EM.Terrano Tutorial Lesson 3: Analyzing Indoor Propagation Inside A Multi-Story Building Model
What You Will Learn
In this tutorial you will use a wizard to construct the geometry of a multi-story building model made of penetrable surfaces. You will also learn how to define and change variables. You will change the wall properties including their thickness and conductivity and will examine the effect of these changes on the wireless propagation.
Constructing the Geometry of the Multi-Story Building
For this tutorial lesson, you will use a wizard to build the geometry of a office building. Click on the Office Building Wizard button of the Wizard Toolbar or select the menu item Tools → Propagation Wizards → Office Building.Two arrays of box objects appear in the project workspace, which represent the rooms and hallways of a two-story office building.
Defining the transmitter & Receivers
For this tutorial lesson, you will define three base location sets called "BasePointSet_1", "BasePointSet_2" and "BasePointSet_3" with the colors blue, orange and purple, respectively. Under "BasePointSet_1", create a single point object for the transmitter. Under "BasePointSet_2" and "BasePointSet_3", create two arrays of base points for two separate receiver sets on the first and second floors according to the tables below:
|Part||Object Type||Object Group||Group Color||Dimensions||Coordinates|
|Point_1||Point||Base_Point_1||Blue||N/A||(-15m, 12m, 3m)|
|Point_2||Point||Base_Point_2||Orange||N/A||(1m, 1m, 1m)|
|Point_3||Point||Base_Point_3||Purple||N/A||(1m, 1m, 5m)|
|Array Object||Parent Object||X Count||Y Count||Z Count||X Spacing||Y Spacing||Z Spacing|
Define a new default transmitter set associated with BasePointSet_1. Similarly, define two separate new receiver sets associated with BasePointSet_2 and BasePointSet_3. At this time, your project workspace must show a scene like this figure:
Running a SBR Analysis
At this time, you are ready to run a quick SBR analysis of your propagation scene. But you need to keep in mind that in indoor propagation scene an extremely large number of reflected rays may be produced due to successive bounces from all the walls, ceilings and floors. If you don't limit that maximum number of ray bounces, the simulation time may increase significantly. Open the simulation run dialog and click the Settings button next to the simulation engine type drop-down list. This opens up EM.Terrano's simulation engine settings dialog. At the top of the dialog, you can see a box labeled Max No. Ray Bounces that has a default value of 10. Reduce this value to Nref = 4.
Run an SBR analysis of your indoor propagation scene and visualize the coverage maps of the two receiver sets at the first and second floors.
Now visualize the rays in the scene. You may want to hide the second receiver set for more clarity. Remember that by default, the first receiver of the first receiver set is always selected as the active receiver for ray visualization. Open the property dialog of ReceiverSet_1, select its first receiver element and view its ray data dialog. You will see a total of 9 rays received by the first receiver.
Next, open EM.Terrano's simulation engine settings dialog again and set the value of Max No. Ray Bounces to Nref = 8. Run another SBR analysis of your indoor propagation scene and visualize the coverage maps of the two receiver sets at the first and second floors.
Also visualize the rays received by the first receiver on the first floor. With Nref = 8, this receiver receives a total of 68 rays.
Changing the Wall Properties
The office building created by the wizard is highly parameterized. Open the Variable Dialog by clicking the button on the Simulate Toolbar or selecting the menu item Simulate → Functions.... You will see a long list of variables related to the dimensions of the rooms and hallways, number of rooms along the X, Y, Z directions, as well as the wall properties.
Select and highlight the variable "sig" from the list (corresponding to the wall conductivity) and click the Edit button of the dialog to open "Edit Variable" dialog. Change the definition or numeric value of "sig" from the original value of 0.001 to 0.1.
Similarly, edit the variable "wall_thickness" from the list and change it from the original value of 0.25m to 0.5m.
Once all the changes take effect, run a new SBR analysis of your indoor propagation scene and visualize the receiver power coverage maps on both floors. From the figures below you can see a significant drop in the power levels of the receivers on both floors.