMsg3,
P_SRS_OFFSET, filterCoefficient
Per UE measurements of
• receive power of wanted signal
• interference and noise
Calculation of average
receive level per TTI.
Calculation of SINR (two
methods for I+N values)
Transformation from Watt
into dBm/dB domain.
Transformation into TF
independent format
ENABLE_CLPC
ENABLE_CLPC_PUSCH,
ENABLE_CLPC_SRS;
ENABLE_CLPC_PUCCH
time scale: TTI
SINR_MAX, SINR_MIN, RSSI_MAX,
RSSI_MIN
Clipping using adjustable
parameters
WF_PUSCH_UE, WF_PUSCH_CELL,
WF_SRS_UE, WF_SRS_CELL, WF_PUCCH_UE,
WF_PUCCH_CELL
Weighting
TAVG_PUSCH_SRS_CONT,
TAVG_PUSCH_SRS_DISCONT,
TAVG_PUCCH_CONT,
TAVG_PUCCH_DISCONT
Long term filtering/averaging
of level and SINR using
adjustable filter coefficients
Periodic reading of averaged level
and averaged SINR value (time
constant adjustable)
Comparison with twodimensional decision matrix.
Calculation of DELTA_
PUSCH and DELTA_
PUCCH values for the UE
Commanding DELTA_PUSCH
and DELTA_PUCCH values to the
UE via PDCCH
DELTA_TF_ENABLED,
deltaFListPUCCH
ulpcPuschEn
Including or excluding of RSSI
and SINR measurements from
PUSCH in the Closed Loop PC
component
LNCEL; true; true
ulpcPucchEn
Including or excluding of RSSI
and SINR measurements from
PUCCH in the Closed Loop PC
component
LNCEL; true; true
FILTER_OUTPUT_PERIOD
time scale: filter output
period (adjustable by
O&M)
UP_LEV_PUSCH_SRS, LOW_LEV_PUSCH_SRS,,
LOW_LEV_UP_QUAL_PUSCH_SRS,
LOW_QUAL_PUSCH_SRS, UP_LEV_PUCCHPUCCH,
UP_QUAL_PUCCH, LOW_QUAL_PUCCH,
minCumDeltaPUSCH, maxCumDeltaPUSCH,
minCumDeltaPUCCH, maxCumDeltaPUCCH
DELTA_PUSCH, DELTA_PUCCH
UL-PC: Closed Loop - Process
Measurements and Averaging
Averaged* received level per TTI per UE:
Averaged* received SINR per TTI per UE:
• RSSIPUSCH/UE
Relevant for PUSCH and PUCCH: (I+N)UE and (I+N)cell
• RSSIPUCCH/UE
and for SRS: (I+N)cell
• RSSISRS/UE
(I+N)cell : all potential PRBs
relevant: PRBs allocated to the particular UE
(I+N)UE : allocated PRBs to the particular UE
• SINRPUSCH/UE
* linear, but converted to dBm, dB for further
deployment
• SINRPUSCH/cell
• SINRPUCCH/UE
• SINRPUCCH/cell
• SINRSRS/cell
Transformation in independent format
Normalization applies to:
UE and/or TF specific offsets get subtracted:
• PUSCH
• ∆TF
• PUCCH
• ∆PF_PUCCH
• SRS
• h(n)
• PO_UE_PUSCH
• PO_UE_PUCCH
UL-PC: Closed Loop - Process
Clipping
Averaged received level per TTI per UE:
Averaged received SINR per TTI per UE:
RSSI*** := min(max(RSSImin,RSSI***)RSSImax)
SINR*** := min(max(SINRmin,SINR***)SINRmax)
*** PUSCH/UE,
PUCCH/UE,
*** PUSCH/UE, PUSCH/cell, PUCCH/UE, PUCCH/cell, SRS/cell
SRS/UE
Weighting of MCS independent measurements
PUSCH and SRS - composite SINR and RSSI :
C _ SINR PUSCH
/ SRS
=
SINR PUSCH
C _ RSSI PUSCH / SRS =
/ UE
⋅ WF _ PUSCH _ UE + SINR PUSCH / cell ⋅ WF _ PUSCH _ CELL + SINRSRS / cell ⋅ WF _ SRS _ CELL
WF _ PUSCH _ UE + WF _ PUSCH _ CELL + WF _ SRS _ CELL
RSSI PUSCH / UE ⋅ WF _ PUSCH _ UE + RSSI SRS / UE ⋅ WF _ SRS _ UE
WF _ PUSCH _ UE + WF _ SRS _ UE
PUCCH - composite SINR and RSSI :
C _ SINR
PUCCH
=
SINR
PUCCH
/ UE
⋅ WF _ PUCCH _ UE + SINR PUCCH / cell ⋅ WF _ PUCCH
WF _ PUCCH _ UE + WF _ PUCCH _ CELL
C _ RSSI PUCCH = RSSI PUCCH / UE
_ CELL
Weighting factors WF_*** : range [1, 100]
UL-PC: Closed Loop - Process
Filtering
RSSIPUSCH/SRS,filtered
SINRPUSCH/SRS,filtered
Decision matrix for the
PUSCH/SRS component
of the CLPC algorithm
RSSIPUCCH,filtered
SINRPUCCH,filtered
Decision matrix for the
PUCCH component of
the CLPC algorithm
ulpcReadPeriod
DELTA_PUSCH
value
DELTA_PUCCH
value
Low pass filter first order (exponential moving average) :
y ( n) = c ⋅ y ( n − 1) + (1 − c ) ⋅ x( n)
x: input (composite RSSI, SINR)
c: filter coefficient
y: output (filtered RSSI, SINR)
c = exp(-T/Tavg) i.e. impact = (1/e) at t = -Tavg
n: step, max frequency = 1/TTI
Example: T = 1ms, Tavg = 25 ms
Initialization: y(0) := target RSSI/SINR
c = 0.96
Time interval for sending averaged
RSSI and SINR values to the decision
matrix to determine power corrections
in Closed Loop uplink power control.
LNCEL; 10…2000ms; 10ms; 50 ms
filterCoeff
Filter coefficient for RSRP
measurements used to calculate
pathloss. Value fc0 corresponds to k =
0, fc1 corresponds to k = 1, and so on.
LNCEL; fc0 (0), fc1 (1), fc2 (2), fc3 (3),
fc4 (4), fc5 (5), fc6 (6), fc7 (7), fc8 (8),
fc9 (9), fc11 (10), fc13 (11), fc15 (12),
fc17 (13), fc19 (14); fc4(4)
ULUL-PC: Parameters
UL-PC: Closed Loop - Process
ulpcUpqualSch
Decision matrix
1dB
High Thresh. For SINR for PUSCH
LNCEL; -47...80dB; 1dB ; 11dB
SINR
+ 1 dB or
+ 3 dB
ulpcUpqualCch
High Thresh. For SINR for PUCCH
LNCEL; -47...80dB; 1dB ; 4dB
- 1 dB
- 1 dB
1
2
3
UP_QUAL_**
+ 1 dB or
+ 3 dB
0 dB
-1 dB
4
LOW_QUAL_**
5
6
1dB
ulpcLowqualSch
+ 1 dB or
+ 3 dB
Low Thresh. For SINR for PUSCH
LNCEL; -47...80dB; 1dB ; 8dB
+ 1 dB or
+ 3 dB
7
ulpcLowqualCch
Low Thresh. For SINR for PUCCH
LNCEL; -47...80dB; 1dB ; 1dB
LOW_LEV_**
ulpcLowlevCch
Low Thresh. For RSSI for PUCCH
LNCEL; -127...0dBm;1dBm ;-103dBm
Decision
whether to
+1dB or +3dB
+ 1 dB or
+ 3 dB
8
UP_LEV_**
9
RSSI
ulpcUplevCch
High Thresh. For RSSI for PUCCH
LNCEL; -127...0dBm;1dBm ;-98dBm
ulpcLowlevSch
ulpcUplevSch
Low Thresh. For RSSI for PUSCH
LNCEL; -127...0dBm;1dBm ;-103dBm
