NSN BSSPAR Power Control

6-90384v 1.0

© Nokia Oyj 1 (40)

BSSPAR

Power ControlTraining Document

BSSPAR- Power Control

6-90384v 1.0

© Nokia Oyj 2 (40)

The information in this document is subject to change without notice and describes only the product defined in the introduction of this documentation. This document is intended for the use of Nokia Networks' customers only for the purposes of the agreement under which the document is submitted, and no part of it may be reproduced or transmitted in any form or means without the prior written permission of Nokia Networks. The document has been prepared to be used by professional and properly trained personnel, and the customer assumes full responsibility when using it. Nokia Networks welcomes customer comments as part of the process of continuous development and improvement of the documentation.

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Copyright © Nokia Oyj 2003. All rights reserved.


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Contents

1 Module Objectives.................................................................... 4

2 Introduction To Power Control ................................................ 52.1 Strategy...................................................................................... 52.2 PC Threshold Comparison And PC Command ........................... 7

3 Power Control Algorithms ..................................................... 113.1 MS/BTS Power Increase Due To Signal Level.......................... 123.2 MS/BTS Power Increase Due To Signal Quality ....................... 153.3 BTS Power Decrease Due To Signal Level .............................. 183.4 BTS Power Decrease Due To Signal Quality ............................ 203.5 MS Power Decrease Due To Signal Level ................................ 243.6 MS Power Decrease Due To Signal Quality ............................. 263.7 MS Power Optimisation ............................................................ 303.8 Conclusions.............................................................................. 31

4 Power Control Exercise.......................................................... 33

5 Key Learning Points ............................................................... 34

6 Review Questions................................................................... 37


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1 Module ObjectivesAt the end of the module, the participant will be able to:

• State the purpose and the important considerations for power control in GSM networks

• List the steps involved in the power control process

• Explain the difference between fixed and variable power-change step-size

• Discuss the Power Control Algorithms that are used to increase or decrease the MS or BTS transmit power based on received signal levels and quality

• Name the parameters that are used for Power Control


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2 Introduction To Power Control In a communication link, when one side is received well by the other side, it is beneficial to reduce the transmit power by a suitable amount. This is to maintain the quality of the communication link while at the same time reducing the interference caused on other calls in surrounding areas, thus increasing the spectral efficiency and capacity of the network. Uplink power control also extends the mobiles' battery endurance. Power control refers to the mechanism that is used to modify, within some limits, the transmit power of the radio at the Mobile Station, and Base Station.

In GSM, uplink and downlink power control is carried out independently. Furthermore, power control is applied independently on each mobile call or transaction. Depending on the MS power class, the range of power levels specified for uplink power control is between 20 and 30 dB of attenuation in steps of 2 dB. The range used for downlink control is manufacturer dependent and in steps of 2 dB.

An operator may choose to apply power control in one direction, in both directions, or none at all. However, all MS must support power control to comply with the GSM specs.

Thus, power control is used for two purposes:

a) Decrease the power consumption of each Mobile Stations in the uplink direction and hence achieve a longer serving time for the Mobile Station rechargeable battery

b) Decrease interference in both uplink and downlink directions by using the lowest possible transmitting power in the Mobile Station and BTS, so increasing network capacity and spectral efficiency.

2.1 Strategy

Power control can be used in the downlink direction in every TRX, except in a TRX with the BCCH RTSL. This is because each MS is continually measuring the RX level of the adjacent cell BCCH’s in any one of the RTSL of the BCCH TRX, and because the BTS has to send system information messages continuously at full planned power on the BCCH to all MS in the cell and neighbouring cells. The Mobile Station can use power control on each frequency continuously, if needed.

In order to use BTS power control, the parameter PowerCtrlEnabled (PENA)(POC) should be enabled on a cell by cell basis by the operator.

When using power control, enough margin has to be reserved for Rayleigh fading and it has to be taken into account that handover always has higher priority than power control.


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REASONS

• Optimize Uplink and Downlink QOS � decrease interference

• Decrease power consumption of the Mobile

STRATEGY

• Handled by the BSC

• Enough margin against Rayleigh fading

• HO has always higher priority than POC

• Controlled by interval

• Increase and decrease act independently (can be fixed or variable step size)

• BTS and MS apply Power Control independently

• BCCH TRX doesn't use Power Control

• DL/UL Power Control can be disabled

• Initial POC level used by MS in new cell after HO, is determined by the BSC - default is max permitted level:MsTXPwrMaxGSM (PMAX1)(BTS)(5..43)(33dB) for GSM850-900MsTXPwrMaxGSM (PMAX2)(BTS)(0..36)(30dB) for GSM1800-1900and when accessing the CCH of a cell:MsTXPwrMaxCCH (TXP)(BTS)(5..43/0..30/0..32)(33/30/30dB) for GSM850-900/1800/1900

• Optionally POC/HOC processes can optimise the initial RF power in case of intra BSC HO


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2.2 PC Threshold Comparison And PC Command

After every SACCH multiframe period, the BSC compares each of the processed measurement results (averages) with the relevant power control thresholds.

Measurements Measurements

BtsMeasAverage

AveragingWindow SizeAdjCellAllAdjacentCellsAveragedNumberOfZeroResults

AveragingAveraging

AveragingAveraging

BookkeepingBookkeeping

ho/pc_Averaging_Lev/Qual_UL/DLWindowSize

WeightmsDistanceAveragingParameter

WIndowSize

DTXMode

Measurements Measurements

Power Control ?

EnaFastAveCallSetupEnaFastAvePCEnaFastAveHOMS + BTS

MS

Figure 1. Overview

If the power control (PC) threshold comparison indicates that the MS or the BTS needs an increase or decrease in RF power, then the BSC sends a PC command to the MS/BTS including the new transmission power level of the MS/BTS.

When the BSC defines the new transmission power level of the MS, it takes into account both the RF power capability and the revision level of the MS. The BSC may send the PC command simultaneously both to the MS and the BTS or to one of them. Power control for the MS and BTS runs independently.

The minimum and maximum MS transmission powers are determined on cell-by-cell basis. The maximum transmission power that an MS may use in the serving cell is controlled by the parameter msTxPwrMax… The minimum MS transmission power is controlled by the parameter minMSTxPwr (PMIN)(BTS).

The maximum transmission power of the BTS is controlled by the parameter BsTxPwrMax (PMAX)(POC). The parameter BsTxPwrMin (PMIN)(POC)indicates the minimum transmission power of the BTS.


