Mesh networks have been around almost as long as Wi-Fi. They have actually been very popular in the developing world (check out http://villagetelco.org/) where there are very few landlines, which spurred the widespread use of cell phones for voice and mesh for data. Most mesh networks operate around 2.4 GHz – pretty much line of sight – so rural Africa has a key advantage over us in that they have far fewer man-made obstructions. The networks are high speed at 54 megabits/second wireless, self-assembling, and fault tolerant. Also of interest to both hams and third world countries is that the network is built from standard off-the-shelf routers designed for the home market. These cost less than $70 brand new including 5 wired network connections, a stripped-down version of the Linux operating system, a power supply and the RF hardware, which can be cranked up as high as 250mw. Coupled with high gain antennas really long distances can be achieved, occasionally in excess of 100km (over water).

The key to this is the software. The standard software supplied by Linksys is replaced with free code from a group of amateurs in Texas (see http://hsmm-mesh.org/). Loading the software and basic configuration is pretty simple, and once done the router will seek out other of its kind to talk to, limiting itself to the 2.4 GHz amateur band. The routers will also act as relays from device to the next, just like land-line routers do, so data will automatically hop from router to router to get to its destination. In Texas, they’ve built a network that covers the city of Austin, so hams can move data, voice and video (at 54 megabits, all these are possible, even at the same time) even when the Internet is not available. Hams are putting units in “go boxes” to deploy networks wherever they need them (drawing 250ma at 12v, they can run on a battery for a long time). Hams are putting them in balloons, tethered or otherwise. Hams are pulling the boards out of their cases and soldering on their own modifications. In other words, hams are being hams.

Another key feature is fault tolerance. If a router goes off the air, the network will automatically try to reroute around it. So with enough routers deployed, a large area can be covered reliably even if something goes wrong. This is a key concept. If each router can communicate with 3 or 4 others, the result is coverage across a region that can withstand multiple failures and keep on working. The first club mesh experiment (“mesh-up”) was at the last D-Star meeting on September 13th.

In and around York Region, a bunch of hams have already started to experiment with them, mostly using the Linksys WRT54-GL router. It appears that the Aurora/Newmarket area is pretty well covered already with VA3XS, VE3GS, VE3CT, VE3NRT and VA3DXZ so far, and in the more far-flung reaches we have VE3HII, VE3WY, VA3IL, VE3UT, and VE3PIP already getting going. Also Steve VA3SRV in Bradford is trying it out but as he lives in a valley he might have to get creative to connect with the rest of us.

So if you’re interested, all you need is a router, a computer, some cable and a couple of antennas which can be home-brew or inexpensive commercial units. In most cases, because the routers are cheap, light and low power, it’s best to put the near the antenna as network cable is much cheaper than low-loss feed line at 2.4gHz. If you want to discuss coverage or need help, talk to me or one of the other hams listed above. If you live somewhere high-up or in-between two other hams or have access to a tower we may find you first.

Chris VE3NRT