3. learnings from china unicom (mei yun).ppt

Confidential / 1 © Nokia Siemens Networks

New optimization ideas for China Unicom 3rd party auditMei Yun, China 2011.11.27


• Time delay of HSUPA

• Ptx parameters optimization to improve EcNo+CQI-MPO

• UE Tx power


Time delay of HSUPA “PDP active” to “transfer first data”----problem description ：

18:48:17.687 PDP activate accept >>>> 18:48:17.905 4a >>>> 18:48:19.249 RB Config complete


18:48:17.687 PDP avtivate accept >>>>>>>>>> 18:49:11:500 HSUPA transfer first data

It takes 54s from “PDP active accept” to “transfer first data”




Only R99 service ， no HSUPA service:

—— Prx Power<(PrxNoise+)PrxTarget + PrxOffset

R99 & HSUPA service:

—— R99 Prx Power<(PrxNoise+)PrxTargetPS, (PrxTargetPSMin< PrxTargetPS<PrxTargetPSMax)

—— R99+UPA Prx Power<(PrxNoise+)PrxMaxTargetBTS


Time delay of HSUPA “PDP active” to “transfer first data”----Prx parameters setting (before optimizationmization) ：

　　 NED default

China default

SJZ1(6340)

SJZ2(26)

SJZ3(456)

SJZ4(72) SJZ5(3)

R99 onlyPrxTarget 4 10 12 14 16 18 22

PrxOffset 1 6 4 4 4 4 4

R99+HSUPA

PrxMaxTargetBTS 6 16 16 18 20 22 26

PrxTargetPSMax 4 8 12 14 16 16 18

PrxTargetPSMin 4 8 6 6 6 6 6

SJZ1 ：When there is only R99 service in the cell ， Prx threshold is Prxtarget+PrxOffset (12+4=16dB). If R99 service is full load and an new HSUPA service want to be activated in the cell, now Prx threshold is changed to PrxMaxTargetBTS(16dB).

Prxtarget+PrxOffset= PrxMaxTargetBTS.

if PrxTarget has been set high to allow for long term increases in uplink interference then there is more danger that UE are allocated HSUPA but are not able to transfer any data.


　　 NED default

China default

SJZ1(6340)

SJZ2(26)

SJZ3(456)

SJZ4(72) SJZ5(3)

R99 onlyPrxTarget 4 10 11 13 15 17 21

PrxOffset 1 6 3 3 3 3 3

R99+HSUPA

PrxMaxTargetBTS 6 16 16 18 20 22 26

PrxTargetPSMax 4 8 9 11 13 13 15

PrxTargetPSMin 4 8 6 6 6 6 6

PrxTarget reduces1dB, PrxOffset reduces 1dB, PrxTargetPSMax reduces 3dB

SJZ1 ：1. PrxMaxTargetBTS> Prxtarget+PrxOffset, 2dB for new UPA.

2. PrxTargetPSMax is reduced by 3dB, which gives more power for HSUPA when there is both HSPA & R99 service in the cell.

Time delay of HSUPA “PDP active” to “transfer first data”----Prx parameters setting (after optimization) ：


Time delay of HSUPA “PDP active” to “transfer first data”----optimization compare ：

before optimizationmization the time delay is 12.71s, after optimization it is 8.45s


Time delay of HSUPA “PDP active” to “transfer first data”----optimization compare ：

PrxMaxTargetBTS should be greater than PrxTarget+PrxOffset and PrxTargetPS. So when the RNC is scheduling as much resource as it is allowed for R99 connections, there is still some resource available for the Node B to schedule HSUPA. However, if PrxTarget has been set high to allow for long term increases in uplink interference then there is more danger that UE are allocated HSUPA but are not able to transfer any data.


Ptx parameters optimization to improve EcNo+CQI-MPO---Reported CQI & NSN implementation

• Measurement power offset, is the default power offset between HS-PDSCH and P-CPICH. Measurement power offset is signaled to the UE when HS-DSCH MAC-d flow is set-up or if updating is needed due to serving HS-DSCH cell change.

• Ptx_Allowed HSDPA is calculated as follows:

– Pmax is the cell maximum output power

– Ptx_non_HSPA is the latest received PtxNonHSPA measurement.

– The PtxMaxHSDPA parameter defines the maximum allowed HSDPA transmission power.

– GammaFactor is an RNC-internal (hidden) parameter which has an actual value of 0.5.

