19560434 microsoft power point 5 omf010003 power control issue1

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Power Control


Contents

1. Power Control Overview

2. HWⅡPower Control


Power Control Overview

� Power control

� Adjust the transmitting power of BTS and MS when needed.

� Based on measurement reports of BTS and MS

� Purpose

� Save the power of BTS and MS

� Reduce the interference of the network

� Increase the quality of the network



� Power control includes uplink power control and downlink

power control, Which are performed independently

� Uplink power control: Adjust TX power of MS to let BTS receive

stable signal, reduce the uplink co-channel and adjacent

channel interference, reduce power consumption of MS

� Downlink power control: Adjust BTS TX power to let MS receive

stable signal, reduce the downlink co-channel and adjacent

channel interference, reduce power consumption of BTS



� Process of power control commands

� It takes 3 measurement report periods(480ms/period) from

command sending to execution.

SA0 SA1SA0 SA0SA1SA1 SA2SA2SA2 SA3SA3SA3

BTS sends the command for power

control and TA in SACCH header.

MS obtains SACCH

block

MS begins to send the

measurement report of the

last multi-frame.

In the 26 multi-frames,

frame 12 sends

SACCH.

BTS receives the

measurement report

SACCCH report period:

26X4=104 frames (480ms)

MS adopts the new

power level and TA

MS begins to set up a new SACCH header

to report the new TA and power control

message.



� Power control judgment

� Power control judgment is controlled by BTS measurement

report pre-processing item which can be selected in handover

control data table

� MR. Pre-process (measurement report pre-processing): This

switch decide where power control be processed. If

measurement report pre-processing is “yes”, power control is

processed in BTS, and when setting it “no”, power control is

processed in BSC



� Up link and Down link power control can be enabled

independently


Contents

1. Power Control Overview

2. HWⅡⅡⅡⅡ Power Control


� Original data of power control -- measurement report

Network

Downlink Downlink measurement measurement

reportreport

Uplink MRUplink MR

BTS

HW II Power ControlHW II Power Control


Uplink Uplink

measurement measurement

reportreport

Downlink Downlink

measurement measurement

reportreport


� Measurement report


� Measurement report pre-processing -- interpolation

� Each measurement report has a serial number. When the

serial numbers are discontinuous, this indicates that some

measurement reports must be missed. In this case, the

network will fill up the measurement report according to

interpolation algorithm.

MR MR MR MR MR

Measurement report serial number n

Measurement report

serial number n+4

Consecutive measurement report flow

3 missing measurement reports3 missing measurement reports



� Measurement report pre-processing -- filtering

� Calculate average results of several consecutive measurement

reports to obtain the current information, reduce the influence

of some abnormal measurement reports for the judgment of

power control.

MRMR MRMR MR MR

Consecutive measurement report flow

FilterFilter



HW II Power Control

� Power control judgment process

Measurement report pre-processing

The power control

demand according to the

receiving level

Send the power control command

The power control

demand according

to receiving quality

General power control judgement


HW II Power Control

� Measurement report compensation

� Purpose: Ensure the accuracy of selection of the history measurement

report before filtering.

� Implementation steps:

� 1. Put the current receiving measurement report into the measurement report

compensation queue.

� 2. Record the changed information of the transmitting power according to the

MS and BTS power levels in the measurement report.

� 3. After finish the measurement report interpolation, system will compensate

the receiving level of the history measurement report according to the power

change information. The compensated measurement reports will be the

original data in the filter process.

� 4. Filter the compensated measurement reports.


HW II Power Control

� Measurement report compensation

The expected receiving signal level: 30

The power control will be more effective with measurement report compensation.


The power control will be more effective with measurement report compensation.

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xis

Power control diagram when there is measurement report compensation

Diagram when there is no power control

Power control diagram when there is no measurement report compensation

Power control effect diagram of measurement report compensation


HW II Power Control

� Measurement report prediction

� Purpose: Avoid power control later than needed, the delay is

dangerous in case of poor level or bad quality

� Implementation procedure

� 1. Analyze the tendency of MR by the historical measurement

reports after interpolation.

� 2. Guide by the tendency, to predict the values of measurement

report to be received. There are 0~3 measurement reports

prediction, which are configured on OMC.

� 3. Filter the interpolated, compensated and predicted

measurement reports, and implement power control judgment.


HW II Power Control� Measurement report prediction

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xis

No power control

Mean filter power

control

Prediction filter power

control

Diagram of power control effect comparison between prediction filter and mean filter


The power control with prediction filter will be more effective than that with

mean filter


The power control with prediction filter will be more effective than that with

mean filter


HW II Power Control Implementation

� Power control demand based on receiving level.

� After measurement report pre-processing, the power control

module makes a comparison between the expected signal

level and the current receiving signal level.

