BSSPAR115 Chapter 05 Power Control MO

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NOKIA BSSPAR / 10.05.2004

Power Control

CHAPTER 5


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Module Objectives

Explain the motivation for power control

Indicate the BSS parameters required for power control in general (outputpower levels, fixed step sizes)

Describe the principle steps to be executed for power control (averaging,triggering, power change step size estimation)

Discuss the algorithms used to estimate the power change step size, whenthe power has to be increased / decreased due to signal level / quality

Explain the motivation for power optimisation

Indicate the BSS parameters required for power optimisation additionally

Discuss, how power control and traffic channel allocation are modified bypower optimisation


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PowerControl

Power Control Motivation

Longer service time of battery

Realization of power class

Reduced interference on DL/UL

Activation of DL power control

powerCtrlEnabled Y,N

Power control independent

for DL and ULfor each call


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30 dBRange

Powerclassdependentrange

Attenuations

Power Values

PowerControl

Power Control ParameterOutput Power Limits

Maximum MS output power

msTxPwrMaxGSM 5..39 dBm GSM 900 TCHmsTxPwrMaxGSM1x00 0..36/32,33 dBm GSM 1800/1900TCHmsTxPwrMaxCCH 5..39 dBm GSM 900 CCHmsTxPwrMaxCCH1x00 0..30 dBm GSM 1800 CCH

0..32 dBm GSM 1900 CCH

Minimum MS output power

minMSTxPower 5..39 dBm GSM 9000..36 dBm GSM 18000..32 dBm GSM 1900

Maximum BTS output power (by minimum attenuation)

bsTxPwrMax 0..30 dB GSM 900bsTxPwrMax1x00 0..30 dB GSM 1800/1900

Minimum MS output power (by maximum attenuation)

bsTxPowerMin 0..30 dB

Additional attenuation for super reuse TRx

bsTxPowerOffset 0..30 dB


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PowerControl

Power Control ParametersPower Change Step Sizes

Fixed increment step size

powerIncrStepSize 2,4,6 dB

Fixed decrement step size

powerDecrStepSize 2,4,6 dB

Desired power level can be achieved in 1 or 2 commands

Yes

Fixed step size

No

Variable step size


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UL Level

UL Quality

DL Level

DL Quality

POWER CONTROLUPLINK

THRESHOLDCOMPARISON

POWER CONTROLDOWNLINK

PowerControl

Power Control StrategyMeasurement Averaging

Power control interval

powerCtrlInterval 0..31 s


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PowerControl

Power Control StrategyTriggering

threshold

Actual average samples

Nx samples

Less than Px samples exceed thresholdNo power change triggered

Nx samplesPx samples exceed thresholdPower change triggered

Signal level thresholds

pcUpperThresholdLevelDL/UL -110..-47 dBmpcLowerThresholdLevelDL/UL -110..-47 dBm

Signal quality thresholds

pcUpperThresholdQualDL/UL 0..7

pcLowerThresholdQualDL/UL 0..7

Number of average samples

Nx 1..32Px 1..32

Power change step size estimation


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PowerControl

Power Control StrategyScenarios

Exceeded threshold Action Reason

pcUpperThresholdLevelDL BTS power decrease Signal levelpcLowerThresholdLevelDL BTS power increase Signal levelpcUpperThresholdLevelUL MS power decrease Signal levelpcLowerThresholdLevelUL MS power increase Signal level

pcUpperThresholdQualDL BTS power decrease Signal qualitypcLowerThresholdQualDL BTS power increase Signal qualitypcUpperThresholdQualUL MS power decrease Signal qualitypcLowerThresholdQualUL MS power increase Signal quality


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Power Increase Due to Signal LevelPowerControl

pcLowerThresholdsLevelDL/UL

Power control triggered

UL: Power increase of MSDL: Power increase of BTS

RXLEV_DL/UL > pcLowerThresholdLevelDL/UL - 2 powerIncrStepSize

Yes

Fixed step size

PWR_INCR_STEP = powerIncrStepSize

No

Variable step size

PWR_INCR_STEP = pcLowerThresholdLevelDL/UL RXLEV_UL/DL

Actual receive level RXLEV_DL/UL


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Power Decrease Due to Signal Level(BTS)