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powerControlInterval 0 … 30 secpowerIncrStepSize 2, 4, 6 dBpowerRedStepSize 2, 4 dBpowerControlEnabled Y / N

Parameter Value

Uplink Level

Uplink Quality AV_RXQUAL_UL_PC

AV_RXLEV_UL_PC

Downlink Level

Downlink Quality AV_RXQUAL_DL_PC

AV_RXLEV_DL_PC

POWER CONTROL

UPLINK

POWER CONTROL

UPLINK

THRESHOLD COMPARISON

Separate Averaging Parameters For Handover and for Power Control

POWER CONTROL

DOWNLINK

POWER CONTROL

DOWNLINK

POCINTERVAL

Figure 2. Overview

The range of the BTS transmission power is 30 dB to 0 dB of attenuation applied to the maximum peak power of the base station. The parameter PowerCtrlEnabled (PENA)(POC) indicates whether the BTS power control is enabled. When the power control is enabled, it concerns every transceiver of the BTS with the exception of the BCCH (broadcast control channel) transceiver which always transmits with the maximum power level (parameter BsTxPwrMax (PMAX)(POC)).

In order to prevent repetitive power changes for the same MS/BTS, there is a timer for the minimum time interval between the changes in the RF output power level. The timer is controlled by the parameter PowerControlInterval (INT)(POC), which is the minimum interval between the changes in the RF power level. The averaging and PC threshold comparison do not stop during this time but the PC commands are not possible.

The BSC observes the power changes from the measurement results it receives from the BTS. The measurement result includes the RF power level, which the MS and the BTS have used during the previous SACCH multiframe period. If the MS does not change its output power in time, the BSC sends the PC command once more. The power control of the MS does not stop even if the MS did not change its RF output power. If the BTS does not change its output power with the first PC command, the BSC does not send any further PC commands to the BTS.

The measurement results (uplink or downlink) preceding the MS/BTS power change are not valid after the power change. If the scaling of measurement results is disabled (selected by means of the parameter EnaFastAvePC


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(EFP)(HOC), the averaging and threshold comparison based on those measurement results (uplink/downlink) must start from the beginning after the power change (this concerns both Handover and Power control).

When the scaling of measurement results is enabled, the BSC scales the relevant measurement results preceding the power change so that they correspond to the new transmission power level of the MS/BTS and thus the averaging and threshold comparison can continue without interruption, with the exception of the PC threshold comparison which always starts from the beginning after the power change.

Parameter Value pcUpper/LowerThresholdsLevUL

rxLevel px nx

pcUpper/LowerThresholdsLevDL rxLevel

px nx

pcUpper/LowerThresholdsQualUL rxQual

px nx

pcUpper/LowerThresholdsQualDL rxQual

px nx

-110 ...-47 dBm1 ... 321 ... 32

-110 ... -47 dBm1 ... 321 ... 32

0 ... 71 ... 321 ... 32

0 ... 71 ... 321 ... 32

Figure 3. POC Parameters

LowerLEV UpperLEV

UpperQUAL

LowerQUAL

Applicable in both Downlink and Uplink Directions

Figure 4. Safety Region


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bsTxPwrMax 0 … 30 dBbsTxPwrMin 0 … 30 dBminMsTxPower 0 … 36 dBmmsTxPwrMax 0 … 36 dBm

Parameter Value

30 dB Range

System Dependent Range

Attenuations

Power Values

Figure 5. Power Control Ranges


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3 Power Control AlgorithmsOnce the comparison of the averaged values with the corresponding thresholds has indicated the need for the MS or the BTS to increase or decrease their transmission power, the BSC has to determine the size of the increase/decrease.

This size is calculated by the Power Control algorithm, starting from a fixed power change step size, on the basis of the averaged values, of the relevant thresholds and in some cases of the current (non-averaged) measured values.

Fixed power change step size is selected by means of the parameter powRedStepSize (RED)(POC)(2 or 4 dB), which impacts on the size of the step for the decrease of the MS/BTS transmission power, and the parameter powIncrStepSize (INC)(POC)(2, 4 or 6 dB), which impacts on the size of the step for the increase of the MS/BTS transmission power.

In some cases the size of the increase or decrease corresponds to the fixed power change step size, while in other cases a variable power change step size is calculated from the fixed power change step size.

The BSC uses a variable power change step size for increasing and decreasing the MS transmission power and for increasing the BTS transmission power in such situations where the required power change is so large that the use of the fixed step size would require several power control commands and a lot of time.

By using the variable power change step size instead of the fixed step, it is possible to reach the required power level in one step. A detailed explanation of the variable power change step size can be found in the flowcharts below.


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3.1 MS/BTS Power Increase Due To Signal Level

IFAV_RXLEV_UL/DL_PC <=PcLowerThresholdsLevUL/DL

THENMS/BTS power increase due to signal level

IFRXLEV_UL/DL + 2 *PowIncrStepSize <=PcLowerThresholdsLevUL/DL

THENPWR_INCR_STEP =PcLowerThresholdsLevUL/DL - RXLEV_UL/DL

ELSEPWR_INCR_STEP = PowIncrStepSize

PowerControlIinterval

Figure 6. MS / BTS power control due to signal level

The parameters pcLowerThresholdsLevUL and pcLowerThresholdsLevDL are used in comparison with the averaged values of uplink/downlink signal level to trigger the power control. Both thresholds are composed of three parts:

RxLev (-110 … -47 dBm) is the threshold level to be compared with the averaged level.

Nx (1 … 32) is the total number of averages to be taken into account before decision is possible.

Px (1 … 32) is the number of averages out of total averages that have to be lower than or equal to the threshold, before power increase is possible.

As described by Figure 6, the BSC compares the averaged measurement result AV_RXLEV_UL/DL_PC with pcLowerThresholdsLevUL/DL.

AV_RXLEV_UL/DL_PC <= PcLowerThresholdsLevUL/DL

If this condition is met for Px averaged values out of Nx, then the power control is triggered.

