03 power control

M900/M1800 Base Station Subsystem Feature Description Contents

Issue 02 (2007-06-30) Huawei Technologies Proprietary i

Contents

3 Power Control .............................................................................................................................3-1

3.1 Introduction...................................................................................................................................................3-2

3.1.1 Application...........................................................................................................................................3-2

3.1.2 Availability...........................................................................................................................................3-2

3.1.3 Restriction and Limitation ...................................................................................................................3-2

3.2 Technical Description....................................................................................................................................3-3

3.2.1 Classification of Power Control ...........................................................................................................3-3

3.2.2 Execution of Power Control.................................................................................................................3-9

3.2.3 Power Control Algorithms .................................................................................................................3-10

3.2.4 HW_I Algorithm ................................................................................................................................3-11

3.2.5 HW_II Algorithm...............................................................................................................................3-17

3.3 Function Configuration ...............................................................................................................................3-23

3.3.1 Configuring Power Control................................................................................................................3-23

3.3.2 Parameters..........................................................................................................................................3-27

3.4 Maintenance Information ............................................................................................................................3-34

3.4.1 Alarm .................................................................................................................................................3-34

3.4.2 Traffic Statistics Update.....................................................................................................................3-34

Figures M900/M1800 Base Station Subsystem

Feature Description

ii Huawei Technologies Proprietary Issue 02 (2007-06-30)

Figures

Figure 3-1 Configuration of MS TXPWR_MAX_CCH.....................................................................................3-3

Figure 3-2 Configuration of POWER OFFSET .................................................................................................3-6

Figure 3-3 Configuring static power class..........................................................................................................3-8

Figure 3-4 Execution process of power control..................................................................................................3-9

Figure 3-5 Selecting the power control algorithm............................................................................................3-10

Figure 3-6 Power control decision of the HW_I algorithm HW_I ...................................................................3-11

Figure 3-7 Reporting the MR ...........................................................................................................................3-12

Figure 3-8 A BSS MR ......................................................................................................................................3-12

Figure 3-9 Power control decision of HW_II algorithm...................................................................................3-18

Figure 3-10 Advance cell property ...................................................................................................................3-23

Figure 3-11 Configuring power control............................................................................................................3-24

Figure 3-12 BTS power control........................................................................................................................3-25

Figure 3-13 MS power control .........................................................................................................................3-26

Figure 3-14 Huawei II power control ...............................................................................................................3-27

M900/M1800 Base Station Subsystem Feature Description 3 Power Control

Issue 02 (2007-06-30) Huawei Technologies Proprietary 3-1

Tables

Table 3-1 MS power classification .....................................................................................................................3-4

Table 3-2 Static power class ...............................................................................................................................3-7

Table 3-3 Dynamic power class..........................................................................................................................3-8

Table 3-4 DCS1800/GSM900/PCS1900 tolerance table ..................................................................................3-14

Table 3-5 Examples of HW_I algorithm...........................................................................................................3-16

Table 3-6 Power control decision .....................................................................................................................3-19

Table 3-7 Examples of HW_II algorithm .........................................................................................................3-22

Table 3-8 Cell power control parameters..........................................................................................................3-27

Table 3-9 BTS power control parameters .........................................................................................................3-29

Table 3-10 MS power control parameters.........................................................................................................3-32

Table 3-11 Statistic items related to power control...........................................................................................3-34



3 Power Control About This Chapter

The following table lists the contents of this chapter.

Section Describes

3.1 Introduction Introduces the power control.

3.2 Technical Description Describes the technology of the power control.

3.3 Function Configuration Describes the configuration about the power control.

3.4 Maintenance Information Describes the maintenance information about the power control.

3 Power Control M900/M1800 Base Station Subsystem

Feature Description

3-2 Huawei Technologies Proprietary Issue 02 (2007-06-30)

3.1 Introduction

3.1.1 Application

As an important method to control the radio link, power control judges the measurement report (MR) of the received signal level (RXLEV) and the received signal quality (RXQUAL) on the uplink (UL) and downlink (DL) from the BTS, and then adjusts the transmit power of the MS and BTS.

The basic principles of power control are as follows:

z If the RXLEV or RXQUAL is above the expected value, reduce the transmit power.

z If the RXLEV or RXQUAL is below the expected value, increase the transmit power.

z Consider both the RXLEV and the RXQUAL to control the power accurately and effectively.

Power control can maintain a transmission quality better than the specified threshold and reduce the transmit power of the MS and BTS, and thus reduce the interference to other channels.

The M900/M1800 BSC provides three algorithms to control the transmit power.

z 0508 power control algorithm (GSM 0508 algorithm)

z Huawei I power control algorithm (HW_I algorithm)

z Huawei II power control algorithm (HW_II algorithm)

Flexible, efficient, and easy to operate, HW_I algorithm and HW_II algorithm can also be used in the GSM900 and DCS1800.

