PowerPoint Presentation

BTS and MS Power Control1Power ControlThe aim with Power Control is to increase the number of connections while maintaining good C/I (Carrier to Interference Ratio)Why Power Control is important ? 1. Decreases the total interference in the system ( Interference ) So when Traffic increases (no. of MSs) then good C/I can be maintained. When Traffic is normal, C/I is improved. When Interference is low, MSs with poor quality will be able to successfully complete their calls. 2. Decreases the consumption of the MS battery and the BTS backup batteries when the main supply is down.24/6/2015BTS/ MS Power Control - Mustafa Uurdoan2BTS Power ControlThe Algorithms for both BTS and MS dynamic power control are the same.The below graph shows the relation between BTS o/p power and the measured (received) signal strength at the MS vs. the path loss between BTS and MS34/6/2015

BTS/ MS Power Control - Mustafa Uurdoan3BTS Power Control For the area before point 1, the received power at the MS in the DL is very good and sufficient, however the BTS cant make any sort of down regulation and sends with power less than its minimum power.

As the MS is moving away from the BTS, the received power is decreasing, so after crossing point 1, the BTS will start up regulating its power in steps to compensate for the path loss.

At point 2, the BTS cant up regulate its power for a value above the max. allowed power level even if the received power in the MS is deteriorated or the path loss increased.

44/6/2015BTS/ MS Power Control - Mustafa Uurdoan4BTS Power ControlFor Quality measurements the below graph shows the up regulations in the BTS o/p power when quality is deteriorated (SS is not into consideration here)

As the Quality got worse ( 0 --> 7), the BTS will try to increase its power to compensate for the quality drop.54/6/2015

BTS/ MS Power Control - Mustafa Uurdoan5BTS Power ControlAlgorithm: BTS Power Control algorithm is done on 3 stages

1. Preparation of the Input Data.

2. Filtering of measurements.

3. Calculation of Power Order

64/6/2015BTS/ MS Power Control - Mustafa Uurdoan6BTS Power Control Algorithm: 1) Preparation of the Input Data

Power Control is made on TCHs time slots as well as on the SDCCH time slots(on TCH carriers), while the BCCH frequency with all its time slots is sent with max. power with no power control.

Type of measurements

Both SS_DL and Quality_DL measurements will be used in the equation through which the next power order is calculated

74/6/2015

BTS/ MS Power Control - Mustafa Uurdoan7BTS Power Control REGINTDL: A parameter that defines the minimum time period between two consecutive power orders in the DL. Measured in SACCH periods (0.48 Seconds) from 1 to 10 SACCH periods i.e. Regulating Interval in DL. (It is a BSC parameter).

The BTS is able to changes its output power , the resolution in o/p power is in the form of steps of 2 dBs and maximum change is 30 dBs. (ex: 2dBs, 4dBs,. , max to 30 dBs).

When power control is in use the BTS output power level will be given as: Down Regulation: BTS o/p power new (dBm) = BTS o/p power old 2*PL used, PL used = 0 to 15

PL used is the power regulation step

84/6/2015BTS/ MS Power Control - Mustafa Uurdoan8BTS Power Control SSDESDL: A parameter that defines the desired Signal Strength in DL which we aim to maintain using power control. Measured in dBm

The SS measured will be checked against SSDESDL to know if Down regulation in the BTS power or up regulation is needed.

QDESDL: A parameter that defines the desired Quality in DL which we aim to maintain using power control. Measured in dtqu ( 0 to 70).

The Quality measured will be checked against QDESDL to know if Down regulation in the BTS power or up regulation is needed.

94/6/2015BTS/ MS Power Control - Mustafa Uurdoan9BTS Power Control The equation used to calculate the power order in the next SACCH period contains information on SSDESDLSS_Dl measured and QDESDLQuality_DL measured.

