02 - OWJ200102 WCDMA Power Control Algorithm and Parameters RAN10 ISSUE2.00

8/14/2019 02 - OWJ200102 WCDMA Power Control Algorithm and Parameters RAN10 ISSUE2.00

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WCDMA Power Control and Relevant Parameters

Confidential Information of Huawei. No Spreading Without Permission 1




CDMA system have the embedded characteristics of self-interference, for uplink one

Confidential Information of Huawei. No Spreading Without Permission

user’s transmission power become interference to others.

The more connected users, the higher interference. Generally the capacity is limited by

interference level.

WCDMA suffer from Near-far effect, which means if all UE use the same transmission

power, the one close to the NodeB may block the entire cell.

Uplink power control can guarantee the service quality and minimize the required

transmission power. It will resolve the near-far effect and resist fading of signal

propagation. By lowering the uplink interference level, the system capacity will be

increased.

4




The downlink has different characteristics from the uplink, for downlink interference is


caused by multi-path, part of one user’s power also become interference to others.

Downlink power from adjacent cells also is one part of interference to the own cell.

Transmission power of NodeB is shared by all users channels, so downlink capacity

usually is considered to be limited by transmission power.

Downlink power control also can guarantee the service quality and minimize the required

transmission power, so the capacity is maximized in case that interference is lowered.

5




Because of channel fading in mobile communication system, the radio signal is


deteriorated and fluctuated, the fast power control become one key technology to resist

this phenomenon.

In this figure, the channel fading is compensated by the transmitting power, which is

adjusted by the fast power control, so the receiving power is almost constant and theradio propagation condition is improved.

6




In WCDMA system, power control includes open loop and closed loop power control.


Open loop power control is used to determine the initial transmission power, and the

closed loop power control adjusts the transmission power dynamically and continuously

during the connection.

For uplink, the UE’s transmission power is adjusted; and for downlink, the NodeB’s

transmission power is adjusted.

7




Open loop power control is used in two cases:


1. to decide the initial transmission power of PRACH preamble.

2. to decide the initial transmission power of DPCCH / DPDCH.

Closed loop power control is only applied on DPCCH and DPDCH

For other common channels, power control is not applied, they will use fixed transmission

power:

The PCPICH power is defined by the PCPICH TRANSMIT POWER parameter as

an absolute value in dBm.

All other common channels power is defined in relation with the PCPICH

TRANSMIT POWER parameter, and measured in dB.

8




MAXTXPOWER


Parameter name: Max transmit power of cell

Value Range: 0 to 500

Physical Value Range: 0dBm to 50 dBm, step 0.1dB

The recommended value is 430, namely 43dBm

Content: The sum of the maximum transmit power of all DL channels in a cell.

Set this parameter through ADD CELLSETUP, query it through LST CELL and modify it

through MOD CELL

PCPICHPOWER

Parameter name: PCPICH transmit power

Value Range: -100 to 500

Physical Value Range: -10dBm to 50 dBm, step 0.1dB

The recommended value is 330, namely 33dBm

Content: This parameter should be set based on the actual environment and the downlink

coverage should be guaranteed firstly. If PCPICH transmit power is configured too great, the

cell capacity will be decreased, for power resources is occupied by common channel and

the interference to traffic channels is also increased.

Set this parameter through ADD PCPICH, query it through LST PCPICH and modify it

through MOD CELL

9




PSCHPOWER or SSCHPOWER


Parameter name: PSCH / SCCH transmit power

Value range: -350 to 150.

Physical value range: -35 to 15, step 0.1dB

The recommended value is -50, namely -5dB

Content: The offset between the PSCH / SSCH transmit power and PCPICH transmit power.

For PSCH Power, set it through ADD PSCH, and query it through LST PSCH; for SSCH

Power, set it through ADD SSCH, and query it through LST SSCH. And modify it through

MOD CELL

BCHPOWER

Parameter name: BCH transmit power

Value Range：

-350 to 150

Physical Value Range： -35 to 15 dB, step 0.1dB


Content: The offset between the BCH transmit power and PCPICH transmit power.

Set this parameter through ADD BCH, query it through LST BCH, and modify it through

MOD CELL

10




MAXFACHPOWER


Parameter name: Max transmit power of FACH

Value range : -350 to 150


The recommended value is 10, namely 1dB

Content: The offset between the FACH transmit power and PCPICH transmit power.

Set this parameter through ADD FACH, query it through LST FACH, and modify it

through MOD SCCPCH

PCHPOWER

Parameter name: PCH transmit power

Value Range： -350 to 150



Content: The offset between the PCH transmit power and PCPICH transmit power.

Set this parameter through ADD PCH, query it through LST PCH, and modify it

through MOD SCCPCH

11




AICHPOWEROFFSET


Parameter name: AICH power offset


Physical Value Range： -22 to 5 dB, step 1dB

The default value of this parameter is -6, namely -6dB

Content: The offset between the AICH transmit power and PCPICH transmit power.

Set this parameter through ADD CHPWROFFSET, query it through LST

CHPWROFFSET, and modify it through MOD AICHPWROFFSET

PICHPOWEROFFSET

Parameter name: PICH power offset


Physical Value Range： -10 to 5 dB , step 1dB

The default value of this parameter is -7, namely -7dB

Content: The offset between the PICH transmit power and PCPICH transmit power.

Set this parameter through ADD CHPWROFFSET, query it through LST

CHPWROFFSET, and modify it through MOD PICHPWROFFSET

12




In downlink open loop power control, the initial transmission power is calculated according


to the downlink path loss between NodeB and UE.

In uplink, since the uplink and downlink frequencies of WCDMA are in the same

frequency band, a significant correlation exists between the average path loss of the two

links. This make it possible for each UE to calculate the initial transmission powerrequired in the uplink based on the downlink path loss.

However, there is 90MHz frequency interval between uplink and downlink frequencies,

the fading between the uplink and downlink is uncorrelated, so the open loop power

control is not absolutely accurate.

15




In access procedure, the first signaling “RRC CONNECTION REQUEST” is transmitted in


message part on PRACH.

Before PRACH message part transmission, UE will transmit PRACH preamble, and the

transmission power of first preamble is calculated by this PRACH open loop power control.

17




In this formula, where


PCPICH TRANSMIT POWER defines the PCPICH transmit power in a cell. It is

broadcast in SIB5 .

CPICH_RSCP means received signal code power, the received power measured

on the PCPICH. The measurement is performed by the UE.

UL interference is the UL RTWP measured by the NodeB. It is broadcast in SIB7 .

CONSTANT VALUE compensates for the RACH processing gain. It is broadcast in

SIB5 .

The initial value of PRACH power is set through open loop power control. UE operation

steps are as follows:

1. Read “Primary CPICH DL TX power ”, “UL interference ” and “Constant value ”

from system information.

2. Measure the value of CPICH_RSCP ;

3. Calculate the Preamble_Initial_Power of PRACH.

18




CONSTANTVALUE


Parameter name: Constant value for calculating initial TX power

Value range : -35 ~ -10

Physical Value Range： -35 to -10 dB

Content: It is used to calculate the transmit power of the first preamble in the

random access process.

Recommended value: -20

Set this parameter through ADD PRACHBASIC, query it through LST PRACH, and

modify it through MOD PRACHUUPARAS

19




After UE transmit the first Preamble on PRACH, it will wait for the corresponding AI


(Acquisition Indicator) on the AICH. The timing relationship of PRACH and AICH is shown

in above figure.

There will be 3 parameters used to define the timing relationship:

τ ττ τ p-p : time interval between two PRACH preambles. τ p-p is not a fixed value, it is

decided by selecting access slot of PRACH preambles,

Here τp-p has one restriction, it must be longer than a minimum value τ ττ τ p-p min ,

namely τ p-p ≥ τ p-p min .

τ ττ τ p-a : time interval between PRACH preamble and AICH Acquisition Indicator. If UE

sends the PRACH preamble, it will detect the responding AI after τ p-a time.

τ ττ τ p-m : time interval between PRACH preamble and PRACH message part. If UE

sends the PRACH preamble and receives positive AI from the AICH, it will send the

message part after τ p-m time.

