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I am an electornics hobbyist. A friend of mine, who is building an organics farm, wants to wirelessly automate some devices in his property, and asked for ideas.

His problem is to "talk" to remote devices, namely the front driveway sliding door (around 100m away from home) and water pump (200m away from home in the opposite direction). This "talk", that is, sending and receiving commands and data, would be handled by some sort of dashbord or "control center" yet to be devised.

At first, he expressed the desire to use WiFi, but as far as I know, at least the water pump would be too far from the control center.

I am pretty sure this type of scenario is pretty common, but could not find an obvious protocol for the "100+ meters" range, up to, say, 500m or 1km.

What are the protocols commonly used for this, specially in rural areas?

UPDATE: At first, we would not like to depend on third-parties, such as cell-phone operators or similar paid services.

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    \$\begingroup\$ You can use WiFi if your AP has a directional antenna. There are numerous outdoor APs with that feature. \$\endgroup\$
    – Janka
    Jun 4, 2018 at 19:37
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    \$\begingroup\$ @Janka that sounds like a great solution. I didn't know about these directional antennas, to be honest. \$\endgroup\$
    – heltonbiker
    Jun 4, 2018 at 19:41
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    \$\begingroup\$ amazon.com/dp/B076KRTXQ6 \$\endgroup\$
    – Robert Harvey
    Jun 4, 2018 at 19:45
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    \$\begingroup\$ If you don't need the BW of WiFi, and esp. if you want battery operation, the LoRa scheme might work. \$\endgroup\$
    – mike65535
    Jun 4, 2018 at 20:07
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    \$\begingroup\$ You could try LoRaWan, it has up to 5km radio link distance, at the price of VERY low data rate. \$\endgroup\$
    – Stefan Wyss
    Jun 4, 2018 at 20:07

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This sounds like a perfect match for LoRa. 10km in rural areas, no additional licence required, and lots of example designs to learn from.

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    \$\begingroup\$ Yes, that could be a fit. Technically that's a modulation not a protocol, though LoRaWAN is often used on top of it. A big question will be if the nodes have sufficient power to have wide receive windows (ie, time periods when the receive is on and listening); if they have to run on battery, receive windows may have to be short and infrequent so there may be a lot of latency in downlinking messages to them - but that's a limitation with almost any active-receiver radio scheme, not just this. \$\endgroup\$
    – Chris Stratton
    Jun 4, 2018 at 20:18
  • \$\begingroup\$ @ChrisStratton thanks for your comment. In principle, the endpoints will contain mains-operated devices - the devices being controlled, proper - so I don't think it would be a big problem. \$\endgroup\$
    – heltonbiker
    Jun 4, 2018 at 20:45
  • \$\begingroup\$ It should work fairly well then; however you may want to use a more barebones point-to-point type of implementation rather than a typical LoRaWAN one that may have the inapplicable limitations of battery powered nodes assumed. Or at least look into what sort of reconfiguring/rethinking might be appropriate. \$\endgroup\$
    – Chris Stratton
    Jun 4, 2018 at 20:56
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In large the right wireless solution for you will depend on the automation (MCU selection) at the remote points.
If you are building based on a single board computer such as Raspberry Pi then you might consider the Nordic Semi NRF24L01+. This is readily available at low cost ($3-5) on Ebay with a PA that raises the line of sight distance to about 1Km. Hard to beat for the price.

enter image description here

There are readily available libraries to support this device and endless follow the bouncing ball projects for Raspberry Pi and Arduino that should be able to kick off your project.

You could potentially use WiFi (or ESP8266 with a PA) based endpoints with a directional antenna, but the antenna cost alone will be outlandish, and most modern APs have multiple antenna to deal with, and if you have multiple directions to service this will become very challenging.

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A picture worth thousand words. You should first ask the question yourself, "what is the data rate I'm looking at?" If you're looking for higher data rate, then sigfox will not work.

At first, he expressed the desire to use WiFi, but as far as I know, at least the water pump would be too far from the control center.

In order to solve this problem, extended wifi is introduced with 802.11ah standard called WiFi HaLow. It works at lower frequency of 900MHz and thus bigger range upto 1km as per your requirement.

LTE Category 0 is another option you should look at as it is now begin adopted in M2M.

https://www.postscapes.com/internet-of-things-protocols/

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If power is a concern, 802.15.4 is designed specifically for low rate, low power communications over these ranges. If you don't want to write your own mesh stack, Zigbee and 6lowpan are available over the 802.15.4 transport.

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I currently use TP-Link. Google for CPE210 from them. It goes 5k+ and it is relatively cheap. Just set it up as a repeater from your current router or you can use it as an AP.

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