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tombrdfrd66
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Dual Chain

Fri Oct 24, 2014 6:20 am

Beginner Basics? OK, could someone explain what 'dual chaining' is, why you'd do it and how it's implemented on RouterOS and something like the QRT5.

Thx.
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lambert
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Re: Dual Chain

Fri Oct 24, 2014 6:33 am

 
tombrdfrd66
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Re: Dual Chain

Sat Oct 25, 2014 3:37 am

Thanks Lambert, but this is a beginner basics board. Your response is the kin to pointing me at a manual of advanced brain surgery because I complained of a headache.

Do I take it from what I've read that:

1. Dual chain means the same as MIMO?
2. MIMO involves two antennas at each end of the link?
3. The Mikrotik QRT5 has two antennas built in and can do MIMO even though it looks like one antenna?
4. To use MIMO you need two free at-least 20MHz spectrum bands? If so, how much separation is required?
5. Do these two 'antenna's-in-one' use the same polarity or is one vertical and the other horizontal?
6. Has Mikrotik published anywhere an explanation as to how RouterOS is actually configured to utilise MIMO? (Or as is so often the case does Mikrotik work on the assumption that the users of its products imbibed this information with their mother's milk?)

Thx anyone.
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mrphreak
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Re: Dual Chain

Sat Oct 25, 2014 4:18 am

1. Yes
2. MIMO is just what it says, Multiple In Multiple Out and isn't restricted to just two antennas at each end, 3x3 and higher are becoming more common although more for AP's than PtP or PtMP links
3. Yes, there are two antennas in the single housing, one horizontal, one vertical
4. Depends how you've set it up and what you're trying to do, but to get higher bandwidths you need to use wider channels
5. Generally they're horizontal/vertical setups
6. Not sure what you're after here, if you're just after how to set it up?? Or a more indepth look at the RF theory behind it
 
lambert
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Re: Dual Chain

Sat Oct 25, 2014 5:06 am

4. there is one channel for both polarities.

We can answer specific questions such as these. We usually don't have time to write a curriculum of study to take someone from zero to knowledgeable practitioner. Search engines, with the right query terms, are more time effective.

I apologize if that seems too brusque.
 
tombrdfrd66
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Re: Dual Chain

Sun Oct 26, 2014 12:40 am

4. there is one channel for both polarities.

We can answer specific questions such as these. We usually don't have time to write a curriculum of study to take someone from zero to knowledgeable practitioner. Search engines, with the right query terms, are more time effective.

I apologize if that seems too brusque.
Thx guys.

Lambert, your suggested search brought up a million ads for MIMO antennas and a Wikipedia article on the subject which required a degree in advanced physics to understand it. If we struggling consumers can't get at least a primer on the subject from the suppliers, who else is going to do it?

I had to learn the basics of wifi in order to set up a small, non-profit, system to bring internet to a small and very remote community it was hopeless unprofitable for any commercial operation to consider. That was in 2006 when the current RouterOS was 2.9.27. Since then the technology has advanced by leaps and bounds, and while the big commercial operations might be able to afford to send their techs to training courses we small guys haven't a hope of keeping up. Hence we come to fora with titles like "beginner basics" for help.

The alternative is for wireless internet to be taken out of the reach of 'unprofitable' areas - and potentially whole parts of the world - because it just becomes too esoteric for the commons.

So, if I buy a couple of QRT5s in order to upgrade our backhaul, am I going to be able to work out how to configure them IN ROUTEROS to work optimally on the basis of information freely available, or would I just be wasting the community's money because it can't afford to send me to a MUM somewhere for the information?
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mrphreak
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Re: Dual Chain

Sun Oct 26, 2014 1:36 am

Assuming the QRT5s are similarly spec'd (Antenna gain, TX Power etc) to your current back haul then there's no reason you couldn't.
 
lambert
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Re: Dual Chain

Mon Oct 27, 2014 5:08 pm

You are overthinking it. As an appliance operator, you get to check the bullet points.

Side A has two chains? Check

Side B has two chains? Check

Side A has X dBi of antenna gain? Check

Side B has X dBi of antenna gain? Check

(where X is equal or greater than what you already have installed.)

Install it.

If you figured it out in 2006, you can handle it today. The hardware has gotten faster. The software has gotten easier. If you have problems during installation, ask us about those questions then.

I am not your vendor. If you call the place from which you are going to buy your hardware, they may take the time to give you a primer. I, like most people on this forum, am just a busy volunteer.

All searches come up with a billion advertisements. You can modify the search to focus in on the level of information you desire, once you know the key term. In this case, "mimo".

In honor of the book series:

https://duckduckgo.com/?q=mimo+for+dummies

A potentially less insulting way to say what the book series means:

https://duckduckgo.com/?q=mimo+for+beginners
 
lambert
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Re: Dual Chain

Mon Oct 27, 2014 5:15 pm

Just to be sure we've answered your first questions without requiring any physics. (You had three questions):

Dual chains means faster wireless throughput.

Second question:

In RouterOS, there are two checkboxes under the wireless interface configuration to enable or disable each chain.

Third question:

The QRT has two chains so you can use the checkboxes in RouterOS to enable or disable them.
 
tombrdfrd66
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Re: Dual Chain

Thu Oct 30, 2014 11:26 am

OK. Thanks.

I've spent a chunk of the community's cash on some QRTs which should arrive tomorrow. Hopefully I'll be able to get them to work.

So does the system itself work out which chain is MIMing and which is MOMing?
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CyberTod
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Re: Dual Chain

Thu Oct 30, 2014 12:04 pm

Just install them rotated the same way and don't worry about the chains.
After that try to configure them. Come here with specific questions and I think someone will help.
 
tombrdfrd66
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Re: Dual Chain

Sun Nov 09, 2014 4:07 am

OK. Specific question/s:

For a while we're going to have a QRT at one end of the link and the old 'single-chain' wireless and (vertical polarity) antenna at the other end. Do we need to turn one chain off on the QRT or will having the 'other', ie horizontal, chain on still add some dB to the signal? If we have to turn one off is there any way of knowing which chain on the QRT is horizontal or is it a case of experimenting to find out which give the strongest signal?
The more I know, the more I know I don't know.
 
mrphreak
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Re: Dual Chain

Sun Nov 09, 2014 5:10 am

No, leave both chains running.

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