4- OMO131030 BSC6900 GSM V9R11 Power Control Algorithm and Parameters ISSUE1.14.Ppt [Compatibility Mode]

www.huawei.com

Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.

GSM Power Control Algorithm and Parameters

PDF created with pdfFactory Pro trial version www.pdffactory.com

http://www.huawei.com

http://www.pdffactory.com


Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page1

Contents1. Power Control Overview

2. HWⅡ Power Control Algorithm

3. HWⅢ Power Control Algorithm

4. Other Algorithms





Power Control Overviewl Power control

p Adjust the transmitting power of BTS and MS when needed.

p Based on measurement reports of BTS and MS

l Purpose

p Save the power of BTS and MS

p Reduce the interference of the network

p Increase the quality of the network





Power Control Overviewl Power control includes uplink power control and downlink

power control, Which are performed independently

p Uplink power control: Adjust TX power of MS to let BTS receive

stable signal, reduce the uplink co-channel and adjacent

channel interference, reduce power consumption of MS

p Downlink power control: Adjust BTS TX power to let MS receive

stable signal, reduce the downlink co-channel and adjacent

channel interference, reduce power consumption of BTS





Power Control Overviewl Up link and Down link power

control can be enabled

independently





Power Control Overviewl Process of power control commands

p It takes 3 measurement report periods(480ms/period) from

command sending to getting the feedback.

SA0 SA1SA0 SA0SA1SA1 SA2SA2SA2 SA3SA3SA3

BTS sends the command for power control and TA in SACCH header.

MS obtains SACCH block

MS begins to send the measurement report of the last multi-frame.

In the 26 multi-frames, frame 12 sends SACCH.

BTS receives the measurement report

SACCCH report period: 26X4=104 frames (480ms)

MS adopts the new power level and TA

MS begins to set up a new SACCH header to report the new TA and power control message.





Data Configuration of Power Control Period





Power Control Overviewl Power control judgment

p Power control judgment is controlled by BTS measurement

report pre-processing item which can be selected in handover

control data table

p MR. Pre-process (measurement report pre-processing): This

switch decide where power control be processed. If

measurement report pre-processing is “BSC_Preprocessing”,

power control is processed in BSC, and when setting it

“BTS_Preprocessing”, power control is processed in BTS





Data Configuration of MR Preprocessing(1)





Data Configuration of MR Preprocessing(1)





Contents1. Power Control Overview



4. Other Algorithms





HW II Power Controll Power control judgment process

The power control demand according to

receiving level

General power control judgment

Send the power control command

The power control demand according to

receiving quality

MR. preprocessing





HW II Power Controll Original data of power control -- Measurement Report(MR)

or Enhanced Measurement Report(EMR)

Network

Downlink MRDownlink MR

Uplink MRUplink MR

BTS





HW II Power Controll Measurement report

Uplink Uplink measurement measurement

reportreport

Downlink Downlink measurement measurement

reportreport





l MR. preprocessing in HW II PC algorithm consists of four

steps

p Interpolation

p Compensation (optional)

p Prediction (optional)

p Filter

HW II Power Control





HW II Power Controll MR Interpolation – recover the lost measurement report

p BTS may fail to receive the MR from MS, and it needs to

recover the lost measurement reports. If the lost MR amount is

within the allowed range (Allowed MR Number Lost), then

recovers the lost MR according to the specific algorithm.

n Service cell: linear algorithm

n Neighboring cell: the lowest value defined in GSM specification (-

110dBm)





HW II Power Control

MR

MR

No. n

No. n+4MR

MRMR

Missing by some reasons

l MR Interpolation – recover the lost measurement report





Data Configuration of MR Preprocessing





HW II Power Controll MR. compensation

p Purpose: Ensure the accuracy of selection of the history measurement report before filter.

p Implementation steps:n 1. Put the current receiving measurement report into the measurement report

compensation queue.

n 2. Record the changed information of the transmitting power according to the MS and BTS power levels in the measurement report.

n 3. After finish the measurement report interpolation, system will compensate the receiving level of the history measurement report according to the power change information. The compensated measurement reports will be the original data in the filter process.

n 4. Filter the compensated measurement reports.





