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Author: Paco Esteban <paco@onna.be>
Date: Sat, 20 Jul 2019 18:06:08 +0200
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+title: Long Wireless links and monitoring.
+author: paco
+date: 2019-07-19
+css: style.css
+
+XXmenuXX
+
+---------
+# Long Wireless links and monitoring.
+2019-07-19
+
+## Intro
+
+Some time ago I built 2 [P-t-P][1] links between some family members buildings.
+
+Thing is that my brother and my sister live in an area with no coverage from
+traditional ISPs, but that is quite close (5.5km on a straight line, with no
+obstacles) to my parent's which have good coverage (even FTTH) and plenty of
+providers to choose from.
+
+This project has grown _organically_ so to speak, and the requisites kept
+changing.
+
+That, and my lack of experience on the subject make all this far from an
+optimal solution.
+
+In the end it has been working for almost 3 years now. This is an attempt to
+document all the infrastructure and the bits and pieces used so I do not forget
+about it and maybe it can be of use to somebody else.
+
+## First steps and research
+
+As I said, I knew nothing about this before tackling the project. I have some
+solid knowledge about networking, but I knew little about long (for me)
+wireless links, antennas, propagation and a bunch of other stuff I did not know
+existed, so I had to do some research.
+
+If you want to do something like this, is better to plan ahead. See what the
+requisites are and start digging.
+
+Some things to take into consideration are:
+
+* Budget. This is an important one in this scenario, as this is for personal
+ use only.
+* Distance between the endpoints of the link. Modern hardware (more on my
+ choice later), can easily cover 10km or maybe more, but read the
+ manufacturer's datasheet and look for output power, antenna gain and
+ sensitivity. And always take their numbers with a grain of salt, as they
+ are usually tested on ideal conditions you won't encounter. You'll find
+ later a way to calculate the ideal numbers to have an estimate.
+* Obstacles. There has to be perfect clear vision between endpoints. Wireless
+ communications, especially WiFi either on 2.4GHz or 5GHz, are very
+ sensitive to obstacles. Even partial cover can have a big impact on link
+ quality. And clear vision does not mean _"I can see a single point in the
+ distance"_, there's this thing called [Fresnel zone][2], under some
+ atmospheric conditions or spectrum saturation it will give you a lot of
+ trouble.
+* Materials. Don't be cheap. This will have to resists the outdoor conditions
+ for as long as possible.
+* Neighbours and regulations. There's the legal part (RF regulations in your
+ country and things like that) and the _"social"_ part, in this case my
+ family does not live in detached houses but on apartments, so that has to
+ be taken into consideration if there are any rules about this.
+* Infrastructure. And by that I mean all the necessary to be able to install
+ the antennas, route the cables, install connectors, etc. I'm not only
+ talking about tools, but also access to the best spots to put the antennas,
+ etc.
+* Antenna location. As a rule of thumb, the higher the better. But this
+ depends a lot on your particular situation. It deserves some thought.
+* Spectrum saturation. Wifi is ubiquitous now. That may be a challenge for
+ any installation specially on urban areas. Ideally, you should check how
+ _crowded_ the spectrum is, but this is usually pretty difficult for
+ amateurs without special equipment. Some antennas have a built in spectrum
+ analyser, but it may perform badly.
+
+## Materials
+
+This is a list of materials I choose and why I choose them. It is short, as it
+is really an easy installation.
+
+### Antennas
+
+I ended up using [Ubiquity PowerBeams][2] to create the 2 links. Four in
+total, 2 for each link.
+
+I was looking for some reputable manufacturer trying to avoid problems in the
+future. Also, I wanted something as simple as possible. This kind of antennas
+have the _"emitter/receiver"_ and the antenna all in the same device. So no
+special connectors to be crimped, virtually no losses on cables, just an easy
+[PoE][4] setup from the house to the rooftop.
+
+Also, this antenna has an easy to setup web interface _and_ an SSH server that
+leaves you in a busybox with some proprietary commands that are pretty handy
+for automation and data collection.
+
+There are newer models now and other manufacturers. Do your research, read on
+forums and all the usual stuff. I can say those work for this setup with minor
+issues.
+
+If you know something about this subject you may be wondering why I did not use
+something with a wider angle on the _"access point"_ side and use just 3
+antennas instead of 4. Truth is, I tried, but I had some problems with the 2nd
+link giving poor performance. Not being an expert on this I can only guess
+that the partial obstruction on the LOS (line of sight) path for the second
+link was the cause of the poor performance, specially on bad weather days (WiFi
+is pretty sensitive to heavy rain) and episodes of spectrum saturation.
+
+Creating a separate link with a dedicated pair of antennas improved the
+situation a lot.
+
+### Cables
+
+As the antennas only need a network connection, we only need Ethernet cable.
+Be sure that is CAT5e or better.
+
+Always use cable rated for outdoor use. Regular network cable will not last
+long exposed to rain and the sun's UV. I went for [this one][5] because it was
+available at the time on Amazon.
+
+### Connectors
+
+Don't go extra cheap on this, but anything with reasonable quality will do
+here. The antennas are built in a way that the connectors are never exposed,
+so this part is not that critical.
+
+### Antenna pole and other hardware
+
+I cannot say much about this. What to buy here depends a lot on your
+particular setup. Remember that the higher the better for the antennas, and
+remember wind is a thing ... you do not want it to fly away like a plastic bag.
+
+----
+[1]: https://en.wikipedia.org/wiki/Point-to-point_(telecommunications)
+[2]: https://en.wikipedia.org/wiki/Fresnel_zone
+[3]: https://www.ui.com/airmax/powerbeam/
+[4]: https://en.wikipedia.org/wiki/Power_over_Ethernet
+[5]: https://www.konigelectronic.com/computer/networking/network-cable-reel-cat5e-futp-100-m-black-solid-55896639
+
+Last updated: XXlastXX