� Calculate the transmitting power level step size to be adjusted,

making the receiving level value closer to the expected value.

� Adopt variable step size when adjusting the transmitting power

according to the receiving level, so as to achieve the expected

level as soon as possible.



� Power control demand based on receiving quality

� After measurement report pre-processing, the power control module

makes comparison between the expected quality level and the current

receiving quality level.

� Calculate the step size of the transmitting power level to be adjusted.

� Increase the transmitting power in case of poor receiving quality.

� Decrease the transmitting power in case of good receiving quality.

� Adopt fixed step size when adjust the transmitting power according to

the receiving quality.



� General power control judgment

Power control by receiving

level

Power control by receiving

quality

Power control by signal level and

quality

↓ AdjStep_Lev ↓ AdjStep_Qul ↓ max(AdjStep_Lev,AdjStep_Qul)

↓ AdjStep_Lev ↑ AdjStep_Qul No action

↓ AdjStep_Lev No action ↓ AdjStep_Lev

↑ AdjStep_Lev ↓ AdjStep_Qul ↑ AdjStep_Lev

↑ AdjStep_Lev ↑ AdjStep_Qul ↑ max(AdjStep_Lev,AdjStep_Qul)

↑ AdjStep_Lev No action ↑ AdjStep_Lev

No action ↓ AdjStep_Qul ↓ AdjStep_A

No action ↑ AdjStep_Qul ↑ AdjStep_B

No action No action No action


HW II Power Control Feature

� Adaptive power control:

� Adaptive power control refers to changeable power control

strategy according to the communication environment, it makes

power control more effective and stable.

� Automatically change the adjustable maximum step size of power

control according to different communication environment

(different receiving quality).

� Adopt different power control strategies according to different

communication environments (different receiving quality and level).

� Max. step is different between increase and decrease.


HW II Power Control Feature

� Power control within the upper/lower thresholds

� As for HW II power control in case of calculating power

control step size according to signal level and quality, the

signal level and quality have upper/lower thresholds. Power

control will not execute if the signal level and quality is within

the threshold bands.

� Avoid the signal level up-and-down caused by power control.

� The upper threshold can be increased dynamically in case of

bad quality.


� Measurement report compensation -- makes power control

judgment more accurate

� Measurement report prediction --to avoid power control later

than needed, the delay is dangerous in case of poor level or

bad quality

� Power control expected signal level and quality threshold

falls within a band, this avoids receiving signal level

fluctuate up and down frequently

HW II Power Control Advantages


HW II Power Control Configuration

[HW II power control table] main parameters [HW II power control table] main parameters –– 1 1

Parameter name

Meaning Value range

Recommended value

filter length for UL

RX_LEV

How many uplink measurement reports obtained for the average uplink signal level to be used for uplink power control adjustment.

1~20 6

filter length for DL

RX_LEV

How many downlink measurement reports obtained for the average downlink signal level to be used for downlink power control adjustment.

1~20 6

filter length for UL Qual.

How many uplink measurement reports obtained for the average uplink quality level to be used for uplink power control adjustment.

1~20 6

filter length for DL Qual.

How many downlink measurement reports obtained for the average downlink quality level to be used for downlink power control adjustment.

1~20 6

MR compensation

allowed

If “yes”, System put the currently received measurement report into the measurement report compensation queue, and record the transmitting power information according to MS and BTS power values. And then interpolation, compensate the receiving level value of the record measurement report according to the power change information.

Yes, no Yes

UL MR number

predicted

The number of uplink pred. MR in the filter using for power control judgment.

0~3 reports

2

DL MR number

predicted

The number of downlink pred. MR in the filter using for power control judgment.

0~3 reports

2



[HW II power control table] main parameters [HW II power control table] main parameters –– 22

Parameter name

Meaning Value range

Recommended value

PC interval Time between two power control command implementation 1~30

(SACCH period)

5

UL RX_LEV upper

threshold

This parameter specifies the uplink signal level upper threshold. When the signal level higher than this value, calculate a power

decrement [=receiving level - (upper threshold + lower threshold)/2]. This decrement value should consider together with

the maximum step size allowed for different quality zone which the receiving signal quality located.

0~63 (-110 dBm

– -47 dBm) 35

UL RX_LEV lower

threshold

This parameter specifies the uplink signal level lower threshold. When the signal level lower than this value, calculate a power

increase [= (upper threshold + lower threshold)/2- receiving level]. This increase also consider together with the maximum step size

allowed for different quality zone which the receiving signal quality located.

0~63 (-110 dBm

– -47 dBm) 25

UL Qual. upper

threshold This parameter specifies the uplink quality upper threshold.

