4- omo133030 bsc6900 gsm v9r13 power control algorithm and parameters issue 1.01.ppt

8/21/2019 4- OMO133030 BSC6900 GSM V9R13 Power Control Algorithm and Parameters ISSUE 1.01.ppt

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Copyright 2011 Huawei Technologies Co., Ltd. All rights reserved.

GSM Power ControlAlgorithm and

Parameters


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Copyright 2011 Huawei Technologies Co., Ltd. All rights reserved. Page1

Contents

1. Power Control Overview

2. HWPower Control Algorithm


4. Other Algorithms


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Power Control Overview

Power control

Adjust the transmitting power of BTS and MS when needed.

Based on measurement reports of BTS and MS

Purpose

Save the power of BTS and MS

Reduce the interference of the network

Increase the quality of the network


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Up link and Down link power control can be enabled independently


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Process of UL power control commands

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

command sending to getting the feedback.

SA SA1A SAA1A1 SA2A2A2 SA3A3A3

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 newpower level and TA

MS begins to set up a new SACCH header

to report the new TA and power control

message.


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Data Configuration of Power Control Period


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Power control judgment

Power control judgment is controlled by BTS measurement

report pre-processing item which can be selected in handover

control data table

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


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Data Configuration of MR

Preprocessing


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Data Configuration of Power Control

Switch

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Contents


2. HW Power Control Algorithm


4. Other Algorithms


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HW II Power Control

Power control judgment process

The power control

demand according to

receiving level

General power controljudgment

Send the power control

command

The power control

demand according to

receiving quality

MR. preprocessing


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HW II Power Control

Original data of power control -- Measurement Report(MR)

or Enhanced Measurement Report(EMR)

Network

Downlink MR

Uplink MR

TS


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HW II Power Control

Measurement report

Uplink

measurement

report

Downlink

measurement

report


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MR. preprocessing in HW II PC algorithm consists of

four steps

Interpolation

Compensation (optional)

Prediction (optional)

Filter

HW II Power Control


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HW II Power Control

MR Interpolationrecover the lost measurement report

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.

Service cell: linear algorithm

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

110dBm)


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HW II Power Control

MR

MR

No. n

No. n+4

MRMR MR

Missing bysome reasons

MR Interpolationrecover the lost measurement report


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Data Configuration of MR

Preprocessing


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HW II Power Control

MR. compensation Purpose: Ensure the accuracy of selection of the history measurement

report before filter.

Implementation steps:

1. Put the current receiving measurement report into the measurement reportcompensation queue.

2. Record the changed information of the transmitting power according to the

MS and BTS power levels in the measurement report.

3. After finish the measurement report interpolation, system will compensate

the receiving level of the history measurement report according to the powerchange information. The compensated measurement reports will be the

original data in the filter process.

4. Filter the compensated measurement reports.


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Data Configuration of MR.

Compensation


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HW II Power Control

MR. prediction

Purpose: Avoid power control later than needed, the delay is

dangerous in case of poor level or bad quality

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.


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Data Configuration of MR. Prediction


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HW II Power Control

MR. filterSmooth the instantaneous fading point

Calculate the average value within the filter window

MR

MRMR

MR

MR

Filter----Average several

consecutive MRs

MR


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Data Configuration of MR. filter


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HW II Power Control Judgment

Power control demand based on receiving level.

After measurement report pre-processing, the power control

module makes a comparison between the expected signal

level and the current receiving signal level.

Calculate the transmitting power level step size to be adjusted,

making the receiving level value closer to the expected value.

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.


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Power control demand based on receiving quality After measurement report pre-processing, the power control

module makes comparison between the expected quality level

and the current receiving quality level.

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.

Adopt fixed step size when adjust the transmitting poweraccording to the receiving quality.


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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


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HW II Power Control Feature

Adaptive power control:

Adaptive power control refers to changeable power control

strategy according to the communication environment, it makes

power control more effective and stable.

Automatically change the adjustable maximum step size of power

control according to different communication environment

(different receiving quality).

Adopt different power control strategies according to different

communication environments (different receiving quality and level).

Max. step is different between increase and decrease.


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HW II Power Control Feature

Power control within the upper/lower thresholds

Power control will not execute if the signal level and quality

is within the threshold bands.

Avoid the signal level fluctuation caused by power control.

The upper threshold can be increased dynamically in case of

bad quality.


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Data Configuration for UL Rx_Lev

Upper/Lower Threshold


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Data Configuration of Power Control

(Rx_Lev)


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HW II Power Control Advantages

Measurement report compensationto makes power control

judgment more accurate

Measurement report prediction --to avoid power control later

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

Power control expected signal level and quality threshold

falls within a band, this avoids receiving signal level

fluctuate up and down frequently


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Exercise

Exercises for HW II power control Given conditions:

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

HW II.