SSDESDL SS_Dl measured is measured in dBm, while QDESDL Quality_DL measured is measured in dtqu so to be used in the same equation some sort of mapping should be done,i.e. QDESDLQuality_DL measured should be represented in the form of dBs as well

104/6/2015

BTS/ MS Power Control - Mustafa Uurdoan10BTS Power ControlSS Compensation

We aim to get the SS of the pure TCH time slot compensated for both frequency hopping when BCCH frequency is included and compensated for power control.Compensating for frequency hopping:

When the MS is using a TS on BCCH carrierSS_DLTCH= SS_DL Measured [ BSPWR (BSTXPWR - 2*PL used) ]SS_DLTCH= SS_DL Measured [ BSPWR (BSTXPWR + 2*PL used) ]

When the MS is using a TS on TCH frequencySS_DLTCH= SS_DLMeasured

By Averaging the results then:SS_DLTCH= SS_DL Measured ( BSPWR BSTXPWR + 2*PL used )/ Nf ,Nf = no. of hopping frequencies

114/6/2015BTS/ MS Power Control - Mustafa Uurdoan11BTS Power ControlSS Compensation

ii. Compensating for power control:SS_DL Compensated= SS_DLTCH+ 2*PL used Now in further calculations SS_DL Compensated will be used, where SS Compensated is the signal strength compensated for both frequency hopping and power regulations.

Quality Compensation

Quality_DL Compensated is calculated in the same way such that:Quality_DL Compensated= Quality_DL measured(in dBs) + 2*PL used Where the Quality_DL measured(in dBs) is the Quality_Dl measured (07) after transforming it into dBs

124/6/2015BTS/ MS Power Control - Mustafa Uurdoan12BTS Power Control Algorithm: 2) Filtering of measurements

Filtering for both SS and Quality is done with exponential non-linear filters in order to eliminate variations of temporary nature.

Filtering of SS Measurements

SS_DLFiltered(k) = b* SS_DLCompensated(k) + a* SS_DLFiltered (K-1), k is the SACCH period

a & b (b=1-a) are the non-linear filters coefficients and a will define the length of the filter L, where each filter length L corresponds to certain value of a

But how the length of the non-linear filter is calculated?

134/6/2015BTS/ MS Power Control - Mustafa Uurdoan13BTS Power ControlSS_DLFiltered(k) = b* SS_DLCompensated(k) + a* SS_DLFiltered (K-1), k is the SACCH period

144/6/2015 If SS_DL Compensated(k) < SS_DL Filtered(K-1)

then L = SSLENDL where,SSLENDL = between 3 and 15 SACCH Periods

In this case up regulation is needed and it should be done very fast in order to not lose the connection. If SS_DL Compensated(k) > SS_DL Filtered(K-1)

then L = SSLENDL *UPDWNRATIO/100 where,SSLENDL = between 3 and15 SACCH periodsUPDWNRATIO = between 100 and 700

In this case Down regulation is needed and it should be done in a smooth way, decreasing the power suddenly may harm the connection.BTS/ MS Power Control - Mustafa Uurdoan14BTS Power ControlFiltering of Quality Measurements

Quality_DL Filtered(k) = b* Quality_DL Compensated(k) + a* Quality_DL Filtered (K-1),

154/6/2015 If Quality_DL Compensated(k) < Quality_DL Filtered (K-1)

then L = QLENDL where,QSLENDL = between 1 and 20 SACCH periods

In this case up regulation is needed and it should be done very fast in order to not lose the connection If Quality_DL Compensated(k) > Quality_DL Filtered(K-1)

then L = QSLENDL *UPDWNRATIO/100 where, QSLENDL = between 1 and 20 SACCH periods UPDWNRATIO = between 100 and 700In this case Down regulation is needed and it should be done in a smooth way, decreasing the power suddenly may harm the connectionBTS/ MS Power Control - Mustafa Uurdoan15BTS Power Control SS_DL Filtered(K-1) is set initially = SSDESDL, that will lead to start power regulations immediately after the first valid measurement report.

Also Quality_DL Filtered(K-1) is set initially = QDESDL, that will lead to start power regulations immediately after the first valid measurement report.