High Thresh. For RSSI for PUSCH
LNCEL; -127...0dBm;1dBm ;-98dBm
PRACH Power Control
LTE Uplink Power Control for PRACH
• 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:
PPRACH = min{PCMAX , Po _ pre + PL + ∆ preamble + ( N pre − 1) ⋅ ∆ step }
Category
Parameter
LTE PRACH
power
PRACH Power
Control
Value
Nokia
Value
isHuawei
calculated
with following
formula :
P0_pre
[RACHCfg]
PreambInitRcvTargetPwr
7 (-106
dBm)
[LNCEL]
ulpcIniPrePwr
Δ step
[RACHCfg]
PwrRampingStep
1 (2dB)
[LNCEL]
prachPwrRamp
Ericssons
12 (-98 dBm) [EUtranCellFDD]
preambleInitialReceivedTargetPower
1 (2 dB)
Value
ZTE
-110 dBm [PrachFDD]
preambleIniReceivedPower
[PrachFDD]
powerRampingStep
Value
10 (-100
dBm)
1 (2 dB)
Nokia DLDL-PC
Nokia DL-PC
RL20: (static) cell power reduction
dlCellPwrRed
Reduction of DL Tx power; deducted
from max. antenna TX power.
LNCEL; 0..10; 0.1; 0 dB
• based on single parameter CELL_PWR_RED = 0.0, 0.1 … 10.0 dB
•
cell size adjustment and coverage control
• flat Power Spectral Density (PSD)
pMax
• semi-static MIMO_COMP (if enabled)
Maximum output power
LNCEL; 37.0 (0), 39.0 (1), 40.0 (2), 41.8
(3), 43.0 (4), 44.8 (5), 46.0 (6), 47.8 (7);37.0 dBm = 5 W
39.0 dBm = 8 W
40.0 dBm = 10 W
41.8 dBm = 15 W
43.0 dBm = 20 W
44.8 dBm = 30 W
46.0 dBm = 40 W
47.8 dBm = 60 W
RL30: optional power boost: PCFICH, PHICH, DL RS
PSD
PSD
PSD = (Max_TX_Pwr – CELL_PWR_RED) – 10*log10( 12*# PRBs)
Allocated DL PRBs
Frequency
DL Pilots
PSD = (Max_TX_Pwr – CELL_PWR_RED) – 10*log10( 12*# PRBs)
PDCCH
Time
PDSCH, PCH BCH, SCH
Nokia DL-PC: Power Reduction
Cell Power Reduction
PSD = (pMax - CELL_PWR_RED) - 10*log10( # PRBs_DL *12) - MIMO_COMP [dBm]
PSD: Power Spectral Density, which specifies the constant absolute Power per 15kHz Resource Element (RE)
• pMax: maximum eNodeB transmit power per Antenna in [dBm]
• CELL_PWR_RED:
O&M parameter
• # PRBs_DL: maximum Number of downlink PRBs in given LTE Carrier Bandwidth
• MIMO_COMP: Compensation Factor
• MIMO_COMP = 0 dB for SISO/SIMO
• MIMO_COMP = 0...12 dB for MIMO Diversity and for MIMO Spatial Multiplexing
- PSD given per antenna (RF amplifier output)
- PRBs not scheduled are blanked
dlpcMimoComp
Determines the power
compensation factor for antennaspecific maximum power in case
of a downlink transmission using
at least two TX antennas
LNCEL; 0..10; 0.01; 0 dB
Applied to UE / cell specific channels and signals:
• PSD_CELL_CTRL for BCCH i.e. PBCH+PDSCH, PCFICH and PCH
• PSD_CELL_RS for reference signals (RS) / pilots
dlCellPwrRed
• PSD_CELL_SYNC for synchronization channel
Reduction of DL Tx power; deducted
from max. antenna TX power.