When the power control is triggered, the power increase step size is calculated based on the distance from the relevant threshold. The variable power change step size is used in the following signal strength conditions:


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RXLEV_UL/DL + 2* PowIncrStepSize <= PcLowerThresholdsLevUL/DL

In such case the size of the variable power change step PWR_INCR_STEP is calculated in the following way:

PWR_INCR_STEP = PcLowerThresholdsLevUL/DL - RXLEV_UL/DL

• If RXLEV_UL+ 2*PowIncrStepSize ≤≤≤≤PcLowerThresholdsLevUL

�� PWR_INCR_STEP =PcLowerThresholdsLevUL- RXLEV_UL

(Variable step size)

• Else

�� PWR_INCR_STEP = PowIncrStepSize

• RXLEV_UL is the current signal levelmeasured by the BTS

• RXLEV_UL <> AV_RXLEV_UL_PC ( usedfor threshold comparison)

PcLowerThresholdsLevUL

Power Control Triggered

Figure 7. MS Power Increase Due to Signal Level

• If RXLEV_DL + 2*PowIncrStepSize <=PcLowerThresholdsLevDL

• PWR_INCR_STEP =PcLowerThresholdsLevDL -RXLEV_DL

• (Variable step size)

• Else• PWR_INCR_STEP =

PowIncrStepSize

• RXLEV_DL is the current signal levelmeasured by the MS

• RXLEV_DL <> AV_RXLEV_DL_PC(used for threshold comparison)

PcLowerThresholdsLevDL


Figure 8. BTS Power increase due to signal level

In other cases the power increase step size is taken equal to the powIncrStepSize (INC)(POC)(2, 4 or 6 dB).


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In other words if two "regular" steps are not enough to go above the lower thresholds then a variable step is used to increase the transmission power and bring the received level at the threshold.

It should be noted that RXLEV_UL/DL is the current uplink signal level measured by the BTS/MS and not the averaged value. This is due to the fact that the averaged values tend to follow the raw measurements with a certain delay that is longer when the averaging windows gets large.


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3.2 MS/BTS Power Increase Due To Signal Quality

The parameter powerCtrlEnabled (PENA)(POC) enables the BTS power increase.

The following parameters pcLowerThresholdsQualUL and pcLowerThresholdsQualDL are used in comparison with the averaged values of uplink/downlink signal quality to trigger the power control.

RxQual (0 … 7) is the threshold level for the MS/BTS power increase. The range is from 0 to 7



The BSC compares the averaged measurement result AV_RXQUAL_UL/DL_PC with PcLowerThresholdsQualUL/DL.

AV_RXQUAL_UL/DL_PC => PcLowerThresholdsQualUL/DL

If this condition is met Px times out of Nx then the power control is triggered.

NOTE: For 14.4 kbit/s data (see High Speed Circuit Switched Data and 14.4 kbit/s Data Services in BSC /13/), the BSC compares the averaged measurement result AV_RXQUAL_UL_PC with the power control threshold pcLowerThresholdsQual144 instead of the "standard" pcLowerThresholdsQualUL.

The BSC always uses a variable power change step size for increasing the MS/BTS transmission power due to signal quality.

The BSC is able to calculate the variable power change step size by means of two alternative algorithms, taking into account the cause of the bad signal quality. The cause in fact may be interference or low signal level; in order tocope with the most significant cause of bad quality, the BSC selects the largest step size.

The first way is based on the distance between the current quality and the relevant threshold:


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• Only variable step size• Two different Algorithms• Largest increase is considered

PWR_INCR_STEP =(1+MAX(0,Qa))*PowIncrStepSizewhereQa = RXQUAL_UL - PcLowerThresholdsQualUL

PWR_INCR_STEP =(1+MAX(0,Qa))*PowIncrStepSizewhereQa = RXQUAL_UL - PcLowerThresholdsQualUL

PWR_INCR_STEP =PcLowerThresholdsLevUL - RXLEV_ULPWR_INCR_STEP =PcLowerThresholdsLevUL - RXLEV_UL

Based on Current Level

Based on Current Quality

IF : RXLEV_UL + 2*PowIncrStepSize< =PcLowerThresholdsLevULIF : RXLEV_UL + 2*PowIncrStepSize< =PcLowerThresholdsLevUL

LARGEST INCREASELARGEST INCREASE

Figure 9. MS Power increase due to signal quality

• Only variable step size• Two different Algorithms• Largest increase is considered

PWR_INCR_STEP = (1+MAX(0,Qa))*PowIncrStepSizewhereQa = RXQUAL_DL - PcLowerThresholdsQualDL

PWR_INCR_STEP = (1+MAX(0,Qa))*PowIncrStepSizewhereQa = RXQUAL_DL - PcLowerThresholdsQualDL

PWR_INCR_STEP = PcLowerThresholdsLevDL - RXLEV_DLPWR_INCR_STEP = PcLowerThresholdsLevDL - RXLEV_DL

Based on Current Level

Based on Current Quality

IF : RXLEV_DL + 2*PowIncrStepSize <= PcLowerThresholdsLevDLIF : RXLEV_DL + 2*PowIncrStepSize <= PcLowerThresholdsLevDL

LARGEST INCREASELARGEST INCREASE

Figure 10. BTS Power increase due to signal quality

PWR_INCR_STEP = (1+MAX (0,Qa)) * PowIncrStepSize

where Qa = RXQUAL_UL/DL – pcLowerThresholdsQualUL/DL

RXQUAL_UL/DL is the current signal quality measured by the BTS/MS and not the averaged value.

The second way is based on the distance between the current received level and the corresponding threshold. This possibility is taken into consideration only when this distance is meaningful, i.e. when

RXLEV_UL/DL + 2* PowIncrStepSize <= PcLowerThresholdsLevUL/DL


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The size of the variable power change step PWR_INCR_STEP is calculated in the following way:

PWR_INCR_STEP = PcLowerThresholdsLevUL/DL - RXLEV_UL/DL

RXLEV_UL/DL is the current uplink signal level measured by the BTS/MS

It should be noted that a low received level doesn't necessarily correlate to bad quality. In such a case, the application of the fixed step in increasing the transmission power can be a reasonable possibility.

When the power control is triggered by quality, the situation is more critical as the radio connection is probably suffering from the transmission power being too low. Therefore, a more aggressive action is taken by the BSC that always applies a variable step. This variable step is affected by the distance of the current quality from the threshold and by the distance of the current level from the relevant threshold.


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3.3 BTS Power Decrease Due To Signal Level

The parameter powerCtrlEnabled (PENA)(POC) should be enabled for BTS power control.

The following parameters pcUpperThresholdsLevDL and pcUpperThresholdsQualDL are used in comparison with the averaged values of downlink signal level and quality measurements to trigger the power control. They are composed of three elements as follows:

The decrease of the transmission power of the BTS due to level is triggered by

RxLev (-110 … -47 dBm) is the threshold level for the BTS power decrease.



