Model Tuning Process on Aircom Asset

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ASSET WORKSHOP

Model Tuning

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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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ASSET WORKSHOP-2007, Rajendra AIRCOM INTERNATIONAL Limited 3

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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CW Measurements and Model Calibration Process

Data Validation

NO YES

Site Selection Drive Route Definition CW Survey Campaign Data Post Processing Calibration

Report _Model?Pass Propagation Model Requirements Identification Data Validation

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CW MEASUREMENT

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More or 10 sites per model. Less number of sites can be considered if modelled

geographical area is fairly small.

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Within geographic region of model

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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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CW MEASUREMENT

Distance

z Must account for expected coverage propagation z Must account for expected interference propagation

Clutter

z Sufficient measurement in all local clutter types ( >1000 )

Roads

z Avoid street canyons, tunnels, elevated roads, cuttings etc z Mix of radial and tangential roads

Miscellaneous

z Do not plan a map along the roads with ground height above the transmitter antenna. z Good balance between measurements taken in LOS and NLOS situations

z 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

z Avoid large blocking objects as high building or long roof z Long enough to ensure sufficient data is captured

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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 Do not drive out of RX noise floor

z Avoid street canyons, tunnels, elevated roads, cuttings etc z Distance/Time triggering

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DATA REQUIREMENT

z In order for model to be realistic, statistically sufficient number of data need to be collected. z Common practice is to take 50 samples which gives one sample every 0.8λ.

z 50 samples should be averaged and give the local mean. z Common practise is to have at least 30000 data.

z 30000 data gives total driven distance of

30000x40λ=198km or

20km per site for 1800MHz range.

z If this distance is not achievable due to limitation in drivable roads it is recommended to have more

than 10 sites per model.

z 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.

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VALIDATION DATA

z Compare the site data (photographs, surrounding clutter and terrain profile) to the Clutter and DTM

layer of the map data provided.

z Check the driven routes against vectors within the map data.

z Filter out any invalid data that may cause anomalies in the calibration process

z Make sure that details relating to a site (EIRP, Location, Height, Antenna file) correspond to

reports from CW Survey.

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VALIDATION DATA

z Filter clutter types that have less than 500 bins. Clutter offsets or them will be estimated later in the

model tuning process.

z Filter out any file which shows extreme in signal level.

z 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.

z Unusually weak signal level can be caused by driving behind blocking object.

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K PARAMETERS

z 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.

z K7 is the diffraction parameter. It can be determined by tuning just NLOS data.

z All K parameters must keep the same polarity as in the original Okumura Hata model

K1, K2, K7 >0 K3, K5, K6 <0

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K PARAMETERS

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K PARAMETERS

K1 and K2 Near Calibration

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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.

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Tune model again with k5,k6 and k7 locked and filter out distances above 700m.

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Result will be k1near and k2 near.

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If standard deviation is still bad try with other distances until you find the best

fit.

CLUTTER OFFSET

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Some through clutter offsets and clutter offsets need to be estimated due to

insufficient data.

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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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K PARAMETERS

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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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MODEL TUNING PRACTICAL IN ASSET

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MODEL TUNING PRACTICAL IN ASSET

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MODEL TUNING PRACTICAL IN ASSET

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MODEL TUNING PRACTICAL IN ASSET

CW Signal

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