• Based on formulas above, half of the available HSDPA power is signalled to UE. CQI value reported by UE is then 3 less than it should be based on actual available power

However, this impact only reported CQI values and has no negative impact to final performance as BTS make decision (about TBS) based on compensated CQI (by knowing how much power there is actually available for HSDPA)

0,*, __max__ rGammaFactoPPAPtxMaxHSDPMINMAXP HSPAnontxHSDPAallowedtx

CPICHHSDPAallowedtxPP

__0.5


Ptx parameters optimization to improve EcNo+CQI-MPO---CQI

• Reported CQI – Reported by UE, this is the CQI we can capture from drive test logs and counter stats.– Legacy UEs are reporting CQI values from 0-30

– MIMO UEs are reporting both CQI type A (from 0-14) and B (from 0-30)

• BTS decides transport block size based on compensated CQI

• Compensated CQI – BTS link adaption compensates CQI (based on internal algorithm) for differences between assumed HS-PDSCH transmit power and actual available HS-PDCH transmit power – by targeting 10% HARQ retransmission rate – Compensated CQI can have values from 1-35

– It is not possible to capture compensated CQI values from drive test logs and counters stats

In CUC 3rd party audit, the CQI in “CQI-MPO” is Report CQI


Ptx parameters optimization to improve EcNo+CQI-MPO ---Measurement power offset - calculations

Below is MPO value with different PtxCellMax & PtxCPICH ：• now the network has no load.

CPICHHSDPAallowedtxPP

__

PtxCellMax 43(20W) 40(10W) 40(10W)

PtxCPICH 33(2W) 30(1W) 33(2W)

CCCH total 35.5 32.5 35.5

Available HSDPA pwr 42.15(16.4W) 39.14(8.2W) 38.13(6.5W)

Gammafactor 0.5 0.5 0.5

Ptx_Allowed HSDPA 39.14(8.2W) 36.13(4.1W) 35.05(3.2W)

MPO, dB (calculated) 6.14 6.13 2.05

MPO Dingli 6 6 2

0,*, __max__ rGammaFactoPPAPtxMaxHSDPMINMAXP HSPAnontxHSDPAallowedtx


Ptx parameters optimization to improve EcNo+CQI-MPO .

Ptx ↑

PHSPDSCH ↑ MPO ↑

No ↑ EcNo ↓

CQI ↑

CQI ↓

CQI ↑ CQI-MPO ↓

.

PHSPDSCH ↓ MPO ↓

No ↓ EcNo ↑

CQI ↓

CQI ↑

CQI ↓ CQI-MPO ↑Ptx ↓

Why in the high-load cell, the EcNo and CQI-MPO is bad?


PtxMax 43 dBm

PtxTargetPS

PtxNC

PtxNRT

PtxHSDPA

2

PtxNonHSDPA

PtxTotal

Ptx parameters optimization to improve EcNo+CQI-MPO ---Ptx Power

PtxTargetPSMin-10..50; 0.1; 36 dBm

PtxTargetPSMax-10..50; 0.1; 40 dBm

PtxHighHSDPAPwr-10..50; 0.1; 41 dBm


Ptx parameters optimization to improve EcNo+CQI-MPO ---parameters optimization idea

Total power （ CPICH

power）

PtxMaxHSDPA PtxHighHSDPAPwr PtxTargetPSMax

Maximum allowed HSDPA power

High threshold of PtxTotal for dynamic HSDPA pwr

alloc

High threshold of PtxTotal for dynamic HSDPA pwr

alloc

20W （ 33dBm ）before

optimizationafter

optimizationbefore

optimizationafter

optimizationbefore

optimizationafter

optimization

430 420 420 415 420 405


optimizationafter

optimizationbefore

optimizationafter

optimizationbefore

optimizationafter

optimization

430 400 420 395 420 390


optimizationafter

optimizationbefore

optimizationafter

optimizationbefore

optimizationafter

optimization

460 450 450 445 450 435


optimizationafter

optimizationbefore

optimizationafter

optimizationbefore

optimizationafter

optimization

460 430 450 420 450 420


UE Tx power optimization---parameters change

1 、 PrxMaxtargetBTS 、 Prxtarget are reduced by 1dB (to decrease RTWP and make the UE speak not too loudly )

Below: more PrxMaxtargetBTS, more uplink interference



2 、 EbNoDCHOfCSNBAMRQua is changed from 0.2% to 0.5%

UE NodeB RNC

Uu interface

Iub Interface

Signal

TPC cmd

SIRtarget

User data

UL ILPC UL OLPC

UL power control



3 、 Reduce PS R99 load

MaxBitRateULPSNRT 384 ->128

SIRDPCCHInitialDCHHSX(X=4,8,16,64,128,256) is reduced by 3dB

EbNoDCHOfPSNRTPriQua:-2->-1

3. learnings from china unicom (mei yun).ppt

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