2g power control issue1.5

OMD0560 Power control ISSUE1.1Power Control
Contents
Power Control Overview
Adjust the transmitting power of BTS and MS when needed.
Based on measurement reports of BTS and MS
Purpose
Reduce the interference of the network
Increase the quality of the network
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
1. During handover, MS will access the target cell with the maximum transmitting power (associated with handover command) allowed by the target cell. But if “MS power prediction after HO” is enabled, then MS will use the optimized power to access the target cell.
2. During intra-cell handover, the current power will be retained.
3. Power control can be implemented on TCH carriers only, BCCH carrier is not allowed power control. Because MS needs to measure the receiving level of BCCH from the adjacent cell. It will be inaccurate when power control is performed on BCCH.
4. Power control is performed independently for each channel.
It takes 3 measurement report periods(480ms/period) from command sending to execution.
SA0
SA1
SA0
SA0
SA1
SA1
SA2
SA2
SA2
SA3
SA3
SA3
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.
When MS accesses the network via RACH channel, its transmitting power is the “MS max. TX power level”, which is gotten from the system information on BCCH. MS sends the first message on dedicated channel also uses the “MS max TX power level” ,this is not under the control of the system before the power control command which is carried on SACCH of SDCCH or TCH. The implementation procedure is as following:
1. According to the uplink receiving level and receiving quality reported by BTS, and considering the maximum transmitting power of MS, BSC calculates the proper transmitting power for the MS.
2. Power control command and the TA value will be transmitted to MS at layer 1 header carried by each downlink SACCH block.
3. MS receives the power control command carried by SACCH header at the end of each SACCH report period, Then MS will carry out the command in the beginning of next report period. MS can change power 2dB per 13 frames (60ms) maximum.
4. After MS executed the power control command, it will set the current power class at the layer 1 message header of the next uplink SACCH, and transmit it to BTS in the measurement report. Therefore, it will take 3 measurement report periods for the new power class (in each power control command) to be available.
Note: Each integral SACCH message block (measurement report) is composed of 4 burst. A power control implementation process in whole takes the time of 3 measurement reports.
Huawei power control algorithm: HW I and HW II power control
Measurement report pre-processing
algorithm
HWII power control is developed based on HWI. It’s more sensitive and the data configuration is simpler. For details, see later sections.
Huawei can support GSM0508 power control algorithm.
Power control judgment and the selection of HWI algorithm or HWII algorithm
Power control algorithm selected in power control data table
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
Set pre-processing “yes” is to reduce the signaling load in Abis interface.
i.e.:
1.If Abis E1 is in 15:1 mode, it should be set “yes”, otherwise the Abis capacity for speed is not enough;
2.BTS22C 0110 version should be set “No”;
3.Satellite transmission BTS should be set “yes”;
4.We should consider few type of BTS has relationship with HWI algorithm and HWII algorithm, please check the product manual.
Contents
HW I Power Control
HW I power control
MR pre-processing
Comparison of uplink power control with downlink power control
Process of HW I power control
Measurement report pre-processing
HW I Power Control
In HWI power control, after the BSC or BTS performs pre-processing (interpolation and filtering) on the original measurement report, it will start HWI power control algorithm, and send the power control command.
HWI power control can be separate into initial mode and stationary mode, system will consider signal strength only in initial mode,and consider both signal strength and quality in stationary mode.
Original data of power control -- measurement report
Network
HW I Power Control
The original data of power control is from measurement report. MS submits a measurement report to the network on SACCH channel every 480ms, the content reported by MS is the downlink measurement values which received by MS.
Uplink measurement report are about the uplink signal received by BTS.
HW I Power Control
Uplink measurement report
Downlink measurement report
There are two kind of measurement report for system: FULL (full measurement) and SUB (sub measurement).
FULL--Averaging over 100 TCH bursts(except four idle frames of four 26-multiframes).
SUB--Averaging over 12 bursts(four SACCH bursts, eight TCH bursts).
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.
HW I Power Control
Measurement report serial number n+4
Consecutive measurement report flow
3 missing measurement reports
The network receives the measurement reports n and n+4, which are with discontinuous serial numbers. Therefore the three missed measurement reports n+1, n+2 and n+3 will be filled up with some algorithm.