LNCEL; 0..10; 0.1; 0 dB
• PSD_UE_PDSCH for UE specific part of PDSCH
• PSD_UE_CTRL for PDCCH and PHICH
Nokia DL-PC: DL power boosting for control channels
• Power offsets to the PCFICH, PHICH, DL RS.
• Introduced with RL30 (LTE430).
• Better detection of PCFICH indicating the number of OFDM symbols for the PDCCH.
• Better channel estimation in case of RS boosting may improve HO performance.
• Higher reliability of ACK/NACK transmission via PHICH.
PCFICH
OFDM
symbols
The eNB ensures that total Tx power is not exceed, i.e.
the sum power for any OFDM symbol must not exceed
the commited maximum power, otherwise all the
configured boosts (PHICH) may not be applied.
Subcarrier power boosting is only allowed if the excess
power is withdrawn from the remaining subcarriers.
Coverage in LTE is very often limited by UL, and in
such cases it does not make much sense to improve
the coverage in DL. UL coverage should be checked
before applying DL control channels power boost.
RS
OFDM
Nokia DL-PC: DL power boosting for control channels
PCFICH power boosting
PCFICH provides information about the number of OFDM symbols for the PDCCH.
The eNB supports dedicated power control settings for the PCFICH in order to
ensure that especially cell edge UEs can properly receive the PCFICH.
A relative offset between the flat PSD (Power Spectral Density) on PDSCH and
PCFICH can be configured by O&M on cell level.
PHICH power boosting
dlPcfichBoost
Downlink PCFICH transmission
power boost
LNCEL; 0..6; 0.1; 0 dB
dlPhichBoost
The PHICH provides ACK/NACK information for the uplink transmission.
Downlink PHICH transmission power
boost
The eNB supports dedicated power control settings for the PHICH in order to ensure
LNCEL; 0..6; 0.1; 0 dB
that the UE can properly receive the PHICH.
PHICH power boost may not be (fully) applied if PDCCH PSD goes too low in the first OFDM symbol. In
that case, the eNB rises the PHICH Power Boost not applied warning.
A maximum relative offset between the flat PSD on PDSCH and PHICH can be configured by O&M on cell level.
Downlink reference signal boosting
dlRsBoost
The downlink reference symbols are used by the UE for
Downlink RS transmission power
channel estimation and cell measurements (Level, Quality) for mobility.
boost
The eNB supports relative RS / PDSCH power control settings.
LNCEL; 0dB (0), 1.77dB (1), 3dB
A relative offset between the PDSCH and RS
(2), 4.77dB (3), 6dB (4); 0 dB
can be configured by O&M on cell level.
The eNB ensures that total Tx power is not exceed.
The sum power for any OFDM symbol must not exceed the commited maximum power, otherwise all the configured boosts
(PHICH) may not be applied.
Huawei DLDL-PC
Downlink Power Control Strategy
Fixed Power Assignment. Applicable for :
Category
–CRS (Cell Reference Signal)
–Synchronization Signal
–PBCH (Physical Broadcast Channel)
–PCFICH (Physical Control Format Indicator Channel)
–PHICH (Physical Hybrid-ARQ Indicator Channel)
–PDCCH that carry common control information (SIB,
RACH response, Paging)
–PSDCH (Physical Downlink Shared Channel)
The configured power must meet the requirement for
downlink coverage of the cell.
