model tuning - process

ASSET WORKSHOPModel Tuning

MOBILINK-PAKISTAN

ASSET WORKSHOP-2007, Rajendra AIRCOM INTERNATIONAL Limited 2

AGENDA

Aim of Model TuningCW Measurement- Site Selection- CW Drive Route Definition- Equipment configurationModel Tuning ProcessModel Calibration Analysis


Aim of Model Tuning

Determine model parameters in accordance to realistic propagation effects existing within proposed regions.

Minimise Standard Deviation Error.

Make sure calibrated model corresponds well with the collected data is essential.

Provide cost efficient Nominal Plan


CW Measurements and Model Calibration Process

Data Validation

NOYES

Site Selection Drive Route Definition

CW Survey Campaign

Data Post Processing

Calibration

ReportPass

Model?

Propagation Model

Requirements Identification

Data Validation


CW MEASUREMENT

More or 10 sites per model. Less number of sites can be considered if modelled geographical area is fairly small.Within geographic region of modelSpread of site heights representative of network sites heights within modelled regionAllow measurements in all clutter typesRooftop sites are preferred in a case test transmitter has to be mountedEase of accessNo blocking objects in close vicinityNothing unusual, we are characterising the majority of the network not the minority


CW MEASUREMENT

DistanceMust account for expected coverage propagationMust account for expected interference propagation

ClutterSufficient measurement in all local clutter types ( >1000 )

RoadsAvoid street canyons, tunnels, elevated roads, cuttings etcMix of radial and tangential roads

MiscellaneousDo not plan a map along the roads with ground height above the transmitter antenna. Good balance between measurements taken in LOS and NLOS situationsDo not plan a route across a big water surface, if site is on the one side of the lake, do not drive other lake sideAvoid large blocking objects as high building or long roofLong enough to ensure sufficient data is capturedCheck map data validity


CW MEASUREMENT

Spectrum clearanceDuring CW survey allocated test frequency shouldn’t be use for other purposes10-15KHz bandwidth monitoringCheck restrictions on test frequency TX EIRP

Equipment configurationAccurate Radiated Power setting, EiRP should be greater than 40dBmRaw/Averaged dataUse Omni antenna with minimum vertical beam width of 12 degreesDirectional antenna can be used but in post processing everything beyond 3dBm should be dismissed

DrivingDo not drive out of RX noise floorAvoid street canyons, tunnels, elevated roads, cuttings etcDistance/Time triggering


DATA REQUIREMENT

In order for model to be realistic, statistically sufficient number of data need to be collected.Common practice is to take 50 samples which gives one sample every 0.8λ.50 samples should be averaged and give the local mean. Common practise is to have at least 30000 data.30000 data gives total driven distance of

30000x40λ=198km or20km 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


VALIDATION DATA

Compare the site data (photographs, surrounding clutter and terrain profile) to the Clutter and DTM layer of the map data provided.

Check the driven routes against vectors within the map data.

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

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.


VALIDATION DATA

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.Unusually weak signal level can be caused by driving behind blocking object.Okumura –Hata can’t model above situations, therefore these data must be filtered out.


K PARAMETERS

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 >0K3, K5, K6 <0

Above step can be easily fulfil by determining the delta range under Auto tune window


K PARAMETERS

Default K PARAMETERS


K PARAMETERS

K1 and K2 Near CalibrationIf 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.Tune model again with k5,k6 and k7 locked and filter out distances above 700m.Result will be k1near and k2 near.If standard deviation is still bad try with other distances until you find the best fit.

CLUTTER OFFSETSome through clutter offsets and clutter offsets need to be estimated due to insufficient data.

Estimation is done relative to the clutter offsets with sufficient data.

Clutter offsets must be realistic relative to each other.

Water will have the smallest offset while building and forest the highest.


K PARAMETERS

Mean error is usually altered after estimation of clutter offsets.

ME can be easily bring back to 0 by changing k1

If mean error is ∆ change k1 to k1+ ∆


MODEL TUNING PRACTICAL IN ASSET

LOAD CW DATA AND SETTING CW MEASUREMENT



DEFINE DEFAULT MODEL AND FILTER


MODEL TUNING PRACTICAL IN ASSETGRAPH FOR DATA VALIDATION


MODEL TUNING PRACTICAL IN ASSETCW Signal

CW Signal ERROR



AUTO TUNE

model tuning - process

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