3.1.2 Availability

All the existing BSC software support power control. The BTS2X supports only HW_1 algorithm.

3.1.3 Restriction and Limitation

None.



3.2 Technical Description

3.2.1 Classification of Power Control

Power control can be divided into uplink power control and downlink power control, that is, MS power control and BTS power control.

MS Power Control

MS power control is to adjust the output power of the MS so that the BTS can receive a stable signal level, and thus the interference to the adjacent channels is reduced.

MS power control has two adjustment stages: initial adjustment stage and stable adjustment stage.

z Initial adjustment

Initial adjustment is used in the initial stage of a call proceeding. The MS uses the transmit power of the cell system information as the output power, that is, the parameter MS_TXPWR_MAX_CCH, as shown in Figure 3-1.

Figure 3-1 Configuration of MS TXPWR_MAX_CCH

For the 900M cell, the value of TXPWR_MAX_CCH ranges from 0 to 19, 20 classes in total. For the 1800M cell, the value of TXPWR_MAX_CCH ranges from 0 to 255.


Feature Description


Table 3-1 shows the power classification.

Table 3-1 MS power classification

900M 1800M

Class Power (dBm) Class Power (dBm)

0 43 0 30

1 41 1 28

2 39 2 26

3 37 3 24

4 35 4 22

5 33 5 20

6 31 6 18

7 29 7 16

8 27 8 14

9 25 9 12

10 23 10 10

11 21 11 8

12 19 12 6

13 17 13 4

14 15 14 2

15 13 15 0

16 11 16 0

17 9 17 0

18 7 18 0

19 5 19 0

- - 20 0

- - 21 0

- - 22 0

- - 23 0

- - 24 0

- - 25 0

- - 26 0



900M 1800M

Class Power (dBm) Class Power (dBm)

- - 27 0

- - 28 0

- - 29 36

- - 30 34

- - 31 32

If the MS does not support a certain power class, it will use the available power class closest to this class.

As the BTS can support several calls at the same time, the RXLEV of a new call must be reduced. Otherwise, the quality of other calls supported by the BTS will be deteriorated because the BTS multi-coupler is saturated. In addition, the calls in other cells will also be affected because of the strong interference.

The purpose of initial power adjustment is to quickly reduce the MS transmit power to a certain degree until the stable MR is obtained, so that the MS can use the stable power control algorithm to adjust the power.

For the Class 3 DCS1800 MS, the initial power is MS_TXPWR_MAX_CCH + POWER OFFSET.

POWER OFFSET is divided into four classes from class 0 to class 3. Class 0 is 2 dB; class 2 is 4 dB; and class 3 is 6 dB. The value is set through the parameter Power Deviation, as shown in Figure 3-2, and delivered in the system information 3.


Feature Description


Figure 3-2 Configuration of POWER OFFSET

If the filtered level is lower than the expected level, no power control is performed. If the filtered level is higher than the expected level, adjust the power to the values as follows:

Power decrease = (Initial level - Expected level) Uplink RXLEV compensation

Power after adjustment = Current power - Power decrease

z Stable adjustment

After the BTS receives a number of uplink MRs, it gets the actual values of the RXLEV and RXQUAL on the uplink by means of interpolation and filtering, and compares them with the expected values. Then the BTS calculates the power class that the MS should be adjusted to. If this power class is different from the current power class of the MS, and the application restrictions such as power adjustment step limit and MS power range limit, the power adjustment command is delivered.

The uplink power control is to improve the uplink RXLEV and RXQUAL to gradually approach the expected values. The interpolation and filtering can handle the lost MRs to ensure the stability of the power control algorithm.

The differences between the initial power control and stable power control are as follows:

z The expected uplink RXLEV and RXQUAL are different.

z The filter length is different.

z Only the downward adjustment is perform in the initial stage.



BTS Power Control

BTS power control is to adjust the BTS power for the MS to get stable signal strength, and thus reduce the adjacent interference and BTS power consumption.

As an optional function, the BTS power control is similar to the MS power control, except that the former uses stable power control algorithm only.

The mandatory parameters in power control include RX_LEV_ACCESS_MIN and MS TXPWR_MAX_CCH. The RXLEV is divided into 64 classes, ranging from 0 to 63. The minimum RXLEV is 0 and the maximum RXLEV is 63.

BTS power control includes static power control and dynamic power control.

z Static power control

Huawei BSC static power control is divided into 11 classes, ranging from 0 to 10 with an increment of 2 dBm.

Table 3-2 shows the classification of static power control when the maximum power is 46.

Table 3-2 Static power class

Static class

0 1 2 3 4 5 6 7 8 9 10

Power (dBm)

46 44 42 40 38 36 34 32 30 28 26

For the TRX property, the parameter Static TRX Power Class determines the static power class, as shown in Figure 3-3.


