Chapter 05_Power_Control_MO_v3.2

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Power Control:

Power Control CHAPTER 5

Legal Notice:

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Module Objectives:

Module Objectives Explain the motivation for power control Indicate the BSS parameters required for power control in general (output power 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, when the 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 by power optimisation

Power Control Motivation:

Power Control 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 UL for each call

Power Control Parameter Output Power Limits:

30 dB Range Power class dependent range Attenuations Power Values Power Control Power Control Parameter Output Power Limits Maximum MS output power msTxPwrMaxGSM 5..39 dBm GSM 900 TCH msTxPwrMaxGSM1x00 0..36/32,33 dBm GSM 1800/1900 TCH msTxPwrMaxCCH 5..39 dBm GSM 900 CCH msTxPwrMaxCCH1x00 0..30 dBm GSM 1800 CCH 0..32 dBm GSM 1900 CCH Minimum MS output power minMSTxPower 5..39 dBm GSM 900 0..36 dBm GSM 1800 0..32 dBm GSM 1900 Maximum BTS output power (by minimum attenuation) bsTxPwrMax 0..30 dB GSM 900 bsTxPwrMax1x00 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

Power Control Parameters Power Change Step Sizes:

Power Control Power Control Parameters Power Change Step Sizes Fixed increment step size powerIncrStepSize 2,4,6 dB Fixed decrement step size powerDecrStepSize 2,4 dB Desired power level can be achieved in 1 or 2 commands Yes Fixed step size No Variable step size

Power Control Strategy Measurement Averaging:

UL Level UL Quality <Av_RXQUAL_UL> <Av_RXLEV_UL> DL Level DL Quality <Av_RXQUAL_DL> <Av_RXLEV_DL> POWER CONTROL UPLINK THRESHOLD COMPARISON POWER CONTROL DOWNLINK Power Control Power Control Strategy Measurement Averaging Power control interval powerCtrlInterval 0..31 s

Power Control Strategy Triggering:

Power Control Power Control Strategy Triggering threshold Actual average samples Nx samples Less than Px samples exceed threshold No power change triggered Nx samples Px samples exceed threshold Power change triggered Signal level thresholds pcUpperThresholdLevelDL/UL -110..-47 dBm pcLowerThresholdLevelDL/UL -110..-47 dBm Signal quality thresholds pcUpperThresholdQualDL/UL 0..7 pcLowerThresholdQualDL/UL 0..7 Number of average samples Nx 1..32 Px 1..32 Power change step size estimation

Power Control Strategy Scenarios:

Power Control Power Control Strategy Scenarios Exceeded threshold Action Reason pcUpperThresholdLevelDL BTS power decrease Signal level pcLowerThresholdLevelDL BTS power increase Signal level pcUpperThresholdLevelUL MS power decrease Signal level pcLowerThresholdLevelUL MS power increase Signal level pcUpperThresholdQualDL BTS power decrease Signal quality pcLowerThresholdQualDL BTS power increase Signal quality pcUpperThresholdQualUL MS power decrease Signal quality pcLowerThresholdQualUL MS power increase Signal quality

Power Increase Due to Signal Level:

Power Increase Due to Signal Level Power Control pcLowerThresholdsLevelDL/UL Power control triggered UL: Power increase of MS DL: 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

Power Decrease Due to Signal Level (BTS):

Power De crease Due to Signal Level (BTS) Power Control pc Upper ThresholdsLevel D L Power control triggered Power de crease Yes Fixed step size PWR_ DECR _STEP = power Decr StepSize No Variable step size PWR_ DECR _STEP = Min ( RXLEV_ D L – pcUpperThresholdLevelDL, 10) Actual received level RXLEV_ D L RXLEV_ D L < pc Upper ThresholdLevel D L + 2 power De crStepSize OR variableDLStepUse = No

Power Decrease Due to Signal Level (MS):

Power De crease Due to Signal Level (MS) Power Control pc Upper ThresholdsLevelUL Power control triggered Power de crease Yes Fixed step size PWR_ DECR _STEP = power Decr StepSize No Variable step size PWR_ DECR _STEP = RXLEV_UL – pcUpperThresholdLevelUL Actual received level RXLEV_UL RXLEV_UL < pc Upper ThresholdLevelUL + 2 power De crStepSize

Power Increase Due to Signal Quality:

Power Increase Due to Signal Quality Power Control pcLowerThresholdsQualDL/UL Power control triggered UL: Power increase of MS DL: 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 – pcLowerThresholdQual DL/UL Step size based on actual level Take algorithm for power increase due to signal level Take largest step size

Power Decrease Due to Signal Quality (No Power Optimisation):

Power Decrease Due to Signal Quality ( N o Power Optimisation) Power Control pcUpperThresholdsQualDL/UL Power control triggered 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

Power Control Summary:

Power Control Lower Level Upper Level Upper Quality Lower Quality Power Control Summary No action Power decrease due to level Power increase due to quality Power increase due to level or quality Power increase due to quality Power decrease due to level or quality Power increase due to level Power decrease due to quality 6 dB Power increase due to level

Power Control Parameters Power Optimisation:

Power Control Power Control Parameters Power Optimisation Maximum decrement step size in dependence on signal quality pwrDecrLimitBand0 0..38 dB used for quality 0 pwrDecrLimitBand1 0..38 dB used for quality 1 pwrDecrLimitBand2 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 dBm optimumRxLevUL -109..-47 dBm

Power Decrease Due to Signal Quality (With Power Optimisation):

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 - <RXQUAL_UL> 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] Power Control Power Decrease Due to Signal Quality (With Power Optimisation)

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