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.

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


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Exercise

Exercises for HW II power control Answer.

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.

Second, the transmitting power to be decreased according to receiving

quality = as power control adjustment step size by quality is 4dB, thus

decrease 4dB.

Therefore, according to the general judgement on power control, 15dB

should be decreased.


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Exercise

Exercises for HW II power control

Answer .

After the implementation of step 1 power control, the receiving

level becomes: -55dBm-15dB= -70dBm, Suppose the quality reach

already in level 1 here.

First: the receiving level value is between -80dBm~-60dBm,

neednt adjust.

Second: the receiving quality value is between 0 and 2, neednt

adjust.

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


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Content



3. HW Power Control Algorithm

4. Other Algorithms


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Contents

3. HW III Power Control Algorithm

3.1 HW III Power Control Algorithm

3.2 HW III Power Control Optimization Algorithm


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RXLEV and RXQUALare both within theexpected window?

Calculate the PC step

The number ofMRs[SdMrCutNum/

TchMrCutNum]?

Is PC allowed?

Exponential filtering

Slide window filtering

Interpolated MRs

PC interval >[PwrCtrlAdjPeriod]

Begin

The new transmitpower 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=currentone+[MAXUpStep]

Adjust transmit power

Implement PC End

If the active PC is allowd & MRs number


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For the measurement report preprocessing, there are three

differences between HW II and HW III power control

Initial discarded MR. number

Interpolation method

Filter calculation

Measurement Report Preprocessing


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Initial discarded MR. number

Avoiding the access period measurement report influence power

control accuracy, system discards some initial measurement report.

HW II: discard 4 initial MR. fixedly.

HW III: set it via [SdMrCutNum/TchMrCutNum]

MR. interpolation method

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

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


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Data Configuration of Initial Discarded

MR. Number


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MR. filter calculation

Quality filter

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

correspondence relationship with CIR as below table.

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


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MR. filter calculation

filter algorithm: exponent filter and slide window filter

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


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Filter algorithm

Slide window filter

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

ca_filtered (k) = [ca_filtered 1(1)++ca_filtered1 (k)] / k 1


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Data Configuration of Filter (DL)


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Power Control Judgment

During HW III power control judgment, system will calculate

radio channel gain.

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_lev Useful signel Interference

C/I qa_filtered(k)= c(k) I(k) (2)

c(k) = p(k) g(k) (3)

(1)


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Radio channel gain calculation:

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

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


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Power Control Judgment 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]

BsTxMaxPowerthe 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.


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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) >0then step(k) =0;


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Data Configuration of Power Control Judgment


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Adjustment protection

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

DownStep/UpStep]is used to control the maximum power

control step.

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 powercontrol command step(k).


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Data Configuration of Power Control Step


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HW III Power Control Features

Exponent filter enhance the measurement report process speed.

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.

Difference quality threshold be set for the difference service, such

as AMR, FS and HS.


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Given condition

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

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

HWIII is availabledata configuration is as following:

ULRexLevHighThred30

ULRexLevLowThred20

ULFSRexQualHighThred20

ULFSRexQualLowThred16

ULRexLevAdjustFactor4ULRexQualAdjustFactor6

ULMAXDownStep8ULMAXUpStep8

QuestionWhat 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


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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


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Contents

3. HW III Power Control Algorithm

3.1 HW III Power Control Algorithm

3.2 HW III Power Control Optimization Algorithm


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HW III PC Optimization Algorithm

The basic process of HW III PC optimization algorithm is almostthe same as the HW III PC algorithm, including MR preprocessing,

PC step calculation, PC implementation, etc.

The improvement for HW III power control optimization algorithm:

MR power control compensation (available for RXLEV and RXQUAL) Dual-coefficient filter algorithm can achieve fast increasing and slow

decreasing

The power control step calculation adopt dual factors to protect low

RXLEV area.

Update the formula of power control step calculation.