Note: Due to the power control judgment needs to be based on consecutive measurement reports, the missed measurement reports should be filled up.
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.
HW I Power Control
Filter
Filter the last 4 measurement reports. There are filters respectively for uplink/downlink receiving level and receiving quality and TA.
HW I power control judgment (Stable adjustment stage)
Transmitting power adjustment =
(expected stable uplink or downlink RXLEV – actual uplink or downlink RXLEV) * uplink or downlink RXLEV compensation factor + (actual uplink or downlink RXQUAL - expected uplink or downlink RXQUAL)*10* uplink or downlink quality compensation factor
The final adjustment power level should not exceed the maximum power control step size
Final stable level = current level + transmitting power adjustment
HW I Power Control
HW I Power Control
Transmitting power adjustment = (actual initial RXLEV – expected initial RXLEV) * uplink RXLEV compensation factor
Final transmitting power = initial RXLEV – transmitting power adjustment
If the RXLEV lower than the expected initial RXLEV, power control will not occur within initial adjustment stage
HW I Power Control Configuration
HW I power control data configuration and parameter introduction
[BTS power control table]
The parameter configuration for HW I includes two sheets: [BTS power control table] and [MS power control table] for downlink and uplink power control. When the “HW_1” in “PC algorithm ” is selected, the network will perform power control according to these two sheets.
Only some of key parameters are listed above.
Parameter name
DL RX_LEV Expected
The expected signal level of MS in stable status, Expected stable downlink signal level > downlink edge HO thresholdOtherwise, ping-pang HO will be caused.
063
DL RX_LEV Compensation
The power adjustment value varies with this parameter. The adjustment value caused by power level equal to the difference between the expected signal level and the actual receiving signal level multiply this factor.
0100
DL Qual. Expected
07 Levels
DL Qual.Compensation
The power adjustment value varies with this parameter. The adjustment value caused by signal quality equal to 10*difference between the expected signal quality level and the actual receiving signal quality level multiply this factor.
0100
MAX PC Step
Levels 0~16, 2dB each step
8
[BTS power control table]
Parameter name
Period
Time interval for implementing two power control commands (unit count of SACCH period)
110
Filter length for DL RX_LEV
Content: indicating the number of measurement reports in which the average of uplink signal strength is taken before MS power adjustment at stable stage. The purpose is to remove the influence of some abnormal reports. When the filter length is too long, the influence due to abnormal reports will be weakened, but the MS power adjustment is not timely.
132
BTS Min Tx power
Indicating the minimum transmitting power allowed by the base station. No matter what the original base station power is, how many levels it can be down-tuned, the transmitting power of the base station cannot be lower than this value.
0~36dBm
PC Adj. Range
Indicating the maximum level the base station dynamic power can be adjusted
1~16,
[MS power control data table]
Only meanings of key parameters are listed above.
Parameter name
Initial RX_LEV expected
The expected BTS receiving signal level in the initial stage when MS access the network.
0~63
Stable EX_LEV Expected
The expected BTS receiving signal level in stable status. Expected stable signal level > uplink margin HO threshold (HO parameter). Otherwise, “ping-pang” HO will be caused.
0~63
UL RX_LEV compensation
Give an adjustment for the power control level value, the actual power level value MS should change is the result of this parameter multiply the difference between the expected uplink signal level and the actual BTS receiving signal level.
0~100
UL Qual. compensation
The power adjustment value varies with this parameter. The adjustment value caused by signal quality equal to 10*difference between the expected signal quality level and the actual receiving signal quality level times this factor.
0100
Max PC step
The maximum level of MS power that can be dynamically adjusted.
Level 1~16, 2dB/level.
[MS power control table]
Value range
Value recommended
PC interval
Time interval between the implementations of two power control algorithms; unit: SACCH period
0~30
Filter length for Initial RX_LEV
This is the number of measurement reports required for predicting the signal strength at the initial stage. Unit: Measurement reports
1~32
Filter length for stable RX_LEV
This is the number of measurement reports required for predicting the signal strength at the stable power control stage. Unit: Measurement reports
1-31
5
Filter length for Qual.
This is the number of the measurement reports required for assessing signal quality at the stable stage. Unit: Number of measurement reports
1~30
HW I Power Control
Power control will not occur in case of these four conditions
Both level and quality equal to the setting values (HW I power control), or level and quality are within threshold band(HW II power control)
Adjusting range for MS less than error tolerance
Adjusting range less than minimum power control step of BTS
The RXLEV lower than the expected initial RXLEV within initial adjustment stage
HW I Power Control
HW I power control judgment
Before judging the signal level to be adjusted, query the error tolerance table according to the current transmitting power level. Adjustment will not be done if the power adjustment value is less than the error tolerance value.
Error tolerance table for 900M and 1800M is as follows:
1800M:
900M:
Level
0
1
2
3
4
5
6
7
8
9
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12
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Error tolerance: Measured in dB, varies with MS transmitting power.
For example: The current MS is in 900M cell, with power level of 5 and error tolerance of 4dB as listed in the sheet. BSC calculates that the power should be increased(or reduced) 3dB, which is less than the error tolerance allowed, hence no further power control is needed.
HW I Power Control
Similarity:
1. To avoid frequently changes of signal level, the PC interval time between the two consecutive uplink and downlink power control are limited.
2. To reduce the influence caused by abnormal reports, all measurement reports should be filtered.
3. Both uplink and downlink power controls include level-specific and quality-specific power controls.
4. Both uplink and downlink power controls have maximum power control step size limit and compensating factor.
Comparison uplink and downlink of HW I power control .
Differentia:
1. Including power control for the stable stage, MS also has power control when MS access the network, thus to reduce transmitting power of MS as soon as possible.
2. For uplink, precautions are ready for increase MS transmitting power in case HO fails.
3. For downlink, there are maximum and minimum transmitting power limits in power control data configuration.
4. MS has the error tolerance table.
HW I Power Control
HW I power control exercise
Given conditions:
900M MS transmitting at the maximum power, uplink receiving level of the 900M BTS is –60dBm, uplink quality level is always 0.
Parameter configuration in [BTS power/MS power control table] is as follows – “stable RX_LEV Expected” is 35, “UL RX_LEV Compensation” is 80, “UL Qual. expected ” is 1, and “UL Qual. compensation” is 20, and the max. PC step is 16dB.
HW I Power Control
Question:
1. Suppose that power control will no longer be done once the power value to be adjusted is less than 2dB, what is the approximate stable power value after power control with the above data configuration?
2. According to the error tolerance list, suppose the initial MS transmitting power is level 3, what is the maximum uplink receiving level in stable status after power control?
Exercise
Answers for question 1:
Stable level = current actual level + [(expected signal intensity in stable status – current actual level) * uplink path loss compensating factor] + [actual current quality – expected uplink signal quality) * 10 * uplink quality compensating factor] = -60+[(-75-(-60))*80]+[(0-1)*10*20] = -60-12-2 -74dBm. Now it’s necessary to adjust -14dB (no larger than the maximum power control step size), but it needs further adjustment because it fails to reach -75dBm, the “expected signal level in stable status”. Use -74 in the above formula again for calculation, and the power to be adjusted is -2.8dB. Because no power control adjustment will be done when the power value to be adjusted is smaller than -2, it still needs to be changed 2dB lower, so the uplink receiving level is -76dBm at last.
Exercise
Answers for question 2:
Query the error tolerance table, the tolerance of level 3 is 4dB, the power to be adjusted for the second time is 2.8, which is less than 4 and up to the requirement, so the final uplink receiving level is -74dBm in stable status.
Exercise
Contents
HW II Power Control
Power control judgment process
Send the power control command
The power control demand according to receiving quality
General power control judgement
Pre-processing of the measurement reports (interpolation, compensation, prediction and filtering),
2. Calculate power control demand according to the receiving level,
3. Calculate power control demand according to the receiving quality,
4. Make comprehensive judgment on the receiving level and receiving quality.
The same as HWI power control, measurement report pre-processing includes interpolation and filtering. But in HWII it has compensation and forecast functions before filtering.
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.
When system makes a power control judgment, the power control module will extract the values of receiving level and receiving quality from several history measurement reports for filtering. In these measurement reports,MS or BTS maybe use different transmitting power. Therefore, to ensure the accuracy of receiving level values used for filtering, compensation should be made for receiving level values in history measurement report whose history transmitting power is different from the current transmitting power.
HW II Power Control
The expected receiving signal level: 30
The power control will be more effective with measurement report compensation.
X axis
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.
After the power control module send the power control command, due to the propagation delay and power control process delay, the transmitting power will usually be executed after several measurement report periods. This delay will affect the validity of power control. In order to make up some influence of power control delay, the prediction for measurement reports should be adopted so that the power control command will perform a little earlier.
HW II Power Control
The expected receiving signal level: 30
The power control with prediction filter will be more effective than that with mean filter
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Mean filter power control
Prediction filter power control
Diagram of power control effect comparison between prediction filter and 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.
When power control is performed based on the receiving level, it adopts three step sizes respectively for different receiving qualities band:
“MAX. Adj. Value for Qual. Zone 0 (receiving quality level 0)
“MAX. Adj. Value for Qual. Zone 1 (receiving quality level 1~2)
“MAX. Adj. Value for Qual. Zone 2 (receiving quality level 3~7)
The worse the quality, the shorter the allowable step size.
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.
To change the transmitting power according to receiving quality, fixed step size should be adopted --”Adj. PC Value by RXqual” for each receiving quality zone.
General power control judgment
Note:
Control as required when either level or quality needs to be controlled.
AdjStep_A
If uplink or downlink RXLEV - AdjStep_Qul < lower threshold of uplink or downlink RXLEV, AdjStep_A = 0. No adjustment is required.
If uplink or downlink RXLEV - AdjStep_Qul ≥ lower threshold of uplink or downlink RXLEV, AdjStep_A = AdjStep_Qul.
The purpose is to avoid the power control request when the RXQUAL is good and the RXLEV requires no power control. If power control is made, the RXLEV may become worse and request for power control again, thus leading to frequent power control.
AdjStep_B
If AdjStep_Qul + uplink or downlink RXLEV > upper threshold of uplink or downlink RXLEV, AdjStep_B = upper threshold of uplink or downlink RXLEV –uplink or downlink RXLEV.
If AdjStep_Qul + uplink or downlink RXLEV <= upper threshold of uplink or downlink RXLEV, AdjStep_B = AdjStep_Qul.
The purpose is to avoid the power control request due to bad RXQUAL when the RXLEV requires no power control. If power control is made, the RXLEV may become too good and request for power control again, thus leading to frequent power control.
2. When the controls based on signal level and quality are in an opposite direction, and the level requires decreasing power, so no action should be performed for power control; when the level requires increasing power, then just perform as level required.
3. When they work in the same direction, perform according to the larger value.
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
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.
Automatic adjustable step size:
When the power control caused by receiving level in HWII power control algorithm, the power control will be performed also considering the receiving quality which are set into three quality zones (0, 1~2, ≥3). Each quality zone allow different maximum adjustment step size. The worse the quality is, the less the adjustable step size will be.
If the maximum step size allowed for power control is set too small, the algorithm can not achieve the purpose of power control as soon as possible; when set it too big, it will decrease the validity of power control.
The step size is fixed when the power should be changed according to receiving quality.
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.
Configuration parameters include ([HWII power control data table]):
UL RX_LEV upper thrsh/ UL RX_LEV lower thrsh
DL RX_LEV upper thrsh/lower thrsh
UL Qual upper thrsh/lower thrsh
DL Qual upper threh/lower threh
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 – 1
Parameter name
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
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
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
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
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
UL MR number predicted
The number of uplink pred. MR in the filter using for power control judgment.
0~3 reports
DL MR number predicted
The number of downlink pred. MR in the filter using for power control judgment.
0~3 reports
Note: when configuring s-strength thresholds that: upper/lower thresholds> edge handover threshold + inter-cell handover hysteresis.
This is designed to avoid handover caused by improper power control.
