gsm zte p&o training material for special subject-power controlv2.0

8/2/2019 GSM ZTE P&O Training Material for Special Subject-Power ControlV2.0

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GSM P&O Training Materials for Special SubjectsPower Control

Suitable for staff with P&O skill certificate IV or lowerIssued by GSM Network P&O Dept.


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Internal Use Only

Training goals

To know the aim of power control

To master the types and process of

power controlTo understand power control algorithms

To master the setting and application ofpower control parameters


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Contents

Overview of Power Control

ZTE Power Control Algorithms

Power Control Parameters & Application


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Aim of power control

What is power control?

Why should we carry outpower control?

Definition: Power control is to adjust the transmitting power of BTS and MSaccording to real needs. Base: result of UL/DL measurementGoal: to lower transmitting power, reduce interference in the whole network and power consumption, on condition that speech quality is ensured.


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Main body of power control


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Overall flow of power control

Collection of MS/BTSmeasurement reports

Weighted average of MRs

If the average satisfies conditions of power control decision?

Condition forpower increase is satisfied

Condition for powermaintenance is satisfied

Condition for powerdecrease is satisfied

Increase MS/BTStransmitting power

Maintain MS/BTStransmitting power

Decrease MS/BTStransmitting power

Save the averageNo

Yes


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Scenarios of power control application

Normally UL ordinary power control is enabled.

Other power control types are mainly applied in areas withdense sites, which can help reduce interference.

This table is for reference only. Setting of power control shall be in

accordance with actual network situations.


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Influence of power control - KPI

It improves RQ0-4 ratio and MOS;It helps reduce call drops;

It may have positive effects on other KPIs, such as assignment

success rate, HO success rate, etc.;It may impose some negative effects on the level of coverage,

and result in dramatic decrease in the proportion of level

above -75dbm;

Inappropriate setting of power control may lead to deterioration

of KPIs.


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Contents





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Power control algorithms supported in ZTE BSS

UL and DL fastpower control arenot discriminated inversion 6.20 andprevious ones.


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Features of ZTE BSS power control algorithms


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Process of MRS ( I)Perform sliding-window processing according to window size;

Adopt weighted averaging in the averaging process;Enable fast averaging to shorten the time of the first power control triggering;Use the original MRs in the initial state.


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Process of MRS ( II) weighted-averagingRxLev Sum = Lev off *Weight+ Lev on*1

Weighted average=Sum/ n*weight+m*1 Lev off : the level value at DTX off

Lev on : the level value at DTX on

Weight: =preset value at DTX off ; =1 at DTX on

m : number of MRs at DTX onn : number of MRs at DTX off

Example:

The current window size is set 3, weight is 2;Take RxLev as an example, the Rxlev reported by three MRsare:- 80dBm DTX off -70dBm DTX on -82dBm DTX off

Weighted average=[(-80)*2+(-82)*2+(-70)*1]/(2+2+1)=-78.8dBm


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Power control decision (I)

High level

Low level

Low quality rank High quality rank

Level HO threshold

Quality HO

Increase power

Decrease power

Maintain power

Margin

Poor signal qualityGood signal quality


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Power control decision (II)

LEVELCAUSE QUALCAUSE Conclusion

0 0 POWER_STAY 0 1 DECREASE_BYQUALITY 0 2 INCREASE_BYQUALITY 1 0 INCREASE_BYLEVEL 1 1 INCREASE_BYLEVEL1 2 INCREASE_ BYQUALITY 2 0 DECREASE_BYLEVEL 2 1 DECREASE_BYLEVEL 2 2 INCREASE_BYQUALITY

LEVELCAUSE Explanation

1 Among a certain number (N) of level values, at least a certainnumber (P) of them are lower than the lower limit of levelthreshold.

2 Among a certain number (N) of level values, at least a certainnumber (P) of them are higher than the higher limit of levelthreshold.

0 Others

QUALCAUSE Explanation

1 Among a certain number (N) of RQ values, at least a certainnumber (P) of them are lower than the higher limit of qualitythreshold.

