cap06 power control
DESCRIPTION
Optimizacion GSMTRANSCRIPT
1 © Nokia Siemens Networks
BSSPAR1: Chapter 6Power Control
2 © Nokia Siemens Networks
Legal Notice
Intellectual Property Rights
All copyrights and intellectual property rights for Nokia Siemens Networks training documentation, product documentation and slide presentation material, all of which are forthwith known as Nokia Siemens Networks training material, are the exclusive property of Nokia Siemens Networks . Nokia Siemens Networks owns the rights to copying, modification, translation, adaptation or derivatives including any improvements or developments. Nokia Siemens Networks has the sole right to copy, distribute, amend, modify, develop, license, sublicense, sell, transfer and assign the Nokia Siemens Networks training material.
Individuals can use the Nokia Siemens Networks training material for their own personal self-development only, those same individuals cannot subsequently pass on that same Intellectual Property to others without the prior written agreement of Nokia Siemens Networks .
The Nokia Siemens Networks training material cannot be used outside of an agreed Nokia Siemens Networks training session for development of groups without the prior written agreement of Nokia Siemens Networks.
3 © Nokia Siemens Networks
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
• Discuss, how power control and traffic channel allocation are modified by power optimisation
• AMR Power Control is presented in chapter on AMR
4 © Nokia Siemens Networks
• Longer service time of battery• Realization of power class• Supported by default on UL
Reduced interference on DL/UL
Activation of DL power control
powerCtrlEnabled (PENA) Y,N
Power control independent
• for DL and UL• for each call
Power Control Motivation
5 © Nokia Siemens Networks
30 dB Range
Power classdependentrange
Attenuations
Power Values
Maximum MS output power
msTxPwrMaxGSM (PMAX1) 5..39 dBm GSM 900 TCHmsTxPwrMaxGSM1x00 0..36/32,33 dBm GSM 1800/1900 TCH (PMAX2)msTxPwrMaxCCH (TXP1) 5..39 dBm GSM 900 CCHmsTxPwrMaxCCH1x00 0..30 dBm GSM 1800 CCH(TXP2) 0..32 dBm GSM 1900 CCH
Minimum MS output power
minMSTxPower (PMIN) 5..39 dBm GSM 9000..36 dBm GSM 18000..32 dBm GSM 1900
Maximum BTS output power (by minimum attenuation)
bsTxPwrMax (PMAX1) 0..30 dB GSM 900bsTxPwrMax1x00 (PMAX2) 0..30 dB GSM 1800/1900
Minimum MS output power (by maximum attenuation)
bsTxPowerMin 0..30 dB
Power Control ParameterOutput Power Limits
6 © Nokia Siemens Networks
Fixed increment step size
• powerIncrStepSize (INC) 2,4,6 dB
Fixed decrement step size
• powerDecrStepSize (RED) 2,4,6 dB
Desired power level can be achieved in 1 or 2 commands
Yes
Fixed step size
No
Variable step size
Power Control ParametersPower Change Step Sizes
7 © Nokia Siemens Networks
UL Level
UL Quality <Av_RXQUAL_UL>
<Av_RXLEV_UL>
DL Level
DL Quality <Av_RXQUAL_DL>
<Av_RXLEV_DL>
POWER CONTROLUPLINK
POWER CONTROLUPLINK
THRESHOLD COMPARISON
POWER CONTROLDOWNLINK
POWER CONTROLDOWNLINK
Power control interval
powerCtrlInterval (INT) 0..31 s
Power Control StrategyMeasurement Averaging
8 © Nokia Siemens Networks
threshold
Actual average samples
Nx samplesLess than Px samples exceed thresholdNo power change triggered
Nx samplesPx samples are equal to or exceed thresholdPower change triggeredSignal level thresholds
pcUpperThresholdLevelDL/UL (UDR/UUR) -110..-47 dBmpcLowerThresholdLevelDL/UL (LDR/LUR) -110..-47 dBm
Signal quality thresholds
pcUpperThresholdQualDL/UL (UDR/UUR) 0..7pcLowerThresholdQualDL/UL (LDR/LUR) 0..7
Number of average samples (for each threshold)
Nx 1..32Px 1..32
Power change step size estimation
Power Control StrategyTriggering
9 © Nokia Siemens Networks
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
Power Control StrategyScenarios
10 © Nokia Siemens Networks
pcLowerThresholdsLevelDL/UL
Power control triggeredUL: 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
Power Increase Due to Signal LevelFor MS & BTS
11 © Nokia Siemens Networks
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 (VDLS) = No
Power Decrease Due to Signal LevelFor BTS
12 © Nokia Siemens Networks
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
Power Decrease Due to Signal LevelFor MS
13 © Nokia Siemens Networks