Parameter
CRS
Syncronization Signal
PBCH
PCFICH
PHICH
Fix DL Power
Allocation
Huawei
Value
PDSCHCfg.ReferenceSignalPwr 18.2 dBm for 20 watt RRU
CellChPwrCfg.SchPwr
-6 dB
CellChPwrCfg.PbchPwr
-6 dB
CellChPwrCfg.PcfichPwr
-6 dB
Off
CellAlgoSwitch.DlPcAlgoSwitch PhichInnerLoopPcSwitch Off
0 dB
CellDlpcPhich.PwrOffset
CellChPwrCfg.RaRspPwr,
CellChPwrCfg.PchPwr,
CellChPwrCfg.DbchPwr
0 dB
-6 dB
-6 dB
PDSCH Other than SIB,
PDSCHCfg.Pb
RACH response & Paging CellDlpcPdschPa.PaPcOff
1 dB
-3 dB
PDSCH (SIB, RACH
response, Paging)
• Dynamic Power Control. Applicable for
–PDCCH (Physical Downlink Control Channel) that carry Dedicated Control Information.
Category
Dynamic Power Control
PDCCH
Parameter
CellAlgoSwitch.DlPcAlgoSwitch PdcchPcSwitch
Huawei
On
Nokia
On
Ericssons
N/A
ZTE
N/A
Downlink Power Control Parameter
Category
Parameter
CRS
Syncronization
Signal
PBCH
PCFICH
PHICH
Fix DL Power
Allocation
PDSCH (SIB, RACH
response, Paging)
PDSCH Other than
SIB, RACH
response & Paging
Dynamic Power Switch
Control PDCCH
Huawei
Value
Nokia
Value
Ericssons
N/A. CRS power calculated
PDSCHCfg.
18.2 dBm N/A. CRS power
ReferenceSignalPwr for 20 watt calculated from 430 (20 watt) from
[LNCEL] pMax
1000 (0 dB) [SectorEquipmentFunction]
[LNCEL] dlRsBoost
configuredOutputPower
[EUtranCellFDD] crsGain
CellChPwrCfg.
-6 dB
SchPwr
CellChPwrCfg.
-6 dB
PbchPwr
CellChPwrCfg.
-6 dB
dlPcfichBoost
0
PcfichPwr
CellAlgoSwitch.
Off
dlPhichBoost
0
DlPcAlgoSwitch PhichInnerLoopPcS
0 dB
witch Off
CellDlpcPhich.
PwrOffset
0 dB
CellChPwrCfg.
RaRspPwr,
-6 dB
CellChPwrCfg.
PchPwr,
CellChPwrCfg.
-6 dB
DbchPwr
1 dB
[EUtranCellFDD]
PDSCHCfg.Pb
-3 dB
pdschTypeBgain
CellDlpcPdschPa.Pa
PcOff
On
enablePcPdcch
1 (true)
CellAlgoSwitch.