PowerControl

pcUpperThresholdsLevelDL

Power control triggeredPower decrease

Yes

Fixed step size

PWR_DECR_STEP = powerDecrStepSize

No

Variable step size

PWR_DECR_STEP = Min (RXLEV_DL pcUpperThresholdLevelDL, 10)

Actual received level RXLEV_DL

RXLEV_DL < pcUpperThresholdLevelDL + 2 powerDecrStepSize OR

variableDLStepUse = No


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Power Decrease Due to Signal Level(MS)

PowerControl

pcUpperThresholdsLevelUL

Power control triggeredPower decrease

Yes

Fixed step size

PWR_DECR_STEP = powerDecrStepSize

No

Variable step size

PWR_DECR_STEP = RXLEV_UL pcUpperThresholdLevelUL

Actual received level RXLEV_UL

RXLEV_UL < pcUpperThresholdLevelUL + 2 powerDecrStepSize


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Power Increase Due to Signal QualityPowerControl

pcLowerThresholdsQualDL/UL


UL: Power increase of MSDL: Power increase of BTS

Actual receive quality RXQUAL_DL/UL

Variable step size based on actual quality

PWR_INCR_STEP = (1 + Max (0,QUAL)) * powerIncrStepSize

QUAL = RXQUAL_DL/UL

pcLowerThresholdQualDL/UL

Step size based on actual level

Take algorithm for power increase due to signal level

Take largest step size


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Power Decrease Due to Signal Quality(No Power Optimisation)

PowerControl

pcUpperThresholdsQualDL/UL


Actual received quality RXQUAL_DL/UL

Actual RXLEV_DL/UL pcLowerThresholdLevelDL/UL < 6 dB

Yes No

No power decrease

Avoid ping pong effect

Power decrease

Take algorithm for power decrease due to signal level

S Q


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Lower Level Upper Level

Upper Quality

Lower Quality

Power decrement due to quality Power increment due to level

PowerControl

Power Decrease Due to Signal Quality(Ping Pong Effect)


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PowerControl

Lower Level Upper Level

Upper Quality

Lower Quality

Power Control Summary

No action Power decreasedue to level

Power increase

due to quality

Power increase

due to levelor quality

Power increase

due to quality

Power decreasedue to levelor quality

Power increasedue to level

Power decreasedue to quality6 dB

Power increasedue to level

P C t l P t


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PowerControl

Power Control ParametersPower Optimisation

Maximum decrement step size in dependence on signal quality

pwrDecrLimitBand0 0..38 dB used for quality 0pwrDecrLimitBand1 0..38 dB used for quality 1pwrDecrLimitBand2 0..38 dB used for quality 2 and worse

Enable power decrement below optimum level for UL

powerDecrQualFactor 0,1 enabled, if set to 1

Activation of power optimisation

optimumRxLevDL -109..-47 dBmoptimumRxLevUL -109..-47 dBm

P D D t Si l Q lit


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Power decrease step size for MS

PWR_DECR_STEP = Min (pwrDecrLimit, Max (A,B))

A = Max (0, RXLEV_UL - optimumRxLevUL)

B = (powerDecrQualFactor + Max (0,QUAL)) * powerDecrStepSize

with QUAL = pcUpperThreshold -

Term A: Would bring actual receive level exactly to optimum level

Term B: Considers difference between average receive quality and threshold quality

Power decrease step size for BTS

PWR_DECR_STEP = Min [Min (pwrDecrLimit, Max (A,B)),10]

PowerControl

Power Decrease Due to Signal Quality(With Power Optimisation)

TCH All ti


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PowerControl

TCH Allocation(With Power Optimisation)

MAX_INTF_LEV = max (min (RXLEV_UL + msTxPrwMax - MS_TXPWR, optimumRxLevUL),

RXLEV_UL + msTxPrwMin- MS_TXPWR) - cnThreshold

MAX_INTF_LEV = max (min (AV_RXLEV_NCELL (n) - rxLevBalance, optimumRxLevUL(n)),

AV_RXLEV_NCELL (n) - rxLevBalance+

msTxPrwMin (n)- msTxPrwMax (n)) - cnThreshold (n)

Call set up or intra cell handover

Inter cell handover

Modified maximum acceptable interference level

BSSPAR115 Chapter 05 Power Control MO

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