Data Configuration of MR. Compensation





HW II Power Controll MR. prediction

p Purpose: Avoid power control later than needed, the delay is dangerous in case of poor level or bad quality

p Implementation procedure

1. Analyze the tendency of MR by the historical measurement reports after interpolation.

2. Guide by the tendency, to predict the values of measurement report to be received. There are 0~3 measurement reports prediction, which are configured on LMT.

3. Filter the interpolated, compensated and predicted measurement reports, and implement power control judgment.





Data Configuration of MR. Prediction





HW II Power Controll MR. filter – Smooth the instantaneous fading point

p Calculate the average value within the filter window

MR

MRMR

MR

MR

Filter----Average several consecutive MRs

MR





Data Configuration of MR. filter





l Refer to the notes





HW II Power Control Judgmentl Power control demand based on receiving level.

p After measurement report pre-processing, the power control module makes a comparison between the expected signal level and the current receiving signal level.

p Calculate the transmitting power level step size to be adjusted, making the receiving level value closer to the expected value.

p Adopt variable step size when decreasing the transmitting power according to the receiving level, so as to achieve the expected level as soon as possible.





HW II Power Control Judgmentl Power control demand based on receiving quality

p After measurement report pre-processing, the power control module makes comparison between the expected quality level and the current receiving quality level.

p Calculate the step size of the transmitting power level to be adjusted: increase the transmitting power in case of poor receiving quality, and decrease the transmitting power in case of good receiving quality.

p Adopt fixed step size when adjust the transmitting power according to the receiving quality.





HW II Power Control Judgmentl General power control judgment

Power control by receiving

level Power control by receiving

quality Power control by signal level and

quality

↓ AdjStep_Lev ↓ AdjStep_Qul ↓ max(AdjStep_Lev,AdjStep_Qul)

↓ AdjStep_Lev ↑ AdjStep_Qul No action

↓ AdjStep_Lev No action ↓ AdjStep_Lev

↑AdjStep_Lev ↓ AdjStep_Qul ↑AdjStep_Lev

↑AdjStep_Lev ↑ AdjStep_Qul ↑ max(AdjStep_Lev,AdjStep_Qul)

↑AdjStep_Lev No action ↑AdjStep_Lev

No action ↓ AdjStep_Qul ↓ AdjStep_A

No action ↑ AdjStep_Qul ↑ AdjStep_B

No action No action No action





HW II Power Control Featurel Adaptive power control:

p Adaptive power control refers to changeable power control strategy according to the communication environment, it makes power control more effective and stable.

n Automatically change the adjustable maximum step size of power control according to different communication environment (different receiving quality).

n Adopt different power control strategies according to different communication environments (different receiving quality and level).

n Max. step is different between increase and decrease.





HW II Power Control Featurel Power control within the upper/lower thresholds

p Power control will not execute if the signal level and quality

is within the threshold bands.

p Avoid the signal level fluctuation caused by power control.

p The upper threshold can be increased dynamically in case of

bad quality.





Data Configuration for UL Rx_Lev Upper/Lower Threshold










Data Configuration for UL Upper/Lower Quality Threshold





Data Configuration for DL Rx_Lev Upper/Lower Threshold










Data Configuration for DL Upper/Lower Quality Threshold





Data Configuration of Power Control (Rx_Lev)





l See the notes















Data Configuration for UL/DL Bad Quality





HW II Power Control Advantagesl Measurement report compensation – to makes power control

judgment more accurate

l Measurement report prediction --to avoid power control later

than needed, the delay is dangerous in case of poor level or

bad quality

l Power control expected signal level and quality threshold

falls within a band, this avoids receiving signal level

fluctuate up and down frequently





Exercisel Exercises for HW II power control

p Given conditions:

n The uplink receiving level is -55dBm, the quality is level 0. Power control algorithm is HW II.

n Data configuration is as follows: Uplink signal level upper threshold: -60dBm, uplink signal level lower threshold: - 80dBm. Uplink signal upper quality threshold: level 1. Uplink signal lower quality threshold: level 2. The downward adjustable step size of quality band 0 is 16dB, of quality band 1 is 8dB, and of quality 2 is 4 dB. The upward adjustable step size of receiving level is 16dB. The upward or downward adjustable step size for power control by quality are both 4dB.

