To improve coverage and solve coverage hole by increasing CPICH Power Initial

Author Phoon Kok Jin ID 00742221Representative UMTS RNP Product RNP&RNO

Date 2013-04-16Version(VxxxRxxxCxxxBxxx)

RNC

V900R014ENGC00SPC330

Checked by

Name： To improve capacity and solve DL power congestion by using 30W solution.Phenonema：

In country M, operator M is facing serious DL power congestion issue. To solve this issue, operator M agreed to conduct 30W trial to check the possibility of this solution on solving DL power congestion issue. This trial will be separated into 2 parts, which is 30W max power with 3W CPICH power and 30W max power with 2W CPICH power.

The circled area showed a crowded housing area which was covered by nearby sites GSTMMU and WMSEMU, both sites were having power congestion issue.

BAM version: V900R014ENGC00SPC330MBSC Mode: GUL

Alarm： None.

Cause： 30W solution was needed because of several reasons below.(1.) Sites were having very high traffic level and capacity wasn’t enough to sustain all traffic.(2.) Tilting couldn’t be adjusted as it would reduce coverage and no other nearby sites were able to cover the created coverage hole.

Process Part 1: 30W Transmit Power with 3W CPICH.

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To improve coverage and solve coverage hole by increasing CPICH Power Initial

1. Deactivate Local Cell.DEA UCELL: CellId=xxxxx;

2. Modify the maximum and minimum CPICH power allowed.MOD UPCPICHPWR: CellId=xxxxx, MaxPCPICHPower=365, MinPCPICHPower=330;

3. Modify Maximum Transmit Power and CPICH Power.MOD UCELL: CellId=xxxxx, MaxTXPower=448, PCPICHPower=348;

4. Modify Power setting in Local Cell.MOD LOCELL:LOCELL=x, SEC=REMOTE_SECTOR, MXPWR=448;

5. Activate back Locel Cell.ACT UCELL: CellId=xxxxx;

Part 2: 30W Transmit Power with 2W CPICH.1. Deactivate Local Cell.

DEA UCELL: CellId=xxxxx;2. Modify the maximum and minimum CPICH power allowed.

MOD UPCPICHPWR: CellId=xxxxx, MaxPCPICHPower=365, MinPCPICHPower=330;

3. Modify Maximum Transmit Power and CPICH Power.MOD UCELL: CellId=xxxxx, MaxTXPower=448, PCPICHPower=330;

4. Modify Power setting in Local Cell.MOD LOCELL:LOCELL=x, SEC=REMOTE_SECTOR, MXPWR=448;

5. Activate back Locel Cell.ACT UCELL: CellId=xxxxx;

In both cases, NodeB will be required to restart before new power setting takes effect, therefore command 1 is used to deactivate NodeB. Command 2 is then used to change the maximum and minimum PCPICH threshold. Command 3 and command 4 are used to modify the Maximum transmit power and CPICH power setting on both NodeB side and Cell side. After that, command 5 is being executed to reactivate the local cell with new power setting.

Suggest and Summary：

Part 1: 30W Transmit Power with 3W CPICH.

It is found out that with this power setting, although capacity has been increased

to 30W, but at the same time congestion level will also increase because now it

will attract even more traffic due to coverage is larger with 3W CPICH power.

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To improve coverage and solve coverage hole by increasing CPICH Power Initial

From above graph we can observe that 30W 3W setting is having more serious

power congestion problem than previous 20W 2W setting. The blocked call rate

(power) is calculated using formula as below.

VS.RAB.FailEstabCS.DLPower.Cong/VS.RAB.AttEstabCS.Conv * 100

Performance stats for site WMSEMU were collected over 3 days and looking at

the KPI table below, we could observe that although after using 30W and 3W

CPICH solution, AMR traffic and HSDPA user number had increased

significantly, but the rest of the KPI such as CSSR and DCR degraded very

badly. It was due to congestion level had became even worse.

WMSEMU KPI 20W and 2W 30W and 3W

CS CSSR 79.90% 55.16% Degraded

CS DCR 1.03% 1.18% Degraded

AMR Traffic 1640.83 Erl 1725.73 Erl Improved

PS CSSR 97.07% 95.49% Degraded

PS DCR 1.23% 1.20% Remained

HSDPA Traffic 112540.09 MB 105024 MB Remained

HSDPA User Number 122.8 130.13 Improved

HSDPA Throughput 252.85 kbps 217.15kbps Degraded

In conclusion, although 30W and 3W CPICH solution was able to increase

capacity, but it was not a good solution to solve power congestion because it

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To improve coverage and solve coverage hole by increasing CPICH Power Initial

would further degrade KPI very badly and caused congestion level to become

even worse.

Part 2: 30W Transmit Power with 2W CPICH. An alternative to 30W solution was to pair it with 2W CPICH power. With this

setting we were able to remain same coverage area but with an larger capacity.

From the graph below, we could clearly see that with 30W and 2W CPICH

solution, power congestion level was able to reduce significantly.

Looking on the KPI stats collected over 3days. We could observe a few

improvement especially on CSSR and DCR performance since power

congestion had now been released. HSDPA Throughput had also observed

significant improvement.

WMSEMU KPI 20W and 2W 30W and 2W

CS CSSR 79.90% 99.09% Improved

CS DCR 1.03% 0.98% Improved

AMR Traffic 1640.83 Erl 1569.3 Erl Degraded

PS CSSR 97.07% 99.13% Improved

PS DCR 1.23% 1.06% Improved

HSDPA Traffic 112540.09 MB 138782.4 MB Improved

HSDPA User Number 122.8 112.14 Degraded

HSDPA Throughput 252.85 kbps 727.34 kbps Improved

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To improve coverage and solve coverage hole by increasing CPICH Power Initial

However, there was a slight degradation on AMR traffic and HSDPA user

number. It was due to the Ec/Io level had now became worse due to the huge

increase in HSDPA traffic, causing CS traffic to handover to either 2G or

surrounding sites.

Ec/Io level can be further optimized with the parameter power margin in order

to limit the power available for PS. This could reduce the PS traffic level but it

would improve Ec/Io level and thus attract more CS traffic. Beware that the

value of power margin set had to be an intermediate value so that PS

performance will not be affected too badly while improving CS performance at

the same time. Suggested power margin value is 23% based on general cases in

M country.

In conclusion, 30W and 2W CPICH power solution will be able to solve power

congestion issue but with a tradeoff in Ec/Io level. However, this tradeoff would

depend on site to site situation and could be optimized through changing power

margin to reduce PS traffic level and improve Ec/Io performance.

Attached：Others:

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