20




Parameter AICHTXTIMING is used to define the set of τ p-p min , τ p-a , τ p-m .


AICHTXTIMING

Parameter name: AICH transmission timing

Value range： 0,1

Content:

When AICHTXTIMING = 0,

τ ττ τ p-p,min = 15360 chips, τ ττ τ p-a = 7680 chips, τ ττ τ p-m = 15360 chips

When AICHTXTIMING = 1,

τ ττ τ p-p,min = 20480 chips, τ ττ τ p-a = 12800 chips, τ ττ τ p-m = 20480 chips

Recommended value: 1

Set this parameter through ADD AICH, query it through LST AICH, and modify it

needs de-activated the cell through DEA CELL. After the old configuration of AICH

is deleted through RMV AICH , a new AICH can be established through ADD AICH

21




After UE transmit the first Preamble,


If no positive or negative AI on AICH is received after τ p-a time,

UE shall increase the preamble power by POWER RAMP STEP , andretransmit the preamble.

This ramping process stops until the number of transmitted preambles has

reached the MAX PREAMBLE RETRANSMISSION within an access cycle,

or when the maximum number of access cycles has reached MAX

PREAMBLE LOOP .

If a negative AI on AICH is received by the UE after τ p-a time,

which indicates rejection of the preamble, the UE shall wait for a certain

“Back-off Delay” and re-initiate a new random access process.

When a positive AI on AICH is received by UE after τ p-a time,

it will transmit the random access message after the uplink access slot of the

last preamble. The transmit power of the random access message control part should be

POWER OFFSET higher than the power of the last transmitted preamble.

22




POWERRAMPSTEP


Parameter name: Power increase step

Value range : 1 to 8

Physical Value Range: 1 to 8 dB

Content: The power increase step of the random access preambles transmitted

before the UE receives the acquisition indicator in the random access process.




PREAMBLERETRANSMAX

Parameter name: Max preamble retransmission

Value range : 1 to 64

Content: The maximum number of preambles transmitted in a preamble ramping

cycle.




23




MMAX


Parameter name: Max preamble loop

Value range: 1 to 32

Content: The maximum number of random access preamble loops.


Set this parameter through ADD RACH, query it through LST RACH, and modify it

first de-activated the cell through DEA CELL, then MOD RACH.

NB01MIN / NB01MAX

Parameter name: Random back-off lower / upper limit


Content: The lower / upper limit of random access back-off delay.

The recommended value: 0 for both NB01MIN / NB01MAX

Set this parameter through ADD RACH, query it through LST RACH, and modify it

first de-activated the cell through DEA CELL, then MOD RACH.

24




POWEROFFSETPPM


Parameter name: Power offset

Value range: -5 to 10dB

Content: The power offset between the last access preamble and the message

control part. The power of the message control part can be obtained by adding the

offset to the access preamble power.

The recommended value of this parameter is -3dB for signalling transmission , and

that -2dB for service transmission

Set this parameter through ADD PRACHTFC, query it through LST PRACH, and

modify it de-activated the cell through DEA CELL . After the old configuration of

PRACH is deleted through RMV PRACHTFC , a new parameters can be

established through ADD PRACHTFC

The PRACH message also consists of control part and data part, here the POWER

OFFSET is the difference between the PRACH preamble and the message control part.

The PRACH message uses GAIN FACTOR to set the power of control / data part:

GAIN FACTOR BETAC ( β c ) is the gain factor for the control part.

GAIN FACTOR BETAD ( β d ) is the gain factor for the data part.

25




According to the RRC connection establishment procedure, after RNC received the “RRC


CONNECTION REQUEST ” message, and NodeB set up the radio link for UE, then Iub

interface resources is established between NodeB and RNC.

When DCH-FP of Iub interface finished downlink and uplink synchronization, the downlink

DPCH starts to transmit, and DPDCH initial transmission power is calculated throughopen loop power control.

27




In this formula, where


R is the requested data bitrate by the user

W is the chip rate

(Eb/No) DL is the Eb/No target to ensure the service quality. RNC searches for the

(Eb/No)DL dynamically in a set of pre-defined values according to specific cell

environment type, coding type, bitrate, BLER target and etc.

