topcs ul power control optimization
TRANSCRIPT
Soc Classification level 1 © Nokia Siemens Networks Presentation / Author / Date
Uplink power control and throughput optimization
DRAFT - material under development
Soc Classification level 2 © Nokia Siemens Networks Presentation / Author / Date
Recap: PUSCH open-loop power control formula, simple version
][)(log10 10_0, dBmMPLPP PUSCHPUSCHtxPUSCH OLPC:
PUSCH tx power
Number of UL PRBs
allocated
PUSCH receive power target (rx power per PRB)
Fractional path loss compensation factor,
alpha
Path loss estimated by UE
• cannot be higher than UE tx power• note: P0 sets UL SINR target
– (roughly speaking, so does closed-loop UL power control, so let‘s just focus on OL for simplicty)
Soc Classification level 3 © Nokia Siemens Networks Presentation / Author / Date
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Pathloss dB
UE T
x po
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dB
m
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UL
tput
kbp
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UE tx power per 1PRB UL Tput kbps
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Pathloss dB
UE
Tx p
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dB
m
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UL
tput
kbp
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UE tx power per 1PRB UL Tput kbps
Motivation: Impact of P0 and alpha
Low P0NomPUSCH• Too low SINR is used close to
BTS• P0_nominal_PUSCH = -
110dBm
High P0NomPUSCH• Too low number of PRBs is
used with high path loss because ATB tries to maintain SINR
• P0_nominal_PUSCH = -90dBm
Throughput too low with low pathloss
Throughput too low with
high path loss
Soc Classification level 4 © Nokia Siemens Networks Presentation / Author / Date
Motivation: OL-PC parameter example simulation
Cell edge UL tput Cell average UL tput
• Optimum operation point exists for cell edge and cell average throughput there is some optimization to do!
Soc Classification level 5 © Nokia Siemens Networks Presentation / Author / Date
Motivation: Trade-off between coverage and capacity
P0 = -36 dBm a = 0.412924 kbps / 1329 kbps
P0 = -86 dBm a = 0.89044 kbps / 2098 kbps
P0 = -46 dBm a = 0.512625 kbps / 1247 kbps
P0 = -48 dBm a = 0.512318 kbps / 1579 kbps
P0 = -52 dBm a = 0.511186 kbps / 1910 kbps
P0 = -50 dBm a = 0.511833 kbps / 1796 kbps
These P0 and alpha provide best average
cell tput
These P0 and alpha provide best cell edge
tput
Soc Classification level 6 © Nokia Siemens Networks Presentation / Author / Date
How to optimize the average cell throughput in practice?
• What input information we need?– path loss distribution– mapping from SNR to throughput
• What variables we tune (OL)?– PUSCH P0 target– alpha
• What variables we tune (CL)?– Upper/lower target SINR threshold– Upper/lower target RSSI threshold
OLPC:
Distribution of PL needed
][)(log10 10_0, dBmMPLPP PUSCHPUSCHtxPUSCH
Soc Classification level 7 © Nokia Siemens Networks Presentation / Author / Date
How to optimize the average cell throughput in practice?
• Problem: path loss distribution cannot be obtained directly from PM counter measurements…
– Mpusch is not directly given by PM counters
• Another method for trials is to obtain PL distribution from drive tests– Optimization only applies to dt route (showcases)
][)(log10,min _010 dBmPLPMPP PUSCHPUSCHCMAXPUSCH OLPC:
Soc Classification level 8 © Nokia Siemens Networks Presentation / Author / Date
UL SINR versus throughput mapping example
UDP UL
0
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-8 -3 2 7 12 17 22
UL SINR
Mb/
s
EVA LCEVA MCEPA HCETU MCCOV EVA MC
Soc Classification level 9 © Nokia Siemens Networks Presentation / Author / Date
Example optimization
Path Loss = RS tx power per RE – RSRP• RSRP measured by UE, RS tx power = 15dBm
PATH LOSS EMPIRICAL PDF FROM DRIVE TEST
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0.01
0.02
0.03
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0.05
0.06
80 83 86 89 92 95 98 101
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PATH LOSS [dB]
Soc Classification level 10 © Nokia Siemens Networks Presentation / Author / Date
Path loss vs UL tput w/ path loss empirical pdf from dt
0.0E+00
1.0E+07
2.0E+07
3.0E+07
4.0E+07
5.0E+07
6.0E+07
80 90 100 110 120 130 140
path loss [dB]
UL
tput
[dB]
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0.02
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0.06
Imposing path loss pdf on PL-vs-tput curve
Average tput in UL = 26Mbps
Path loss – tput curve taken from simulation.
In this example simulation includes
64QAM
P0= -100dBmalpha=1
Soc Classification level 11 © Nokia Siemens Networks Presentation / Author / Date
Path loss vs UL tput w/ path loss empirical pdf from dt
0.0E+00
1.0E+07
2.0E+07
3.0E+07
4.0E+07
5.0E+07
6.0E+07
80 90 100 110 120 130 140
path loss [dB]
UL
tput
[dB]
0
0.01
0.02
0.03
0.04
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0.06
Finding optimal alpha and P0
P0= -100dBmalpha=1Ave tput=26Mbps
P0= -40dBmalpha=0.4Ave tput=34.5Mbps
Soc Classification level 12 © Nokia Siemens Networks Presentation / Author / Date
Conclusions
• In trials, UL power control optimization criterion is often highest possible peak rate in the test case measurement position• In live networks, optimization criterion can be average cell throughput or cell edge throughput• Example of optimization based on measured path loss distribution was shown• Proof of Concept in real live network still missing
– Volunteering projects for PoC can contact [email protected] or NPO CaMa
Soc Classification level 13 © Nokia Siemens Networks Presentation / Author / Date
Uplink comparison with different power control (from NTN)
Throughput vs RSRP
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-130-128 -126-124-122-120 -118-116-114-112 -110-108-106-104 -102-100 -98 -96 -94 -92 -90 -88 -86 -84 -82 -80 -78 -76 -74 -72 -70 -68 -66
dBm
Mbp
s
ultp_olmimo_olpc_noif_fpc8608ultp_olmimo_olpc_noif_nofpcultp_olmimo_olpc_noif_fpc5005ultp_olmimo_clpc_noif_nofpcultp_olmimo_clpc_noif_fpc8608ultp_olmimo_clpc_noif_fpc5005
Soc Classification level 14 © Nokia Siemens Networks Presentation / Author / Date
Parameters in NTN power control tests
Mimo IF (%) OLPC CLPC P0 Alpha DL/ULTxdiv 0 X -100 1 DLTxdiv 70 X -100 1 DLTxdiv 0 X -100 1 DLTxdiv 70 X -100 1 DLOL MIMO 0 X -100 1 DL
OL MIMO 70 X -100 1 DL
OL MIMO 0 X -100 1 DL
OL MIMO 70 X -100 1 DL
Mimo IF (%) OLPC CLPC P0 Alpha DL/ULCL MIMO 0 X -100 1 DLCL MIMO 70 X -100 1 DLCL MIMO 0 X -100 1 DLCL MIMO 70 X -100 1 DLOL MIMO 0 X -86 0.8 ULOL MIMO 0 X -86 0.8 ULOL MIMO 0 X -50 0.5 ULOL MIMO 0 X -50 0.5 UL