Parameter name
1~30
(SACCH period)
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
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
Level 0~7
UL Qual. lower threshold
This parameter specifies the uplink quality lower threshold for power control
Level 0~7
Parameter name
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
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
DL Qual. upper threshold
This parameter specifies the downlink quality upper threshold for power control
Level 0~7
DL Qual. lower threshold
This parameter specifies the downlink quality lower threshold for power control
Level 0~7
Parameter name
MAX Down Adj. value Qual. zone 0
This parameter specifies the maximum downward power adjustment value when the Rx quality is 0.
0~30dB
This parameter specifies the maximum downward power adjustment value when the Rx quality is 1 or 2
0~30dB
This parameter specifies the maximum downward power adjustment value when the Rx quality is equal to or more than 3.
0~30dB
MAX Down Adj. PC Value by Qual.
The adjustment step allowed for the downward power control due to receiving signal quality.
0~4dB
Parameter name
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
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
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
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
Parameter name
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
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
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?
Exercise
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.
Thank you
quality
Parameter
name
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.
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
The expected signal level of MS in stable status, Expected
stable downlink signal level > downlink edge HO threshold
Otherwise, ping-pang HO will be caused.
063
(-110 dBm–
-47 dBm)
adjustment value caused by power level equal to the difference
between the expected signal level and the act ual receiving
signal level multiply this factor.
0100
07
adjustment value caused by signal quality equal to
10*difference between the expected signal quality level and the
actual receiving signal quality level multiply this factor.
0100
command
Levels
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
It is used to set the maximum adjustment step for
upward power control by receive quality.
0~32dB 8
UL Qual. Bad
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
In uplink power control, when the re ceiving 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.
power control algorithms; unit: SACCH period
0~30 5
Filter length for
required for predicting the signal strength at the
initial stage. Unit: Measurement reports
1~32 2
Filter length for
required for predicting the signal strength at the
stable power control stage. Unit: Meas urement
reports
stage. Unit: Number of measurement reports
1~30 6
(unit count of SACCH period)
110 5
Content: indicating the number of measurement reports in
which the average of uplink signal strength is taken before MS
power adjustment at stable stage. The purpose is to remove
the influence of some abnormal reports . When the filter length
is too long, the influence due to abnormal reports will be
weakened, but the MS power adjustment is not timely .
132 5
BTS Min Tx
base station. No matter what the original base station power
is, how many levels it can be down -tuned, the transmitting
power of the base station cannot be lower than this val ue.
0~36dBm 4
can be adjusted
1~30
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)
This parameter specifies the uplink signal level low er 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)
Level
power control
The expected BTS receiving signal level in the initial stage
when MS access the network.
0~63
Expected stable signal level > uplink margin HO threshold
(HO parameter). Otherwise, “ping -pang” HO will be caused.
0~63
Give an adjustment for the power control level value, the
actual power level value MS should change is the result of
this parameter multiply the difference between the expected
uplink signal level and the actual BTS receiving signal level.
0~100 80
The expected BTS receiving signal quality in stab le status.
UL Qual.
adjustment value caused by signal quality equal to
10*difference between the expected signal quality level and
the actual receiving signal quality level times this factor.
0100 20
The maximum level of MS power that can be dynamically
adjusted.
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.
calculate a power increase [= (uppe r 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)
threshold for power control
Level 0~7 0
threshold for power control
Level 0~7 2
power adjustment value when the Rx quality is 0.
0~30dB 16
MAX Down Adj.
power adjustment value when the Rx quality is 1 or
2
power adjustment value when the Rx quality is
equal to or more than 3.
0~30dB 4
MAX Down Adj.
PC Value by
0~4dB 4
How many uplink measurement report s obtained for the average
uplink signal level to be used for uplink power control adjustment.
1~20 6
How many downlink measurement report s obtained for the average
downlink signal level to be used for downlink power control
adjustment.
How many uplink measurement report s obtained for the average
uplink quality level to be used fo r uplink power control adjustment.
1~20 6
How many downlink measurement report s obtained for the average
downlink quality level to be used for downlink power control
adjustment.
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 meas urement report according to the power
change information.
number
predicted
The number of uplink pred. MR in the filter using for power control
judgment.
number
predicted
The number of downlink pred. MR in the filter using for power
control judgment.
0~3

2g power control issue1.5

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