(Ec/Io) CPICH is the CPICH signal quality measured by UE, then it is sent to RNC

through RACH.

α αα α is the orthogonality factor in the downlink. In Huawei implementation, α is set to

0.

P total is the total carrier transmit power measured at the NodeB

The initial transmission power of downlink DPDCH could be calculated through this

formula, then, initial transmission power of downlink DPCCH can be obtained according

to the power offset: PO1, PO2 and PO3 .

28




This figure shows the power offset of downlink DPCH :


Power offset of DPCCH TFCI to DPDCH is 0

Power offset of DPCCH TPC to DPDCH is 3dB.

Power offset of DPCCH Pilot to DPDCH is 3dB.

29




Note: Both downlink open loop and close loop power control will be limited by this parameter.


RLMAXDLPWR

Parameter name: RL Max DL TX power


Physical Value Range：

-35 to 15 dB, step 0.1dB

Content: The maximum downlink transmit power of radio link. This parameter should fulfill

the coverage requirement of the network planning, and the value is relative to [PCPICH

transmit power]

Set this parameter through ADD CELLRLPWR , query it through LST CELLRLPWR, and

modify it through MOD CELLRLPWR

RLMINDLPWR

Parameter name: RL Min DL TX power



Content: The minimum downlink transmit power of radio link. This parameter should

consider the maximum downlink transmit power and the dynamic range of power control,

and the value is relative to [PCPICH transmit power] .

Since the dynamic range of power control is set as 15dB, this parameter is recommended as

[RL Max DL TX power] – 15 dB.

Set this parameter through ADD CELLRLPWR, query it through LST CELLRLPWR, and

modify it through MOD CELLRLPWR

30




According to the RRC connection establishment procedure, after RNC sent the “RRC


CONNECTION SETUP ” message, UE will try to synchronize with NodeB, and the uplink

DPCCH starts to transmit, here DPCCH initial transmission power is calculated through

open loop power control

33




For Huawei, DPCCH_Power_Offset is calculated with the following formula:


Where

PCPICH Transmit Power defines the PCPICH transmit power in a cell.

UL Interference is the UL RTWP measured by the NodeB.

Default Constant Value reflects the target Ec/No of the uplink DPCCH preamble.

Valuet tanCons Default

ce InterferenULPower Transmit PCPICH Offset _Power _ DPCCH

+

+=

34




DEFAULTCONSTANTVALUE


Parameter name: Constant value configured by default

Value range : -35 to -10 , unit :dB

Content: This parameter is used to obtain DPCCH_Power_Offset , which is used by

UE to calculate the initial transmit power of UL DPCCH during the open loop power

control process.

Recommended value: -22

Set this parameter through SET FRC, query it through LST FRC, and modify it

through SET FRC

35




MAXALLOWEDULTXPOWER


Parameter name: Max allowed UE UL TX power

Value range: -50 to 33

Physical value range: -50 to 33 dBm. Step: 1

Content: The maximum allowed uplink transmit power of a UE in the cell, which is

related to the network planning.


Set this parameter through ADD CELLSELRESEL, query it through LST

CELLSELRESEL, and modify it through MOD CELLSELRESEL

36




MAXULTXPOWERFORCONV


Parameter name: Max UL TX power of Conversational service

MAXULTXPOWERFORSTR

Parameter name: Max UL TX power of Streaming service

MAXULTXPOWERFORINT

Parameter name: Max UL TX power of Interactive service

MAXULTXPOWERFORBAC

Parameter name: Max UL TX power of Background service

Value range: -50 to 33

Physical value range: -50 to 33 dBm. Step: 1

Content: The maximum UL transmit power for specific service in the cell, which is

related to the network planning.


Set this parameter through ADD CELLCAC, query it through LST CELLCAC, and

modify it through MOD CELLCAC

37




Inner Loop Power Control


The receiver compares SIR mea (measured SIR) with SIR tar (target SIR), and decide the TPC to

send.