The BSC compares the averaged measurement result AV_RXLEV_DL_PC with PcUpperThresholdsLevDL

AV_RXLEV _DL_PC >= PcUpperThresholdsLevDL.

If the condition is met for Px averaged values out of Nx then the power control due to level is triggered.

• if VariableDLStepUse = N�PWR_DECR_STEP = PowRedStepSize (no variable step size)

PcUpperThresholdsLevDL


VariableDLStepUse Y/N

Parameter Value

Figure 11. BTS Power decrease due to signal level


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New BSC specific parameter, VariableDLStepUse (VDLS)(BSC), indicates if the variable step size is used, when downlink power is decreased. The parameter has two values, 'yes' and 'no'. The default value is 'no', in other words the variable step size is not in use.

New TRX specific parameter, OptimumRxLevDL (LEVD)(TRX), indicates the optimum downlink RF signal level which both ensures adequate speech/data quality and does not cause downlink interference. The parameter is used by the power control of the BTS.

The range is from -109 dBm to -47 dBm, the use of the parameter is disabled when the value is 'not used'. The default value is 'not used'.

If VariableDLStepUse = Y



• If RXLEV_DL - 2*PowRedStepSize >=PcUpperThresholdsLevDL

�PWR_DECR_STEP =MIN((RXLEV_DL -PcUpperThresholdsLevDL),10) (Variable step size)• Else

� PWR_DECR_STEP =PowRedStepSize

• RXLEV_DL is the current signal levelmeasured by the MS• RXLEV_DL <> AV_RXLEV_DL_PC ( usedfor threshold comparison )

Figure 12. BTS Power decrease due to signal level

The transmission power of the BTS is decreased of a quantity given by the fixedor variable power change step size, based on the distance between the threshold and the current received value uplink. In other words if

RXLEV_DL - 2* PowRedStepSize >= PcUpperThresholdsLevDL

the transmission power of the BTS is decreased by using the variable power change step size; otherwise, the fixed power change step size is used.

The size of the variable power change step PWR_DECR_STEP is calculated in the following way:

PWR_DECR_STEP = MIN((RXLEV_DL - PcUpperThresholdsLevDL), 101)

RXLEV_DL is the current downlink signal level measured by the MS.

1 It must be noted that the power decrease step is limited to 10 dB at a time due to limitations in some mobile phones.


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3.4 BTS Power Decrease Due To Signal Quality

The parameter powerCtrlEnabled (PENA)(POC) should be enabled for BTS power control.

The parameter pcUpperThresholdsQualDL is used in comparison with the averaged values of downlink quality measurements to trigger the power control. They are composed of three elements as follows:

The decrease of the transmission power of the BTS due to quality is triggered by

RxQual (0 … 7) is the threshold level for the BTS power decrease. The range is from 0 to 7



In the same way AV_QUAL_DL_PC and PcUpperThresholdsQualDL are compared by the BSC.

AV_RXQUAL_DL_PC =< PcUpperThresholdsQualDL.

If the condition is met for Px averaged values out of Nx then the power control due to quality is triggered.

VariableDLStepUse =Y/N (S9 new feature)OptimumRxLevDL = -109…-47 dBm/N

• If VariableDLStepUse = N

�PWR_DECR_STEP = PowRedStepSize (no variable step size)

The decrease in power does not take place if there is the possibility that it would triggerthe threshold PcLowerThresholdsLevDL (the safety margin is 6dB)

Figure 13. BTS Power decrease due to signal quality

The BSC will determine the power change step size by using two alternative algorithms. The algorithm is selected by means of the new parameter


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OptimumRxLevDL (LEVD)(TRX) which is controlled on a transceiver-by-transceiver basis.

There are two different algorithms based on whether OptimumRxLevDL(LEVD)(TRX) is used or not. If the resulting receive level downlink (RXLEV_DL) gets close to PcLowerThresholdLevDL (as a result of the BTS power decrease) there could be a consecutive increase due to level which will lead to triggering the decrease again. To avoid this "ping pong" effect BSC makes sure before decreasing the power due to signal quality, that RXLEV_DL is at least 6 dB higher than the PcLowerThresholdLevDL , i.e. 6 dB Margin is in-built in BSC

Calculation based on non-defined optimum downlink RF signal level

The transmission power of the BTS is decreased of a quantity given by the fixedor variable power change step size, based on the distance between the threshold and the current received value uplink.

If RXLEV_DL – 2 * PowRedStepSize >= PcUpperThresholdsLevDL

the transmission power of the BTS is decreased by using the variable power change step size; otherwise, the fixed power change step size is used.


PWR_DECR_STEP = MIN ((RXLEV_DL - PcUpperThresholdsLevDL), 101)

RXLEV_DL is the current downlink signal level measured by the MS. The parameter PcUpperThresholdsLevDL is the threshold (signal strength) level for the BTS power decrease.

If VariableDLStepUse = Y andIf OptimumRxLevDL = < not defined >• If RXLEV_DL - 2*PowRedStepSize >=


� PWR_DECR_STEP =MIN((RXLEV_DL -PcUpperThresholdsLevDL) ,10)


• Else

� PWR_DECR_STEP = PowRedStepSize

� RXLEV_UL is the current signal level measured by the BTS

1 It must be noted that the power decrease step is limited to 10 dB at a time due to limitations in some mobile phones


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� RXLEV_UL <> AV_RXLEV_UL_PC (used for threshold comparison)

Calculation based on defined optimum downlink RF signal level

If the optimum downlink RF signal level has been defined for the transceiver by means of the parameter OptimumRxLevDL (LEVD)(TRX), the variable power change step size will be based on:

� averaged downlink signal quality

� quality threshold for BTS power decrease

� the optimum downlink RF signal level

� current downlink signal level

In this case, the BSC uses merely a variable power change step size for decreasing the BTS transmission power. The size of the variable power change step PWR_DECR_STEP is calculated in the following way:

