SPM (Standard Propagation Model) is a model originating from Planet and using K parameters. The SPM model has also a relation with the Hata model. The SPM model may be calibrated with CW measurements.
3.5.1.1 Import of CW measurements
Note: the CW measurements used by this document are just for the purpose of helping the user to be familiar with the use of the software. The detailed requirements for CW measurements (including data quantity) are described in the SPM model calibration document, which can be provided upon request.
To import the measurements, there are 2 methods: Copy/Paste and import. 1、 Copy/Paste method
（1） Open the “Site46_2 survey” worksheet in the “GSM_Brussels_Network.xls” document.
This worksheet provides the measurements corresponding to the “Site46_2” cell with the longitude, the latitude and the received signal level for each sampling point.
（2） In Atoll, right click on the “CW measurements” folder in the “Explorer\Network” window, and select “New” in the context menu, as shown in the following figure.
Atoll Getting Started-GSM Version 3.1.2
（3） In “New CW measurement path” dialog box, fill in the file name, the corresponding
transmitter, the receiver height. Then paste the Excel table data into the table, as shown in the following figure.
Note: Set the coordinate system with “WGS84” corresponding to the projection system as stated in the Excel tab.
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After clicking on “OK”, the test data are immediately displayed on the Map Window. Each point represents a measurement sampling.
2、 Import method
（1） Atoll supports the formats .dat, .txt, .csv and .hd (PlaNET).
（2） Please find 3 .txt documents inside the “\Atoll312 GSM demo projects and
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（3） In Atoll, right click on “CW measurements” in the “Explorer\Network” window and
select “Import” as shown in the following figure.
（4） In the appeared “Open” dialog box, browse for the document to be imported. Atoll
supports the multi selection of files. Several measurements corresponding to the same transmitter can be imported at the same time, but if the measurements belong to different transmitters, then each measurement has to be imported separately. Provided test data corresponding to different transmitters, the measurements have to be imported one by one.
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（5） The appeared dialog box contains two tabs, “General” and “Setup”. In the “General”
tab, define the corresponding reference transmitter, the frequency and receiver height, as shown in the following figure.
（6） In the “Setup” tab, fill in the “1st Measurement Row” field with 2 (because the drive
test document has a title line and the data start at the second line). Then click on the “Setup” button.
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（7） After clicking on the “Setup” button, the “CW Measurement Setup” dialog box appears, as shown in the following figure. Define “X-Coordinates” and “Y-Coordinates” fields with respectively the longitude and latitude.
（8） Click on the “Import” button in the import main window and then the measurement
data will be imported into the project. After the import, the measurement data will be automatically put in the “CW measurements” folder of the Explorer Window. Use “Centre in the Map Window” function to display the imported measurements in the center of the map.
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Import also the “Measures_Site4_2_Street.txt” and the “Measures_Site4_3_Street.txt” documents into the project by the similar operations above. Please note that the 3 measurements files correspond to different transmitters.
（9） Setting of the CW measurements display —— double click on the “CW measurement” folder and open the “CW measurements properties” dialog box. In the “Display” tab, define the “Display type” as “Value Intervals” and “Field” as “M(dBm)”.
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（10） Right click on the CW measurement data file and select the Filtering Assistant, a new dialog window “Filtering Assistant on CW Measurement points” will be opened. Based
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3.5.1.2 Automatic calibration of the SPM model
A good propagation model calibration requires having enough data, filtering them and carrying a careful tuning of each factor of the model. The tuning steps are quite complex, which is not described in details in this document. A document of specific SPM model calibration can be provided upon request.
Bellow the SPM model basic operations are introduced.
The SPM automatic calibration may help the user to find the best K parameters, the “Effective antenna height” method, the “Diffraction” method and the clutter losses.
(1) Duplicate the existing standard propagation model and make the calibration for the
duplicated model. This method has the advantage to preserve the existing model and to allow a calibration of the SPM for each kind of environments.
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(3) Select the CW measurement(s) and click on the “Next” button.
(4) In the appeared dialog box, select the K parameters that will be used for the calibration.
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Double click on a K parameter or select a K parameter and click on “Define Range”, will open the “Define Domain” dialog box, where the range of the K parameter can be defined, as shown in the following figure. But generally it is recommended to keep the default values defined above.
After choosing the range, click on “OK”.
(5) According to the selected CW measurements and the tuning parameters, Atoll
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(6) After the computation, Atoll provides in the same dialog box the results and the
statistics concerning the model, as the average error and the standard deviation. According to the results, the user may choose to commit the K parameters list by clicking on the “Commit” button.
(7) If the results are not satisfactory and the K parameters have been already committed,
the propagation model can be deleted by right clicking on it and selecting “Delete” (or by pressing the “Delete” key on the keyboard).
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CTRL+C and paste it with CTRL+V in the “Modules” tab of another project.
Note: the automatic model calibration is only a mathematical computation method. The result depends on the quality of the CW measurements. Therefore a high quality of CW measurements is required.
3.5.1.3 Verified model by using CW measurement data
To judge if a model fits an area (at least fits the CW data), the most direct way is to check the standard deviation after calibration. The smaller the standard deviation is, the better result will be. In general, the standard deviation required to be less than 8dB after calibration.
In most case, users will use automatic calibration as mentioned above. If needed, they can use another method to verify their models that is to check the chart showing difference between measured values and predicted values.
The verification process is:
（1） Right click a measurement path in Explorer/Network tab, choose Properties.
In Parameter tab of properties dialogue window, choose you propagation model in Parameter tab like below:
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（2） Right click a measurement path in Explorer/Network tab, choose Refresh geo data command.
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（3） Right click a measurement path in Explorer/Network tab, choose Calculations-> Calculate Signal Level.
（4） Atoll will calculate predicted values on all the points on the path by chosen model. If you need to look the statistic report, you can right click the measurement path in Explorer/Network tab and choose Display statistics. Atoll will prompt the report as in below picture, you can check the standard deviation of model on this path.
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（5） Right click a measurement path, choose Open the Analysis tool command, then a CW measurements window will pop up as below:
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（6） Click in the CW measurement window, you will simultaneously have a receiver in the map window and its measured value (M) and predicted value (P). You can choose other display option in the roll down menu, e.g. Error for the difference between M and P.
Note: It can be used for other model like Cost-Hata and Okumura-Hata.
3.5.1.4 Define models for transmitters
After calibration, you need to define for each transmitter which propagation model would be used. You can use shortcut Ctrl + D.
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If all transmitters use the same model, the most efficient way is to define in Transmitters properties window. In Propagation tab, choose a model you want to use, and give it a radius and resolution (generally the resolution is the same as digital map). Note: If you do not want to use one
propagation model for all of the transmitters, do not use this feature.