Feature Description


Figure 3-3 Configuring static power class

z Dynamic power control

Dynamic power control is a find control on the basis of static power control. It uses the static power of a certain class as the maximum value Pn. Dynamic power contrl supports 15-class adjustment with an increment of 2 dBm for each class. Table 3-3 shows the dynamic power control when Pn = 42.

Table 3-3 Dynamic power class

Dynamic class

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Power (dBm)

42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12



z If the dynamic power control cannot achieve the required value, you need to adjust the class of static

power control to improve the maximum output power Pn in the dynamic power control.

z The BTS only has the stable power control. The BTS power control is performed only when the BTS enters stable state in which sufficient MRs are received.

3.2.2 Execution of Power Control

The power control from command sending to execution takes three periods of MR.

Figure 3-4 shows the execution process of power control.

Figure 3-4 Execution process of power control

SA0 SA1SA0 SA0SA1SA1 SA2SA2SA2 SA3SA3SA3

The BTS sends thecommand to adjust the

power and TA.

The MS receivesthe SACCHinformation

The MS begins tosend the MR of the

last multiframe

SACCH information issent in the frame 12 of

the 26 multiframe

The BTSreceives the

MR

The period of SACCH report is26 4=104 frames (480ms)

The MS beginsto use the newpower and TA.

The MS reports thenew TA and powercontrol message

The execution process is as follows:

Step 1 During the first period of MR, the MS receives the power control message on the SACCH. The MS will execute the power control command when the next period begins.

Step 2 During the second period of MR, the power control begins. The maximum change rate of the MS power is 2 dB/13 frames (60 ms). If the step is set to 8, that is, 8 2 = 16 dB, then 104 frames (480 ms, one period of MR) are required to adjust the power. If the step is set to 16, that is, 16 2 = 32 dB, then two periods are required to adjust the power.

Step 3 During the third period of MR, the current transmit power (the power level used by the last burst during the period of the SACCH MR) is stored and then reported to the BTS in the next uplink MR of the SACCH.

----End


Feature Description


3.2.3 Power Control Algorithms

The BSC can control the power of each MS and each BTS.

The power control has the following three algorithms:

z GSM 0508 algorithm

z HW_I algorithm

z HW_II algorithm

Figure 3-5 shows the process for selecting the algorithm.

Figure 3-5 Selecting the power control algorithm

MR pre-processing

Power control algorithmselection

GSM0508 algorithm HW_I algorithm HW_II algorithm

Based on the GSM 05.08 protocol, the GSM 0508 algorithm sets the upper and lower thresholds for the RXLEV and RXQUAL and the counters P' and N. When N' MRs among the successive P' MRs go beyond the threshold, the power control is performed to improve or reduce the power.

The process of power control is as follows:

Step 1 MR pre-processing

Step 2 Power calculation

Step 3 Power control decision

Step 4 Power adjustment through power control commands

----End



3.2.4 HW_I Algorithm

Features

HW_I algorithm has the following features:

z Compared with the GSM 0508 algorithm, HW_I algorithm has the initial adjustment added.

z The data configuration is rather complicated as it involves many parameters.

z The power control decision depends on both the RXLEV and the RXQUAL. If the power adjustment of the RXLEV contradicts that of the RXQUAL, the power control will persist and the level will fluctuate.

Power Control Decision

Figure 3-6 shows the power control decision of the HW_I algorithm.

Figure 3-6 Power control decision of the HW_I algorithm HW_I

MR pre-processing

powercontrol objectis achieved?

Y

N

PC calculation andadjustment in the initalstate and stable state

z MR

To perform power control decision, the network has to get the information of current communications from the MS and the BTS. This information includes the RXLEV conversation quality.

The network receives the MRs from the MS and the BTS every 480 ms. The MRs carry all the required information for power control decision on the network side.

Figure 3-7 shows the reporting process of the MR.


Feature Description


Figure 3-7 Reporting the MR

MR

MRMR

DL measurement

UL measurement

MR

Figure 3-8 shows a BSS MR.

Figure 3-8 A BSS MR

The MR has two values.



Full: the mean value of 100 TCH bursts, except for the four idle frames in the four 26-multiframes.

Sub: the mean value of 12 bursts (four SACCH bursts and eight specific TCH bursts).

Sub is selected when the discontinuous transmission function is enabled. Otherwise, Full is selected.

z MR pre-processing

The pre-processing of the MR consists of interpolation and filtering.

Interpolation

Each MR has a sequence number. If the network detects incontinuous numbers, some MRs are missing. The network will complete the MRs according to interpolation algorithm.

The interpolation algorithm is as follows:

If the MR numbered n is received after the MR numbered m (n > m), the number of the missing reports is n - m - 1 (less than or equal to the number that the interpolation algorithm allows). Therefore, m - n - 1 MRs need to be interpolated. The level of the MR numbered i (0 i < n - m - 1) = [the level of the MR numbered m (n - m - 1 - i) + the level of the MR numbered n (n - m - 1-1)] / (n - m - 1 + 1)

The RXQUAL and the receiving quality indicator (RQI) use the same interpolation mode.

Filtering

Several successive MRs reflect the status of a handset during a certain period of time. Filter algorithm takes the mean value of the MRs according to the filter length.

z Power control decision

Transmit power adjustment = (expected uplink or downlink RXLEV actual uplink or downlink RXLEV) uplink or downlink RXLEV compensation + (actual uplink or downlink RXQUAL expected uplink or downlink RXQUAL) 10 uplink or downlink RXQUAL compensation

If the transmit power adjustment is greater than twice of the maximum power control step, then the transmit power adjustment = maximum power control step 2.

The formula above is used to calculate the transmit power adjustment in both the MS power control and the BTS power control.

The final adjustment of power class should not exceed the maximum power control step.

Actual stable level = current level + transmit power adjustment

For the MS power control, no adjustment is made if the final adjustment of power class is lower than the specified tolerance.

Table 3-4 lists the tolerances of the DCS1800, GSM900, and PCS1900.


Feature Description


Table 3-4 DCS1800/GSM900/PCS1900 tolerance table

DCS1800 GSM900 PCS1900

C P T C P T C P T

0 30 2 0 43 2 0 30 2

1 28 2 1 41 2 1 28 2

2 26 2 2 39 2 2 26 2

3 24 2 3 37 4 3 24 2

4 22 2 4 35 4 4 22 2

5 20 2 5 33 4 5 20 2

6 18 2 6 31 4 6 18 2

7 16 2 7 29 4 7 16 2

8 14 2 8 27 4 8 14 2

9 12 3 9 25 4 9 12 3

10 10 3 10 23 4 10 10 3

11 8 3 11 21 4 11 8 3

12 6 3 12 19 4 12 6 3

13 4 3 13 17 4 13 4 3

14 2 4 14 15 4 14 2 4

15 0 4 15 13 4 15 0 4

16 0 4 16 11 6 16 0 4

17 0 4 17 9 6 17 0 4

18 0 4 18 7 6 18 0 4

19 0 4 19 5 6 19 0 4

20 0 4 - - - 20 0 4

21 0 4 - - - 21 0 4

22 33 4 - - - 22 0 4

23 33 4 - - - 23 0 4

24 33 4 - - - 24 0 4

25 33 4 - - - 25 0 4

26 33 4 - - - 26 0 4

27 33 4 - - - 27 0 4

28 33 4 - - - 28 0 4



DCS1800 GSM900 PCS1900

C P T C P T C P T

29 33 2 - - - 29 36 2

30 33 2 - - - 30 34 2

31 32 2 - - - 31 32 2

Note:

C = Class; P = Power; T = Tolerance

Unit of P and T: dBm

The BTS power control has no tolerance table. If the power adjustment is less than 2 dBm, no power adjustment is required.

Comparison Between the MS Power Control and the BTS Power Control of HW_I Algorithm

The comparison between the uplink power control and the downlink power control of HW_I algorithm is as follows:

z Similarities

They both define the interval of power control to avoid signal fluctuation due to frequent power control.

All the MRs are filtered to avoid the influence of discontinuous factors.

They both provide the RXLEV-based power control and the RXQUAL-based power control.

They both have maximum step of power control and compensation factors.

z Differences

The MS power control has both the initial power control and the stable power control to quickly reduce the transmit power. The BTS power control has only the stable power control that begins when sufficient MRs are received for filtering.

The MS power control provides strategies to improve transmit power after the MS handover fails.

The BTS power control sets upper and lower thresholds for the BTS transmit power.

The MS power control has tolerance tables while the BTS power control does not.

Examples of HW_I Algorithm

Assume that a 900M handset sends signals with the maximum power and its RXLEV is -60 dBm. The RXQUAL is 0.


Feature Description


The parameter settings in the data tables of the BTS and MS power control are as follows:

z Stable RX_LEV Expected: 35 (-75 dBm)

z UL RX_LEV Compensation: 80

z UL Qual. Expected: 1

z UL Qual Compensation: 20

z MAX PC Step: 16 dB

Table 3-5 lists the calculation steps.

Table 3-5 Examples of HW_I algorithm

Question Solution

Step 1: Power adjustment = [-75 - (-60)] 80% + (0 - 1) 10 20% = -14 dBm

As -14 dBm is less than the maximum step 16 dBm and greater than the tolerance 2 dBm, power control is made.

Power after adjustment = -60 + (-14) = -74 dBm

Step 2: Power adjustment = [-75 - (-74)] 80% + (0 - 1) 10 20% = -2.8 dBm

As -2.8 is less than the maximum step and greater than the tolerance, power control is made.

The adjustment must be a multiple of 2 dBm. Therefore, the stable power after adjustment = -74 + (-2) = -76 dBm.

Assume that the MS transmit power is proportional to the BTS RXLEV, which means that if the MS transmit power increases by 2 dBm, then the BTS RXLEV increases by 2 dBm. No adjustment is made if the power adjustment is less than 2 dBm.