PWR_DECR_STEP = MIN ((

MIN (PwrDecrLimit, MAX (MAX (0, RXLEV_DL - OptimumRxLevDL), (PwrDecrQualFactor + MAX (0,Qa)) * PowRedStepSize))), 10)

where Qa = PcUpperThresholdsQualDL - AV_RXQUAL_DL_PC

PWR_DECR_STEP =

MIN ((MIN{PwrDecrLimit, MAX[ MAX (0, RXLEV_DL - OptimumRxLevDL),(PwrDecrFactor+ MAX(0, Qa)) *PowRedStepSize]}),10)

where

Qa = PcUpperThresholdsQualDL - AV_RXQUAL_DL_PC

PWR_DECR_STEP =

MIN ((MIN{PwrDecrLimit, MAX[ MAX (0, RXLEV_DL - OptimumRxLevDL),(PwrDecrFactor+ MAX(0, Qa)) *PowRedStepSize]}),10)

where

Qa = PcUpperThresholdsQualDL - AV_RXQUAL_DL_PC

IF : optimumRxLevDL <> NIF : optimumRxLevDL <> N

If VariableDLStepUse = Y andIf OptimumRxLevDL = defined

Figure 14. Power Decrease Step Calculation

The parameter PwrDecrLimit/Band0-2 is the maximum size of the variable power decrease step:

PwrDecrLimitBand0 (PD0)(POC) indicates the maximum size of the power decrease step when the BTS power is decreased due to signal quality and the averaged signal quality (bit error rate) is better than 0.2% (quality band 0). The values range from 0 to 38 dB with a step size of 2 dB.


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PwrDecrLimitBand1 (PD1)(POC) indicates the maximum size of the power decrease step when the BTS power is decreased due to signal quality and the averaged signal quality (bit error rate) is between 0.2% and 0.4% (quality band 1). The values range from 0 to 38 dB with a step size of 2 dB.

PwrDecrLimitBand2 indicates the maximum size of the power decrease step when the BTS power is decreased due to signal quality and the averaged signal quality (bit error rate) is worse than 0.4 (quality bands from 2 to 7). The values range from 0 to 38 dB with a step size of 2 dB.

AV_RXQUAL_DL_PC is the averaged signal quality band for power control and the parameter PcUpperThresholdsQualDL indicates the quality band which corresponds to the quality threshold for the BTS power decrease

The parameter PwrDecrQualFactor (PDF)(POC) indicates whether the power decrease takes place when the current downlink signal level (RXLEV_DL) is lower than the optimum downlink RF signal level (OptimumRxLevDL) and the averaged signal quality (AV_RXQUAL_DL_PC) equals to the quality threshold PcUpperThresholdsQualDL.

Additionally it should be noted that the power decrease due to quality does not take place if there is a possibility that it would trigger the threshold pcLowerThresholdsLevDL. A safety margin is used which is equal to 6 dB.


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3.5 MS Power Decrease Due To Signal Level

The parameter pcUpperThresholdsLevUL is used in comparison with the averaged values of uplink signal level measurements to trigger the power control. As usual, the threshold is composed of three parts:

rxLev (-110 … -47 dBm) is the threshold level for the MS power decrease.


Px (1 … 32) is the number of averages out of total averages that have to be greater than or equal to the threshold before power decrease is possible

• If RXLEV_UL - 2*PowRedStepSize>=PcUpperThresholdsLevUL

�PWR_DECR_STEP = RXLEV_UL -PcUpperThresholdsLevUL


• Else�PWR_DECR_STEP =

PowRedStepSize

• RXLEV_UL is the current signal levelmeasured by the BTS

• RXLEV_UL <> AV_RXLEV_UL_PC ( used forthreshold comparison )

PcUpperThresholdsLevUL


Figure 15. MS Power decrease due to signal level

The BSC compares the averaged measurement result AV_RXLEV_UL_PC with pcUpperThresholdsLevUL.

AV_RXLEV _UL_PC >= PcUpperThresholdsLevUL.

If at least Px averages out of Nx averages are greater than or equal to the threshold RxLev, the power control due to level is triggered.

The transmission power of the MS is decreased of a quantity given by the fixedor variable power change step size, based on the distance between the threshold and the current received value uplink. In other words if

RXLEV_UL - 2* PowRedStepSize >= PcUpperThresholdsLevUL


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the transmission power of the MS is decreased by using the variable power change step size; otherwise, the fixed power change step size is used.


PWR_DECR_STEP = RXLEV_UL - PcUpperThresholdsLevUL

where (again) the current uplink signal level RXLEV_UL is considered. The reason for using the current value of the uplink level measured by the BTS instead of the averaged value AV_RXLEV _UL_PC, is that the average is always delayed with respect to the raw values and consequently the power decrease might result too small when e.g. the MS is approaching the BTS.


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3.6 MS Power Decrease Due To Signal Quality

Two different algorithms are used based on OptimumRxLevUL (LEV)(TRX)being used or not. If the resulting RXLEV_UL would get too close to PcLowerThresholdLevUL (as a result of the decrease) there could be a consecutive increase due to level, which will lead to triggering the decrease again. To avoid this "ping pong" effect BSC makes sure before decreasing the power due to signal quality that RXLEV_UL is at least 6 dB higher than the PcLowerThresholdLevUL , i.e. 6 dB Margin is in-built in BSC

LowerLEV UpperLEV

UpperQUAL

LowerQUAL

Power decrement due to qualityPower increment due to level

Figure 16. Ping Pong Effect

The parameter pcUpperThresholdsQualUL is used for comparing the averaged values of uplink signal quality measurements for triggering the power control. As all the other thresholds related with power control, this parameter is composed of three parts:

RxQual (0 … 7) is the threshold level for the MS power increase. The range is from 0 to 7




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The condition

AV_RXQUAL_UL_PC <= PcUpperThresholdsQualUL

for at least Px averages out of Nx triggers the power control due to quality.

The BSC determines the variable power change step size by using two alternative algorithms. The algorithm is selected by means of the parameter optimumRxLevUL (LEV)(TRX)(-109 dBm to -47 dBm) which is controlled on a transceiver-by-transceiver basis. OptimumRxLevUL (LEV)(TRX)(-109 dBm to -47 dBm) indicates the optimum uplink RF signal level that is high enough to ensure adequate speech/data quality and low enough to avoid unnecessary uplink interference. The use of the parameter is disabled when the value is 'not used'.

Additionally it should be noted that the power decrease due to quality does not take place if there is a possibility that it would trigger the threshold pcLowerThresholdsLevUL. A safety margin is used which is equal to 6 dB.

IF : optimumRxLevUL = NIF : optimumRxLevUL = N

• if RXLEV_UL - 2*PowRedStepSize >= PcUpperThresholdsLevUL



• else

PWR_DECR_STEP =PowRedStepSize

Same as in the MS Power decrease due toSignal Level,

but Triggered by different condition (quality)

Figure 17. MS Power decrease due to signal quality

OptimumRxLevUL = 'not used'

Fixed step is the default, but if the signal level is very high, besides the excessive signal quality, the variable power change step size is used. In other words if:

RXLEV_UL - 2* PowRedStepSize >= PcUpperThresholdsLevUL

then a variable step is used. The size of the variable power change step is calculated in the following way:



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where RXLEV_UL is the current uplink signal level measured by the BTS and not the averaged value.

