Slide 1
NokiaEDU
RA4121
LTE Radio Parameters 1 [FL16]
Power Control
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Slide 4
Module Objectives
After completing this module, the participant should be able to describe, discuss
and analyze:
• Principles of LTE PC
• UL open loop PC part
• DL power settings
• PSD
• PC impacts on network performance
PSD: Power Spectral Density
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Slide 5
Module Contents
• Overview
• UL-PC: PUSCH
• UL-PC: PUCCH
• DL-PC
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Slide 6
Module Contents
• Overview
• UL-PC: PUSCH
• UL-PC: PUCCH
• DL-PC
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Slide 7
Overview
Objective
Improve cell edge behavior, 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 [0...10] dB attenuation in 0.1 dB steps
DL Power Control on PDCCH*
dlCellPwrRed
Reduction of DL Tx power; deducted
from max. antenna TX power.
LNCEL; 0..20; 0.1; 0 dB
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)
* see “LTE Radio Parameters 2”
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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 Df + 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.
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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
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Slide 10
Module Contents
• Overview
• UL-PC: PUSCH
• UL-PC: PUCCH
• DL-PC
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UL-PC: PUSCH
Open Loop (OL)
Closed Loop (CL)
PPUSCH (i)  min {PCMAX ,10 log10 (M PUSCH (i))  PO_PUSCH ( j )   ( j )  PL  DTF (i)  f (i)} dBm
PH (i)  PCMAX  10 log10 (M PUSCH (i))  PO_PUSCH ( j )    PL  DTF (i)  f (i) dB
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
DTF (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)
Semi-persistent: j=0 / dynamic scheduling: j=1
PO_NOMINAL_PUSCH(0,1): cell specific (SysInfo)
PO_UE_PUSCH(0,1): UE specific (RRC)
 (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 + DPreamble_Msg3
PO_UE_PUSCH(2) = 0
 (2) = 1.0 (i.e. full PL compensation)
*PH = Power Headroom
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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 )   ( 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
PSD: Power Spectral Density
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Open Loop PC
PPUSCH (i)  min {PCMAX ,10 log10 (M PUSCH (i))  PO_PUSCH ( j )   ( j )  PL  DTF (i)  f (i)} dBm
PO_PUSCH(j) = PO_NOMINAL_PUSCH(j) + PO_UE_PUSCH(j)
j=0 -> PUSCH transmission with semi-persistent grant (not in FL16)
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; -80 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.
p0NomPusch - This parameter defines the UE-specific nominal power for the PUSCH. Used for P0_PUSCH calculation in
UE uplink power control equation (P1) for controlling the mean received SNR for user data during (re)transmission
corresponding to a received PDCCH with DCI format 0 associated with a new packet transmission. This parameter is used
to control mean received SNR for user data.
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PUSCH Formula
PPUSCH (i)  min {PCMAX ,10 log10 (M PUSCH (i))  PO_PUSCH ( j )   ( j )  PL  DTF (i)  f (i)} dBm
PL: pathloss [dB] = referenceSignalPower –
higher layer filtered RSRP
This path loss compensation factor a is adjustable by
O&M. α is a cell - specific parameter (broadcasted on
BCH).
Alpha
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
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α ≠ { 0 ,1 } , fractional compensation
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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
Fractional Power
UL
SINR
SINR
Control: α ≠ { 0 ,1}
Conventional Power
If Path Loss
Control: α=1
UE Tx
increases by 10
Power
UE Tx
dB the UE Tx
Power
If Path Loss increases
power increases
by 10 dB the UE Tx
by < 10 dB
power increases by 10
dB
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MCS dependent component
PPUSCH (i)  min {PCMAX ,10 log10 (M PUSCH (i))  PO_PUSCH ( j )   ( j )  PL  DTF (i)  f (i)} dBm
DTF (i)  10 log10 (2MPRK s  1)
0
for
K S  1.25
Otherwise
deltaTfEnabled
Enabled TB size (MCS) impact to
UE PUSCH power calculation
LNCEL; false 0, true 1- false
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
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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 (P1) takes the Transport Block
size in account during the power calculation.
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Slide 17
Module Contents
• Overview
• UL-PC: PUSCH
• UL-PC: PUCCH
• DL-PC
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UL-PC: PUCCH
PPUCCH (i)  min{ PMAX , P0_PUCCH  PL  h(nCQI , nHARQ )  D F_PUCCH( F )  g (i)} dBm
PPUCCH: PUCCH Power in subframe i
Pmax: max. allowed power
P0_PUCCH = P0_NOMINAL_PUCCH + P0_UE_PUCCH
p0NomPucch
Nominal Power for UE
PUCCH Tx Power Calculation
LNCEL; -127..-96; 1; --116dB
P0_NOMINAL_PUCCH : cell specific (SysInfo)
P0_UE_PUCCH : UE specific (RRC)
PL: pathloss [dB] = referenceSignalPower – higher layer filtered RSRP * For PUCCH higher degree of
H(nCQI, nHARQ )
• PUCCH format 1, 1a, 1b: h(n) = 0
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 extended CP also nHARQ to be considered, n:number of information bits)
DF_PUCCH (F) : dFListPUCCH
(see next slide)
g(i): TPC (closed loop adjustment)
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Compensation Factor for different
PUCCH formats
For example if format 1a (1ACK) is
having offset 0 then format 1b
(2ACK) could have offset 3dB
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Slide 19
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
LNCEL
dFpucchF2
-2, 0, 1, 2 dB
Used to define the PUCCH format 2
0 dB
DeltaF PUCCH
Format 2a
LNCEL
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
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Slide 20
Module Contents
• Overview
• UL-PC: PUSCH
• UL-PC: PUCCH
• DL-PC
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Slide 21
DL-PC
Semi-static cell power reduction
• based on single parameter CELL_PWR_RED = 0.0, 0.1 … 20.0 dB
dlCellPwrRed
Reduction of DL Tx power; deducted
from max. antenna TX power.
LNCEL; 0..20; 0.1; 0 dB
•  cell size adjustment and coverage control
pMax
Maximum output power
LNCEL; 10.0 (100), 37.0 (370), 39.0
(390), 40.0 (400), 41.8 (418), 43.0 (430),
• semi-static MIMO_COMP (if enabled)
44.0 (440), 44.8 (448), 46.0 (460), 47.8
RL30: LTE430: DL power boosting for control channels (PCFICH, PHICH, DL RS*) (478), 49.0 (490) dBm;10.0 dBm = 10 mW
RL70: LTE1894 Reference signal power de-boosting*
37.0 dBm = 5 W
39.0 dBm = 8 W
* see “LTE Radio Parameters 2”
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
49.0 dBm = 80 W
• flat Power Spectral Density (PSD)
PSD
PSD
PSD = (Max_TX_Pwr – CELL_PWR_RED) – 10*log10( 12*# PRBs)
Allocated DL PRBs
Frequency
DL Pilots
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PSD = (Max_TX_Pwr – CELL_PWR_RED) – 10*log10( 12*# PRBs)
PDCCH
Time
PDSCH, PCH BCH, SCH
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Slide 22
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
• PSD_CELL_SYNC for synchronization channel
• PSD_UE_PDSCH for UE specific part of PDSCH
dlCellPwrRed
Reduction of DL Tx power; deducted
from max. antenna TX power.
LNCEL; 0..20; 0.1; 0 dB
• PSD_UE_CTRL for PDCCH and PHICH
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