According to the data above, what is the final stable uplink RXLEV after the power control?


As 1.2 is within the tolerance, no power control is made. The stable power is -76 dBm.

Under the same conditions above, assume that the initial transmit power class is 3, what is the stable RXLEV after the power control?

According to Table 3-4, the initial transmit power of the MS is 37 dBm (class 3) and the corresponding tolerance is 4 dBm.

Step 1: Power adjustment = [-75 - (-60)] 80% + (0 - 1) 10 20% = -14 dBm

As -14 dBm is less than the maximum step 16 dBm and greater than the tolerance 4, power control is made.

Power after adjustment = -60 + (-14) = -74 dBm.

MS transmit power = 37 - 14 = 23 dBm (class 10). The corresponding tolerance is 4 dBm.



Question Solution


As 2.8 dBm is within the tolerance, no power control is made. The stable uplink RXLEV is -74 dBm.

3.2.5 HW_II Algorithm

Benefits of HW_II Algorithm

Compared with HW_I algorithm, HW_II algorithm has the following benefits:

z MR compensation provides more accurate power control decision.

z MR prediction reduces power control hysteresis.

z Adaptive power control ensures the stability and efficiency of the algorithm.

z The expected value of power control is within the upper and lower thresholds to avoid power control oscillation.

z Simple and flexible data configuration provides effective adjustment of network parameters.

z The uplink power control and downlink power control are independent of each other.


Figure 3-9 shows the process of power control decision of HW_II algorithm.


Feature Description


Figure 3-9 Power control decision of HW_II algorithm

MR pre-processing

RXLEV requirespower control

RXQUAL requirespower control

Power controldecision

The process is as follows:

Step 1 Power control request according to the RXLEV

z The power control module judges whether power control is required according to the RXLEV.

The power control module checks whether the uplink or downlink RXLEV is between the upper threshold and the lower threshold. If yes, no power control is required. If no, power control is required.

z If the RXLEV is less than the lower threshold, the power will be increased. The value of power increase is (upper threshold + lower threshold) / 2 - RXLEV.

If this value exceeds the value of MAX Up Adj. PC Value by RX_LEV, the value of power increase is the value of MAX Up Adj. PC Value by RX_LEV.

z If the RXLEV is greater than the upper threshold, the power will be reduced. The value of power decrease is RXLEV - (upper threshold + lower threshold) / 2.

If this value exceeds the range of maximum power control of the corresponding zone, the maximum value is used.

Step 2 Power control request according to the RXQUAL

z The power control module judges whether power control is required according to the RXQUAL

The power control module checks whether the uplink or downlink RXQUAL is between the upper threshold and the lower threshold. If yes, no power control is required. If no, the power control is required.



z If the RXQUAL is greater than the lower threshold, the power will be increased. The value of power increase is the value of MAX Up Adj. PC Value by Qual.

z If the RXLEV is less than the upper threshold, the power will be reduced. The value of power decrease is the value of MAX Down Adj. PC Value by Qual.

Step 3 Power control decision

Table 3-6 lists the power control decision under different situations.

Table 3-6 Power control decision

RXLEV RXQUAL RXLEV Adjustment RXQUAL Adjustment


Bad Bad AdjStep_Lev AdjStep_Qul MAX(AdjStep_Lev, AdjStep_Qul)

Bad RXLEV

Good AdjStep_Lev AdjStep_Qul No action

Bad OK AdjStep_Lev No action AdjStep_Lev

Good Bad AdjStep_Lev AdjStep_Qul AdjStep_Lev

Good Good AdjStep_Lev AdjStep_Qul MAX(AdjStep_Lev, AdjStep_Qul)

Good OK AdjStep_Lev No action AdjStep_Lev

OK Bad No action AdjStep_Qul AdjStep_A

OK Good No action AdjStep_Qul AdjStep_B

OK OK No action No action No action

In Table 3-6,

z 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 upper 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.

z 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.


Feature Description


If AdjStep_Qul + uplink or downlink RXLEV



z Dual threshold power control algorithm

Dual threshold power control algorithm has the following three strategies:

Adjusting power control step according to the RXLEV The purpose of power control is to get good conversation quality with a low RXLEV. But because of the unstable feature of radio links and the interferences from outside, the transmit power cannot be too low. Dual threshold power control ensures that the RXLEV is within the dual threshold.

Adjusting power control step according to the RXQUAL The change of RXQUAL is usually caused by interferences. The major interference is co-frequency interference. The influence of this kind of interference is mutual, which means that the power of one call increases and that of another call decreases. Therefore, the power control caused by RXQUAL change should avoid frequent power increase due to bad RXQUAL. The RXQUAL also has dual threshold. The RXQUAL beyond the threshold requires power adjustment. A fixed step is used to avoid oscillation.