Level 0~7

0

UL Qual. lower

threshold

This parameter specifies the uplink quality lower threshold for power control

Level 0~7

2




Parameter name

Meaning Value range

Recommended value

DL RX_LEV upper threshold

This parameter specifies the downlink signal level upper threshold. When the signal level higher than this value, calculate a power decrement [=receiving level – (upper threshold + lower threshold)/2]. This decrement should consider together with the maximum step size allowed for different quality zone which the receiving signal quality located.

0~63 (-110 dBm –

-47 dBm) 40

DL EX_LEV lower threshold

This parameter specifies the downlink signal level lower threshold. When the signal level lower than this value, calculate a power increase [= (upper threshold + lower threshold)/2- receiving level]. This increase also consider together with the maximum step size allowed for different quality zone which the receiving signal quality located.

0~63 (-110 dBm –

-47 dBm) 30

DL Qual. upper threshold

This parameter specifies the downlink quality upper threshold for power control

Level 0~7 0

DL Qual. lower threshold

This parameter specifies the downlink quality lower threshold for power control

Level 0~7 2



Parameter name

Meaning Value range Recommended

value

MAX Down Adj. value Qual.

zone 0

This parameter specifies the maximum downward power adjustment value when the Rx quality is 0.

0~30dB 16


zone 1

This parameter specifies the maximum downward power adjustment value when the Rx quality is 1 or

2 0~30dB 8


zone 2

This parameter specifies the maximum downward power adjustment value when the Rx quality is

equal to or more than 3. 0~30dB 4

MAX Down Adj. PC Value by

Qual.

The adjustment step allowed for the downward power control due to receiving signal quality.

0~4dB 4





Parameter name


value

MAX Up Adj. PC Value by

RX_LEV

It is used to set the maximum adjustment step for upward power control by receive level.

0~32dB 16

MAX Up Adj. PC Value by

Qual.

It is used to set the maximum adjustment step for upward power control by receive quality.

0~32dB 8

UL Qual. Bad TrigThrsh

In uplink power control, when the receiving quality of uplink is not less than this start threshold, the

actual "upper threshold of signal strength of uplink" will be added with "upper threshold offset of level when the receiving quality of uplink is poor" in the

data configuration. Thus, the expected level in uplink power control can be increased furthermore.

0~7 5

UL Qual. Bad UpLEVDiff

In uplink power control, when the receiving quality is not less than "start threshold when the receiving

quality of uplink is poor", the actual "upper threshold of signal strength of uplink" will be added with this

offset value.

0~63dB 0




Parameter name


value

DL Qual. Bad TrigThrsh

In downlink power control, when the receiving quality of downlink is not less than this start

threshold, the actual "upper threshold of signal strength of downlink" will be added with "upper

threshold offset of level when the receiving quality of downlink is poor" in the data configuration. Thus, the expected level in downlink power control can be

increased furthermore.

0~7 5

DL Qual. Bad UpLEVDiff

In downlink power control, when the receiving quality is not less than "start threshold when the receiving quality of downlink is poor", the actual

"upper threshold of signal strength of downlink" will be added with this offset value.

0~63dB 0


� Exercises for HW II power control

� Given conditions:

� The uplink receiving level is -55dBm, the quality is level 0. Power control

algorithm is HW II.

� Data configuration is as follows: Uplink signal level upper threshold: -

60dBm, uplink signal level lower threshold: - 80dBm. Uplink signal upper

quality threshold: level 1. Uplink signal lower quality threshold: level 2. The

downward adjustable step size of quality band 0 is 16dB, of quality band 1

is 8dB, and of quality 2 is 4 dB. The upward adjustable step size of

receiving level is 16dB. The upward or downward adjustable step size for

power control by quality are both 4dB.

� Question: What will be the uplink stable receiving level after power

control?

ExerciseExercise


Exercise


� Answer.

� First, transmitting power to be reduced according to receiving level =

actual receiving level -(uplink signal level upper threshold + uplink signal

level lower threshold)/2 ＝-55- (-60 + (-80))/2＝(-55)-(-70)＝15dB. As the

receiving quality is level 0, downward adjustable step size of quality band 0

can be used -- decrease 16dB.

� Second, the transmitting power to be decreased according to receiving

quality = as “power control adjustment step size by quality” is 4dB, thus

decrease 4dB.

� Therefore, according to the general judgement on power control, 15dB

should be decreased.


Exercise


� Answer .

� After the implementation of step 1 power control, the receiving

level becomes: -55dBm-15dB= -70dBm, Suppose the quality reach

already in level 1 here.

� First: the receiving level value is between -80dBm~-60dBm,

needn’t adjust.

� Second: the receiving quality value is between 0 and 2, needn’t

adjust.

� Therefore, the uplink stable receiving level =-70dBm.

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