ASSET WORKSHOP Model Tuning MOBILINK-PAKISTAN
AGENDA
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Aim of Model Tuning
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CW Measurement - Site Selection - CW Drive Route Definition - Equipment configuration
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Model Tuning Process
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Model Calibration Analysis
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
2
Aim of Model Tuning
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Determine model parameters in accordance to realistic propagation effects existing within proposed regions.
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Minimise Standard Deviation Error.
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Make sure calibrated model corresponds well with the collected data is essential.
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Provide cost efficient Nominal Plan
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
3
CW Measurements and Model Calibration Process
Propagation Model Requirements Identification
Drive Route Definition
Site Selection
CW Survey Campaign Data Post Processing Data Data Validation Validation
Calibration
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YES Report
ASSET WORKSHOP-2007, Rajendra
Pass Model?
AIRCOM INTERNATIONAL Limited
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CW MEASUREMENT z
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More or 10 sites per model. Less number of sites can be considered if modelled geographical area is fairly small. Within geographic region of model Spread of site heights representative of network sites heights within modelled region
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Allow measurements in all clutter types
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Rooftop sites are preferred in a case test transmitter has to be mounted
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Ease of access
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No blocking objects in close vicinity
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Nothing unusual, we are characterising the majority of the network not the minority
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
5
CW MEASUREMENT Distance z z
Must account for expected coverage propagation Must account for expected interference propagation
Clutter z
Sufficient measurement in all local clutter types ( >1000 )
Roads z z
Avoid street canyons, tunnels, elevated roads, cuttings etc Mix of radial and tangential roads
Miscellaneous z z z z z z
Do not plan a map along the roads with ground height above the transmitter antenna. Good balance between measurements taken in LOS and NLOS situations Do not plan a route across a big water surface, if site is on the one side of the lake, do not drive other lake side Avoid large blocking objects as high building or long roof Long enough to ensure sufficient data is captured Check map data validity
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
6
CW MEASUREMENT Spectrum clearance z During CW survey allocated test frequency shouldn’t be use for other purposes z 10-15KHz bandwidth monitoring z Check restrictions on test frequency TX EIRP Equipment configuration z Accurate Radiated Power setting, EiRP should be greater than 40dBm z Raw/Averaged data z Use Omni antenna with minimum vertical beam width of 12 degrees z Directional antenna can be used but in post processing everything beyond 3dBm should be dismissed Driving z z z
Do not drive out of RX noise floor Avoid street canyons, tunnels, elevated roads, cuttings etc Distance/Time triggering
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
7
DATA REQUIREMENT z
In order for model to be realistic, statistically sufficient number of data need to be collected.
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Common practice is to take 50 samples which gives one sample every 0.8λ.
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50 samples should be averaged and give the local mean.
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Common practise is to have at least 30000 data.
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30000 data gives total driven distance of 30000x40λ=198km or 20km per site for 1800MHz range. If this distance is not achievable due to limitation in drivable roads it is recommended to have more than 10 sites per model. As stated before, in a case of modelling small geographical area with 3 sites, tuning can be performed with 10000 data or 22km per site. The more data the model is more realistic
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
8
VALIDATION DATA z
Compare the site data (photographs, surrounding clutter and terrain profile) to the Clutter and DTM layer of the map data provided.
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Check the driven routes against vectors within the map data.
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Filter out any invalid data that may cause anomalies in the calibration process
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Make sure that details relating to a site (EIRP, Location, Height, Antenna file) correspond to reports from CW Survey. Use Asset utilities to get visual representation of the received signal vs distance.
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
9
VALIDATION DATA z
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Filter clutter types that have less than 500 bins. Clutter offsets or them will be estimated later in the model tuning process. Filter out any file which shows extreme in signal level. Unusually high signal level at far distance can be caused by reflection over big water surface, or driving along route which is higher than antenna.
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Unusually weak signal level can be caused by driving behind blocking object.
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Okumura –Hata can’t model above situations, therefore these data must be filtered out.
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
10
K PARAMETERS z
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K3 and K4 are not altered. This is because they relate to mobile height which in a typical cellular system is constant making these coefficients redundant. K7 is the diffraction parameter. It can be determined by tuning just NLOS data. All K parameters must keep the same polarity as in the original Okumura Hata model K1, K2, K7 >0 K3, K5, K6 <0 Above step can be easily fulfil by determining the delta range under Auto tune window
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
11
K PARAMETERS Default K PARAMETERS
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
12
K PARAMETERS K1 and K2 Near Calibration z If model is not good close to the site, for example up to 700m, auto tune the model from 700m to 10k. Apply found k parameters. z Tune model again with k5,k6 and k7 locked and filter out distances above 700m. z Result will be k1near and k2 near. z If standard deviation is still bad try with other distances until you find the best fit. CLUTTER OFFSET z Some through clutter offsets and clutter offsets need to be estimated due to insufficient data. z
Estimation is done relative to the clutter offsets with sufficient data.
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Clutter offsets must be realistic relative to each other.
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Water will have the smallest offset while building and forest the highest.
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
13
K PARAMETERS z
Mean error is usually altered after estimation of clutter offsets.
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ME can be easily bring back to 0 by changing k1
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If mean error is ∆ change k1 to k1+ ∆
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
14
MODEL TUNING PRACTICAL IN ASSET LOAD CW DATA AND SETTING CW MEASUREMENT
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
15
MODEL TUNING PRACTICAL IN ASSET DEFINE DEFAULT MODEL AND FILTER
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
16
MODEL TUNING PRACTICAL IN ASSET GRAPH FOR DATA VALIDATION
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
17
MODEL TUNING PRACTICAL IN ASSET CW Signal
CW Signal ERROR
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
18
MODEL TUNING PRACTICAL IN ASSET AUTO TUNE
ASSET WORKSHOP-2007, Rajendra
AIRCOM INTERNATIONAL Limited
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