Adjusting power control according to both the RXLEV and the RXQUAL This strategy meets the requirements of the RXLEV and RXQUAL on one hand, and keeps the stability of the algorithm when the requirements of the RXLEV and RXQUAL are inconsistent or contradict on the other hand.

z Variable step power control

When there is a big difference between the actual value of the RXLEV or RXQUAL and the expected value, big step is used to quickly adjust the power. When this difference is small, small step is used to quickly and accurately adjust the power.

z Adaptive power control

Adaptive power control changes strategies under different communication situations to make the power control more effective and stable.

Adaptive power control has the following strategies:

Changing the maximum step of power control under different communication situations

Using different power control strategies under different communication situations.

z Adjusting the upper threshold of the RXLEV when the RXQUAL is bad

When the RXQUAL is bad (higher than the value of UL/DL Qual. Bad TrigThrsh, the value of UL/DL RX_LEV Upper Thrsh. is increased by the value of UL/DL Qual. Bad UpLEVDiff.

When the RXQUAL is good, a low value of UL/DL RX_LEV Upper Thrsh. is used to reduce the transmit power of the MS or the BTS.

When the RXQUAL is bad, a high value of UL/DL RX_LEV Upper Thrsh. is used to improve the conversation quality.

z Configuring the uplink power control step and downlink power control step separately

When the uplink or downlink RXLEV or the uplink or downlink RXQUAL declines, this strategy can quickly improve the power to avoid call drop.


Feature Description


Examples of HW_II Algorithm

Assume that the uplink RXLEV is -85 dBm and the RXQUAL class is 4.

The data configuration is as follows:

z UL RX_LEV Upper Thrsh.: -60 dBm

z UL RX_LEV Lower Thrsh.: -80 dBm

z UL Qual. Upper Thrsh.: 0

z UL Qual. Lower Thrsh.: 2

z MAX Down Adj. Value Qual. Zone 0: 16 dB



z MAX Up Adj. PC Value by RX_LEV: 16 dB

z MAX Up Adj. PC Value by Qual.: 4 dB

Table 3-7 lists the calculation steps.

Table 3-7 Examples of HW_II algorithm

Question Solution

Step 1: The uplink RXLEV is -85 dBm, which exceeds the threshold. The RXLEV requires power control.

Power adjustment = [(-60) + (-80)] / 2 - (-85) = -70 - (-85) = 15 dBm

As 15 dBm is less than the value of MAX Up Adj. PC Value by RX_LEV, power control is required. As the uplink RXQUAL is 4, which exceeds the threshold, power control is required. The power increase based on RXQUAL is fixed. According to the RXLEV and the RXQUAL, the power increase is 15 dBm.

What is the stable uplink RXLEV after power control?

Step 2: RXLEV = -85 dBm + 15 dBm = -70 dBm

As -70 dBm is within the threshold, no power control is required. If the uplink RXQUAL is 2, which is also within the threshold, no power control is required either. Therefore, the final stable RXLEV is -70 dBm.



3.3 Function Configuration

3.3.1 Configuring Power Control

To configure the power control function, perform the followings steps:

Step 1 In the initial data configuration work mode, select a cell from the Object List pane.

Step 2 In the Cell Property tab page, click Power Control in the Advanced Cell Property area, as shown in Figure 3-10.

Figure 3-10 Advance cell property

Step 3 Click Power Control.

The Cell Power Control Data dialog box as shown in Figure 3-11 is displayed.


Feature Description


Figure 3-11 Configuring power control

In the Cell Power Control Data dialog box, you can choose the power control algorithm such as GSM 0508 algorithm, HW I algorithm, and HW II algorithm. The tab page as shown in Figure 3-11 is used to configure the GSM 0508 algorithm.

Figure 3-12and Figure 3-13 show the BTS Power Control tab page and MS Power Control tab page respectively. These two tab pages are used to configure the parameters of Huawei I power control.



Figure 3-12 BTS power control


Feature Description


Figure 3-13 MS power control

Step 4 In the Huawei II Power Control tab page, configure the related parameters, as shown in Figure 3-14.



Figure 3-14 Huawei II power control

For the configuration of the AMR, see the M900/M1800 BSC Data Configuration Manual.

----End

3.3.2 Parameters

Table 3-8, Table 3-9, and Table 3-10 show the parameters related to power control.

Table 3-8 Cell power control parameters

Parameter Unit Value Range

Default Value

Description

RX_LEV Thrsh. for UL increase

Grade 063. (-110 dBm -47 dBm)

20 Indicates that when the receiving signal level of an uplink is less than the set value of this parameter, the power output of MS should be increased.


Feature Description



Default Value

Description

RX_LEV Thrsh. for DL increase

Grade 063. (-110 dBm -47 dBm)

20 Indicates that when the receiving signal level of a downlink is less than the set value of this parameter, the power output of BTS should be increased.

P1 132 12 Statistics of the receiving signal level of uplink or downlink will be performed during P1 MR period (P1 is the number of MRs), so as to judge whether adjustment of uplink or downlink power is required.