SSDESDL: has value range from -110 to -47 dbm and default value is -90 dbm

QDESDL: has value range from 0 to 70 dtqu and default value is 30 dtqu

164/6/2015BTS/ MS Power Control - Mustafa Uurdoan16BTS Power ControlTill now we finalized two stages from the algorithm:

1. Preparation of the Input Data.2. Filtering of measurements.

174/6/2015

BTS/ MS Power Control - Mustafa Uurdoan17BTS Power Control184/6/2015Algorithm: 3) Calculation of Power Order (PU)

This will be done on three stages:

(A) Calculating the two basic Power Orders(B) Applying the Power Orders constraints(C) Conversion of output data.

BTS/ MS Power Control - Mustafa Uurdoan18BTS Power Control194/6/2015(A) Calculating the two basic Power Orders

i = 1,2 and 1 & 1 are parameters to compensate for the path loss and quality.

1 = LCOMPDL/100, 1 = QCOMPDL/100, 2 = 0.3, 2 = 0.4

pu1 is calculated according to settings of 1 & 1 ( The operator will set the proper values from his point of view for LCOMPDL & QCOMPDL), Default values: LCOMPDL=5 and QCOMPDL=55 pu2 is calculated according to recommended settings of 2 & 2 based on trials and field measurements

BTS/ MS Power Control - Mustafa Uurdoan19BTS Power Control204/6/2015(A) Calculating the two basic Power Orders

i = 1,2 and 1 & 1 are parameters to compensate for the path loss and quality.

pu1 and pu2 both of them aim to maintain the SS within the desired value defined according to SSDESDL and to maintain the Quality within the desired value defined according to QDESDL but each will calculate the path loss in different way.

pu_used = max (pu1,pu2), max of pu1 and pu2 will be used as the desired power order in the next measurement report . the max of both of them will mean lower down regulation/higher up regulation.

BTS/ MS Power Control - Mustafa Uurdoan20BTS Power ControlThe highest allowed power order pu_used = zero, which means keeping the output power at maximum value with no power control.

The lowest allowed power order is given by the minimum of the following: pu_used= minimum (30 dB, BSPWRT- minimum BTS o/p power) i.e. it is not allowed to decrease the o/p power or increase it by a value > 30 dB

(C) Conversion of output data

pu_used will be interpreted into final form PL_used which takes from015PL_used =Integer(-pu_used/2) ex: if PL_used = 3 and Down regulation for power is required, then in the next measurement report the BSC will inform the BTS to decrease its current power by 2* PL_used = 6 dBs

214/6/2015(B) Applying Power Order constraints

BTS/ MS Power Control - Mustafa Uurdoan21BTS Power Control224/6/2015Parameters Summary:

BTS/ MS Power Control - Mustafa Uurdoan22MS Power ControlThe Objective of the MS power control algorithm is to adjust the output power of the MS so that a desired signal strength is received in the BTS.The below graph shows the relation between MS o/p power and the measured (received) signal strength at the MS vs. the path loss between BTS and MS234/6/2015

BTS/ MS Power Control - Mustafa Uurdoan23MS Power Control For the area before point 1, the received power at the BTS in the UL is very good and sufficient, however the MS cant make any sort of down regulation and sends with power less than its minimum power.

As the MS is moving away from the BTS, the received power is decreasing, so after crossing point 1, the MS will start up regulating its power in steps to compensate for the path loss.

At point 2, the MS cant up regulate its power for a value above the max. allowed power level even if the received power in the MS is deteriorated or the path loss increased.

