Immobi Power Control

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 • eN eNod odeB eB give gives s fixed power density per PRB scheduled for transport.  –  Total Tx powe powerr is max. when all all PRBs are scheduled 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)  –  Calculate Calculated d at the UE based on pathlo pathloss ss mea measurem surements ents • 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

UL-PC: Overview UL-PC:

UL-PC: Overview LTE: orthogonal UL UL Tx, i.e. near-far-problem much less severe than WCDMA  dynamic, slow PC PC – Open Loop (OL) (OL) & Closed Loop (CL (CL)) • UL: dynamic, • 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 main cause: cause: inter-c inter-cell ell Noise (N) = kB T ∆f + NFeNB

Power control does not control the absolute UE Tx power but the Power Spectral Density (PSD), (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 control controls s the Tx pow power er to keep keep the transmitted power spectral density (PSD) constant independent of the allocated transmit bandwidth (#PRBs)

• If no feedback feedback from eNodeB ( in the PDCCH UL UL PC command) the UE performs open open loop PC based on path loss measurements measurements

• If feedback feedback from eNode eNodeB B the UE correct corrects s the PSD when when receiving receiving PC command commands s from eNodeB eNodeB ( in the PDCCH UL PC command) 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

UL-PC: PUSCH UL-PC:

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) + ( 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 ) + ( 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 clas class s 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: pat pathlo hloss ss [d [dB] B] = ref refere erence nceSig Signal nalPower Power – hig higher her lay layer er filt filtere ered d RSRP RSRP ∆TF

(i) = 10 log 10 ( 2MPR Ks – 1) for Ks = 1.25 else 0, MPR = TBS/N RE, 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 c ome from higher layer layer Semi-persistant: j=0 / dyn dynamic amic 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

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 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 dynamically to the channel conditions (take into account e.g. fast fading) • Correct the estimations of power from the open loop PC ulpcEnable

Open Loop PC PPUSCH(i) = min {PCMAX,10 log10 ( M PUSCH(i)) + PO_PUSCH( j ) + ( j) ⋅ PL + ∆TF (i) +  f  (i)} [dBm]

PO_PUSCH(j) = PO_NOMINAL_PUSCH(j) + PO_UE_PUSCH(j)  j=0 -> PUSCH transmission transmission with semi-persistent semi-persistent grant 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 power level for all mobiles in i n 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 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) + ( j ) ⋅ PL + ∆TF (i) +  f  (i)} [dBm]

PL: pat pathlo hloss ss [d [dB] B] = ref referen erenceS ceSign ignalP alPower ower – higher layer filtered RSRP

This path loss compensation factor a is adjustable by

Alpha

O&M. α is a cell - specific specific parame parameter ter (broadca (broadcasted sted on BCH).

α ∈ [0.0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0]

ulpcAlpha LNCEL; 0, 0.4..1.0; 0.1; 1.0

α

= 0 , no compensation

α

= 1 , full compensation

α ≠ {

0 ,1 } , fractional compensation

Conventional & Fractional PC • Conventional PC schemes:  –  Attempt to maintain a constant SINR at the receiver  –  UE increases increases the Tx power to fully fully compensate 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 increases at a reduced rate as the path loss increases. Increases Increases in path loss are only partially compensated. compensated. [+]:: Improve air interface efficiency & increase average cell throughputs by reducing Inter-cell interference  –  [+] • 3GPP specifies fractional power power control for the PUSCH with the option to disable it & revert to conventional based on 

UL SINR

Conventional Power Control: =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:  ! { 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 ) + ( j ) ⋅ PL + ∆TF (i) +  f  (i)} [dBm]  MPR∗ K s

∆ TF  (i ) = 10 log10 ( 2

0

− 1)

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 Enabling/disabling of the transport transport format dependent dependent offset on 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 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 PU PUSCH SCH Powe Powerr Contr Control ol - Par Parame ameter ter PPUSCH  (i ) = min{ PCMAX  ,10 log( M PUSCH  (i )) + Po _ PUSCH  Category

Parameter P0 PUSCH

Huawei CellUlpcComm.P0 NominalPUSCH ' CellUlpcComm.Pa LoCoe((  " )i* CellUlpc#edic.#el ta/cEnaled ()i* ()i* - Cloe Cloe Loop Loop Cell+l2oSwitc!.Ul PUSCH Power Switc! Pc+l2oSwitc! Control 3nnerLoopPuc!S witc!

