Monday 7 April 2014

802.11 Networks on Radio Mobile (Part 2) - Coverage Maps

15:53 Posted by Jurgens Krause , , 1 comment
Now that we have mastered point to point links using RM, the next major feature is generating coverage maps.

For this tutorial we will be continuing with our Fictional WISP, SaharaWisp. We already have our two highsites configured, and we have a link running between the two. We are now going to be adding two 5.8ghz sectorized antennas to each tower, and plotting the resulting coverage.

Start by opening your existing network file in Radio Mobile.

If you don't have RM already, you can grab the installer HERE:

1. Preparing the Settings

Next we will be defining each new antenna as a unit under File->Unit Properties:

If you have been following my tutorials, I have changed the name from SN-Grid-1 to SW-S1-Grid. This is to make identification easier. SW-S1-Grid is SaharaWisp-Site1-Grid.
Our sectors will be for example: SW-S2-SN which is SaharaWisp-Site2-SectorNorth

All units (antennae) at Site 1 will therefore have the same coordinates. The same applies for all units at Site 2.

Start by selecting SW-S1-Grid and click Copy.
This will copy the coordinates to your clipboard.

Proceed by selecting Unit 3 in the left hand pane, and clicking Paste. This will make Unit 3's coords the same as the ones of SW-S1-Grid, also change the name to SW-S1-SN.

Also do the Same for Unit 4, changing the name to SW-S1-SS.

Repeat the process with Unit 5 and Unit 6 using the coordinated from SW-S2-Grid and make the names for the two new units SW-S2-SN and SW-S2-SS

Select Unit 6 and simply name it "Client" without any coordinates.

Close the Units Properties Window and open File->Networks Properties

On the left hand pane, select Net 2  and enter the following on the Parameters tab:

  • Net name: Coverage
  • Min Freq: 5180mhz
  • Max Freq: 5800mhz
  • Polarization: Vertical (or Horizontal if it applies)
  • Mode of Variability: Spot
  • % of situations: 70%

In the topology tab, you can untick the Visible box, since we don't need to generate links for any of these units. Similarly, the Topology does not actually matter, since these units don't simulate any inter-connections.

Let's skip forward to the Systems tab again. We need to configure a system to act as our sector, and one to simulate a client. The client system is already configured since I will be using Ubiquiti Bullet m5 with a 27db grid antenna as my client side connection, you may choose to use something else.

Select System 2 in the left hand pane, and select Mtik Metal 5SHPn - 20db/90deg from the dropdown. This is a preconfigured Miktrotik Metal groove on a 90 degree sector antenna.

Ok, lets return to the Membership tab.

Here you want to configure five new units, let us start with a simple one, the client:

Make sure that the Client unit that we created earlier is ticked and selected.
Enter the following values.

  • Role of Client: Command (this can be anything it really makes no difference)
  • System: UBNT BulletM5 - 27db Grid
  • Antenna Height: 3M (you can put the estimated minimum height for client side connections)

Now we want to make sure that each of the Sector antennae is ticked, and configured as below:

  • Role of Client: Command (this can be anything it really makes no difference)
  • System: Mtik Metal 5SHPn - 20db/90deg
  • Antenna Height: 10M
  • Azimuth: 0deg for the north facing sectors, 180deg for the south facing sectors

You can now close the Networks Properties window.

2. Plotting the coverage Map:

You have two ways to plot coverage maps, we will deal with both, starting with the simplest, ie. the Single Polar coverage map.

Let us start by creating the base picture:

Click File->Map Properties. 

In order to contain our coverage plots, let us increase the height of the map to 40km.
Click Extract

2.1 Single Polar Coverage

Single polar coverage allows you to plot the coverage of a single unit's coverage area.

Click on the Single Polar Coverage icon:

Enter the following parameters:

Center Unit: The unit from which you want to plot the coverage
Mobile Unit: The unit that is indicative of a typical client device (CPE)
Network: Should automatically be the Coverage network
Link Direction: Center Tx - Mobile Rx

Radial Range (this determines how far out you plot the coverage):
Minimum: 0.01 km
Maximum: 15 km

Azimuth Range (this determines the angle that will be plotted):
Minimum: 0
Maximum: 360
Step: 0.5 (this is the effective resolution of the plot)

The Plot section is rather subjective, ie. whatever works well for you, but let us make a simple example:
Check the following boxes:
Fill Area
Network Style
This means that it will fill the area based on the parameters defined under Networks Settings/Style Tab.

Initiate the plot by clicking Draw
This can take a while depending on your hardware and the size and resolution of the plot.

You will be asked to redraw the picture in gray mode, since this is a requirement, you can simply click Yes.

When it is done you will be asked what you want to do with the plot. I usually keep it in the current picture.

Now, after all this work, let's have some fun; Save the picture by clicking File-> Save Picture As and give it a name, I will use coverage.png

If you open the folder where you saved these files, you will see that RM created a file called coverage.kml, go ahead and open it.

You can now see your coverage map overlaid into Google Earth as below:

2.2 Combined Cartesian Plot:

The combined Cartesian plot allows you to plot the coverage for a number of units/antennae at the same time. Note that with large networks this can take some time. My network runs for about 8 hours to generate high resolution coverage maps. It works by analyzing each pixel on the map for each tower in the list and determining the best signal from ANY of the selected towers.

Since everything else stays the same, let us start with a new empty image. We are going to generate a white image here so that we don't export the topography to Google Earth.

Click on File->New Picture

Select White and click Draw

This gives you a plain white render of your area.

Now, click on Tools->Radio Coverage->Combined Cartesian.

Make sure all the Sector antennae are selected in the left hand pane.
Enter the following details:
  • Mobile Unit: Client
  • In Network: Coverage
  • Use Network Antenna Settings: Checked
  • Maximum Range: 15km
  • Signal Range Unit:
    • dBm: Selected
    • Draw size: 2.5 Pixels (decreasing this can drastically increase render time)
    • Network Style: Checked
Note: Playing around with the Signal range unit settings can give you more satisfactory results, this is a simple example.

Click Draw

Again, when saving it, you will also get a Google Earth KML file.


Comment if you have any suggestions on how I can improve this.

1 comment: