STEM help / Training

Exercise 13: Coverage model

Let’s look in more detail at the deployment of the WiMAX access sectors.

Save the model as WiMAX-DSL13

  1. Look at the Sites input (Details/Sites) for the location element, Site coverage plan. This is entered directly as an interpolated series.

How could you extend the input parameters for this element to derive this series from the following three assumptions?

  • Total coverage required = 200 sq km
  • Coverage per sector = 20 sq km
  • Roll-out factor = the current sites input normalised to 1.0 at the end.

OK, you don’t have to think too hard! Try these steps.

  1. If the Interpolated Series dialog is still open, then please close it to return to the Details dialog.

Copy and paste

  1. Left-click to select the Sites field (the Interpolated Series, not the preceding Unit field which is currently set to the value ‘Sites’), and then select Copy from the dialog Edit menu (or press <Ctrl + C>).
  2. Click the Move menu again, and this time select User Data. The User Data dialog is displayed.
  3. Left-click to select User 3, and then select Paste Formulae from the dialog Edit menu (or press <Ctrl + V>). User 3 should become an interpolated series.

  1. Change the interpolated-series data to 0.5 in Y1 and 1.0 in Y3, and then close the Interpolated Series dialog.

Rename Field

  1. Move back up to User 1, right-click and select Rename… from the context menu. The Rename Field dialog is displayed.
  2. Type ‘Total coverage required’ into the Element box, and press <Enter>. The field is now labelled as directed in the dialog.
  3. Enter the constant value 200 directly in the field.
  4. Repeat the last two steps for User 2 and User 3 with Coverage per sector = 20 and Roll-out factor = the values already normalised.

  1. Move the User Data dialog to one side, and click back to the top-level dialog (where you copied the Sites input), or press <Ctrl+F6> to switch dialogs without the mouse.

Reference mode

  1. Making sure the Sites field is still selected, press <F2> to start entering a formula on the field (or left-click in the formula bar), and then click on the cell for User 1. A reference to User 1 (renamed) should appear in the formula bar for Sites.
  2. Type a ‘/’ and then click on User 2 to pick up the next part of the formula.
  3. Type a ‘*’ and then click on User 3 to pick up the last part of the formula, and then press <Enter> to commit the formula. It should look something like this:

Save and run the model

  1. Look at the results for Capacities again. The results should be the same as before, but now you can drive the calculation on an area-coverage basis.
  2. Try changing the Coverage per sector assumption. Are the results as expected? What happens in the first two years if the Coverage per sector is only 10.0?

The next exercise will show you how STEM can lead you directly to an explanation of results which you don’t understand.

  1. If there is time, see if you can try changing the input parameters to be driven by cell radius.

Things that you should have seen and understood

Copy and paste (field-wise), Rename Field, reference mode


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