pcLowerThresholdsQualDL/UL
Power control triggeredUL: 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
Power Increase Due to Signal QualityFor MS & BTS
14 © Nokia Siemens Networks
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(different for MS & BTS power decrease)
Power Decrease Due to Signal QualityFor MS & BTS with No Power Optimization
15 © Nokia Siemens Networks
Lower Level Upper Level
Upper Quality
Lower Quality
Power decrement due to quality Power increment due to level
Power Decrease Due to Signal QualityPing Pong Effect
16 © Nokia Siemens Networks
Power Control Summary
Lower Level Upper Level
Upper Quality
Lower Quality
No actionPower decreasedue to level
Power increasedue to quality
Power increasedue to levelor quality
Power increasedue to quality
Power decreasedue to levelor quality
Power increasedue to level
Power decreasedue to quality6 dB
Power increasedue to level
Qual 0
Qual 7
-110 dBm -47 dBm
17 © Nokia Siemens Networks
Maximum decrement step size in dependence on signal quality
pwrDecrLimitBand0 (PD0) 0..38 dB used for quality 0pwrDecrLimitBand1 (PD1) 0..38 dB used for quality 1pwrDecrLimitBand2 (PD2) 0..38 dB used for quality 2
and worse
Enable power decrement below optimum level for UL
powerDecrQualFactor (PDF) 0,1 enabled, if set to 1
Activation of power optimisation
optimumRxLevDL (LEVD) -109..-47 dBmoptimumRxLevUL (LEV) -109..-47 dBm
Power Control ParametersPower Optimization
TRX Level
BTS Level
18 © Nokia Siemens Networks
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 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 Decrease Due to Signal QualityWith Power Optimization
19 © Nokia Siemens Networks
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
TCH AllocationWith Power Optimization
20 © Nokia Siemens Networks
Optimization of MS Power LevelIn call setup
MS_TXPWR_OPT =
MsTxPwrMaxGSM(BTS) - MAX( 0,( RXLEV_UL - OptimumRxLevUL ))
• RXLEV_UL is measured during the initial signalling period of call set-up
• RXLEV_UL is the uplink signal level when the mobile station is transmitting at the maximum RF power that an MS is permitted to use on a channel in the serving cell.
21 © Nokia Siemens Networks
Optimization of MS Power LevelIntra-BSC handover
• When the handover to be performed is an inter-cell handover, the optimisation is controlled by the parameter MS pwr opt level(n).
• When the handover to be performed is an intra-cell handover, the optimisation is controlled by the parameter optimum RX level uplink.
MS_TXPWR_OPT(n) =
MsTxPwrMaxGSM(ADJ)(n) - MAX(0,(AV_RXLEV_NCELL(n) - MsPwrOptLevel(n)))
• AV_RXLEV_NCELL(n) is the averaged downlink signal level of the adjacent cell (n)
• MsPwrOptLevel(n) (POPT) is set for each adjacent cell
MS_TXPWR_OPT = MsTxPwrMaxGSM(BTS) -
MAX( 0,(AV_RXLEV_UL_HO+(MsTxPwrMaxGSM(BTS)-MS_TXPWR)-OptimumRxLevUL) )
• OptimumRxLevUL (LEV) is set for every TRX
Inter-Cell
Handover
Intra-Cell
Handover
22 © Nokia Siemens Networks
AMR Power Control
Exceeded threshold Action ReasonAMR Power Control FR PC Lower Threshold DL Rx Qual
BTS power increase Poor DL signal quality
AMR Power Control FR PC Lower Threshold UL Rx Qual
MS power increase Poor UL signal quality
AMR Power Control FR PC Upper Threshold DL Rx Qual
BTS power decrease Good DL signal quality
AMR Power Control FR PC Upper Threshold UL Rx Qual
MS power decrease Good UL signal quality
AMR Power Control HR PC Lower Threshold DL Rx Qual
BTS power increase Poor DL signal quality
AMR Power Control HR PC Lower Threshold UL Rx Qual
MS power increase Poor UL signal quality
AMR Power Control HR PC Upper Threshold DL Rx Qual
BTS power decrease Good DL signal quality
AMR Power Control HR PC Upper Threshold UL Rx Qual
MS power decrease Good UL signal quality
AMR FR
AMR HR
Details in chapter on AMR
23 © Nokia Siemens Networks
AMR Progressive Power Control
• AMR PPC provides mechanism to change quality thresholds depending on used power level so that it favours increase of power with low power levels and avoid increase of power with higher power levels. Following results are striven by this:
• Better power distribution - introducing less interference to the network
• Better quality distribution - yielding to better speech codec distribution
Details in chapter on AMR