A5c with RF Elements Horn

#1

Considering a build as follows:

Two (2) A5c with four (4) RF Elements Carrier Class Horns (30 Degree)

The idea is to have each Access Point with it’s two horns cover two different directions (East and West for the sake of illustration). I am considering this for the redundancy, no two horns facing the same direction will be connected to the same radio.

Dustin mentioned in this video however that not using the same direction for both antennas, you miss out on 3dB that comes with beam forming.
Reference: https://www.youtube.com/watch?v=ruYRdNS81LI @ 00:41

I’m thinking the value added with redundancy is better than 3dB with beam-forming… however I’ve never seen beam-forming in action.

Thoughts?

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#2

Hi @Renaldo,

It depends on how much area you want to cover with only two A5c radios. If you don’t have the density (sub-44 clients per area), then you should be ok to deploy this way.

If you are pointing two horns in the same direction, from two different APs, please make sure you use different freqencies. If you are on the same frequency, you’ll introduce high UL packet error rates for your client radios.

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#3

I am not sure how you would get the benefits of having 2 sectors without them having the same SSID. If that is not a problem for you then I guess that would be fine.

Channel Reuse won’t work for SRS, or really at all, But that isn’t the end of the world.

As far as beam forming, I couldn’t say, I haven’t measured clients that only have 2 really good chains to a sector compared to clients with 4 good chains to a sector. Probably would be a good idea to check though.

3 dB isn’t all that much, but every little bit helps if you are in a noisy area. On the other hand, I have not heard of A5c’s having issues as long as they are well grounded and the like.

We are our own climbing crew so I would try it out and if it isn’t great swap the antennas around.

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#4

Clients will never have 4 upload chains, only two. So you don’t need to have 4 download chains. The 4 download chains are used for beamforming purposes only, so technically you’d still have the same speeds. You would really only be losing out on the +3dB of signal strength.

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#5

My problems is:

  1. Not having a climbing crew on staff
  2. Having to wait days, possibly a week to get someone on location to replace an Access Point.

Sounds like like the redundancy of two radios each with two horns in different directions outweighs the value of beamforming in this instance. The idea is, if one radio goes down, I’m still covering the subscriber area with a the second radio.

@DustinS are you saying this build will only work well with < 44 clients for two horns in one direction?

Another question… sorry to overload the post:
I have typically used Mikrotik APs with the same BSSID on all radios at site then used Access List (MAC Addresses) on the AP to limit which client can connect to a radio; how do you recommend this be done with MImosa? Can I use the same BSSID in the build mentioned above? OR is it best to two BSSIDs?

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#6

I always assume the customer is using SRS mode. If you’re wanting to use Wifi Interop mode, you should be ok with us to 60 clients per AP (depending on what speeds you want to provide).

In my opinion it’s always best to have different SSIDs per AP. If you are using Wifi Interop mode, you can add more than one SSID per AP if needed. If you lose an AP, you can add the additional SSID with the same name as the one that went down and pick up those customers. Maybe something like that will work.

You can do ACLs with Mimosa, but I’ve never actually experimented with it. That might work well for you as well, since you’re already doing that with Mikrotik.

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#7

Mimosa ACL was a nightmare 2 fw versions ago. Don’t know now but if it is even slightly the same, don’t do it… take you days to get it going. (Due the poor and very slow perfoming GUI combined with auto refresh of the page in those days…)

In regard to redundancy; Although I’ve had many issues with my 4 A5’s in the last 3 years I only had to replace one (the first, according Mimosa an almost prototype unit) for hardware failure.
And since in your case your two units would still be getting same power (or did you also make that redundant? And what about the backbone?) their is still probability of network downers.
I wouldn’t go for that last mile in investing in the extra equipment that then probably never is going to be used…

If my AP would go down I also have to arrange my own crane and do it myself (57yr!) that also takes a day (or two) to arrange.
The C5’s are a much more prone to fail device that the A5 (and presumably the A5c’s)
(A failure rate of 3-5% is huge imho!)

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#8

I’ve had a similar experience to Rudy. We went through a few of the early large (18dB) omni’s. Since we went to the 14 dB, there has not been a single glitch with the exception of some firmware issues and DHCP on our Mikrotiks.

As stated, there are so many other places something can go wrong, I’m not sure I would be putting up two AP’s. Having one on the shelf is better than 2 on a tower in my mind. One lightning strike can take it all out and leave you days or more away from new gear.

My 2 cents

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#9

Are DHCP issues resolved with Mikrotik?

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