N1 132 10 Among P1 MRs, if the RXLEV in N1 MRs is lower than the value of RX_LEV Thrsh. for DL/UL increase, the power output of the MS or BTS will increase.

RX_LEV Thrsh. for UL decrease

Grade 063 (-110 dBm -47 dBm)

40 Indicates that when the uplink RXLEV is higher than the set value of this parameter, the power output of MS will decrease.

RX_LEV Thrsh. for DL decrease

Grade 063 (-110 dBm -47 dBm)

40 Indicates that when the downlink RXLEV is higher than the set value of this parameter, the power output of BTS will decrease.

P2 132 20 Statistics of the uplink or downlink RXLEV will be performed during P2 MR period (P2 is the number of MRs), so as to judge whether the uplink or downlink power should be reduced.

N2 132 19 Among P2 MRs, if the RXLEV in N2 MRs is lower than the value of RX_LEV Thrsh. for DL/UL decrease, the power output of MS or BTS will be reduced.

Qual. Thrsh. for UL increase

Grade 07 5 Indicates that when the uplink RXQUAL is worse than the set value of this parameter, the power output of MS will increase.

Qual. Thrsh. for DL increase

Grade 07 5 Indicates that when the downlink RXQUAL is worse than the set value of this parameter, the power output of BTS should be increased.




Default Value

Description

P3 132 7 Statistics of the uplink or downlink RXQUAL will be performed during P3 MR period (P3 is the number of MRs), so as to judge whether the uplink or downlink power should be increased.

N3 132 5 Among P3 MRs, if the RXLEV in N3 MRs is worse than the value of Qual. Thrsh. for DL/UL increase, the power output of MS or BTS will increase.

Qual. Thrsh. for UL decrease

Grade 07 1 Indicates that when the uplink RXQUAL is better than the set value of this parameter, the power output of MS should be decreased.

Qual. Thrsh. for DL decrease

Grade 07 1 Indicates that when the downlink RXQUAL is better than the set value of this parameter, the power output of BTS should be decreased.

P4 132 18 Statistics of the uplink or downlink RXQUAL will be performed during P4 MR period (P4 is the number of MRs), so as to judge whether the uplink or downlink power should be decreased.

N4 132 15 Among P4 MRs, if the RXQUAL in N4 MRs is worse than the value of Qual. Thrsh. for DL/UL decrease, the MS or BTS power output will be reduced.

Power Control Adjust Period

110 10 Normal cell power control adjustment period.

Table 3-9 BTS power control parameters


Default Value

Description

BTS PC Period SACCH period (480 ms)

110 4 The minimum time between two continuous power control commands.


Feature Description



Default Value

Description

DL RX_LEV Expected

Grade 063(-110 dBm -47 dBm)

35 It defines the expected MS RXLEV in a stable state. This value should be greater than the downlink edge handover threshold (handover parameter). Otherwise, the Ping-Pong handover will be triggered.

Filter Length for DL RX_LEV

131 5 Indicate the number of MRs in which the average downlink RXLEV is taken in a stable state before the BTS power adjustment. This parameter is to eliminate the influence of mutation factors so that analysis of whether to make power adjustment is not too partial. When the filtering window is too long, the influence due to mutation will be weakened, but the BTS power adjustment will not be timely. If the window is too short, the BTS power adjustment will not be accurate.

DL RX_LEV Compensation

% 0100 80 The power adjustment will change as according to the difference between the actual RXLEV and the expected RXLEV. The downlink compensation factor acts as the weight co-efficient of such adjustment. When the difference is fixed, the greater the compensation factor, the greater the BTS power adjustment.

The sum of downlink path loss compensation factor and downlink quality compensation factor must be 100.

DL Qual. Expected

Grade 07 1 The expected MS RXQUAL in a stable state




Default Value

Description

Filter Length for DL Qual.

131 5 Indicates the number of MRs in which the average downlink RXQUAL is taken in a stable state before the BTS power adjustment. This parameter is to decrease the influence of mutation factors. When the filtering window is too long, the influence due to mutation will be weakened, but the BTS power adjustment will not be timely. If the window is too short, the BTS power adjustment will not be accurate.

DL Qual. Compensation

% 0100 20 The power adjustment will change as according to the difference between the actual downlink quality and the expected downlink quality. The downlink compensation factor acts as the weight co-efficient of such adjustment. When the difference is fixed, the greater the compensation factor, the greater the BTS power adjustment.

BTS Min Tx Power

dBm 010 4 Indicates the minimum transmitting power allowed by the BTS. No matter what the original BTS power is and how many levels it can be down-tuned, the transmit power of the BTS cannot be lower than this value.

MAX PC Step grade, 2 dB at each level

015 8 Defines the maximum range of BTS power adjustment each time.