If SIR mea is greater than SIR tar , the TPC is set as “0” to increase transmission power

If SIR mea is less than SIR tar , the TPC is set as “1” to decrease transmission power

TPC is sent to the transmitter in DPCCH, the transmitter will adjust the power according to the

value of received TPC.

Through inner loop power control, the SIR mea can be ensured to approach SIR tar .

Outer Loop Power Control

The receiver compares BLER mea (measured BLER) with BLER tar (target BLER), and decide how to

set the SIR tar .

If BLER mea is greater than BLER tar , the SIR tar is increased

If BLER mea is less than BLER tar , the SIR tar is decreased

The adjusted SIR tar is sent for the inner loop power control, then it will be used in previous process

to guide the transmitter power adjustment.

Through outer loop power control, the BLER mea can be ensured to approach BLER tar .

40




RNC sends SIR tar (target SIR) to NodeB and then NodeB compares SIR mea (measured


SIR) with SIR tar once every timeslot.

If the estimated SIR is greater than the target SIR, NodeB sends TPC “0” to UE on

downlink DPCCH TPC field.

Otherwise, NodeB sends TPC “1” to UE.

After reception of one or more TPC in a slot, UE shall derive a single TPC_cmd (TPC

command, with value among -1,0,1):

For UE is in soft handover state, more than one TPC is received in a slot, so firstly

multiple TPC_cmd is combined.

Two algorithms could be used by the UE for deriving the TPC_cmd , those are

PCA1 and PCA2 (PCA means Power Control Algorithm).

When deriving the combined TPC_cmd , UE shall adjust the transmit power of uplink

DPCCH with a step “UL Closed Loop Power Control Step Size “, as following:

△ DPCCH = △ TPC × TPC_cmd

This adjustment is executed on the DPCCH, then associated DPDCH transmit power is

calculated according to DPDCH / DPCCH power ratio β d / β c .

42




When UE has single radio link, only one TPC will be received in each slot. In this case,


the value of TPC_cmd shall be derived by PCA2 as follows:

For the first 4 slots of a set, TPC_cmd = 0.

For the fifth slot of a set, UE make the decisions on as follows:

If all 5 TPC within a group are 1, then TPC_cmd = 1 in the 5th slot.

If all 5 TPC within a group are 0, then TPC_cmd = -1 in the 5th slot.

Otherwise, TPC_cmd = 0 in the 5th slot.

According to DPCCH channel structure, there are 15 time slots in a 10ms radio frame,

and the control is performed once in each 5-slot group, so the frequency of uplink inner

loop PCA2 is 300Hz.

44




On the NodeB side, there are two phases during the soft handover state:


Uplink synchronization phase

The NodeB should send durative “TPC = 1” to the newly-added RL before

successful synchronization.

Multi-radio link phase

Each NodeB and each cell will estimate the SIR individually and the general TPC

individually. Therefore, the UE may receive different TPC from different RLS.

Especially, when UE is in softer handover state, it means UE has radio links to the same

NodeB, in this case, these RLs (Radio Link) belong to the same RLS (Radio Link Set),

and the all TPCs are the same from each RL.

45




When UE is in soft handover state, multiple TPC will be received in each slot from


different cells in the active set. UE will generate the TPC_cmd by PCA1 as follows:

1. Combine the TPC from the same RLS and derive the Wi

When the RLs (Radio Link) are in the same RLS (Radio Link Set), they will transmit

the same TPC in a slot. In this case, the TPC s from the same RLS shall be

combined into one.

After combination, UE will obtain a soft symbol decision Wi for each RLSi .

2. Combine the TPC from different RLSs and derive the TPC_cmd

UE derives TPC_cmd , it is based on a function γ and all the N soft symbol

decisions Wi :

TPC_cmd = γ (W 1, W 2 , … W N ),

Where TPC_cmd can only take the values 1 or -1.

In Huawei implementation, the function γ shall fulfil the following criteria:

If the TPCs from all RLSs are “1” , the output of γ shall be equal to “1” ;

If one TPC from any RLS is “0” , the output of γ shall be equal to “-1” .

46




The example of the uplink inner loop PCA2 in soft handover state.





