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Page 0 Rikard SlungaNetwork Optimisation, Nice 0
Ensuring the reliability of
RF field optimisation
Roger Rüland, Vodafone Netherlands
Dietrich Hunold, Actix
Page 1 Rikard SlungaNetwork Optimisation, Nice 1
Overview
Vodafone Netherlands network optimisation project
Importance of using measurements throughout the optimisation process
Time efficient and reliable RF field optimisation method
Successful verification of optimised network by measurements
Page 2 Rikard SlungaNetwork Optimisation, Nice 2
Vodafone Netherlands
Part of the Vodafone Group
3.4 million customers
3500 employees
Mobile phone penetration in NL: 81%
55% UMTS population coverage
Highly competitive market (5 Operators, several MVNOs)
Page 3 Rikard SlungaNetwork Optimisation, Nice 3
UMTS Optimisation Project
VF live! UMTS launch in June 2004
Need for optimisation of parts of the VF-NL radio network topology on very short term
Network covers all major Dutch cities
Due to size and timeframe of the project external help was necessary
Page 4 Rikard SlungaNetwork Optimisation, Nice 4
UMTS Coverage
Maastricht
Amsterdam
Rotterdam
The Hague Utrecht
Page 5 Rikard SlungaNetwork Optimisation, Nice 5
Optimisation Targets
Rollout of a new network is focussed on coverage, not capacity
Maximise the area with good CPICH Ec/Io and decrease the pilot pollution without decreasing the area with good RSCP
Downlink based optimisation
Only downtilt changes allowed
Page 6 Rikard SlungaNetwork Optimisation, Nice 6
UMTS Optimisation Project
Deadline was strict so the external party had to absolutely deliver within timeframe
Lots of existing drive test measurements which should be used in the optimisation
Radioplan selected as one of the delivering companies
Page 7 Rikard SlungaNetwork Optimisation, Nice 7
Optimisation Workflow
Deliver planning data (Quantum) and measurements to Actix
Verify consistency and completeness based on delivered data
Find logical errors (swapped sectors, down sites, etc.)
Pathloss tuning to increase reliability and accuracy
Receive and discuss optimisation results from Actix
Implement changes in the network
Evaluate optimisation predictions with measurements
Page 8 Rikard SlungaNetwork Optimisation, Nice 8
Pre Optimisation / Rollout Process
Planning data must reflect network data
Check sites when handovered from contractor
Done by VF-NL drive test team using TEMS equipment
Handover test
Pathloss test
Page 9 Rikard SlungaNetwork Optimisation, Nice 9
RF Network Check in Actix Radioplan
Compare measurements with planning data
VF-NL site assessment procedure works well, only 1 site found with logical errors (exchanged feeder)
Measured RSCP level in line with predicted RSCP level; good fit of propagation model (Std. Dev.: 6 to 8 dB)
Improve accuracy of pathloss matrices even more by pathloss tuning
One drive test route rejected for pathloss tuning due to obvious unrealistic offset
Page 10 Rikard SlungaNetwork Optimisation, Nice 10
One Occurrence of Exchanged Sectors
Sector 3 measured
Sector 2 measured
Page 11 Rikard SlungaNetwork Optimisation, Nice 11
Pathloss Prediction Accuracy
Pilot RSCP error (measurement – prediction):
Avg. -2.9dB
Std.Dev. 8.0dB
Page 12 Rikard SlungaNetwork Optimisation, Nice 12
Optimisation and Change Implementation
Work orders for optimisation delivered by Radioplan
Implementation of downtilt proposals in clusters and prioritised
Installing Remote Electrical Tilt unit during site visit
1
2
3
4
Page 13 Rikard SlungaNetwork Optimisation, Nice 13
Assess Improvement by Measurements
Measurements show good improvement of KPIs
Ec/Io strongly increased, cell overlap reduced
RSCP coverage maintained
Measured improvements in the order of predicted improvements
Ec/Io measurements
Page 14 Rikard SlungaNetwork Optimisation, Nice 14
Drive Test Verification in Central Rotterdam
-0.2 cells97.8%94.9%meas.
-0.5 cells90.2%79.2%predict.
improv.afterbefore
+1.0dB98.1%90.5%meas.
+0.9dB91.5%81.1%predict.
improv.afterbefore
Ec/Io >= -8dB improvement
Cell overlap <= 3 cells
cell overlap measurements
Page 15 Rikard SlungaNetwork Optimisation, Nice 15
Optimisation Workflow with Actix Radioplan
Data import
Data consistency/correctness check
Pathloss tuning
Optimisation
Result analysis
Deliver work orders
Evaluate improvements with measurements
Actix Radioplan
PlanningData
Measurement Data
Optimised Network
Page 16 Rikard SlungaNetwork Optimisation, Nice 16
Pathloss Tuning
Direct use of drive test measurements
Goal: Improve planning data accuracy
Very efficient (1 town in < 5 sec)
Example:Shifting sand dunes at coast line
No reliable clutter data possible
Uncertainty in pathloss prediction
Shifting sand dunes
DEM
Page 17 Rikard SlungaNetwork Optimisation, Nice 17
Pathloss Tuning Example
Low measured pilot RSCP
Effect of Pathloss Tuning
Page 18 Rikard SlungaNetwork Optimisation, Nice 18
Actix Radioplan Optimisation Approach
Reconfigurationof the
network setup
DEM map clutter map
Objectivefunction
network setup pathloss maps
Pre-Analysis Verification
constraints
traffic maps
Planning Data /Measurements
Planning Data /Measurements
High-speed iterative process
Page 19 Rikard SlungaNetwork Optimisation, Nice 19
Result AnalysisGraphical analysis of network KPIs
Pilot RSCP
Pilot Ec/Io
Pilot pollution areas / cell overlap
KPI statistics report
Coverage percentage of RSCP, Ec/Io per clutter class
Number of cell/site changes, cost overview
Improvement analysis
Graphical clustering of site changes
Page 20 Rikard SlungaNetwork Optimisation, Nice 20
Ec/Io Before Optimisation
Page 21 Rikard SlungaNetwork Optimisation, Nice 21
Ec/Io After Optimisation
Page 22 Rikard SlungaNetwork Optimisation, Nice 22
Cell Overlap Before Optimisation
Page 23 Rikard SlungaNetwork Optimisation, Nice 23
Cell Overlap After Optimisation
Page 24 Rikard SlungaNetwork Optimisation, Nice 24
QoS Validation
Network simulations before/after optimisation with same traffic:
Ec/Io rejections reduced by 70%
SHO users reduced by 5%
UL load reduced by 16%
Throughput increased by 11%
At same GoS (5% outage):at least 25% more traffic possible!
Simulated Ec/Io80% Speech, 20% WWW
Page 25 Rikard SlungaNetwork Optimisation, Nice 25
Summary
Make sure that the planning data reflects the actual situation in the network
Do not merely rely on predictions, use measurements when optimising a radio network
Consistent network improvements within short time
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