PcUpperThresholdQualUL = 1

0

2

4

6

8

10

12

14

16

-109

-107

-105

-103

-101 -99

-97

-95

-93

-91

-89

-87

-85

-83

-81

-79

-77

-75

-73

-71

-69

-67

-65

-63

RxLev_UL

Pwr_Decr_Step

B = Max ( 0 , RXLEV_UL - OptimumRxLevUL ) C = (PwrDecrFactor + Max(0,Qa)) *PwrRedStepSize Min(Max(B;C) , PwrDecrLimit)

• PWR_DECR_STEP = MIN[ PwrDecrLimit, MAX(MAX (0, RXLEV_UL - OptimumRxLevUL),(PwrDecrFactor + MAX(0, Qa)) *PowRedStepSize ) ]

• where Qa = PcUpperThresholdsQualUL - AV_RXQUAL_UL_PC

• PWR_DECR_STEP = MIN[ PwrDecrLimit, MAX(MAX (0, RXLEV_UL - OptimumRxLevUL),(PwrDecrFactor + MAX(0, Qa)) *PowRedStepSize ) ]

• where Qa = PcUpperThresholdsQualUL - AV_RXQUAL_UL_PC

IF : optimumRxLevUL <> NIF : optimumRxLevUL <> N

PwrDecrLimitBand0 : ifAV_RXQUAL_UL_PC = 0

PwrDecrLimit = 10dB



Figure 18. MS Power decrease due to signal quality

The philosophy behind this solution is that the condition of good quality doesn't necessarily correspond to a high-received level and in such a case, the application of the fixed step is a reasonable choice.

If the received level is above the threshold pcUpperThresholdsLevUL , then the step in the power decrease can be easily and safely determined. In this case, the step size calculation is based on a different threshold than the one that triggered the power control.

OptimumRxLevUL <> 'not used'

If the optimum uplink RF signal level has been defined for the transceiver by means of the parameter optimumRxLevUL (LEV)(TRX), the variable power change step size will be based on:

• the averaged uplink signal quality

• the quality threshold for the MS power decrease

• the optimum uplink RF signal level

• the current uplink signal level.


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In this case, the BSC always uses the variable power change step size for decreasing the MS transmission power. The variable step is calculated as follows:

PWR_DECR_STEP = MIN (PwrDecrLimit, MAX (MAX (0, RXLEV_UL -OptimumRxLevUL), (PwrDecrQualFactor + MAX (0,Qa)) * PowRedStepSize))

The formula is quite complicated and can be simplified as follows:

PWR_DECR_STEP = MIN (PwrDecrLimit, MAX (A, B))

The parameter pwrDecrLimit indicates the maximum possible reduction to the power of the MS and in reality takes three different values depending on the value of the averaged quality that triggered the power control.

pwrDecrLimitBand0 (PD0)(POC)(0, 2, … 38) maximum size of the power decrease, when the averaged signal quality (bit error rate) is better than 0.2% (quality band 0).

pwrDecrLimitBand1 (PD1)(POC)(0, 2, … 38) maximum size of the power decrease, when the averaged signal quality (bit error rate) is between 0.2% and 0.4% (quality band 1).

pwrDecrLimitBand2 (PD2)(POC)(0, 2, … 38) maximum size of the power decrease, when the averaged signal quality (bit error rate) is worse than 0.4% (quality bands 2-7)

The term A = MAX (0, RXLEV_UL - optimumRxLevUL), generates a decrease in the MS transmission power that would bring the received level Uplink (not the averaged level, but the current received level) to the optimum level as defined by the parameter optimumRxLevUL (LEV)(TRX)(-109 dBm to -47 dBm). It can be noted that A may be equal to 0.

The term B = (PwrDecrQualFactor + MAX (0,Qa)) * PowRedStepSize

where Qa = pcUpperThresholdsQualUL - AV_RXQUAL_UL_PC

takes into account the distance in quality between the averaged quality and the threshold that triggered the power control. This distance is multiplied by the powRedStepSize (RED) POC)(2 , 4).

The parameter pwrDecrQualFactor (PDF)(POC)(2 , 4) is used to have always B > 0. In fact if Qa=0 and A=0, then the calculation of the variable step gives

PWR_DECR_STEP = PwrDecrQualFactor * PowRedStepSize

The parameter allows the operator to avoid that there is no reduction of transmission power in the MS when good quality uplink is encountered.


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3.7 MS Power Optimisation

• Normally MS accesses the TCH with the maximum Tx Power allowed in the cell:

msTxPwrMax

• When power optimization is employed

MS_TXPWR_ OPT = MsTxPwrMax - MAX ( 0, (RXLEV_UL - OptimumRxLevUL) )

• Parameter OptimumRxLevUL must be defined for each TRX in the cell. If there aredifferent values defined for different TRXs then maximum value is considered in thecalculation.

• RXLEV_UL is measured during signalling phase

OptimumRxLevUL -109 … -47 / N dBm

Parameter Value

Figure 19. Call Set-up

• Normally MS uses the maximum Tx Power allowed in the target cell

msTxPwrMax

• When power optimization is employed

MS_TXPWR_ OPT = MsTxPwrMax - MAX( 0, (AV_RXLEV_UL_HO + (MsTxPwrMax - MS_TXPWR) - OptimumRxLevUL)

• Parameter OptimumRxLevULmust be defined for each TRX in the cell. If differentvalues then maximum is considered

Example: AV_RXLEV_UL_HO= -75 dBm

OptimumRxLevUL= -80 dBm MS_TXPWR_OPT = 33 dBm -MAX( 0, -75 dBm+80 dBm)

MS_TXPWR_MAX= 33 dBm = 33 dBm -5 dB = 28 dBm

MS_TXPWR = 33 dBm

Figure 20. Intracell Handover


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• Normally MS uses the maximum Tx Power allowed in the target cell

msTxPwrMax

• When power optimization is employed;

MS_TXPWR_ OPT(n) = MsTxPwrMax(n) - MAX ( 0, (AV_RXLEV_NCELL(n) - MsPwrOptLevel) )

• Parameter msPwrOptLevel is defined on a per adjacent cell basis

msPwrOptLevel -110 … -47/N dBm

Parameter Value

6 dB

Handover

Serving Cell DL

Adjacent Cell DLAdjacent Cell UL

msPwrOptLevel

• Affects Uplink• Either Uplink signal equalsdownlink signal

• Or Differences in UL / DL considered when defining msOptPwrLevel

Figure 21. Internal Intercell Handover

3.8 Conclusions

When trying to understand the power control algorithm, it should be kept in mind that the whole process is composed of four steps:

• Measurements done by the MS and by the BTS

• Measurement processing in the BSC

• Threshold comparison

• Calculation of the power change

The last step may appear complicated due to the large differentiation in the formulas used by the algorithm. The situation is different when the power control is triggered by quality (good or bad) or by level (high or low) and depending on the transmission power being required for the MS or the BTS.

