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Every now and then the question arises for me to link two Ethernet segments over some kind of outdoor wireless connection.

It is usually over comparatively short distances (at some places maybe some 20m, but once I needed 200m), within private premises, with direct visibility.

Most of the hardware I have seen, talk about using some form of 802.11 protocol. But I am getting confused, because the answers to a similar question here: Ethernet connection wireless bridge talk about utilizing a standard COTS WIFI bridge/router, which are generally inherently meant to be used for multiple connections to single AP.

What I want, is a direct point to point link from one single device to the other with (1) as little additional overhead as possible, and (2) for it to be as transparent (to the rest of Ethernet) as possible, and (3) with reasonable assurance that this link can be used only by those two endpoints. Essentially a wireless Ethernet wire.

There are devices which seem to do this kind of link, such as, eg, Ubiquiti LiteBeam, but I would like to understand:

(1) are there any reasonable alternatives to 802.11 protocol being used nowadays for such links?

(2) as the 802.11 is "a set of MAC and physical protocols", does it mean that these kinds of direct links can avoid the whole "acting as AP" that COTS WIFI routers do? I don't want a situation where people could theoretically connect to one or both ends of the link with their equipment -- the link is just for the endpoints.

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    What you are alluding to predates Wi-Fi. There have been such things for many years, but each has some problems, e.g. optical (laser) links can be stymied by weather (fog, rain, snow), microwaves are killed by water, either weather or vegetation, or things like lakes. You need to research to find a solution that will work for you.
    – Ron Maupin ♦
    Commented Nov 9, 2020 at 13:29
  • @RonMaupin Thank you. My situation is quite simple in that we are talking about above ground links in urban environment over paved ground, so I only need to worry about weather. Is "microwave bridge"(as suggested in the answer) the commonly used name for such a solution that I would be able to find brands and models for?
    – Gnudiff
    Commented Nov 9, 2020 at 17:30
  • That depends on the country you are in. In the U.S., it will require an FCC license for anything outside the Wi-Fi bands.
    – Ron Maupin ♦
    Commented Nov 9, 2020 at 17:34
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    As Ron alludes in his last comment, the reason so many devices today use 802.11 is to avoid licensing requirements. For a few hundred meters, that would be an insane expense. But otherwise, yes, there are plenty of non-ISM band radio links on the market. (and some non-802.11 ISM devices. I have some that predate 802.11.)
    – Ricky
    Commented Nov 9, 2020 at 22:47

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are there any reasonable alternatives to 802.11 protocol being used nowadays for such links?

Yes. The first that comes to mind is optical bridges (See FSO). They require line of sight, obviously. There are also microwave bridges. Some are license-free, while others require radio licensing, depending on where you are.

... does it mean that these kinds of direct links can avoid the whole "acting as AP" that COTS WIFI routers do?

Yes. When configured as bridges, they do not act like "regular" APs. Also, the use of encryption keeps your communications confidential.

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    Also known as a "point to point link"
    – Criggie
    Commented Nov 9, 2020 at 21:05

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