244/6/2015BTS/ MS Power Control - Mustafa Uurdoan24MS Power ControlFor Quality measurements the below graph shows the up regulations in the MS o/p power when quality is deteriorated (SS is not into consideration here)

As the Quality got worse ( 0 --> 7), the BTS will try to increase its power to compensate for the quality drop.254/6/2015

BTS/ MS Power Control - Mustafa Uurdoan25MS Power ControlAlgorithm: MS Power Control algorithm is done on 3 stages

1. Preparation of the Input Data.

2. Filtering of measurements.

3. Calculation of Power Order

264/6/2015BTS/ MS Power Control - Mustafa Uurdoan26MS Power Control Algorithm: 1) Preparation of the Input Data

Power Control is made on TCHs time slots as well as on the SDCCH time slots.Type of measurements

Both SS_UL and Quality_UL measurements will be used in the equation through which the next power order is calculated

274/6/2015

BTS/ MS Power Control - Mustafa Uurdoan27MS Power Control REGINTUL: A parameter that defines the minimum time period between two consecutive power orders. Measured in SACCH periods (0.48 Seconds) from 1 to 30 SACCH periods.

The BTS is able to changes its output power in the form of steps of 2 dBs (ex: 2dBs, 4dBs,. , max to 16 dBs)

When power control is in use the MS output power level will be given as: MS o/p power new (dBm) = MS o/p power old 2*PL used where PL used = 0 to 8

284/6/2015BTS/ MS Power Control - Mustafa Uurdoan28MS Power Control SSDESUL: A parameter that defines the desired Signal Strength in UL which we aim to maintain using power control in the UL. Measured in dBm

The SS measured will be checked against SSDESUL to know if Down regulation in the MS power or up regulation is needed.

QDESUL: A parameter that defines the desired Quality in UL which we aim to maintain using power control in the UL. Measured in dtqu ( 0 to 70).

The Quality measured will be checked against QDESUL to know if Down regulation in the MS power or up regulation is needed.

294/6/2015BTS/ MS Power Control - Mustafa Uurdoan29MS Power Control The equation used to calculate the power order in the next SACCH period contains information on SSDESULSS_Ul measured and QDESULQuality_UL measured.

SSDESUL SS_Ul measured is measured in dBm, while QDESUL Quality_UL measured is measured in dtqu so to be used in the same equation some sort of mapping should be done,i.e. QDESULQuality_UL measured should be represented in the form of dBs as well

304/6/2015

BTS/ MS Power Control - Mustafa Uurdoan30MS Power ControlSS Compensation

Compensating for power control:SS_UL Compensated= SS_ULMeasured+ 2*PL used Now in further calculations SS_UL Compensated will be used, where SS Compensated is the signal strength compensated for power regulations.

Quality Compensation

Quality_UL Compensated is calculated in the same way such that:Quality_UL Compensated= Quality_UL measured(in dBs) + 2*PL used Where the Quality_UL measured(in dBs) is the Quality_Ul measured (07) after transforming it into dBs

314/6/2015BTS/ MS Power Control - Mustafa Uurdoan31MS Power Control Algorithm: 2) Filtering of measurements

Filtering for both SS and Quality is done with exponential non-linear filters in order to eliminate variations of temporary nature.

Filtering of SS Measurements

SS_ULFiltered(k) = b* SS_ULCompensated(k) + a* SS_ULFiltered (K-1), k is the SACCH period

a & b (b=1-a) are the non-linear filters coefficients and a will define the length of the filter L, where each filter length L corresponds to certain value of a

But how the length of the non-linear filter is calculated?

324/6/2015BTS/ MS Power Control - Mustafa Uurdoan32MS Power ControlSS_ULFiltered(k) = b* SS_ULCompensated(k) + a* SS_ULFiltered (K-1), k is the SACCH period

334/6/2015 If SS_UL Compensated(k) < SS_UL Filtered(K-1)

then L = SSLENUL where,SSLENUL = between 3 and 15 SACCH Periods

In this case up regulation is needed and it should be done very fast in order to not lose the connection. If SS_UL Compensated(k) > SS_UL Filtered(K-1)

then L = SSLENUL *UPDWNRATIO/100 where,SSLENUL =between 3 and 15 SACCH periodsUPDWNRATIO = between 100 and 700

