PGM-A Technical Notes.pdf

Technical Note

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PGM-A Propagation Model

The PGM-A propagation model emulates the Asset  propagation model and is intended to enable users to re-use  propagation models in Planet EV  that  that have been tuned using Asset. This propagation model is not distributed with Planet EV  and  and is only available upon request.

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PGM-A Propagation Model PGM-A Technical Note

Introduction The PGM-A propagation model enables customers migrating from Asset to re-use their tuned Asset macrocell models within Planet EV . The algorithms used in the PGM-A propagation model are modified versions of those used in the PGM propagation model included with Planet EV . As you would do in Asset, you can define model parameters (k-factors) that influence results. Using the PGM-A propagation model, you will produce results that are comparable to those achieved using Asset in the most common implementations of the model. Results will not be precisely the same. However, performance is very comparable to Asset. Although it is typically recommended that you use Planet EV  models and tune them using measurements, it can be a more cost effective approach to replicate Asset models in Planet EV  using the PGM-A model as there is no need to retune models. This document provides the information necessary to successfully use the PGM-A propagation model, and it is intended for use during evaluation  periods or when Marconi Wireless implementation services are not being used. This document explains how to add the PGM-A propagation model and associated user documentation to Planet EV , details some key differences  between the PGM and the PGM-A propagation models, and explains how to edit the PGM-A propagation model. The performance of prediction generation using the PGM-A model has proven to be very similar to that of the original Asset predictions. However, the performance is not guaranteed and use of this model is optional.  All efforts will be made to support this propagation model in the event of a defect; however, it is distributed as an Add-on tool that is not part of the standard software warranty.

Prerequisites to PGM-A propagation model use In order to successfully use the PGM-A propagation model to migrate tuned Asset macrocell models to Planet EV , the following requirements must be met  before using the PGM-A propagation model: 1

Project data and site configurations must be converted for use in Planet EV . The project must be set up to replicate the Asset project. It is imperative that the site configuration, antenna data, and all related parameters are

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PGM-A Technical Note

identical to those in Asset. Planet EV  utilities are available to support this effort. For more information, contact Technical Support. 2

The geodata (height and clutter data) must be the same files as those available in Asset in order to achieve similar results.

3

Clutter classes must have the same names or be mapped using the Planet EV  Clutter Property Assignment dialog box.

Currently, there is no automated method of converting Asset model data into Planet EV model (.dpm) files or related Clutter Property  Assignment (.cpa) files. This must be done manually.

In Asset, model parameters are saved in the Model-List001.XML file. This file provides quick access all model parameters (alternatively, you can view model parameters in the Asset user interface).

 Adding the PGM-A propagation model and user documentation to Planet EV The PGM-A propagation model is not part of the standard Planet EV  installation. As the model has a very specific purpose (i.e., supporting customers migrating from Asset), it is only distributed to specific customers or for specific projects. It is available upon request from Technical Support or Product Management. Typically, the distribution and installation of this propagation model and the conversion of Asset models will be part of a Planet EV Implementation service. It is strongly recommended that customers make use of these services for migration projects.

To add the PGM-A propagation model and user documentation to Planet EV

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1

Copy the PGM-A.mdl to the Planet EV /mdl folder.

2

Copy the PGMA.chm file to the Planet EV /Help folder.

3

Copy the PGM-A Technical Notes.pdf file to the Planet EV /Help/User Guides folder.

PGM-A Propagation Model PGM-A Technical Note

Workflow for using the PGM-A propagation model Step 1

Open the Model-List001.XML file generated using Asset. The model name is listed in the ID column and is shown on multiple lines (one line for each clutter class). K factors for a model will be listed on several lines but the values will all be the same.

Step 2

Edit PGM-A propagation model parameters replicating the Asset model. See “Editing PGM-A propagation model parameters” on page 5. Ensure that the model name is exactly the same as that used in  Asset.

Step 3

Create a Clutter Property Assignment (.cpa) file to associate with the new model. See “Creating a .cpa file for the PGM-A propagation model” on page 10.

Step 4

For every Asset model, repeat the steps of the workflow to create a model (.dpm) file in Planet EV.

Editing PGM-A propagation model parameters The first step in the creation of a new propagation model is to edit model  parameters. Then, you need to create a clutter property assignment (.cpa) file to associate with it.

To edit PGM-A propagation model parameters 1

Open a project in Planet EV .

2

In the Project Data category, right-click Propagation Models and choose New.

3

In the Propagation Model Type dialog box, choose PGM-A and click OK. The Propagation Model Editor opens.

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PGM-A Technical Note

4

On the Settings tab, in the Frequency box, define the frequency as shown in the FREQUENCY column of the Model-List001.XML file.

5

In the Receiver Height box, define the receiver height as shown in the MOBILE-HEIGHT column of the Model-List001.XML file.

6

From the Earth Curvature list, choose one of the following options: ■

■

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4/3 Earth Curvature —when the value in the EARTH-RADIUS column of the Model-List001.XML file is approximately 8500. Normal Earth Curvature —when the value in the EARTH-RADIUS column of the Model-List001.XML file is approximately 6400.

Click Edit. The PGM-A Parameters dialog box opens.

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PGM-A Propagation Model PGM-A Technical Note

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On the General tab, in the Model Type section, choose one of the following options: ■

■

1 piece —this type of model uses factors K1 to K7. Factors K1 (near) and K2 (near) are not used to define a 1-piece model. 2 Piece —this type of model uses factors K1 to K7 as well as K1 (near) and K2 (near).

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If you chose the 2-piece model, in the Distance box, define the distance (in meters) at which to use the constants K1 (near) and K2 (near).

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In the K Factors section, define the K1 to K7 values as the K1 to K7 values in Model-List001.XML file or Asset GUI.

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If you are using a 2-piece model, in the K1 (near) and the K2 (near)  boxes enter a value between -150 and 250.

12

Click the Path Clutter tab.

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PGM-A Technical Note

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13

If clutter through loss is used in the Asset model, enable the Enable the Path Clutter check box and define the distance as the K12 value contained in the Model-List001.XML file or Asset GUI.

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Click the Diffraction tab.

PGM-A Propagation Model PGM-A Technical Note 15

In the Knife-Edge Merging Distance box, define the distance as K11 in the Model-List001.XML file or Asset GUI.

16

Click the Effective Antenna Height  tab.

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Choose one of the following options: ■

■

■

■

Absolute —this is the same as the “Base Height” algorithm in Asset. Relative —this is the same as the “Spot Height” algorithm in Asset. Average —this is the same as the “Average Height” algorithm in Asset. You must define the ground level in the prediction area when you chose this type. Slope —this is the same as the “Slope” algorithm in Asset. You must define the slope distance, the minimum height, and the maximum height when you chose this type.

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When you have finished editing the propagation model parameters, click OK.

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Create a .cpa file to associate with the model. See “Creating a .cpa file for the PGM-A propagation model” on page 10.

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PGM-A Technical Note

Creating a .cpa file for the PGM-A propagation model In order to create a new model, you must create a .cpa file to associate with it. 1

In the Propagation Model Editor, click the Clutter Properties tab.

2

Click Edit CPA. If your project uses clutter, clutter classes are automatically displayed in the Clutter Property Assignment dialog box.

3

In the Clutter Property Assignment dialog box, ensure that the clutter classes contained in the Model-List001.XML  file are listed in the Reference Name box.

4

Define the Clutter Absorption Loss for each clutter class as contained in the OFFSET column of the Model-List001.XML  file.

5

Define the Through Clutter Loss for each clutter class as contained in the MOBILE-HEIGHT3 column of the Model-List001.XML  file.

6

From the File menu, choose Save As to save the .cpa file.

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In the Save As dialog box, in the File Name box, type a name for the file and click Save.

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Click Close.

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In the Propagation Model Editor, choose File ➤ Save to save the new  propagation model.

PGM-A Propagation Model PGM-A Technical Note 10

In the Save As dialog box, in the File Name box, type the same name for the propagation model as that used in Asset and click Save.

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Click Close. The new propagation model is added to the Propagation Models node in the Project Data category of the Project Explorer.

For additional information on propagation models, or for information on working with Planet EV , see the Planet EV User Guide.

Comparing the PGM and PGM-A propagation models Both the Asset model and PGM model support two-piece models, where two sets of slope and intercept K 1 and K 2 are defined. One set is used for near Tx  predictions (d < distance) and the second set for predictions (d > distance). In the PGM model, distance is entered in meters while in the Asset model, distance is entered in km.

PGM propagation model The received signal strength at the mobile is given by the following equation in the PGM propagation model.

P RX  = P TX  + K 1 + K 2 log ( d ) + K 3 log ( H ef f ) + K 4 Di ff ra ct io n + K 5 log ( H ef f ) log ( d ) + K  ( H  6 meff ) + K CLUTTER

Equation 1.1 Received signal strength in the PGM propagation model Where

P RX   is

the receive power in dBm.

P TX   is

the transmit power (ERP) in dBm.

K 1  is

the constant offset in dB.

K 2  is

the multiplying factor for log(d).

With the two-piece model, both K 1 and K 2 can be assigned two sets of values. One set is used for d< distance and the other for d> distance, where distance is the distance in meters away from the base site specified in the Model Editor. K 3  is the multiplying factor for log( H ef f  ). It compensates for gain due to antenna

height.

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PGM-A Technical Note K 4  is the multiplying factor for diffraction calculation. K 5 is the Okumura-Hata type of multiplying factor for log ( H ef f ) log ( d ) . K 6  is the correction factor for the mobile effective antenna height gain (K 6 H ef f  ).

d is the distance, in meters, of the receiver from the base site.  H ef f   is the effective height of base site antenna from ground.

Diffraction is the value calculated for loss due to diffraction over an obstructed path. The value produced is a negative number, so a positive multiplication factor, K 4 is required. K CLUTTER  is the gain in dB for the clutter type at the mobile position in Planet DMS. In

Planet  EV , K CLUTTER represents a loss.  H meff  is the mobile effective antenna height.

PGM-A propagation model In order to achieve similar results to those obtained using the Asset model, the PGM-A propagation model received signal equation (Equation 1.1) was modified. The following sections detail key mappings between the two models: ■

■

■

■

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K-factor mapping. See “K-Factor mapping” on page 13. effective transmit antenna height mapping. See “Effective receive antenna heights mapping” on page 13. clutter parameters. See “Clutter parameters” on page 13. diffraction loss calculations. See “Diffraction loss calculations” on page 14.

PGM-A Propagation Model PGM-A Technical Note

K-Factor mapping K factors in the Asset propagation model can be mapped to those in the PGM model as follows:

K 1

= –

K 2

=

K 3

= –

K 4

=

K 5

= –

k 6

K 6

= –

k 3

( k 1 – 3 k 2 + k 4 log ( H ms ) )

k 2 pa

( k 5 – 3 k 6 )

k 7

Where

The capital letter K indicates a K-factor in the PGM propagation model and small letter k indicates a K-factor in the Asset model. In the mapping equation for K 1, the k 4(logHms) term is only valid if the Rx height is defined globally and not per clutter. If the Rx height is defined by clutter, then the Rx height must be set to zero.

Effective receive antenna heights mapping In Asset model, the height of Rx antenna is defined as the height of the mobile above ground. However, in the PGM model, an effective Rx height is used, as this typically leads to more accurate predictions.

Clutter parameters The following table contains a comparison between the parameters in the Asset model versus those in the PGM model.

 As set Mod el

PGM

Offset-loss (dB)

Clutter Absorption Loss

Height

Clutter Height (m)

Separation (m)

Clutter Separation

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PGM-A Technical Note

 As set Mod el

Through-loss (dB) Through-loss Distance

PGM

Through Clutter Loss is mapped to the Path Clutter parameter in PGM via the following: ■

Through-loss Distance was mapped to Path Clutter Distance

■

Function Coefficient was set to 1

■

Triangular Function type was selected

■

The Clutter Properties Assignment dialog box was modified to include the Through-loss parameter defined in the Asset model

Diffraction loss calculations In the Asset model, there are four methods for computing diffraction losses due to radio wave propagation over obstacles. These methods include the Bullington, Japanese Atlas, Deygout, and Epstein-Peterson methods. PGM only includes a modified version of the Epstein-Peterson method for computing losses due to diffraction, which is automatically balanced with a Bullington algorithm, as a function of the profile characteristics; this method  provides more accuracy as it allows for an automated adaptation of the algorithm for each predicted point. In this method, if there are more than three knife edges between the Tx and Rx, the first two knife edges are fixed, but the remaining knife edges are combined into the third knife edge. Both PGM and Asset models include an option for merging the distance of knife edges where knife edges with a distance of less than the merging distance are represented as a single knife edge.

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