It is possible to get a more clear idea by noting that in all cases a range of good values is defined by an upper threshold and lower threshold. The power control works tries to keep the received level and the received quality into that range by changing the transmitter power "on the other side" of the radio connection.

In case of power control due to level, the averaged value is out of the range (or on its border) and the action is taken to bring it within the defined band. The variable step is calculated very easily in this case.


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When the quality is out of range, then issue is more complicated because the reason for good (or bad) quality could be a very high (or too low) received power. Therefore, the calculation of the power change step size involves both level and quality.

For the MS, in particular a dedicated parameter optimumRxLevUL (LEV)(TRX) is used to define what can be considered an optimum level to be received by the BTS. When used, this parameter affects the calculation of the step used in the power decrease.

Finally

The power decrease due to quality does not take place if there is a possibility that it would trigger the threshold pcLowerThresholdsLevUL/DL. A safety margin is used which is equal to 6 dB.

The power control of the BTS can be disabled by means of the parameter powerCtrlEnabled (PENA)(POC).


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4 Power Control Exercise1) Look-up the default and recommended values for the thresholds named on

this diagram, and compare those values to the values that are shown on the diagram.

2) State the optimum range of values for RX level & RX quality, for both UL & DL.

0

1

2

3

4

5

6

7

-110

-108

-106

-104

-102

-100 -98

-96

-94

-92

-90

-88

-86

-84

-82

-80

-78

-76

-74

-72

-70

-68

-66

-64

-62

-60

-58

-56

-54

-52

-50 dBmdBm

QualityQuality

RxlevAccMinRxlevAccMinRxlevAccMinRxlevAccMin(n)(n)

PcLowerThresholdLevULPcLowerThresholdLevUL/DL/DL

PcUpperThresholdLevULPcUpperThresholdLevUL/DL/DL

PcLowerThresholdQualULPcLowerThresholdQualUL/DL/DL

PcUpperThresholdQualULPcUpperThresholdQualUL/DL/DL

No Action NeededNo Action Needed

Increase PowerIncrease Power

Decrease PowerDecrease Power

PcUpperThresholdQualUL/DL

Power decrease

No action needed

PcUpperThresholdLevUL/DL

PcLowerThresholdLevUL/DL

PcLowerThresholdQualUL/DLRxLevMinCell(n)

RxLevAccMin

Power increase

Thresholds

Actions

Figure 22. Power Control Thresholds and Actions – Uplink & Downlink


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5 Key Learning PointsPower control (PC): is a method of battery charge endurance improvement and interference reduction. The aim is to maintain a good link quality at lowest possible transmit powers. It can be applied in uplink and downlink direction. It is controlled by the BSC and performed in both base station and mobile station.

When power control is enabled, it concerns every transceiver of the BTS with the exception of the BCCH (broadcast control channel) transceiver which always transmits with the maximum power level. This is because

a) Mobiles detecting a BCCH carrier in the power-up procedure need a constant carrier signal

b) Every MS is also continuously measuring the RX level of the adjacent cell BCCH’s so this signal has to be always at its highest value in every RTSL of the BCCH TRX.

When in dedicated or connected mode, the mobile reports on a regular basis received signal power of the serving cell to the base station. BS commands the mobile to reduce/ increase its transmit power in incremental steps of 2 dB.

Power control can be level-based, quality based or both.

Level-based power control means the BTS aims for a target RX level. Transmit power of mobiles and BS is regulated such, that the received signal is always near the target level.

In order to use BTS power control, an operator should enable it on a cell by cell basis using the parameter Power Control Enabled:

• PowerCtrlEnabled (PENA)(POC)

Power control algorithm is composed of the following steps:

a) Measurements done by the MS and by the BTS and sent to BSC

b) Measurement processing in the BSC

c) Threshold comparison: a threshold is compared with BTS measurements. A range of good values is defined by an upper threshold and lower threshold for signal level and quality for uplink and downlink. The power control works tries to keep the received level and quality into this range by changing the transmitter power

d) Calculation of the power change: comparison indicates that the MS or the BTS needs an increase or decrease in RF power

The BSC sends a PC command to the MS/BTS including the new transmission power level of the MS/BTS

The minimum and maximum MS transmission powers are determined on cell-by-cell basis by the parameters

• MsTxPwrMaxGSM…


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• minsTxPwrMin (PMIN)(BTS)

The maximum and minimum transmission power of the BTS is controlled by the following parameters respectively

• BsTxPwrMax (PMAX)(POC)

• BsTxPwrMin (PMIN)(POC)

The range of the BTS transmission power is from 30 dB to 0 dB of attenuation from the maximum peak power of the base station transmitter.