PWRCTRLALG


Parameter name: Power control algorithm selection

Value range: ALGORITHM1, ALGORITHM2

Content: This parameter is used to inform the UE of the method for translating the

received TPC commands.

Recommended value: ALGORITHM1


through SET FRC

ULTPCSTEPSIZE

Parameter name: UL closed loop power control step size

Value range :1dB, 2dB

Content: The step size of the closed loop power control performed on UL DPDCH.

This parameter is mandatory when the parameter “Power control algorithm

selection” is set as "ALGORITHM1".



through SET FRC

49




Basically the downlink inner loop power control process is similar with uplink, UE L3


sends SIR tar to UE L1 and then UE L1 compares SIR mea with SIR tar :

If the SIR mea is greater than the SIR tar , UE sends TPC “0” to NodeB on uplink

DPCCH TPC field.

Otherwise, UE sends TPC “1” to NodeB.

The UE shall check the downlink power control mode before generating the TPC , two

algorithm DPC_MODE1 and DPC_MODE2 could be used by UE to derive the TPC . Upon

receiving the TPC , NodeB shall estimate the transmitted TPC and adjust its downlink

DPCCH/DPDCH power accordingly.

After reception of one or more TPC in a slot, NodeB shall derive the estimated TPC

TPC est (k) and calculate a P TPC (k), the power adjustment of k: th slot.

Then NodeB shall adjust the current downlink power P(k-1) to a new power P(k), and

adjust the power of the DPCCH and DPDCH with the same amount, since power

difference between them is fixed.

51




The DPC_MODE parameter is a UE specific parameter and controlled by the UTRAN.


The UE shall check the DPC_MODE (Downlink Power Control Mode) before generating

the TPC , and upon receiving the TPC , the UTRAN shall adjust its downlink power

accordingly.

52




DPCMODE


Parameter name: Downlink power control mode

Value range: SINGLE_TPC (DPC_MODE=0), TPC_TRIPLET_IN_SOFT

(DPC_MODE=1), TPC_AUTO_ADJUST

Content:

SIGNLE_TPC , a fast power control mode, indicates that a unique TPC command is

sent in each time slot on DPCCH.

TPC_TRIPLET_IN_SOFT , a slow power control mode, indicates that the same

TPC is sent in three time slots, it is applicable to soft handover and it can decrease

the power deviation.

TPC_AUTO_ADJUST , an automatically adjusted mode, indicates that the value of

DPC_MODE can be modified by sending the message “ACTIVE SET UPDATE” to

UE.

Recommended value: SINGLE_TPC


through SET FRC

53




If DOWNLINK_POWER_BALANCE_SWITCH is OFF , then P bal (k) equals 0.





From the definition above, ∆∆∆∆sum (k) indicates the sum of downlink power adjustment in the


latest DL_Power_Average_Window_Size time slots.

Power_Raise_Limit is set to 10dB.

DL_Power_Averaging_Window_Size is set to 20 Slot.

56




INNER_LOOP_DL_LMTED_PWR_INC_SWITCH


This is one switch in PcSwitch (Power control algorithm switch) parameter.

Value range ： 1 (ON) , 0 (OFF)

Content: When it is checked, limited power increase algorithm is applied in the inner loop

power control. limited power increase algorithm means that when the DL transmit power isincreased, there is a limit for the step, that is, each increase is limited.

Recommended value (default value): 1

Set this parameter through SET CORRMALGOSWITCH, query it through LST

CORRMALGOSWITCH, and modify it through SET CORRMALGOSWITCH

FDDTPCDLSTEPSIZE

Parameter name: FDD DL power control step size

Value range: STEPSIZE_0.5DB, STEPSIZE_1DB, STEPSIZE_1.5DB, STEPSIZE_2DB

Physical value range: 0.5, 1, 1.5, 2 dB

Content: The step size of the closed loop power control performed on DL DPCH in

Frequency Division Duplex (FDD) mode.

Recommended value: STEPSIZE_1DB

Set this parameter through SET FRC, query it through LST FRC, and modify it through SET

FRC

57




During soft handover, the UL TPC is demodulated in each RLS, then due to demodulation


errors, the DL transmit power of the each branch in soft handover will drift separately,

which causes loss to the macro-diversity gain.

