FP7 ICT-SOCRATES Automatic Cell Outage Compensation M. Amirijoo (Ericsson), R. Litjens, L. Jorguseski (TNO ICT), L. C. Schmelz (Nokia Siemens Networks)
FP7 ICT-SOCRATES
Automatic Cell Outage
Compensation
M. Amirijoo (Ericsson),
R. Litjens, L. Jorguseski (TNO ICT),
L. C. Schmelz (Nokia Siemens Networks)
WWW.FP7-SOCRATES.EU
2/18
Mehdi Amirijoo, Ericsson
Background
� Reasons for outages, e.g.:
– software and hardware failures (radio unit, antenna etc),
– external failures such as power supply or network connectivity
� Frequency of outages depends on, e.g.,
– operator policy (level of hardware redundancy)
– geographic location (e.g weather condition)
– maturity and type of technology
– power supply quality (probability of electricity outages)
� Outages
– last from several hours to days
– result in loss of coverage
– customer complaints and dissatisfaction
– loss of potential revenues
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3/18
Mehdi Amirijoo, Ericsson
Solution
MeasurementsDetection
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4/18
Mehdi Amirijoo, Ericsson
Solution
Measurements
CompensationOperator policy
Control parameters
Detection
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5/18
Mehdi Amirijoo, Ericsson
Solution – Operator Policy
� Manage tradeoff between coverage and quality
� Quality Q: Xth-percentile of UE throughput
– e.g., 10th-percentile UE throughput
� Network is dimensioned according to a nominal target quality QT, e.g.,
– QT,DL = 256 kbps
– QT,UL = 128 kbps
� Nominal target quality may not be satisfied during an outage
� Compensating cells have an outage target quality Q’T, e.g.,
– Q’T,DL = 128 kbps
– Q’T,UL = 64 kbps
Maximize coverage such that Q ≥ Q’T
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6/18
Mehdi Amirijoo, Ericsson
Solution – Algorithms
� UL coverage is the limiting factor
� Extensive sensitivity analysis
– control parameters, scenarios, etc
� Control parameters:
– uplink target received power P0
– antenna downtilt
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7/18
Mehdi Amirijoo, Ericsson
Solution – Definition of P0
� Used in open-loop power control
� P0 is the target received power in UL
� UL transmit power spectral density (PSD) is
where
– P0 = SNRtarget * N0
– N0 is the noise PSD
– PL is the path loss, including shadowing and antenna gains
– α is the path loss compensation fraction
αPLPPSD ×= 0
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8/18
Mehdi Amirijoo, Ericsson
Solution – Tuning of P0
� Let k denote interation number
� By decreasing P0 in the cells around the outage site we
– decrease the UL inter-cell interference
– improve the UL coverage
� If QDL > Q’T,DL AND QUL > Q’T,UL then
P0(k) = max(P0_MIN,P0(k-1) - δ)
else
P0(k) = min(P0_MAX,P0(k-1) + δ)
WWW.FP7-SOCRATES.EU
9/18
Mehdi Amirijoo, Ericsson
Solution – Tuning of P0
� P0_MIN is set such that UL SINR is sufficient for lowest MCS
� Let SINRmin be the minimun tolerable UL SINR
� Received signal power must satisfy
� Base max UL interference Imax on historic measurements
� In practice introduce an UL interference margin IM
)()(max0min0max0min
INSINRPINSINRS +≥⇒+≥
)(max0min0 M
IINSINRP ++≥
WWW.FP7-SOCRATES.EU
10/18
Mehdi Amirijoo, Ericsson
Solution – Compensation Network
� Cells that tune P0 are referred to as the
compensation network (CN)
� CN can be derived using UE measurements during nominal operation
� Number of cells in CN is a tradeoff
between
– Coverage improvement
– Overall quality degradation
� Consider the blue cells as the
compensation network (CN)
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11/18
Mehdi Amirijoo, Ericsson
Simulator and Scenario
� Static snapshot simulator
� Network with 57 cells
� Propagation:
– Okumura-Hata (urban)
– Shadow fading
� UEs distributed uniformly
� Channels/signals:
– Reference signal
– DL data channel (”PDSCH”)
– UL data channel (”PUSCH”)
� Truncated Shannon model
� 3D antenna pattern
� SISO system
-1000 -500 0 500 1000
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
-140
-130
-120
-110
-100
-90
-80
-70
Pathgain [dB]
WWW.FP7-SOCRATES.EU
12/18
Mehdi Amirijoo, Ericsson
Simulator and Scenario
� Data traffic characterised by requested data rate DL = 1 Mbps and UL = 250 kbps
� Quality/Coverage network planning targets– Coverage > 98 %
– 10th-% DL Throughput > 256 kbps
– 10th-% UL Throughput > 128 kbps
� Loads– High load: max load such that coverage/quality targets are satisfied (47 UEs/cell)
– Medium load: 50 % of high load (23 UEs/cell)
– Low load: 1 UE/cell
� Capacity driven layout– ISD = 500 m
– Antenna downtilt = 15º
– P0 ~ -96 dBm
– Consider high load, medium load, low load
� Coverage driven layout– ISD: max ISD such that coverage/quality targets are satisfied => ISD = 2200 m
– Antenna downtilt = 5º
– P0 ~ -114 dBm
– Consider low load
� Show results for capacity driven layout with high and medium load
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13/18
Mehdi Amirijoo, Ericsson
Simulation Results
Compensating cell (blue)
Cell in outage (red)
Compensated coverage hole (grey)
10th-perc DL throughput [Mbps] (averaged over compensating cells)
10th-perc UL throughput [Mbps] (averaged over compensating cells)
Increase in number of served UEs (relative to no compensation)
Control Parameter P0
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14/18
Mehdi Amirijoo, Ericsson
Simulation Results – High Load
Outage
Start of compensation
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15/18
Mehdi Amirijoo, Ericsson
Simulation Results – High Load
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16/18
Mehdi Amirijoo, Ericsson
Simulation Results – Medium Load
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17/18
Mehdi Amirijoo, Ericsson
Conclusion
� Outages result in customer dissatisfaction & loss of revenues
� Operator specifies tradeoff between quality and coverage
� Our solution can improve coverage during an outage
� Future work:
– Algorithms for tilt tuning
– Compensation network based on, e.g., UE measurements
– Observability of coverage
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18/18
Mehdi Amirijoo, Ericsson
Contact
Mehdi Amirijoo, Ericsson Research, Ericsson AB
E-mail: [email protected]
Phone: +46107115290