p Question: What will be the uplink stable receiving level after power control?






p Answer.n First, transmitting power to be reduced according to receiving level =

actual receiving level -(uplink signal level upper threshold + uplink signal level lower threshold)/2 ＝-55- (-60 + (-80))/2＝(-55)-(-70)＝15dB. As the receiving quality is level 0, downward adjustable step size of quality band 0 can be used -- decrease 16dB.

n Second, the transmitting power to be decreased according to receiving quality = as “power control adjustment step size by quality” is 4dB, thus decrease 4dB.

n Therefore, according to the general judgement on power control, 15dB should be decreased.






p Answer .

n After the implementation of step 1 power control, the receiving level becomes: -55dBm-15dB= -70dBm, Suppose the quality reach already in level 1 here.

n First: the receiving level value is between -80dBm~-60dBm, needn’t adjust.

n Second: the receiving quality value is between 0 and 2, needn’t adjust.

n Therefore, the uplink stable receiving level =-70dBm.





Content1. Power Control Overview



4. Other Algorithms





Contents3. HW III Power Control Algorithm

3.1 HW III Power Control Algorithm

3.2 HW III Power Control Optimization Algorithm





RXLEV and RXQUAL are both within the expected window?

Calculate the PC stepallow?Is active PC allow?

The number of MRs≥[SdMrCutNum/

TchMrCutNum]?

Is PC allowed?

Exponential filtering

Slide window filtering

Interpolated MRs

PC interval > [PwrCtrlAdjPeriod]

HW III PC

The new transmit power is higher than

the current one?

New transmit power-current one>[MAXUpStep]

Current transmit power-new one>[MAXDownStep]?

New transmit power=current one-[MAXDownStep]

New transmit power=current

one+[MAXUpStep]

Adjust transmit power

Implement PC End

If the active PC is allowd & MRs number <[SdMrCutNum/TchMrCutNum] & the transmit

power will be decreased?

End

NO

YES

YES

YES

End

NO

HW III Power Control Flow

NO

NO

YES

YES

NO

YES

NO

NO

YES YES

YES

NO

MR. Preprocessing





l For the measurement report preprocessing, there are three

differences between HW II and HW III power control：

p Initial discarded MR. number

p Interpolation method

p Filter calculation

Measurement Report Preprocessing






l Initial discarded MR. number

p Avoiding the access period measurement report influence power

control accuracy, system discards some initial measurement report.

n HW II: discard 4 initial MR. fixedly.

n HW III: set it via [SdMrCutNum/TchMrCutNum]

l MR. interpolation method

p Rx_lev: If Rx_lev(k) is lost, recover it as Rx_lev(k-1).

p Rx_qual: If Rx_qual is lost, recover it as quality lever 7.





Data Configuration of Initial Discarded MR. Number






l MR. filter calculation

p Quality filter

n Quality class value will be converted to BER and set up the

correspondence relationship with CIR as below table.

n Calculate the average CIR according to the selected filter method.

Quality Class 0 1 2 3 4 5 6 7

CIR (dB) 22 18 16 14 12 9 6 4





Measurement Report Preprocessingl MR. filter calculation

p Filter algorithm: exponent filter and slide window filter

n Exponent filter

– ca_filtered1 (1)=ca(1) k=1

– ca_filtered1 (k)=a*ca(k)+(1-a)*ca_filtered1 (k-1) k>1

~ ca: original receiving level or quality

~ ca_filtered1: receiving level or quality after exponent filter calculation

~ k: serial number of measurement report

~ a: exponent filter coefficient, a=1 / (2^(w/2)), and w is exponent filter length





Measurement Report Preprocessingl Filter algorithm

p Filter algorithm: exponent filter and slide window filter

n Slide window filter

– ca_filtered (1) = ca_filtered1 (1) k=1

– ca_filtered (k) = [ca_filtered 1(1)+…+ca_filtered1 (k)] / k 1<k<w

– ca_filtered (k) = [ca_filtered1 (k-w+1)+...+ca_filtered1 (k)] / w k>=w

~ ca_filtered1: receiving level or quality after exponent filter

~ ca_filtered: receiving level or quality after slide window filter

~ k: serial number of measurement report

~ w: slide filter window





Data Configuration of Filter (DL)