In this case Down regulation is needed and it should be done in a smooth way, decreasing the power suddenly may harm the connection.BTS/ MS Power Control - Mustafa Uurdoan33MS Power ControlFiltering of Quality Measurements

Quality_UL Filtered(k) = b* Quality_UL Compensated(k) + a* Quality_UL Filtered (K-1),

344/6/2015 If Quality_UL Compensated(k) < Quality_UL Filtered (K-1)

then L = QLENUL where,QSLENUL = between 1 and 20 SACCH periods

In this case up regulation is needed and it should be done very fast in order to not lose the connection If Quality_UL Compensated(k) > Quality_UL Filtered(K-1)

then L = QSLENUL *UPDWNRATIO/100 where, QSLENUL = between 1 and 20 SACCH periods UPDWNRATIO = between 100 and 700In this case Down regulation is needed and it should be done in a smooth way, decreasing the power suddenly may harm the connectionBTS/ MS Power Control - Mustafa Uurdoan34MS Power Control SS_UL Filtered(K-1) is set initially = SSDESUL, that will lead to start power regulations immediately after the first valid measurement report.

Also Quality_UL Filtered(K-1) is set initially = QDESUL, that will lead to start power regulations immediately after the first valid measurement report.

SSDESUL: has value range from -110 to -47 dbm and default value is -92 dbm

QDESUL: has value range from 0 to 70 dtqu and default value is 30 dtqu

354/6/2015BTS/ MS Power Control - Mustafa Uurdoan35MS Power ControlTill now we finalized two stages from the algorithm:

1. Preparation of the Input Data.2. Filtering of measurements.

364/6/2015

BTS/ MS Power Control - Mustafa Uurdoan36MS Power Control374/6/2015Algorithm: 3) Calculation of Power Order (PU)

This will be done on three stages:

(A) Calculating the two basic Power Orders(B) Applying the Power Orders constraints(C) Conversion of output data.

BTS/ MS Power Control - Mustafa Uurdoan37MS Power Control384/6/2015(A) Calculating the two basic Power Orders

i = 1,2 and 1 & 1 are parameters to compensate for the path loss and quality.

1 = LCOMPUL/100, 1 = QCOMPUL/100, 2 = 0.3, 2 = 0.4

pu1 is calculated according to settings of 1 & 1 ( The operator will set the proper values from his point of view for LCOMPUL & QCOMPUL),

pu2 is calculated according to recommended settings of 2 & 2 based on trials and field measurements

BTS/ MS Power Control - Mustafa Uurdoan38MS Power Control394/6/2015(A) Calculating the two basic Power Orders

i = 1,2 and 1 & 1 are parameters to compensate for the path loss and quality.

pu1 and pu2 both of them aim to maintain the SS within the desired value defined according to SSDESUL and to maintain the Quality within the desired value defined according to QDESUL but each will calculate the path loss in different way.

pu_used = max (pu1,pu2), max of pu1 and pu2 will be used as the desired power order in the next measurement report coz the max of both of them will mean lower down regulation/higher up regulation.

BTS/ MS Power Control - Mustafa Uurdoan39MS Power ControlThe highest allowed power order pu_used = zero, which means keeping the output power at maximum value with no power control.

The lowest allowed power order is given by the minimum of 16 dB i.e. it is not allowed to decrease the o/p power or increase it by a value > 16 Db

(C) Conversion of output data

pu_used will be interpreted into final form PL_used which takes from08PL_used =Integer(-pu_used/2) ex: if PL_used = 3 and Down regulation for power is required, then in the next measurement report the BSC will inform the MS to decrease its current power by 2* PL_used = 6 dBs

404/6/2015(B) Applying Power Order constraints

BTS/ MS Power Control - Mustafa Uurdoan40MS Power Control414/6/2015Parameters Summary:

BTS/ MS Power Control - Mustafa Uurdoan

4142THANKS FOR YOUR LISTENING4/6/2015BTS/ MS Power Control - Mustafa Uurdoan