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millenium7
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60ghz products, some clarification?

Fri Feb 14, 2020 5:16 am

Ok so we've had a bunch of 60ghz dishes deployed in the field for a while now and they seem to 'just work' which contradicts the information i'm reading on the wiki and is also vastly different to other 60ghz products on the market. I want to get some clarification on how they actually work, and to best use them in the real world

What do I mean by 'just work'? Well supposedly they have a 1 degree beam width, yet this is completely not at all our experience. I can literally point the dish 45 degrees off to the side and still pass >1gb/s on a 300M link. There seems to be almost no point in even trying to align them, because as long as they are pointing even roughly in the same direction they link up and often work at 1.7-2.3gbit/s of throughput. So why even bother aligning them? And why does MikroTik say its only a 1 degree beam when it clearly isn't
We also use Siklu 60ghz and they are extremely fine and will drop the link entirely if its more than about 2 degrees off center. Totally different to the MikroTiks
Honestly we don't bother to align them beyond "that looks roughly correct" because of this, easiest dishes ever to install because of this. But surely i'm missing something here?

So can someone explain how that works? And why should we bother to try and align them better?
Also the lights, when it's blinking <- does that mean the radio should be moved a bit further left? Or does it mean its too far left and it should be moved right? We don't use them because it seems impossible to have none of them flashing, and as above they often do 2.3gbit/s even when very poorly aimed

The next is we have some of them upgraded to licence level 4 and use them as multipoint. But the only information we get on the AP with other clients is 'Signal' and 'MCS'
What does 'signal' mean? since it goes from 0-100. How exactly is that number determined and should it be possible to get 100? As even when we try and align them correctly we still very rarely see 100. RSSI would be more useful but its not shown for each client, only on the main 'wlan60-1' interface and I don't know which client that refers to, so its useless to me

The last is in relation to rainfade. We have some links that are only 200m yet they drop out for a second or 2 in moderate to rain. I don't believe they should at that distance, our Siklu's don't. Maybe its related to the alignment above? But we also use them in point-to-multipoint mode so we can't align the AP to every client, we could however align each client perfectly to the AP, but we won't bother if its not going to help
 
wpeople
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Re: 60ghz products, some clarification?

Wed Feb 19, 2020 1:59 pm

Mikrotik (and Ubiquiti) uses a low cost wi-gig chip for wireless transmission with beamforming antenna matrix.
If you check the wireless wire kit, it has 6x6=36 antenna elements in the array, while wap60-180 AP has triple antenna elements integrated to cover 3x60=180degress. (in fact 3x32=96 elements)

Those antenna elements are NOT working all the time, like the traditional antennas.
If you have a point to point link, both radios checking from 1 to 36 antenna elements, where is the best signal, and will use only that.
So if the whole beamwidth for the device is 60deg horizontal and vertical - than each segment covers only 10degree part.
That is the same for LHG60 device, where we have same beamforming antenna in the focus of the dish.
As easy as aim to have a working signal - as difficult to have the BEST signal in the center element.

I would NOT compare this to Siklu device - that is totally a different animal.
 
millenium7
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Re: 60ghz products, some clarification?

Thu Feb 20, 2020 1:21 am

Interesting, the multi element array explains why you can just point it practically anywhere and it works
So why is it the center is stronger? Why does it matter if its using any other element in the array? And if MikroTik's beam width of 1 degree still holds any validity then that would mean that 6x6 is not even remotely close enough to cover what it actually does which is closer to about 90 degrees left/right. It's still very misleading and confusing

Personally I prefer the MikroTik over the Siklu, it's much, much faster, a hell of a lot cheaper and far more forgiving and simpler for installation
 
r00t
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Re: 60ghz products, some clarification?

Thu Feb 20, 2020 3:18 pm

This is so called "phased array" antenna. Where multiple elements signal phase is adjusted so antenna can be electronically tilted and signal directed into different ways. Number of elements affects the beam width and overall gain, but it can't be directly mapped to a beam width (ie. 6 elements x 1deg = nonsense).
Because antenna is still on a flat PCB material, it's efficiency falls as it's electronically tilted to the sides. Optimal point is always directly in the front where antenna is pointed, so that's why it's still good to do some precise pointing and aligning, especially if you want best SNR to deal with bad weather conditions and for longer links.
But for shorter hops, this design makes it easy to do links with only roughly pointing antennas at each other, that's why wireless wire is just consumer product anybody can setup. Or you can have multiple clients at a different directions in P2MP scenario, where antenna is electronically pointed at each client for best signal (however note that this pointing takes some airtime).

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