Data Configuration of Filter (UL)





Power Control Judgmentl During HW III power control judgment, system will calculate

radio channel gain.

p Suppose: In SACCH period k, useful signal is c(k), interference

is I(k), radio channel gain is g(k) and transmit power for BTS or

MS is p(k). The below formulas are calculated by logarithm:

=10)(_

10kfilteredca

+10)(

10kc

10)(

10kI

Rx_levRx_lev Useful signelUseful signel InterferenceInterference

C/IC/Ièè qa_filtered(k) = c(k) – I(k) (2)

c(k) = p(k) – g(k) (3)

(1)





Power Control Judgmentl Radio channel gain calculation:

p According to (1) and (2), we can get c(k)

p Input c(k) to (3), get g(k) = p(k) – c(k). So calculate the g(k)

for BTS and MS

)101lg(10)(_)(_)( 10)(_ kfilteredqa

kfilterqakfiltercakc +×−+=





Power Control Judgmentl BTS power control step calculation:

step(k) = - ( sfactor*( BsTxMaxPower - g(k) - SThr)

+ qfactor*( qa_filtered(k) - QThr) )

If step(k) >0, so step(k) =0;

sfactor：[HWIII DL RexLev Adjust Factor]

qfactor：[HWIII DL Rex Qual. Adjust Factor]

BsTxMaxPower：the maximum power level of occupied carrier

SThrUp：[HwIII DL Rexlev Upper Threshold]

SThrDown: [HwIII DL Rexlev Lower Threshold]

SThr = (SThrUp + SThrDown) / 2; the mean level of expected receiving level window.

QThrUp：[HwIII DL FS/HS/AFS/AHS Rex Qual. Upper Threshold(dB)]

QThrDown: [HwIII DL FS/HS/AFS/AHS Rex Qual. Lower Threshold(dB)]

QThr = (QThrUp + QThrDown) / 2; the mean level of expected receiving quality window.





Power Control Judgmentl MS power control step calculation:

step(k) = - ( sfactor*( MsTxMaxPower - g(k) - SThr)

+ qfactor*( qa_filtered(k) - QThr) );

SThr = (SThrUp + SThrDown) / 2;

QThr = (QThrUp + QThrDown) / 2;

If step(k) >0，then step(k) =0;





Data Configuration of Power Control Judgment





l See notes





Data Configuration of Power Control Judgment





l See notes





Data Configuration of Power Control Adjust Factor





Power Control Judgmentl Adjustment protection

p For avoiding too rapid adjustment, parameter [DL/UL MAX

DownStep/UpStep] is used to control the maximum power

control step.

p If the difference between power control step(k) and previous

one step(k-1) is bigger than maximum power control step

configured above, just take the maximum power control step as

the difference between them, so as to limit the current power

control command step(k).





Data Configuration of Power Control Step





HW III Power Control Featuresl Exponent filter enhance the measurement report process speed.

l In HW II PC, receive level and quality be considered independently

and then general power control judgment will be done. While in

HW III PC, the final result will be got from the general formula.

l Difference quality threshold be set for the difference service, such

as AMR, FS and HS.





l Given condition：p The current UL_Re_Level: -75dBm, UL_Re_Quality: 2, Radio channel gain(g(k)):

110dB, Max power output of MS is 2W(33dBm)

p HWIII is available，data configuration is as following:

p 【ULRexLevHighThred】：30

p 【ULRexLevLowThred】：20

p 【ULFSRexQualHighThred】：20

p 【ULFSRexQualLowThred】：16

p 【ULRexLevAdjustFactor】：4 【ULRexQualAdjustFactor】：6

p 【ULMAXDownStep】：8 【ULMAXUpStep】：8

l Question：What will be the power output of MS after power control？

Quality Class 0 1 2 3 4 5 6 7

CIR (dB) 22 18 16 14 12 9 6 4

Question





l Answer:step(k) = - ( sfactor×( BsTxMaxPower - g(k) - SThr)