DlPcAlgoSwitch PdcchPcSwitch
Value
40000
ZTE
[EUtranCellFDD]
cellReferenceSignalPower
Value
12 dBm
[PowerControlDL]
paForBCCH
[PowerControlDL]
pcfichPwrOfst
[PowerControlDL]
phichPwrOfst
4 (0 dB)
[EUtranCellFDD] Pb
1
300 (3 dB)
1
Cell specific Reference Signal (CRS) Power Setting
Type A Symbol: without RS REs
Type B Symbol: RS REs
EPRE: Energy Per Resource Element
The power setting is based on EPRE
EA (EPRE Type A) = Energy Per RE that doesn’t have Rs Power in the symbol
EB (EPRE Type B) = Energy Per RE that have Rs Power in the symbol
ER = Energy per Reference Signal Power RE
Cell specific Reference Signal (CRS) Power Setting
3/4 1
1
3/4 1
1
X
compensate
1
1
3/4 1
1
3/4 1
1
R
X
1 ANT port
2 or 4 ANT ports
0
1
5/4
1
4/5
1
1
3/4 1
1
2
3/5
3/4
3/4 1
1
3
2/5
1/2
1
1
3/4 1
1
3/4 1
1
R
1
1
R
Power of type B symbol / Power of type A
Symbol
1
X
compensate
PB
X
R
PB=2 , 2 Antennas
Bandwidth
PB
PRS ( dBm)
10M
1
18.2
15M
1
16.4
20M
1
15.2
2 antennas, 20w per antenna
RS Power ＝ Total power per channel(dBm) – 10lg(total subcarrier)+10lg(PB + 1)
RRU Power Case Example
Optimal power setting need to utilize all the RRU power. Accumulative power of type A should be equal to accumulative
power of type B
configuration possibilities:
Type A Symbol -> 12 EA
Type B Symbol -> 8EB + 2ER
So Pa, Pb settings have to follow -> 8EB+2Er=12 EA
Pa,Pb (-3,1) -> Er=2Ea, Eb=Ea
8Eb+2Er=12Ea
8Ea+2(2Ea)=12Ea
12Ea=12Ea
Pa,Pb) (0,0) -> Er= Ea, Eb=1.25Ea
8Eb+2Er=12Ea
10Ea+2(Ea)=12Ea
12Ea=12Ea
So, optimal power setting combination is Pa,Pb = -3, 1 and Pa,
Pb = 0, 0
Other setting can’t utilize total power 100%. See next slide
Pa-Pb Power Distribution for 20W, 10 MHz
Power utilization rate
PB
0
1
2
3
Max RS power(dBm)
PB
0
1
2
3
Total Power of symbol with RS(W)
PB
0
1
2
3
Total Power of symbol without RS(W)
PB
0
1
2
3
PA
-6
-4.77
-3
-1.77
0
1
2
3
67%
75%
86%
100%
75%
86%
100%
83%
86%
100%
83%
67%
92%
92%
75%
58%
100%
83%
67%
50%
97%
80%
63%
47%
94%
77%
61%
44%
92%
75%
58%
42%
0
15.2
15.2
15.2
15.2
1
14.2
14.2
14.2
14.2
2
13.2
13.2
13.2
13.2
3
12.2
12.2
12.2
12.2
0
20.0
16.7
13.3
10.0
1
19.3
16.0
12.6
9.3
2
18.8
15.4
12.1
8.8
3
18.3
15.0
11.7
8.3
0
20.0
20.0
20.0
20.0
1
20.0
20.0
20.0
20.0
2
20.0
20.0
20.0
20.0
3
20.0
20.0
20.0
20.0
PA
-6
19.4
20.0
20.5
21.2
-4.77
18.8
19.3
20.0
20.0
-3
17.5
18.2
18.2
18.2
-1.77
16.7
17.0
17.0
17.0
PA
-6
20.0
20.0
20.0
20.0
-4.77
20.0
20.0
20.0
16.7
-3
20.0
20.0
16.7
13.3
-1.77
20.0
18.3
15.0
11.7
PA
-6
13.4
15.0
17.2
20.0
-4.77
15.0
17.1
20.0
20.0
-3
17.2
20.0
20.0
20.0
-1.77
18.5
20.0
20.0
20.0
DLDL-PC: PC on PDCCH
Main target of DL-PC-CCH
• DL Power Control for PDCCH is an additional mechanism interacting with DL AMC for PDCCH in
order to make the signaling as robust as possible
• DL-PC-CCH aims at 1% target BLER but cannot modify AGG assignments
• Main actions performed by DL-PC-CCH
– Power reduction on CCEs with assigned AGG level higher than required (or equal)
– Power boosting on CCEs with assigned AGG level lower than required
– Equal power relocation among all scheduled CCEs
• Macro cell case #1
• Uniform UE distribution
enableLowAgg
4-CCE
8-CCE
Very good CCEs (CQI highly above 1% BLER target)
Bad CCEs (AGG level too high to meet 1% BLER target)
If still some power available, relocate equally among all CCEs
2-CCE
1-CCE
Enable lower aggregation selection
for PDCCH LA .
LNCEL; True/False; False
Principles of DL-PC-AMC
• PDCCH Power Control can be enabled/disabled by O&M switch
• Maximum transmit power of the Power Amplifier cannot be exceeded (pMax; O&M)
• Reduction and boosting range is strictly defined and is always considered as the limit for
power level modification
• DL-PC-CCH operates together with DL-AMC-CCH on TTI basis
• DCI messages with more than one CCE (AGG-…>1) have a flat PSD,
thus all CCEs belonging to one scheduled UE are transmitted with the same power
Short
Name
Description
Range/
Step
Default
Value
Parameter
Scope
true, false
true
Cell
Changing parameter requires object
locking.
Operator configurable.
Remark
enablePcPdcch
Enabling/disabling PC for PDCCH. In case the
parameter is disabled, a flat downlink PSD is
used.
pdcchPcBoost
Maximum power boost per CCE.
0...10 dB, step
0.1 dB
4 dB
BTS
Not modifiable.
Vendor configurable.
pdcchPcRed
Maximum power reduction per CCE.
0...10 dB, step
0.1 dB
6 dB
BTS
Not modifiable.
Vendor configurable.
pdcchPcReloc
Maximum limit on the equal power relocation
per CCE.
0...10 dB, step
0.1 dB
3 dB
BTS
Not modifiable.
Vendor configurable.
General algorithm
Output from DL AMC for PDCCH
• Required AGG levels per UE per DCI format
• Assigned AGG levels per UE per DCI format
• PDCCH CQI per UE
• Calculated TOTAL_NUM_CCEs
(all available CCEs; PHICH&PCFICH considered)
Build the Power Basket
(“free unused” power on PDCCH)
Power Relocation
If the Power Basket is still not empty, relocate the
excess power equally among all scheduled UEs.
• power levels to be applied for all scheduled UEs
Count unused power from unscheduled CCEs
Power Reduction
Decrease the power for all UEs with assigned
AGG level equal to the required AGG level to
meet the 1% BLER target and count the amount
to the Power Basket
Power Boosting
Increase the power for all UEs with the assigned
AGG level lower than the required AGG level to
meet the 1% BLER target.
Modify the Power Basket according to the amount
of power used for boosting.
…to DL-PHY
Graceful Cell Shutdown
Graceful Cell Shutdown
Reduced Service Impact
• Stepwise downlink power reduction in order to enforce active
and idle mode mobility to other cells layers
• Operator configurable settings
enableGrflShdn
The parameter enables the
feature 'Graceful Cell Shutdown'.
LNBTS; Disabled (0), Enabled
(1); Enabled (1)
DL power
time
handover or
cell reselection
Graceful Cell Shutdown
• The eNode B reduces stepwise the DL power to a minimum
power level
• The number of steps and the shutdown time is operator
configurable
• The broadcasted power for the reference symbols is not
changed, i.e. UE assumes that the eNode B power is
unchanged
• A wait timer of 10 seconds is applied after the last power down
step before the administrative state is set to locked and the
operational state is set to disabled.
shutdownStepAmount
shutdownWindow
Number of Steps for Graceful
Cell Shutdown
LNBTS; 1...16;1; 6
Time Interval for Stepwise
Output Power Reduction for
Graceful Cell Shutdown
LNBTS; 6...180;6; 60
PM Counter & dependencies
• No new PM counters are added as the graceful shutdown
behavior can be covered with the existing PM counters
• No dependencies on other entities
Questions
1. What is the purpose of the ulpcAlpha parameter.
2. Assuming that the RSSI signal increased above the level set by ulpcUplevSch
AND the received quality was between ulpcLowqualSch and ulpcUpqualSch
- what would be the closed loop power control decision value?
3. What is the purpose of PDCCH CCE Power Boosting?
THANK YOU