HW III PC O ti i ti Al ith D t


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HW III PC Optimization Algorithm--Data

Configuration


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MR Power Control Compensation

MR power control compensation means compensate the RXLEVand RXQUAL to the values corresponding to the maximum

transmit power.

ca_comp(k) = ca(k) + PowerComp

qa_comp(k) = qa(k) + PowerComp

PowerComp indicates the decrease on the maximum transmit power

of BTS or MS

For Uplink PCPowerComp = min(MsTxPower, MsPoweMax)

PowerUsedUL(k-1)

For Downlink PCPowerComp = 2*PowerLev(k-1)


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Dual-coefficient Filter

HW PC III optimization algorithm adopts exponent filter, but the calculation offactor A is different with PC algorithm III. And it adopts dual-coefficient for

MR filtering.

ca_filtered (k) =(1-A)*ca_comp (k) + A*ca_filtered (k-1)

If ca_comp (k) < ca_filtered1 (k-1), L=B; Otherwise L= FiltAdjustFactor*B

qa_filtered (k) =(1-A)*qa_comp (k) + A*qa_filtered (k-1)

If qa_comp (k) < qa_filtered1 (k-1), L=B; Otherwise L= FiltAdjustFactor*B

A = (1.012*L-0.7505)/(L+1.848)

B: [DLRexLevExponentFilterLen], [DLRexQualExponentFilterLen],

[ULRexLevExponentFilterLen], [ULRexQualExponentFilterLen]

FiltAdjustFactor: [III UL Filter Adjust Factor], [III DL Filter Adjust Factor]


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ca_filtered (k) =(1-A)*ca_comp (k) + A*ca_filtered (k-1) If ca_comp (k) < ca_filtered (k-1), L=B; Otherwise L= FiltAdjustFactor*B

ca_comp (k) < ca_filtered (k-1) means RxLev is worse,

L=B 1), that is L decreases

For A = (1.012*L-0.7505)/(L+1.848) ,when L decreases, A decreases too, while(1-A )

increases,

That is:ca_comp (k) has higher weight than ca_filtered (k-1) , then the result

ca_filtered (k) is lower RxLev.

Example to Dual-coefficient Filter

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-60dBm

0.8(-80dBm)+0.2(-70dBm)=-78dBm(after dual-coefficient Filter)

0.5(-80dBm)+0.5(-70dBm)=-75dBm(without dual-coefficient Filter)

-75dBm

-78dBm

fast increasingslow decreasing

Expected Power

SS SS


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ca_filtered (k) =(1-A)*ca_comp (k) + A*ca_filtered (k-1) If ca_comp (k) < ca_filtered (k-1), L=B; Otherwise L= FiltAdjustFactor*B

ca_comp (k) >=ca_filtered (k-1) means RxLev is better

L=FiltAdjustFactor*B>B (Attention, FiltAdjustFactor>1), that is L increases

For A = (1.012*L-0.7505)/(L+1.848) ,when L increases, A increases too, while(1-A )

decreases,

That is:ca_comp (k) has smaller weight than ca_filtered (k-1) , then the result

ca_filtered (k) is lower RxLev.

Example to Dual-coefficient Filter

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0.2(-70dBm)+0.8(-80dBm)=-78dBm(after dual-coefficient Filter)

0.5(-80dBm)+0.5(-70dBm)=-75dBm(without dual-coefficient Filter)

-60dBm

-75dBm-78dBm

fast increasingslow decreasing

Expected Power

SS

SS

Dual coefficient Filtering Data


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Dual-coefficient Filtering--Data

Configuration


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Power Control Step Calculation

HW PC III optimization algorithm adopts two sets of factors, and it can help thesystem to avoid too low transmit power.

step1(k) = - { RexLev Protect Factor *( ca_filtered(k) - SThr) + RexQual Protect

Factor *( qa_filtered (k) - QThr)}

step2(k) = - { sfactor *( ca_filtered(k) - SThr) + qfactor *( qa_filtered (k) - QThr)}

step (k) = max(step1(k)step2(k))

If step (k) >0, then step (k) =0

Power Control Step Calculation Data


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Power Control Step Calculation--Data

Configuration


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Content




4. Other Algorithms


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Contents

4. Other Algorithms

4.1 SAIC Power Control


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Introduction to SAIC

SAIC: Single Antenna Interference Cancellation

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)

The MSs can bear more serious radio environment after

supporting SAIC.

The SAIC capability is indicated by Classmark 3 message.


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SAIC Power Control

If the MS support SAIC, the system can decrease the DLexpected receive quality level automatically.

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

optimization.

DL Quality

Upper

ThresholdDL Quality

Lower

Threshold

DL Quality

UpperThresholdDL Quality

Lower

Threshold

Power Control

Threshold Adjust for

SAIC

For Normal

MS

For SAIC capable

MS

SAIC Power Control Data


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SAIC Power Control-- DataConfiguration


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Summary

In this course, we have learned: Power control procedure

HW II power control algorithm and its data configuration

HW III power control algorithm and its data configuration

HW III power control optimization algorithm and its data configuration

Active Power Control and its data configuration

SAIC power control and its data configuration


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4- omo133030 bsc6900 gsm v9r13 power control algorithm and parameters issue 1.01.ppt

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