The DL Power Balance (DPB) algorithm is introduced to reduce the power drift between

links during the soft handover.

58




DOWNLINK_POWER_BALANCE_SWITCH


This is one switch in PcSwitch (Power control algorithm switch) parameter.

Value range ： 1 (ON) , 0 (OFF)

Content: When it is checked, Downlink Power Balance (DPB) algorithm is applied to RNC.

Downlink power drift among different RLs, which is caused by TPC bit error or other reasons,

could reduce the gain of soft handover. DPB is mainly used to balance the downlink powerof different RLs for an UE in order to achieve the best gain of soft handover.

Recommended value (default value): 1, ON



DPBSTARTTHD / DPBSTOPTHD

Parameter name: DPB start threshold / DPB stop threshold

Value range: 0~255

Physical value range: 0~127.5dB; step: 0.5

Content: The threshold of start / stop DL power balancing in soft handover. When the

difference of the power values of every two paths is greater / smaller than or equal to this

threshold in soft handover, the RNC shall start / stop DL power balancing; otherwise, shall

not.

The recommended value is DPB start threshold 8, namely 4dB; DPB stop threshold 4,

namely 2dB;

Set this parameter through SET DPB, query it through LST DPB and modify it through SET

DPB

59




The reason of outer loop power control


The QoS which NAS provides to CN is BLER, not SIR

The relationship between inner loop power control and outer loop power control

SIRtar should be satisfied with the requirement of decoding correctly. But different

multi-path radio environments request different SIR

Therefore, the outer loop power control can adjust the SIR to get a stable BLER in

the changeable radio environment

61




Uplink outer-loop power control is performed in the SRNC. The SRNC measures the


received BLER and compares it with the BLER tar . If the BLER mea is greater than the

BLER tar , the SRNC increases the SIR tar ; otherwise, the SRNC decreases the SIR tar .

62




The initial SIR target value is transmitted to the NodeB by using NBAP signaling of each


RADIO LINK SETUP or RADIO LINK RECONFIGURATION PREPARE messages

63




According to the formula above,


SIR tar (n) is the target SIR used for the n:th adjustment period.

MAX means the maximum value among the total i transmission channels.

BLER meas,i (n) is measured for the i:th transmission channel in the n:th adjustment

period.

BLER tar,i is the target BLER of the i:th transmission channel.

Step i is the adjustment step of the i:th transmission channel.

Factor is the adjustment factor.

64




Where,


∆SIR tar is the adjustment of SIR tar , and ∆SIR tar = SIR tar (n+1) - SIR tar (n)

ABS( ∆SIR tar ) means absolute value of ∆SIR tar

65




Where,


CSD: CS domain Data service

I/B: Interactive and Background.

66




OLPC_SWITCH


This is one switch in PCSWITCH (Power control algorithm switch) parameter.

Value range： 1 (ON) , 0 (OFF)

Comments: When it is checked, RNC updates the uplink SIR TARGET of RLs on

the NodeB side by Iub DCH FP signals

Default value: 1



INITSIRTARGET

Parameter name: Initial SIR target value


Physical value range: -8.2 to +17.3 dB, step 0.1

Content: Defining the initial SIR target value of outer loop power control.

Recommended value: refer to the following table.

Set this parameter through ADD TYPSRBOLPC / ADD TYPRABOLPC, query it

through LST TYPSRB / LST TYPRAB, and modify it through MOD TYPSRBOLPC /

MOD TYPRABOLPC

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The downlink outer loop power control is implemented inside the UE. Therefore, this


algorithm is specified by UE manufacturer.

Generally, the UE L3 measures the received BLER and compares it with the BLER tar . If

the BLER mea is greater than the BLER tar , the L3 increases the SIR tar and send it to UE L1;

otherwise, the L3 decreases the SIR tar .

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02 - OWJ200102 WCDMA Power Control Algorithm and Parameters RAN10 ISSUE2.00

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Transcript of 02 - OWJ200102 WCDMA Power Control Algorithm and Parameters RAN10 ISSUE2.00