PC Adj. Range grade, every level corresponding to 2 dB

116. Corresponding to 0 dB30 dB

16 Indicates the maximum level the BTS dynamic power can be adjusted.


Feature Description


Table 3-10 MS power control parameters


Default Value

Description

PC Interval SACCH period (480 ms)

116 4 The minimum time between two continuous power control commands.

Initial RX_LEV Expected

063, (-110 dBm -47 dBm)

063, (-110 dBm -47 dBm)

30 Expected RXLEV which the BTS receives in the initial power control. Normally, its value should be greater than that of Stable RX_LEV Expected.

Filter Length for Initial RX_LEV

131 2 Indicates the number of MRs to be used for uplink power control judgment of the uplink signal strength to avoid the impact of sudden change in the initial power control. If the filtering window is too long, the impact of sudden change will be weakened but the BTS power adjustment will not be timely. If the window is too short, BTS power adjustment will be inaccurate. At the initial stage, the power adjustment of MS depends on only the RXLEV. To quickly decrease MS transmit power, the value should be less than that of Filter length for Stable RX_LEV.

Stable RX_LEV Expected

Grade 063, (-110 dBm- +47 dBm)

30 The expected MS RXLEV in stable state. This value should be greater than the value of Edge HO UL RX_LEV Thrsh. Otherwise, the Ping-Pong handover will be triggered.




Default Value

Description

Filter Length for Stable RX_LEV

131 5 Indicates the number of MRs to be used for uplink power control judgment of the uplink RXLEV to avoid the impact of sudden change in stable stage. If the filtering window is too long, the impact of sudden change will be weakened but the MS power adjustment will not be timely. If the window is too short, MS power adjustment will be inaccurate. In the stable stage, the MS power control depends on both the RXLEV and the RXQUAL. The stable power control starts when Filter length for initial RX_LEV expires, no matter whether the initial power control is performed or not.

UL RX_LEV Compensation

% 0100 80, Indicates when the difference between the current level and the ideal level is 5 dB , power is adjusted by 4 dB, i.e., 5*80/100)

The power adjustment range will change along with the difference between the actual RXLEV and the expected RXLEV. The parameter DL RX_LEV Compensation acts as the weighting coefficient of such difference. When the difference is fixed, the greater the compensating factor, the greater the MS power adjustment.

UL Qual. Expected

Grade 07 1 The expected BTS RXQUAL in stable state.

Filter Length for Qual.

131 6 Indicates the number of MRs to be used for uplink power control judgment of the uplink signal quality to avoid the impact of sudden change in stable stage. If the filtering window is too long, the impact of sudden change will be weakened but the MS power adjustment will not be timely. If the window is too short, the MS power adjustment will be inaccurate.


Feature Description



Default Value

Description

UL Qual. Compensation

% 0100 20 (when the difference between the receiving quality and the expected quality is one class, the power is adjusted by 2 dB, that is 1*20%*10)

The power adjustment range will change along with the difference between the actual RXQUAL and the expected RXQUAL. The parameter UL Qual. Compensation acts as the weighting coefficient of such difference. When the difference is fixed, the greater the compensating factor, the greater the MS power adjustment.

Power Increment after HO Fail

Grade, 2 dB at each level

04 2 Indicates the power to be increased to avoid call drop when the MS returns to the original channel after the handover fails.

MAX PC Step Grade, 2 dB at each level

015 8 Indicates the maximum step that dynamical power control of MS can be performed.

For the parameters of HW_II algorithm, see the M900/M1800 BSC Data Configuration Reference Network Planning Parameters.

3.4 Maintenance Information

3.4.1 Alarm

None.

3.4.2 Traffic Statistics Update

Table 3-11 lists the statistics items related to power control.

Table 3-11 Statistic items related to power control

No. Statistic Item

1 Power control messages to MS for power increasing

2 Power control messages to MS for power decreasing



No. Statistic Item

3 Power control messages to BTS for power increasing

4 Power control messages to BTS for power decreasing

5 Average MS power level

6 Average BTS power level

7 Average downlink strength

8 Average uplink strength

9 Average downlink quality

10 Average uplink quality

11 Maximum downlink power duration percentage

12 Maximum uplink power duration percentage

13 Average distance between MS and BTS

14 Maximum distance between MS and BTS

15 Sum of measurement reports in a cell

For details, refer to the M900/M1800 BSC Traffic Statistic Manual.

ContentsFiguresTables3 Power ControlAbout This Chapter3.1 Introduction3.1.1 Application3.1.2 Availability3.1.3 Restriction and Limitation

3.2 Technical Description3.2.1 Classification of Power Control3.2.2 Execution of Power Control3.2.3 Power Control Algorithms3.2.4 HW_I Algorithm3.2.5 HW_II Algorithm

3.3 Function Configuration3.3.1 Configuring Power Control3.3.2 Parameters

3.4 Maintenance Information3.4.1 Alarm3.4.2 Traffic Statistics Update

03 power control

Documents

power control algorithms

execution of power control

configuration of power

static power class

figures figure

technical description

function configuration

configuration of ms