2 Among a certain number (N) of RQ values, at least a certainnumber (P) of them are higher than the lower limit of qualitythreshold.

0 Others


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Setting of power control step (I)


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Setting of power control step (II)


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Setting of power control step (III)

Graph of UL ordinary

power control:

Graph of UL ordinary

power control with fastaveraging adopted:

Graph of UL rapidpower control:


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Improvement on power control algorithms (I)


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Internal Use Only Improvement on power control algorithms (II) MS initialstate

MS initial state:Power control decision can be performed based on each MR.Increase MS PowerSet to avoid the delay of three MRs.Add protection conditions to prevent excess power adjustment(sub


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Internal Use Only Improvement on power control algorithms (III) BTS initialstate


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Internal Use Only Improvement on power control algorithms (IV) conversionbetween initial state and stable state

Initial state

MS power stops downward modulation for N1 times

Stable stateChannel release

Number of MRs received reaches N2

Channel power control entersinitial state


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Internal Use Only Improvement on power control algorithms (V) process ofinitial state MRs

W

1st average

1st PwrCtrl duration under stable state:: (W+N-1)MRs

2nd average

Nth average

1st average

Nth average

2nd PwrCtrl duration : N MRs

W

PwrCtrl duration

Receive MRs (N) Receive MRs (N)

Clear out the measurement results in initial state;

Adopt sliding-window averaging and weighted-averaging mechanism;Rapid averaging is applicable in stable state;Keep the measurement results of last PwrCtrl, and take them into the calculationof next PwrCtrl average.


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Internal Use Only Improvement on power control algorithms (VI) PingpongPwrCtrl

Pingpong PwrCtrl can be caused by histeresis of three MRs, as shown in thefollowing figure.It can also be caused by the condition of low level and high quality.

P n

PwrCtrl decision: decrease power, send new power rank P

P

PwrCtrl decision: increase power

High level

Low level

Solution:When PwrCtrl decision is to decrease power, make compensation to the actualpower value, and judge whether after the adjustment the power will be less thanthe lower level threshold.


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Measurement of power control result


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PwrCtrl parameters- power adjustment threshold


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PwrCtrl parameters- window & weight


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PwrCtrl parameters- power adjustment step


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Internal Use Only PwrCtrl parameters- power conversion N1/N2parameters

N1 is fixed to be 4

N2 can be adjusted through PcMinInterval; PcMinInterval default= 2means N2=11 MRs.


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PwrCtrl parameters- max/min power limit

900M

1800M


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Internal Use Only PwrCtrl parameters- rapid PwrCtrl & decreasingvalue


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PwrCtrl parameters- rapid averaging

1st average 3rd average2nd average

1st PwrCtrl duration

1st average of 2nd pwrCtrldecision

2nd PwrCtrl

1rd average of 2nd pwrCtrldecision

2nd average of 2nd pwrCtrldecision


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General cares of setting PwrCtrl parameters

l O l


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Recommended values of PwrCtrl parametersThe recommended values are for reference, please make appropriateadjustment according to actual network situations.

Parameter Recommended value

versionsprevious to 6.20.101e

6.20.101e&subsequentversions

Average window size 4 4 UL/DL RQ increase threshold 3 2 UL/DL RQ increase P/N value 2/3 2/3

UL/DL RQ decrease threshold 1 0 UL/DL RQ decrease P/N value 2/3 2/3

UL/DL level increase / decrease threshold default

default

UL/DL level increase / decrease P/Nvalue 2/3 2/3

Increase step 4db 4db

Decrease step 2db 2db Rapid averaging Enabled Disabled

Rapid power control Enabled DisabledPower decrease limit 10 8 6 4 2 2 2 2 default

Power control min interval 1 0 MS min power rank 18 900M 14 1800M) 18 900M 14 1800M) BS min power rank 15(900M) 14 1800M 15(900M) 14 1800M

I l U O l


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Factors influencing PwrCtrl speed


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gsm zte p&o training material for special subject-power controlv2.0

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