You’ve done the flatland model we did Part 1 and now you’re pumped up and ready to start plotting your cell sites, optimizing your coverage and boosting the services you’re offering.
But one thing stands in your way – The predicted & modeled data we get out of Atoll is only going to be as good as the data we’ve given it, the old garbage in garbage out adage.
So let’s get started, we’ll create a new document from Template again and select LTE.
Setting our Projection
Now before we go throwing out cell sites we’re going to have to tell Atoll where we are, this can get a little tricky if you’re setting this up for a different real world location, but stick with me and I’ll give you the data you need for this example.
We’ll select Document -> Properties and we’ve got to define a projection,
A projection is essentially a coordinate system, like Latitude and Longitude, that constrains our project to somewhere on this planet.
In this example we’re in Australia, so we’ll select Asia Pacific from the “Find In” section and scroll until we find MGA Zone 55. We’ll select it and click OK.
All this Zone information makes sense to GIS folks, there’s lots of information online about UTM datums, projections and GIS, which can help you select the right Coordinate system and projection for your particular area – But for us we’ll select MGA Zone 55 and that’s the last we’ll hear about it.
So now we’ve got that information setup we’ll hit Ok again and be on our way. Atoll now knows where in the world we are and we can start filling in the specifics.
So now we’ve still got an empty map with nothing to show, so let’s add some data.
Adding Population and Roads
We’ll start by adding some base data, we’ll import a footprint of the Island and a map of all the roads.
First we’ll import the populated area outline it into Atoll from File -> Import and select the file called EXTRACT_POLYGON.shp
We’ll put it into the population folder, this will be useful later when we try and ensure this area is covered by our network.
Although the population data is kind of rough ( <100 for the entire area) it’s still very useful for limiting our coverage area and saying “We’ve got everyone covered” when it comes to coverage.
Next up we’ll import the roads file, same thing, File -> Import, TR_ROAD.shp
We’ll import it to the Geo folder – This is just data that Atoll doesn’t process but is useful to us as humans.
Finally we’ll enable the layers we’ve just imported and center the map on our imported data to get us in the right region. We’ll do this by expanding “Population”, right clicking on the file we just imported and selecting “Center in Map Window”
Adding Elevation Data
Again, like our Datum elevation data is a standard GIS concept, but if you’re from an RF background you’ve probably not come across it, essentially it’s an image where the shade of each pixel translates to a height above sea level.
We import it into Atoll and it’s used in propagation modeling – after all we need to know if there’s a hill / mountain / valley in the way, and even slight rises / dips in the geography can have an impact on your coverage.
We’ll start by downloading the file above, and then importing it into Atoll
Next we’ll need to tell Atoll the type of data we’re importing (Altitudes) and it’s offset from the 0 point of our coordinate system, I’ve put the information we need for this into a handy table below:
West
337,966
North
5,768,108
Pixel Size
5m
Now when we move our cursor around we’ll see the elevation change in the bottom right ( z is height).
This is because the elevation data is kind of invisible (We’re looking top down) but it’s there.
Adding a Map Overlay
Ok, you’ve made it this far, let’s finally get out of our white blank map and give it some things that make it look like a map!
In order to add Google Maps / Bing Maps etc as an overlay for the first time, we’ve got to restart Atoll, be sure to save your work first.
Done that? Good, let’s add some map tiles.
We’ll right click on Online Maps -> New and select a map source from the drop down menu,
Next we’ll select a tile server, I’m using Open Street Map Standard Map, which I selected from the drop down menu,
Finally we’ll enable the layer by ticking it on the Geo panel on the right hand side. You may need to drag the layer to the top if you’ve added other layers.
All going well you’ll be looking at a map of the area, and by hovering over an area of land you should see the elevation data too.
We can even add other map layers and toggle between them or set the order by dragging them up and down.
Summary
So now we’ve got Atoll configured for our part of the world, imported height data, population data and roads, and added some map layers so we can see what we’re up to.
An important point to keep in mind is the more accurate the data you feed into Atoll, the more real-world the results you’ll get out of it will be.
Although filling in map layers and adding information seems tedious – and it is – the data-in data-out approach applies here, so the more quality data we put in the better.
If you’re doing this yourself in the real world contact your Government, they often publish large amounts of geospatial data like elevation, population, roads, land boundaries, and it’s often free.
I’ve attached my working file for you to play with in case you had any issues.
The Australian Government publishes elevation data online that’s freely available for anyone to use. There’s a catch – If you’re using Forsk Atoll, it won’t import without a fair bit of monkeying around with the data…
You draw around the area you want to download, enter your email address and you’re linked to a download of the dataset you’ve selected.
So now we download the data from the link, unzip it and we’re provided with a .tiff image with the elevation data in the pixel colour and geocoded with the positional information.
Problem is, this won’t import into Atoll – Unsupported depth.
I fired it up, and imported the elevation tiff file we’d downloaded.
Selected “Elevation” waited a few seconds and presto!
We can export from here in the PNG 16 bit grayscale format Atoll takes, but there’s a catch, negative elevation values and blank data will show up as giant spikes which will totally mess with your propagation modeling.
So I found an option to remove elevation data from a set range, but it won’t deal with negative values…
So I found another option in the elevation menu to offset elevation vertically, I added 100 ft (It’s all in ft for some reason) to everything which meant my elevation data that was previously negative was now just under 100.
So if an area was -1ft before it was now 99ft.
