EM.Terrano Tutorial Lesson 4: 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 run a discrete frequency sweep of your propagation scene.
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.
The geometry of the building is highly parameterized. Open the Variables Dialog. Change the length of the individual rooms to 8m, the width of the hallways to 3m and the number of rooms along the Y direction to 5. The table below summarizes the changes you need to make.
|Variable Name||Original Definition||New Definition|
The rooms are represented by an array of square boxes called "Office_Set" and the hallways are represented by an array of long boxes called "Hallway_Set". The two array objects belong to two different penetrable surface groups that happen to have the same brick material properties and the same wall thickness of 0.25m.
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||(-3m, 11m, 3m)|
|Point_2||Point||Base_Point_2||Orange||N/A||(-3m, -3m, 1m)|
|Point_3||Point||Base_Point_3||Purple||N/A||(-3m, -3m, 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.
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 = 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.
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. Note that the coverage maps in this case have expanded significantly meaning the choice Nref = 4 wasn't adequate for your analysis.
Visualizing the Interior Rays
Visualize the rays received by receiver No. 1296 of ReceiverSet_1 on the first floor. With Nref = 8, this receiver receives a total of 47 rays.
Next, visualize the rays received by receiver No. 1296 of ReceiverSet_2 on the second floor. With Nref = 8, this receiver receives a total of 18 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: