3. learnings from china unicom (mei yun).ppt
TRANSCRIPT
Confidential / 1 © Nokia Siemens Networks
New optimization ideas for China Unicom 3rd party auditMei Yun, China 2011.11.27
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• Time delay of HSUPA
• Ptx parameters optimization to improve EcNo+CQI-MPO
• UE Tx power
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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
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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”
Time delay of HSUPA “PDP active” to “transfer first data”----problem description :
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Time delay of HSUPA “PDP active” to “transfer first data”----problem description :
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
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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.
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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) :
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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
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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.
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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
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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
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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
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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?
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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
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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
20W ( 30dBm )before
optimizationafter
optimizationbefore
optimizationafter
optimizationbefore
optimizationafter
optimization
430 400 420 395 420 390
40W ( 36dBm )before
optimizationafter
optimizationbefore
optimizationafter
optimizationbefore
optimizationafter
optimization
460 450 450 445 450 435
40W ( 33dBm )before
optimizationafter
optimizationbefore
optimizationafter
optimizationbefore
optimizationafter
optimization
460 430 450 420 450 420
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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
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UE Tx power optimization---parameters change
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
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UE Tx power optimization---parameters change
3 、 Reduce PS R99 load
MaxBitRateULPSNRT 384 ->128
SIRDPCCHInitialDCHHSX(X=4,8,16,64,128,256) is reduced by 3dB
EbNoDCHOfPSNRTPriQua:-2->-1