Now I was able to use the remove range for anything from 0 100 ft (previously sea level)
Now my map only shows data above sea level
Now I offset the elevation vertically again and remove 100ft so we get back to real values
Now I was able to export the elevation data from the Elevation -> Export to menu
Atoll seems to like PNG 16 bit greyscale so that’s what we’ll feed it.
In Atoll we’ll select File -> Import and open the PNG we just generated.
Data type will be Altitude, Pixel size is 5m (as denoted in email / dataset metadata).
Next question is offset, which took me a while to work out…
The email has the Lat & Long but Atoll deals in WGS co-ordinates,
Luckily the GeoPlanner website allows you to enter the lat & long of the top corner and get the equivalent West and North values for the UTM dataum.
Enter these values as your coordinates and you’re sorted.
I can even able a Map layer and confirm it lines up:
Forsk Atoll is software for wireless network planning, simulation and optimization.
Atoll can do some amazingly powerful things, especially when you start feeding real world data and results back into it, but for today we’ll be touching upon the basics.
As I’m learning it myself I thought I’d write up a basic tutorial on setting up the environment, importing some data, adding some sites and transmitters to your network and then simulating it.
We’ll be using Christmas Island, a small island in the Indian ocean that’s part of Australia, as it’s size makes it easy and the files small.
The Environment (Geographic Data)
The more data we can feed into Atoll the more accurate the predictions that come out of it.
Factors like terrain, obstructions, population density, land usage (residential, agricultural, etc) will all need to be modeled to produce accurate results, so getting your geographic data correct is imperative.
Starting a new Document
We’ll start by creating a new document:
We’ll simulate an LTE network, so we’ll create it using the LTE project template.
Coordinate Reference
Before we can get to that we’re going to have to tell Atoll where we are and what datum we’re working in.
The data sets we’re working were provided by the Government, who use the Australian Geodetic Datum, and Christmas Island is in Zone 48.
We’ll select Document -> Properties
We’ll set the projection first.
Once that’s set we’ll set our display coordinates, this is what we’ll actually work in.
I’m using WGS 84 in the -xx.xxxxxx format, aka Lat & Long in decimal format.
Elevation
Elevation data is hugely important when network planning, your point-to-point links need LOS, and if your modeling / simulation doesn’t know there’s a hill or obstruction between the two sites, it’s not going to work.
There’s plenty of online sources for this data, some of which is paid, but others are provided free by Government agencies.
In this case the Digital Elevation Models for Christmas Island data can be downloaded from Geo-science Australia.
We’ll download the 5m DEM GDA94 UTM zone 48 Christmas Island.
The real reason I picked Christmas Island is that it’s DEM data is 16Mb instead of many Gigabytes and I didn’t want to wait for the download…
After a lot of messing around I found I couldn’t import the multi layered TIF provided by Geo Science Australia, Atoll gave me this error:
I found I could the TIFF formatted DEM files it in a package called VTBuilder, export it as a PNG and then import it into Atoll.
To save some steps I’ve attached a copy of the converted file here.
You can then import the files straight into Atoll,
We’ll need to define what this dataset is, in our cases our Digital Elevation Models (aka Digital Terrain Models) contain Altitude information, so we’ll select Altitude (DTM)
We know from the metadata on the Geo Science Australia site we got the files from the resolution is 5m, so we’ll set pixel size to 5m (Each pixel represents 5 meters).
We’ll need a Geographic Coordinate, this is the Easting and Westing in relation to UTM Zone 48. The values are:
West
557999.9999999991
North
8849000
All going well you should see the imported topography showing up in Atoll.
I’ve noticed on the version I’m on I had some weirdness when zoomed out, if you try Zooming in to more than 1:10,000 you should see the terrain data. Not sure why this is but I’ve attached a copy of my Atoll config so far so you in case you get stuck with this.
We’ll download real world sites from the ACMA’s database,
I’ll use the cheat way by just looking it up on their map and exporting the data.
We’ll download the CSV file from the Map.
One thing we’ll need to change in the CSV is that when no Altitude is set for the site ACMA puts “undefined” which Atoll won’t be able to parse. So I’ve just opened it up in N++ and replaced undefined with 0.
I’ve attached a copy here for you to import / skip this step. Mastering messing with CSV is a super useful skill to have anyways, but that’s a topic for another day.
Next we’ll import the sites into Atoll, to define our sites, we’ll jump to the Network Tab and double click on Sites.
Now we’ll import our CSV file
Next we’ll need to define the fields for the import
All going well you’ll now have a populated site list.
Now if we go back to view we should see these points plotted.
Clutter
Forested areas, large bodies of water, urban sprawl, farmland, etc, all have different characteristics and will cause different interference patterns, refraction, shadow fading, etc.
Clutter Data is the classification of land use or land cover which impacts on RF propagation.
However this dataset doesn’t include Christmas Island. Really shot myself in the foot there, huh?
For examples’ sake we’ll import the terrain data again as clutter.
We’d normally define terrain classes, for example, this area is residential low rise etc, but as we don’t have areas set out we’ll skip that for now.
You can set different layer visibility by enabling and disabling layers in the Geo tab, in this case I’ve disabled my Digital Terrain Model layer and just left the Clutter Heights we just imported.
I got hit with the same Zoom bug here, not sure if it’s still loading in the background or something but the clutter data is only visible when zoomed to 1:10,000 or more, but after doing so you should see the clutter data:
So now we’ve got our environment stuff we can start to add some cell sites and model the propagation & expected signal levels throughout the island in the next post.