EM.Terrano Tutorial Lesson 4: Analyzing Indoor Propagation Inside a Building Model with Penetrable Walls
What You Will Learn
In this tutorial you will set up objects with penetrable surfaces to model the walls of a building. You will also learn how to run a discrete frequency sweep of your propagation scene.
Open the EM.Cube application. In the New Project Dialog, enter "EMTerrano_Lesson4" as the title of your new project. From the drop-down list labeled Problem Type, select "Simple Indoor Propagation Scene - EM.Terrano". Keep the default choices of project’s Length Units, Frequency Units, and Bandwidth and change the Center Frequency to 2.4 GHz. Click the Create button of the dialog to return to the project workspace. A propagation scene is automatically created the contains two buildings, a transmitter and a grid of receivers.
Start a new project with the following attributes:
Examining the Indoor Scene Template
The template automatically creates two block groups called "BUILDING" and "WALLS" under the Penetrable Surfaces node in the Physical Structure section of the navigation tree. The Interior walls have been drawn as "Rectangle Strip" objects. Partition walls divide the big areas into four rooms.
The geometry of the building is parameterized. Open the Variables Dialog. Change the length and width of the building to 125m and the value of the interior wall thickness to 0.5m. The table below summarizes the changes you need to make.
|Variable Name||Original Definition||New Definition|
The template created a vertically polarized dipole transmitter (TX1) and a grid of vertically polarized receivers (RX1) as indicated in the tables below:
|Part||Object Type||Object Group||Group Color||Dimensions||Coordinates|
|Point_TX1||Point||Base_TX1||Blue||N/A||(-50m, -20m, 5m)|
|Array Object||Parent Object||X Count||Y Count||Z Count||X Spacing||Y Spacing||Z Spacing|
Drawing a new wall
Activate "WALLS" group by right-clicking on its name in the navigation tree and selecting Activate from the contextual menu. Then draw a rectangle object called "Wall_3" with the location and dimension given in the table below:
|Part||Object Type||Object Group||Dimensions||Coordinates||Rotation Angles|
|Wall_3||Rectangle Strip||WALLS||bldg_len × bldg_height||(0, 45m, 0.5*bldg_height)||(90°, 0°, 0°)|
With the rectangle strip tool selected, click on a blank space in the project workspace and drag the mouse to draw the planar rectangle object. A property dialog pops up at the lower right corner of your screen. As you drag the mouse, you will see that the X-dimension and Y-dimension of your new object continuously change. You can enter any values for the side dimensions or the X, Y, Z coordinates of the center of local coordinate system (LCS) at any time.
Your physical structure should look like this:
Running a SBR Analysis of the Indoor Propagation Scene
At this time, you are ready to run a quick SBR analysis of your propagation scene. But keep in mind that in indoor propagation scenes, 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 Ray Tracing Engine Settings dialog. At the top of the dialog, you will see a box labeled Max No. Ray Bounces that has a default value of 10. Reduce this value to Nref = 5.
Run an SBR analysis of your indoor propagation scene and visualize the coverage maps of the receiver sets.
Next, open EM.Terrano's simulation engine settings dialog again and set the value of Max No. Ray Bounces to its defaukt value of Nref = 10. Run another SBR analysis of your indoor propagation scene and visualize the coverage maps of the receiver sets. Note that the coverage maps in this case have expanded meaning the choice Nref = 5 wasn't adequate for your analysis.
Visualizing the Interior Rays
Visualize the rays received by receiver No. 592 of RX1. With Nref = 5, this receiver receives a total of 7 rays.
Next, visualize the rays received by receiver No. 592 of RX1. With Nref = 10, this receiver receives a total of 522 rays.
Running a Discrete Frequency Sweep
The previous results were are all obtained at the operational frequency of fc = 2.4GHz. In this section, you will run a frequency sweep of your indoor propagation scene. EM.Terrano offers two types of frequency sweep simulation: uniform and discrete. In a uniform sweep, the start and stop frequencies and the number of frequency samples are specified. The frequency samples are uniformly spaced. In the discrete frequency sweep, you provide a comma-separated list of frequencies. For this tutorial lesson, this list includes the popular wireless frequencies: 710MHz, 1880MHz, 2400MHz and 5800MHz.
Open the Run Dialog and select Frequency Sweep from the "Simulation Mode" drop-down list. Click the Settings button next to this drop-down list to open the Frequency Settings dialog. For frequency sweep type, select the radio button labeled Discrete Frequency List and enter the frequency value list in GHz (the currently selected frequency units of the project).
Run a new SBR frequency sweep of your indoor propagation scene and visualize the receiver power coverage maps on both floors. At the end of the sweep simulation, in the "Observables" section of the navigation tree, you will see a list of four coverage maps corresponding to the four specified frequencies for each receiver set. Two of these maps at 1880MHz are shown in the figures below: