cw model tuning

7/27/2019 CW Model Tuning

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Model tuning procedure

Contents

1 General....................................................................................................................................2

2 Scope of work..........................................................................................................................2

2.1 Preparing the measurement conditions based on problem analysis..........................................2

2.2 Installation of the transmitter system.........................................................................................3

2.3 Execution of drive tests...............................................................................................................4

2.4 Evaluation of measuring data...................................................................................................... 4

2.5 Comparison of measurement data with the result of calculated radio predictions...................4

2.6 Tuning of the propagation model................................................................................................ 4

2.7 Analyse of radio coverage situation ...........................................................................................4

3 Requirements for model tuning.............................................................................................6


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1 General

A theoretical radio network planning should be proven by practical radio fieldmeasurements. SIEMENS can provide detailed radio measurements using specialequipment and the results of these measurements can be analysed and compared

directly with the prediction of the planning tool computer run. If observeddiscrepancies exceed the specified tolerance, parameter adjustment can be carriedout.

The field strength measurements should be performed in typical areas. Also test siteselection depends on radio frequency planning and the computer aided interferenceanalysis to clarify frequency allocation problems.

To carry out the radio field measurements SIEMENS can provide the following steps:

preparing the measurement conditions based on a problem analysis

carrying out the drive tests

evaluation of measuring data

comparison of measuring data with the result of calculated radio prediction

tuning of the propagation model

analyse of radio coverage situation

For more detailed information please refer to the following chapters.

2 Scope of work

2.1 Preparing the measurement conditions based on problem analysis

It is of prime necessity fixing the data of transmitter location (geographic position,height above sea level, height above ground, etc.) as well as conditions of the testscenario (transmitting power, antenna type, chart orientation, frequency).Secondly the measured area must be specified. It is helpful to clarify the drive routesbefore starting the measurements.

Before starting the measurement campaign the invested area shall be clarified.Especially for model tuning it is helpful to restrict the measurement routes to uniformclutter areas. This additional effort preparing the measurements spares a lot of time

in post processing if the clutters are not set up exactly in the TORNADO database.


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Separation of routes in different clutter areas

Urban

Industrial

Rural

2.2 Installation of the transmitter system

The transmitter location shall have the same requirements like a typical site for basestation, e.g. height, surroundings.The transmitter system consisting of signal generator, power amplifier, cabling andantenna is mounted on top of the roof.Generally an omnidirectional antenna is used with 5-8dBi. The antenna shall beplaced on a variable mast to prevent that any obstacles limit the propagation in thenear field.To reduce interference and increase the receiver sensitivity the signal bandwidthshall be small (around 10kHz).Normally a frequency-modulated signal is generated with 1kHz deviation and 2kHzshift.

Test transmitter system

poweramplifiere.g. 50W

signal generator

omnidirctional antenna

Nevertheless it is also possible to measure existing sites, but the results can befaulty cause of the following points:

Mostly the EIRP isnt exactly defined.

There is the possibility of small differences in planning and installation (e.g. shiftof antenna orientation or downtilt).

It is recommended to measure only in the main beam.


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2.3 Execution of drive tests

At first the transmitter must be installed and all transmission parameters must beadjusted (power, frequency, bandwidth,...). Normally a frequency-modulated signalwith a bandwidth of 6kHz is transmitted to use a lower sensitivity at the receiversystem (receiving bandwidth 10kHz).The receiver system shall provide the reception of signal levels in a sufficient range(e.g. -35..-125dBm) and be able to define the bandwidth for measurements.It is to be clarified that the test receiver is adjusted to the transmitter characteristics.After finishing the measurements the interim transmitter is dismantled.

2.4 Evaluation of measuring data

The measurement data shall be checked for failure and whether the GPS informationof the driven route is continuously given. Otherwise the routes must be digitised to fitthe measured data to the cartographic positions.Plots can be delivered regarding the receive level.To verify the data to prediction results in TORNADO protocol files are prepared foruse in the planning tool.

2.5 Comparison of measurement data with the result of calculated radiopredictions

Firstly the measurements must be transferred to the workstation on that TORNADOis running. In TORNADO the measurement data can be verified according itsgeographical position. Measurements are comparable to prediction of the testscenario.

2.6 Tuning of the propagation model

If the prediction deviates to the carried out measurements the propagationparameters can be tuned decreasing the difference between both. Therefore errorcurves can be generated presenting the deviation between measurement pixels andthe prediction.For this purpose a detailed analyse can be also delivered giving average mean errorand the standard deviation.

2.7 Analyse of radio coverage situation


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By means of the tuned model the existing network state can be predicted anddocumented by plots of different kind.

These steps may help for a first optimisation of the radio network part.

BS / Test transmitter

GPS

Measurement car

Evaluation toolEvaluation + Interface to TORNADO

TORNADO


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3 Requirements for model tuning

Measurement equipment:

Transmitter system: signal generator (frequency modulation is sufficient)

power amplifier (recommended 50W)

power meter for adjustment

antenna tube / mast (adjustable up to min. 5m)

antenna (omnidirectional)

cables

availability of a free test frequency

Receiver system receiver system in-car installed

field strength receiver with selectable bandwidth

field strength receiver with fast trigger modus (if possible every 1ms one

measurement point)

GPS system collecting geographical position

trigger wheel delivering trigger impulses in equal distances (if GPS is not

available then the measurement route can be digitised subsequently)

Evaluation tool capability for statistical considerations (e.g. standard statistic: 100 measurement

data averaged as one block value)

possibility for selection of different probability meridian values (especially 50%

probability meridian corresponding to TORNADO)

possibility for export to TORNADO

digitizer (necessary if GPS data wasnt collected during the measurement run to

merge the measurement data to the driven route)

cw model tuning

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