Power Margin Optimization

Huawei Technologies Co., Ltd.Nov. 1 2011

Contents

1 Background......................................................................................................4

1.1 Maximum Power Utility.......................................................................................4

2 Analysis...........................................................................................................42.1 Power Margin Introduction...................................................................................4

2.2 Why power margin................................................................................................4

2.3 Optimization Suggestion.......................................................................................5

2.4 Value of Suggestion..............................................................................................5

2.5 Gain Prediction.....................................................................................................5

3 Optimization Trial.........................................................................................63.1 Implementation.....................................................................................................6

3.2 Confirmation of parameter effect..........................................................................6

3.3 KPI Trend for Trial...............................................................................................6

4 Implementation for whole network..............................................................64.1 Implementation.....................................................................................................6

4.2 KPI Summary........................................................................................................7

4.3 Cell Throughput Comparison................................................................................7

4.4 Summary...............................................................................................................7

5 Appendix.........................................................................................................85.1 KPI Detail.............................................................................................................8

Power Margin Optimization

Abstract: This technical paper aims to give the readers meaning of power margin and the

optimization of power margin.

Cell throughput can be improved through power margin based on writers’ experience,

and no deterioration of call drop rate was observed after optimization in E operator’s

UMTS network.

1 Background1.1 Maximum Power Utility

According to RNC performance, the highest of maximum power utility (@Busy Hour) is only

96%, far below 100%. Why doesn’t maximum power utility reach 100%?

Max Power Utility Top10

Cell ID Max Power Utility32327 95.78%13283 94.77%13551 94.77%22290 94.77%23134 94.77%23135 94.77%23221 94.77%23379 94.77%23389 94.77%23461 94.77%

2 Analysis2.1 Power Margin Introduction

There is a parameter named Power Margin in NodeB configuration file. The meaning

of power margin is reserved power for R99 power control within next 2ms when HSDPA

scheduling.

Available HSDPA Power = 1- Power Margin - Non HSDPA Power

The default setting of power margin is 5% of the total power.

2.2 Why power margin

If power margin is 0, cell power utility reaches 100% (30%+70%) when HSDPA scheduling in slot1

UE commands NodeB to increase power in slot2

NodeB could not increase power for R99 user within 2ms because power is fully consumed

Therefore, reasonable reserved power for R99 power control is necessary

2.3 Optimization Suggestion

Parameter Current Setting Suggestion

PWRMGN 5% 1%

The highest of Maximum power utility is 96%, 4% power is left. So 5%

power margin is too big, and 1% power margin is enough

R99 use is very few compared to HSDPA user, so required power

margin for R99 power control is low.

R99 User Number vs HSDPA User NumberUCELL Group R99 User Number HSDPA User Number

tkt06 0.3944 3928.0361

2.4 Impact of Suggestion

Value: The power margin decreases, so the HSDPA available power will increase, so the

HSDPA cell throughput may increase.

Risk: Call Drop rate of R99 service may be affected because there is no enough power

for power control.

2.5 Gain Prediction

Performance DataMean CQI Mean Non-HSDPA Power Utility DL User Throughput(kbps)

17.2 23% 914.6

HSDPA Power Gain: Gain=10*lg((99%-23%)/(95%-23%))= 0.23dB Throughput Gain=93.41*0.23= 21.48kbps (2.3%)

Throughput vs CQI

The above curve is based on plenty of statistics of current network

3 Optimization Trial 3.1 Implementation

On Oct 3rd power margin was modified to 1% for as a trial

Parameter Current Setting Suggestion

PWRMGN 5% 1%

3.2 Confirmation of parameter effect

Max Power Utility Comparison

Max Power Utility obvious increased after parameter optimization.

3.3 KPI Comparison for Trial

UCELL Group Tkt06(1847 cells)Time Before(9.27-10.2) After(10.4-10.9) ComparisonDCR 0.98% 0.95% -0.03%

Cell Throughput(kbps) 2066 2133 3.24%Cell Throughput = VS.DataOutput.Mean / (VS.DataTtiRatio.Mean-VS.HSDPA.InactiveDataTtiRatio.Mean)

Cell throughput increased 3.24% after parameter modification, however DCR no obvious degrade.

4 Implementation for whole network 4.1 Implementation

On Oct 17th power margin was modified for all NodeB.

4.2 KPI Summary

KPI Comparison

Cell throughput increased after parameter modification, however DCR no much change.

4.3 Cell Throughput Comparison

Cell Throughput Trend

4.4 Summary

Cell throughput increased obviously

DCR no much change

Since KPI was improved obviously after optimization, 1% power magin is more reasonable.

5 Appendix 5.1 KPI Detail