＋ qfactor×( qa_filtered(k) - QThr) )

After power control：

Power output of MS: 33-2=31dBm

Suppose the current g(k)=115dB, current quality:2(CIR=16dB)，then

For level：-90dBm<31-115<-80dBm

For quality：equal with the [ULFSRexQualLowThred]

So power control stops， the power output of MS 33-2=31dBm

dB2

)}2

162016(6.0)]}1102

2030(11033[4.0{{

−=

+−×+−

+−−×−=

Question





Content1. Power Control Overview

2. HW ⅡPower Control Algorithm

3. HW ⅢPower Control Algorithm

4. Other Algorithms





Contents4. Other Algorithms

4.1 Active Power Control

4.2 0.2dB Power Control

4.3 SAIC Power Control





Active Power Control Overviewl In the initial stage of the channel establishment, both BTS and MS

transmit at full power, thus increasing the power consumption and

the interference.

l In the active power control algorithm, the BSC estimates the

uplink/downlink power through the path loss and issues the power

control command through the CHANNEL ACTIVATION message.





Scenarios of Active Power Control

Scenarios of Active Power Control

Assignment Procedure

Channel Assignment Procedure

During the Intra-BSC Handover

During Normal Call





Active Power Control FlowIs [Power Forecast

Allowed] Yes?Is [Power Forecast

Allowed] Yes?Yes

No

BSC delivers UL PC command via CHAN_ACT message

Estimate PL of UL channel

For Normal call

Estimate PL of DL channel

Band compensation between Main BCCH and TCH

UL/DL transmit power=[Expected receive level] + PL

Is [DL PC Allowed] Yes?Is [DL PC Allowed] Yes?

BSC delivers DL PC command via CHAN_ACT message

End

Yes

Yes

No

Estimate PL of DL channel

For Intra-BSC handover

Estimate PL of UL channel

Is [UL PC Allowed] Yes?Is [UL PC Allowed] Yes?End

Yes

No





Active Power Control in Assignment Procedure

l Step1: Estimate PL of UL channel

p UL_PATH_LOSS=MS_MX_PWR_BCCH – UL_SD_SS

l Step2: Estimate PL of DL channel

p DL_PATH_LOSS=MS_MX_PWR_BCCH – UL_SD_SS+

CMBER_LOSS + DOUBLE_ANT_GAIN

n MS_MX_PWR_BCCH: maximum transmit power of the MS in this cell

n UL_SD_SS: uplink receive level on the SDCCH

n CMBER_LOSS: [Combination Loss]

n TWIN_ANT_GAIN: [Double Antenna Gain]





Active Power Control in Channel Assignment Procedure during Intra-BSC Handoverl Step1: Estimate PL of DL channel

p Inter-cell handover

n DL_PATH_LOSS=NCELL_BCCH_MAX_PWR – DL_NCELL_BCCH_SS

– NCELL_BCCH_MAX_PWR: maximum transmit power of the main BCCH of the neighboring cell

– DL_NCELL_BCCH_SS: downlink receive level of the main BCCH of the neighboring cell

p Intra-cell handover

n DL_PATH_LOSS=DL_MAX_TX_PWR – TCH_DL_SS_CMP

– DL_PATH_LOSS: Path loss of the downlink channel of the serving cell

– DL_MAX_TX_PWR: maximum downlink transmit power of the seized TCHs

– TCH_DL_SS_CMP: downlink receive level of the seized TCHs that is compensated to full power

l Step2: Estimate PL of UL channelp UL_PATH_LOSS=DL_PATH_LOSS

n UL_PATH_LOSS: Loss of the uplink channel of the neighboring cell





Active Power Control Procedure

l Step3: Band compensation between Main BCCH and TCH

p If fmain BCCH and fTCH belong to different frequency bands, the compensation between different frequency bands should be made for the path loss.

