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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Security Level:
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How to analyze Coverage
Issues in DT
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Coverage
Downlink RxLevel and Coverage
Coverage of single cell
Coverage of whole network
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 3
Coverage
EIRP(dBm)
L(dB)
RxLev(dBm)
Unexpected coverage(overshooting)Good coverage
Network Coverage is evaluated by:
RxLev = EIRP(dBm) L(dB)
Where:
EIRP = Effective Isotropic Radiated Power
L = Propagation Losses
In urban area, Lower Antenna Height (=6 degree),
and Lower EIRP (
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 4
Coverage(one cell)
The following example shows thedownlink RxLevel(Dedicated Mode)
decreases when MS is driving away
from BTS.
The RxLevel decrease faster when
Antenna Downtilt increase.
Downtilt: 0 drgree
Downtilt: 8 drgree
Variation
due to
shadowing
Global
means
RxLevel
Variations due to
Rayleigh
fading
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 5
Coverage(Network)
The picture shows the coverage of a city, which contains good and bad
coverage areas. The distribution of downlink RxLev concentrates from -80 to -95 dBm.
Good Coverage
Bad Coverage
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Coverage Issues
What is
Coverage hole
Sudden Decrease on Signal Level
Line of Sight Lost
Lack of Dominant Server
Coverage Overlapping
Overshooting
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Coverage Hole
RxQuality
RxLevel
Legend
Poor Coverage
Areas
RxLevel(Serving Cell) is about (or less than) -95 dBm
RxLevel(Neighbours) are about (or less than) -95 dBm
Bad
RxQualityCall
Drop
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Sudden Decrease on Signal Level
RxLev(Serving Cell and
Neighbors) decrease in ashort time.
Check if there is big
change of testing
environment, e.g. check
if the test was performedon a highway and that
particular area was a
tunnel or not.
Signal level on the chart
will make a curve rather
than unstable changes.
This usually results in
Ping Pong Handovers
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Line of Sight Lost
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Signal Strength of Serving cell make fast up and down due
to far away server being blocked by obstacles from the
terrain. The other way, signal from the server lose line of
sight(LOS) to the mobile because of a hill of something.
RxQuality goes
worse when the
level drops down
fast
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Lack of Dominant Server
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Signal Level of more
than one cell (ServingCell and Neighbors)
are not high enough.
This might happen
because the MS is
located on the cell
borders and there is
no any best server to
keep the call.
Lack of Dominant
Server Causes too
many HandoversBetween the same
Cells
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Coverage Overlapping
Signal Level of 34
cells are too closed
to each other.
This might point
overlapping cells.
This will cause
quality problemsbecause of
frequency reuse
Immediate action to
optimize cell
coverage should betaken by by power
reductions, downtilts
or other
configuration
changes.
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Overshooting
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BTS
Serving
cell
Coverage spot
(island effect)Neighbour cell A
BSIC 1
Freq. A
Other cell B
BSIC 1
Freq. A
MS is covered by the
serving cell, but isoutside the cell
BSC thinks that it is
neighbour cell A and
makes a handover to
cell A
The MS is not nearcell A so the
assigned TCH for the
handover is not used
Cell A will have
unused TCH
(handover)
The call might bedropped because it
cannot make the
handover
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Proposal of Coverage Issue
Solution of low coverage
Solution of overshooting and overlapping
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Solutions of Low Coverage
Possible solution can be listed as below:
New Site ProposalSector Addition
Site Configuration Change (Antenna Type, height, azimuth, tilt changes)
Loss or Attenuation Check ( Feeders, Connectors, Jumpers, etc..)
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Proposal Remark How to do
New Site ProposalMost effective solution,but the cost is highest
Using prediction tool(U-net) to identify the bestlocations to put new sites
Sector AdditionEffective solution
but only for Omni-Site
Using prediction tool(U-net) to identify the
recommended azimuth of new sectors
Antenna
Height Difficult, high cost
Using prediction tool(U-net) to identify the
recommended height, type, azimuth or down tilt of
sector.
Type Difficult, high cost
AzimuthEasy to operate
Downtilt Easy to operate
Hardware
Feeders Only for troubleshooting
Referring to hardware checking guide
Connectors Only for troubleshooting
Jumpers Only for troubleshooting
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Solutions of overshooting or overlapping
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Possible solution can be listed as below:
Site Configuration Change (Antenna Type, height, azimuth, tilt changes)Cell Configuration Change (Carrier Power Type, Static TRX Power Class, Fine
Tuning of Static TRX Power)
Proposal Remark How to do
Antenna
Height Difficult, high cost
Using prediction tool(U-net) to identify the
recommmended height, type, azimuth or
downtilt of sector.
Type Difficult, high costAzimuth Easy to operate
Downtilt Easy to operate
Parameter Output Power relatedEasy to operate, but with
risk of coverage reduction
Referring to Data Configuration Reference
Help
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