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DrivetestDrivetest
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Tools
Mobile TEMS Pocket W600i
GPS
Compass
Inverter input 12V, Output 220 V ac, 400 W
TEMS Software 7.1.1 Data Collection
TEMS Software 7.1.1 Route Analisys
Map Info
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Work Process
Collect
OMC Parameter
Database
RF NetworkDesign
Cell File (TEMS)And
Dot Tab Site (mapinfo)
Drive Test
Measurements
Analysis Programs
Coverage
Dropped Calls
Call Setup Success
HandoverPerf.
Speech Quality
General Check
Verification of
RF NetworkDesign
Site Check
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Test Mobile Measurements
Collect RxLev measurements together with GPS co-ordinates Analyse on planning tool
Reasons for poor coverage:
serving cell not best server
handover problems
best server signal low
check site / network design
Analyse in terms of relevant
thresholds:
indoor level in-car level
outdoor level
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Test Types
Continuous drive test setup a test call and drive over an area for detecting lack of
coverage, missing handovers, interferences etc.
Spot test
detail measurement to be taken at dedicated problem spots for
detail analyzing of specific problem
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Collect / Analyse Drive Test Measurements
Test measurement (TEMS etc. together with a GPS)
Signal Strength
Co-channel and adjacent interference
Handover relations
Test types
Continuos drive test (Trace mode)
Spot test
Network performance test (Statistical mode)
Test Measurement
Collect MS measurement report data (Downlink only!!)
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Coverage: Analysis for Fulfilment of Coverage
Requirements (Urban, rural ...
areas, outdoor, in-car, indoor)
Dropped Call: Analysis for Dropped Calls due to
Interference, SW/HW failures,Transmission Network Failures
Call Setup: Analysis for Blocking and Capacity
Limitations, Analysis for Resource
Allocation Procedures
Handover: Analysis for Efficient HandoverPerformance
Speech Quality: Analysis for Interference
Analysis Programs
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Dropped Call Analysis
How to measure drive tests
repeated call setups (preferred)
continuous calls
OMC measurements
Reasons for dropped calls
lack of coverage
interference problems
handover problems
lack of synchronisation in network problems with other parts of the network
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Call Setup Analysis
Reasons for failed call setups lack of coverage
database problems
database inconsistencies
parameter settings, e.g.
RXLEV_ACCESS_MIN, RACHBT,
RACH_MAX_RETRANS
cell reselection related parameters
network congestion
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Handover Parameters
Fine-tuning of handover parameters Moving cell boundaries in order to
Enhance success rate for critical handovers
Minimise local interference at the cell edge
Traffic load sharing between cells
Compared to other opimisation measures improvement potentialis limited
Affected by
Measurement averaging
Power control parametersPS! Neighbours
should in general
be mutual
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Speech Quality Analysis
Parameters RxQual
Frame ErasureRate (FER)
Speech Quality Index (SQI)
Measurements
Drivetest
preferably continuous
call
OMC statistics
Causeforpoorquality
lowsignal strength
(coveragerelated
interference
lowsignal strength and
interference
Causes ofinterference co-channel interference
adjacentchannel
interference
intermodulation
mainly on one link only
multipathinterference
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Location Area Codes
Purpose identify location area
in incoming call is paged to all BTSs within LA
Large location area
advantage: less location updates (reduced SDCCH load)
disadvantage: more paging traffic
Boundaries should not cross high traffic areas
Cell reselection across LA boundaries
Parameter Cell_Reselect_Hysteresis (typ. 4 dB) used to avoid
unnecessary signalling due to ping-pong cell reselections
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Reporting (example)
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Advantages over test drives
Less labor intensive and time consuming
More comprehensive, based on large number of users
not limited to time of test drive
Uplink and Downlink analysis possible
Subscriber behavior mix of outdoor, indoor, incar use
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FINEFINE
TUNINGTUNING
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Digital Tilt Meter
GPS
Compass
Spanner
Screw Driver Set Safety Belt
Adjustable Wrench
Cutting Pliers
Mesuring Tape
Safety Shoe Map Info
Map Source
Google Earth
Tools
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Antenna Configuration
General points to check antenna type, e.g.
omni
directional 60, 90 or 120 degrees
electrical downtilt
cross-polarised
antenna azimuth angle (for directional antennae)
coverage targets
antenna tilt angle
electrical + mechanical diversity & isolation
e.g. space diversity,
polarisation diversity
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Site Check
Verify thatsiteisimplemented accordingto plan
Checkinstallatione.g.
antenna spacing (diversity, isolation)
antennaein onesectorareinstalledinthesame plane
antennae alignment
omni antenna installation
cableinstallation
k
a
Vertical spacing
d
Horisontal spacing
Rx
Tx
Rx Tx
a
5
ntennas mountedindifferent planes
a
a=
d d d
lignment ofantennas
T
d
k
Rx
Tx
Rxd
k2 k2
Omni
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Antenna Fine Tuning
Horizontal Plane:
Possible coverage weakness between sectors
Interference reduction
Traffic load distribution
Vertical Plane: Interference reduction
Possible coverage weakness in the short to medium distance
range
Traffic load distribution
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Omni vs. Sectorised
OMNI cells - more difficult to optimise
Electrical downtilt possible, however
same for entire cell
Parameters same for entire cell
Directional antennae narrower beam easier to control interference
tilting less efficient with wider beams
Sectorised cell site with differentdowntilt angles
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Tilting
Antenna downtilt often used to minimise interference Minimum: Vertical mail lobe pointing at cell edge
BSh
Maximum: First null angle pointing at cell edge
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0 0
Electrical Mechanical
Advantages:
Better back lobe characteristics
Better lower side lobe characteristics
Disadvantages:
Antennas are more expensive
Tilting
Electrical vs. Mechanical downtilt
A combination of
mechanical / electrical
downtilt may be used
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Reporting (example)
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thanksthanks