p fmain BCCH :DCS1800 or PCS1900, fTCH :GSM900 or GSM850

n UL_PATH_LOSS′=UL_PATH_LOSS – PATH_LOSS_BAND_DIFF

n DL_PATH_LOSS′=DL_PATH_LOSS – PATH_LOSS_BAND_DIFF

p fmain BCCH : GSM900 or GSM850, fTCH : DCS1800 or PCS1900

n UL_PATH_LOSS′=UL_PATH_LOSS + PATH_LOSS_BAND_DIFF

n DL_PATH_LOSS′=DL_PATH_LOSS + PATH_LOSS_BAND_DIFF

n PATH_LOSS_BAND_DIFF: [Path Loss of Different Frequency Band]






l Step4: Calculate the transmit power of UL/DL channel

p UL_TX_PWR=UL_EXP_TCH_SS + UL_PATH_LOSS′

p DL_TX_PWR=DL_EXP_TCH_SS + DL_PATH_LOSS′

n UL_TX_PWR: transmit power of the uplink channel

n DL_TX_PWR: transmit power of the downlink channel

n UL_EXP_TCH_SS: [Expected UL RX_LEV]

n DL_EXP_TCH_SS: [Expected DL RX_LEV]






lStep5: BSC delivers UL/DL PC command via CHAN_ACT message

Parameter Value Configured Value Configured

[Power Forecast Allowed] Yes Yes

[UL PC Allowed] Yes －

[DL PC Allowed] － Yes

BSC issues PC command through CHAN_ACT message UL PC command DL PC command





Data Configuration of Active Power Control





Coordination between Active Power Control and Common Power Controll The active power control strategy “only increasing, no

decreasing” is used instead of the original strategy

discarding MRs.

l The active power control strategy is available in Huawei III

power control, while not available in Huawei II power control.













0.2dB Power Controll For normal power control command, the adjustment

precision is 2dB.

l The system starts to support the 0.2dB downlink power

control precision from BSC6000V9R8C12.

l This feature is available for HW power control algorithm III

and III optimization.





0.2dB Power Control--Data Configuration

l Command: SET GCELLPWR3 (Set Parameters for Power

Control III of Cell)

p FINESTEPPCALLOWED

n Parameter name: 0.2dB Power Control Enable

n Value range: YES, NO













Introduction to SAICl SAIC: Single Antenna Interference Cancellation

p SAIC is a generic name for techniques, which attempt to

cancel or suppress interference by means of signal processing

without the use of multiple antennas. (see 3GPP 45.903)

p The MSs can bear more serious radio environment after

supporting SAIC.

p The SAIC capability is indicated by Classmark 3 message.





l If the MS support SAIC, the system can decrease the DL expected receive quality level automatically.

l This feature is available for HW PC algorithm II, III and III optimization.

SAIC Power Control

DL Quality Upper Threshold

DL Quality Lower Threshold

DL Quality Upper Threshold

DL Quality Lower Threshold

Power Control Threshold Adjust for

SAIC

For Normal MS For SAIC capable MS





SAIC Power Control-- Data Configuration

l Command: SET GCELLPWRBASIC (Set Basic Parameters for Power Control of Cell)

p SAICALLOWED n Parameter name: Saic Allowed

n Value range: YES, NO

l Command: SET GCELLPWR2 (Set Parameters for Power Control II of Cell)

p SAICTHREDAPDTVALUEn Parameter name: Power Control Threshold Adjust for SAIC

n Value range: 0~2

n Unit: dB





SAIC Power Control-- Data Configuration

l Command: SET GCELLPWR3 (Set Parameters for Power Control III of

Cell)

p SAICTHREDAPDTVALUE

n Parameter name: Power Control threshold Adjust for SAIC

n Value range: 0~4

n Unit: dB





Summaryl In this course, we have learned:

p Power control procedure

p HW II power control algorithm and its data configuration

p HW III power control algorithm and its data configuration

p HW III power control optimization algorithm and its data configuration

p Active Power Control and its data configuration

p 0.2dB power control and its data configuration

p SAIC power control and its data configuration




Thank youwww.huawei.com


http://www.huawei.com



Documents

4- OMO131030 BSC6900 GSM V9R11 Power Control Algorithm and Parameters ISSUE1.14.Ppt [Compatibility Mode]