To prevent repetitive changes of RF output power for the MS/BTS, a minimum time interval between the changes can be set using the parameter:

• PowerControlInterval (INT)(POC)

Fast Averaging for power control allows only measurements after a Power Change to be used for averaging and it is enabled using the parameter:

• EnaFastAvePC (EFP)(HOC))

The BSC determine the size of the increase or decrease of transmit power using fixed step size or variable step size (used in situations where the required power change is so large that the use of the fixed step size would require several power control commands and a lot of time)

Fixed transmit power change step size for MS/BTS is selected using parameter

• powRedStepSize (RED)(POC)(2 or 4 dB)

• powIncrStepSize (INC)(POC)(2, 4 or 6 dB)

Variable transmit power step size is enabled using parameter:

• VariableDLStepUse (VDLS)(BSC)(Yes/No): default value = 'no'

There are a number of possibilities during Power Control

1. The MS/BTS power increase due to signal level is carried out when the following condition is satisfied Px averaged values out of Nx values

AV_RXLEV_UL/DL_PC <= PcLowerThresholdsLevUL/DL

where

• pcLowerThresholdsLevUL : lower threshold parameter for uplink

• pcLowerThresholdsLevDL : lower threshold parameter for downlink

• RxLev (-110 … -47 dBm) : threshold level used for comparison

• Nx (1 … 32) number of averages to be taken into account before decision is possible

• Px (1 … 32) is the number of averages that have to be lower than or equal to the threshold, before power increase is possible


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2. The MS/BTS power increase due to signal quality is carried out when the following condition is satisfied Px averaged values out of Nx

AV_RXQUAL_UL/DL_PC <= PcLowerThresholdsQualUL/DL

where

• pcLowerThresholdsQualUL : lower threshold parameter for uplink

• pcLowerThresholdsQualDL: lower threshold parameter for downlink

• RxQual (0 … 7) is the threshold level for the MS/BTS power increase

3. The BTS power decrease due to signal level is carried out when the following condition is satisfied Px averaged values out of Nx

AV_RXLEV_DL_PC <= PcUpperThresholdsLevDL

where

• pcUpperThresholdsLevUL : lower threshold parameter for uplink

A New TRX specific parameter, OptimumRxLevDL (LEVD)(TRX), indicates the optimum downlink RF signal level which both ensures adequate speech/data quality and does not cause downlink interference. The parameter is used by the power control of the BTS. The range is from -109 dBm to -47 dBm, the use of the parameter is disabled when the value is 'not used'. The default value is 'not used'.

4. The BTS power decrease due to signal quality is carried out when the following condition is satisfied Px averaged values out of Nx

AV_RXQUAL_DL_PC <= PcUpperThresholdsQual DL

Where pcUpperThresholdsQualDL: upper threshold for downlink

5. The MS power decrease due to signal level is carried out when the following condition is satisfied Px averaged values out of Nx

AV_RXLEV_UL_PC <= PcUpperThresholdsLevUL

Where pcUpperThresholdsLevUL : lower threshold for uplink.

6. The MS power decrease due to signal quality is carried out when the following condition is satisfied Px averaged values out of Nx

AV_RXQUAL_UL_PC <= PcUpperThresholdsQualUL

Where pcUpperThresholdsQualUL: upper threshold for downlink.


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6 Review Questions Q1. Which of the following is true about Power Control?

A. It reduces battery lifetime.

B. It results in increased interference.

C. It aims to maintain a good link quality at lowest possible transmit powers.

D. It is downlink direction only.

E. It is performed by BTS in both BSC and mobile station.

Q2. Why is power control not used on the TRX that transmits the BCCH?

A. Mobiles detecting a BCCH carrier in the power-up procedure need a constant carrier signal.

B. Every MS is also continuously measuring the RX level of the adjacent cellBCCH’s so this signal has to be always at its highest value.

C. It can reduce battery lifetime for MS.

D. All of the above

E. Choices A and B.

Q3. Which of the following steps are used in Power control algorithm?

A. Measurements done by the MS and by the BTS and sent to BSC.

B. Measurement processing in the BSC

C. Threshold comparison.

D. Calculation of the power change.

E. All of the above.

Q4. Which parameter does an operator use to enable BTS power control on a cell by cell basis?

A. PowerCtrlEnabled (PENA)(POC).

B. MsTxPwrMax

C. MsTxPwrMin

D. BsTxPwrMax (PMAX)(POC).

E. BsTxPwrMin (PMIN)(POC)


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Q5. Which parameter sets the maximum BTS transmission powers?

A. PowerCtrlEnabled (PENA)(POC).

B. MsTxPwrMax

C. MsTxPwrMin

D. BsTxPwrMax (PMAX)(POC).

E. BsTxPwrMin (PMIN)(POC)

Q6. Why is there a need for a variable step size in Power Control?

A. The BSC determines the size of the increase or decrease of transmit power.

B. Using fixed step size would violate threshold comparison.

C. When the required power change is so large that the it would require several power control commands and hence a lot of time.

D. To prevent repetitive changes of RF output power for the MS/BTS.

E. It is a requirement of fast averaging.

Q7. To prevent repetitive changes of RF output power for the MS/BTS, a minimum time interval between the changes can be set using the parameter

A. VariableDLStepUse (VDLS)(BSC)(Yes/No)

B. powRedStepSize (RED)(POC)(2 or 4 dB)

C. powIncrStepSize (INC)(POC)(2, 4 or 6 dB)

D. EnaFastAvePC (EFP)(HOC))

E. PowerControlInterval (INT)(POC)

Q8, Fast Averaging for power control is enabled using the parameter:







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Q9. Fixed step size for MS/BTS transmit power decrease is selected using parameter






Q10. Fixed transmit power increase step size for MS/BTS is selected using parameter






Q11. Variable transmit power step size is enabled using parameter:






Q12. Which of the following is true about Px and Nx in PC Algorithms?

A. Nx represents lower threshold parameter for uplink.

B. Px represent lower threshold parameter for downlink.

C. They are threshold level used for comparison.

D. Nx is number of averages taken into account before decision is possible.

E. Px is the number of averages that have to be lower than or equal to the threshold, before power change is possible.


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Q13. Which TRX parameter indicates the optimum downlink RF signal level ensures both adequate speech/data quality and does not cause downlink interference

A. PcLowerThresholdsQualUL/DL

B. PcLowerThresholdsQualUL/DL

C. PcUpperThresholdsLevUL

D. PcUpperThresholdsQualDL

E. OptimumRxLevDL (LEVD)(TRX)

Q14. Which threshold parameter is used to decrease MS power due to signal level?

A. PcLowerThresholdsQualUL/DL

B. PcLowerThresholdsQualUL/DL

C. PcUpperThresholdsLevUL

D. PcUpperThresholdsQualDL

E. PcUpperThresholdsQualDL:

Q15. Which condition has to be satisfied for Px averaged values out of Nx when the MS power is decreased due to signal quality?

A. AV_RXLEV_UL_PC <= PcUpperThresholdsLevUL

B. AV_RXQUAL_UL_PC <= PcUpperThresholdsQualUL

C. AV_RXQUAL_UL/DL_PC <= PcLowerThresholdsQualUL/DL

D. AV_RXLEV_DL_PC <= PcUpperThresholdsLevDL

E. AV_RXQUAL_DL_PC <= PcLowerThresholdsQualDL

NSN BSSPAR Power Control

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