Utahs K7MSH Mesh Network

I have heard a few questions about the Mesh network here in Utah, how does it work, what do I need to join, how do I get started? I will try to cover the basics of Mesh networking, and focus mainly on the K7MSH network. There are a few different groups here in Utah and while the end goal is the same, the different groups have gone about it in a few different ways.

What is the Mesh network? At its basic form, it is an ad-hoc network consisting of nodes Put together by Ham radio operators. Think of it as a massive wifi network connecting Ham radio operators over several miles. This system is a self configuring, self Healing network that allows nodes to come on and off line at any time and in theory not disrupt the flow of the network. The system is designed so that any node that can Hear (RF) another node will automatically connect to each other. The system is smart enough to calculate routes and when multiple routes to the same destination are available, The system can decide what the fastest route is. If a node goes off line and changes the route, The system will recalculate and find a new path.

Lets talk about nodes. A node can be as simple as a
Ubiquiti Bullet connected to an omni antenna, or it could be a configuration of an RF unit combined with Servers, Switches, and other networking equipment. Basically, this is the same type of gear that you would use in your house for wifi, just a bit more rugged. For now, when I say node, Think of a wifi router. we will cover some of the equipment used a little bit later.

What Makes these “Nodes” different than my home wifi? well, the major difference is the Firmware. Once you flash your node it no longer acts as a basic home wifi router, it now seeks out other nodes to connect to with out any effort on your part. You have 2 big players in the ham radio Mesh network community, There is AREDN (Amateur Radio Emergency Data Network), and there is BBHN (BroadBeand-HamNet). Both of these organizations produce firmware to flash these over the shelf routers and turn them into “Mesh nodes”. While the 2 different firmware upgrades do pretty much the same thing, there are some important differences.

AREDN vs. BBHN. As I stated earlier, The way that both of these operate is almost identical and they accomplish the same thing, but there are some small but important differences in the two systems. BBHN supports Ubiquiti equipment as well as the Linksys WRT54G routers, While AREDN does not support the Linksys series, they do support ubiquiti and a couple of TP Link units.

The other big difference in the 2 systems is that the BBHN system only supports the public wifi channels. The AREDN system supports the use of channels -1, and -2 in the 2.4GHz range. The addition of these 2 channels makes a big difference. Channels -1 and -2 are outside of the public wifi range, but still in the Ham radio range, so this gives us 2 quiet noise free channels to use for the network.

The K7MSH group primarily uses the 2.4GHz Gear on Channel -2 and a bandwidth of 10 MHz. Using Channel -2 keeps the Noise floor down and allows for connections at pretty good distances. We are limited to 10MHz bandwidth to stay inside of the Range that the License gives us, but 10MHz is enough to carry most traffic without issue.

Mountain top nodes. After almost a year of test, driving to remote sites, mountain tops, and key locations, we decided that by setting up Mountain top nodes, we could cover great distances and have more nodes connect to the network. Think of these as repeaters, you may not be able to talk directly to a friend 30 miles away on your 2 meter radio because of terrain or other obstacles, but by going through a repeater, now you can easily talk to that person, plus many more even further away. This isn’t exactly the way the network was designed to work, but for our location it works. let me show you what I mean.

This is what a Mesh network should look like

Notice that some nodes can see each other, some nodes cant. The idea behind mesh networking is that when any node sees another node, it connects, and adds redundancy to the network.

This is more like what we are doing

This is a Star, or Hub and Spoke topology, where the center of the Star is the mountain top node. everyone points to the mountain top node to connect to the network. This is not the best way to do things, but it works for us, and we are working to create more routes, and redundancy into the network.

This setup of Mountaintop nodes greatly improves the distance that our network can extend. We have seen connections from Lake mountain to as far as Layton (close to 70 miles) and our West mountain node is not pointed very far south, but I believe it does see into the Payson area. Our Mountain top nodes consist of Ubiquiti Rocket M2 Mimo devices attached to Ubiquiti 16 DB gain 120 degree sector antennas. our West mountain node points East by NorthEast, and our Lake mountain node points North By NorthEast. We also have a node pointed to the West side of Lake Mountain.

We are still in the process of building the Backbone for our Network, The few pieces that we have implemented are 5GHz NanoBridges. Right now we have a 5GHz nanoBridge set up at our Lake Mountain site that ties us into Nelson Peak to the North. After testing a few months ago we discovered that a direct link between Lake mountain, and West mountain was not possible. We are looking into options to link into the Valley and back to the mountain sites from there, but this is still in the planning stages. Right now we do not have any 5 GHz links in our system that other than Backbone nodes. We plan to add 5GHz to our open nodes in the future, but as of right now the only used for a Backbone.

The 5GHz backbone. One primary reason we like 5GHz for a backbone is because there are a hand full of Ham radio use only channels, and the available 20MHz bandwidth. This gives us the option to use one channel as a backhaul between our main Mountaintop nodes, and a different channel as open access to the mesh. The 20MHz bandwidth also allows us to to pass more data between nodes.

Node choices. There are a few popular choices for nodes. I won’t attempt to cover everything here, but give a few good options. The first option is a Ubiquiti NanoBridge. The Nano Bridge is a 19 DB gain dish about the size of a standard satellite dish. These work great if you have a long distance to link to, or if there are obstructions in the path. The down side to NanoBridge is that you are not helping to expand the network because of the tight beam width, you are only connecting to one node. Another good option is a nanostation. The Nanostation is a 60 degree sector with the radio all built in to a small package. The nice thing about the Nanostation is with a 60 degree BeamWidth and 8db gain, you can connect over several miles and to multiple stations.

If you are interested in The Mesh Network here in Utah and want more information please join the Utah Amateur Radio Mesh Facebook group.