Value -80 dB dBm

& )0.8* 0 )o((* on

+

⋅ PL + ∆ TF  (i ) +

Nokia Value Ericssons [LNCEL] -80 dB dBm [EUtranCell"##] p0NomPuc! p$eroNominalPuc! [LNCEL] % )alp!a ,* [EUtranCell"##] alp!a ulpc+lp!a [LNCEL] 0 delta(Enaled [LNCEL] 6 actUlpc/et!od )Puc!CLPucc [LNCEL] !CL* ulpcLowle4Sc! -,06 dBm [LNCEL] -78 dBm ulpcUple4Sc! ,8 [LNCEL] ,0 ulpcLow5ualSc! [LNCEL] ulpcUp5ualSc!

 f  (i )}

Value Z TE Value -80 -80 dBm dBm [Pow [Power erCo Con ntrol trolUL UL]] -%& p0NominalPUSCH dBm 8 )0.8* [PowerControlUL] & )0.8* alp!a [PowerControlUL] 1 0

[PowerControlUL] witc!"orCLPCo(PUS CH

,

UL PU PUSC SCH H Mess Messge ge 3 Po Powe werr Co Cont ntro roll - Pa Para rame mete terr

When LTE LTE PUSCH carry Message 3, transmit transmit power of Ue’s PUSCH is calculated as follow: PPUSCH  (i ) = min{PCMAX  ,10 log( M PUSCH  (i )) + PO_pre

Category Parameter Huawei PUSCH /26  preamlem preamlem26 26 [CellUlpcComm] [CellUlpcComm] Power Control #eltaPreamle/26

Value 9 ): dB*

Nokia [LNCEL] deltaPre/26

+ ∆ PREAMBLE  _  Msg 3 +

Value , )9 dB*

PL + ∆ TF  (i ) +  f  (i )}

Ericssons

Value

ZT E [PowerControlUL] deltaPreamle/26

Value 0

UL-PC: PUCCH UL-PC:

UL-PC: PUCCH PPUCCH (i ) = min{ PMAX , P0_PUCCH ( j ) + PL + h(nCQI  , n HARQ ) + ∆ 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 pathloss [dB] = referenceSignalPower 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 n CQI < 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

delta de ltaFL FLis istP tPUC UCCH CH Pa Para rame meter ters s 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 form at 1

0 dB

DeltaF PUCCH Format 1b

LNCEL

dFpucchF1b

1, 3, 5 dB

Used to define the PUCCH form at 1b

1 dB

DeltaF PUCCH Format 2

LNCE

dFpucchF2

-2, 0, 1, 2 dB

Used to define the PUCCH form at 2

0 dB

DeltaF PUCCH Format 2a

LNCE

dFpucchF2a

-2, 0, 2 dB

Used to define the PUCCH form at 2a

0 dB

DeltaF PUCCH Format 2b

LNCEL

dFpucchF2b

-2, 0, 2 dB

Used to define the PUCCH form at 2b

0 dB

UL PU PUCCH CCH Powe Powerr Contr Control ol - Par Parame ameter ter PPUCCH (i) = min{PCMAX , P0 _ PUCCH + PL+ h nCQI, n HARQ Category

PUCCH Power Control

Parameter

Huawei

Value

Nokia

Value

+ ∆F _ PUCCH (F ) + g(i)} Ericssons

P0 nomin nominal al PUCCH PUCCH [CellU [CellUlpc lpcCom Comm] m] -,0& dBm [LNCEL] p0NomPucc! -,00 dBm [EUtranCell"##] P0NominalPUCCH p$eroNominalPucc! Cloe Cloe Loo Loop p Swit Switc! c! [Cel [CellP lPc+ c+l2 l2o] o] 0 Pucc!CloeLoopPc