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MVP
Posts: 765
Registered: ‎03-25-2009

AP124 mesh 3x3 and some antenna stuff

I need to provide wireless coverage in a building that has no wired connections and is some 50m from the main building with wired connections.

So I was thinking to use a set of AP120 +AP124 and AP-ANT17 to bridge (mesh) the gap to the building on 5GHz band and then provide coverage into the remote building with the 2.4GHz band and another antenna.

So far so good. But can anyone tell me how I'm supposed to hook all this up antenna-wise? Is it at all possible to provide 300Mbps to those clients?
Is it even useful to use the AP120 at the main building? I'm guessing I won't be able to do 3x3 anyway if i need to do the uplink and client access with just 1 AP124 right?

And how exactly does 3 antennas work for a dual radio (AP124) with 3 transmit and receive streams? Do both radio's use the same 3 antenna's at the same time?
Koen (ACMX #351 | ACDX #547 | ACCP)

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Occasional Contributor II
Posts: 44
Registered: ‎04-02-2007

Re: AP124 mesh 3x3 and some antenna stuff

Firstly - AP-12x's don't do 3x3 MIMO. They do 2x2 with diversity. Which gets you a bit rate of 300Mbps in HT mode with 40MHz channels and SGI. The third antenna just beefs up the signal quality.

There's no good answer with the hardware you're proposing. The best way I can think of, and no guarantee this will work, it very well may not - you could possibly use a single antenna on the 5GHz backhaul radio, with 40MHz channels enabled, and dual antennas on the 2.4GHz radio, with 20MHz channels and 2x2 MIMO. That'd give you a bit rate of 150Mbps (1SS, 40MHz channel, SGI) on the backhaul and a bit rate of 144Mbps (2SS, 20MHz channel, SGI) on the client radio.

The problem is that for 2x2 MIMO on 2.4GHz, you need the "client" antenna connected to 2.4GHz Chain 0 and 1 - the top-left and top-right connector, respectively. Chain 0 on 5GHz is the top-right connector, with Chain 1 on bottom-left. Since the top-right is connected to your 2.4GHz antenna, you'd have to connect the 5GHz antenna to Chain 1 on the 5 GHz radio, and I don't know if that would work by itself. Maybe an Aruba person can chime in here.

If the above is technically impossible, you could do the same, but without the 2x2 MIMO on the 2.4GHz side. Giving you a client bit rate of 72Mbps tops (1SS, 20MHz channel, SGI). Not an excellent use of the hardware, considering the cost.

Instead, you may want to consider a low-cost point-to-point link (I don't think Aruba makes any point-to-point gear any more, check out the Ubiquiti Nanobridge M), and just hang an Aruba AP off of the other end. We've done this before and it's worked great.

HTH,

Adam

Radio Chain info obtained here: http://airheads.arubanetworks.com/vBulletin/showthread.php?t=1820
Guru Elite
Posts: 20,993
Registered: ‎03-29-2007

Re: AP124 mesh 3x3 and some antenna stuff

The AP12X DO 3x3 mimo. Please see the datasheet here: http://www.arubanetworks.com/product/aruba-ap-120-ap-121-access-points/ The post you are referring to was asking if someone could use two antennas instead of three, which is a non-standard deployment. The poster in the other airheads article was talking about streams available when only using two antennas.

As was mentioned, it is difficult to provide backhaul as well as client access using external mimo antennas, because the antenna patterns are similar on both bands, which means if you are pointing the antennas at another location for backhaul at a location 50m away on 5ghz, you are most certainly pointing the 2.4ghz coverage at that access point 50m away, instead of at your clients at that building.

The best way to accomplish this is to ensure that you have a 802.3at or POE+ capable power source powering your AP120 access point on the far end. You can configure the second ethernet port on that AP120 to backhaul wired traffic to your controller, as well as put a separate access point on a switch on that ethernet port to provide client coverage for that building. The 802.3at or POE+ is required to power up that second ethernet port, btw..


Colin Joseph
Aruba Customer Engineering

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MVP
Posts: 765
Registered: ‎03-25-2009

Re: AP124 mesh 3x3 and some antenna stuff



As was mentioned, it is difficult to provide backhaul as well as client access using external mimo antennas, because the antenna patterns are similar on both bands, which means if you are pointing the antennas at another location for backhaul at a location 50m away on 5ghz, you are most certainly pointing the 2.4ghz coverage at that access point 50m away, instead of at your clients at that building.

The best way to accomplish this is to ensure that you have a 802.3at or POE+ capable power source powering your AP120 access point on the far end. You can configure the second Ethernet port on that AP120 to backhaul wired traffic to your controller, as well as put a separate access point on a switch on that ethernet port to provide client coverage for that building. The 802.3at or POE+ is required to power up that second Ethernet port, btw..




I was thinking about using a AP120 (only 1 radio) on the main building so no 2.4Ghz would reach any antenna and then the AP124 at the 'remote' building to provide 2.4GHz inside the building and 5GHz for the uplink.
Guess this theory is invalid as I can't 'split' the 2.4Ghz from the backhaul at the remote building since they use the same antenna's for both bands, right?

I was thinking I might be able to pull it off with just 2 AP's and save some money in the process but if that isn't at all possible we'll probably go for the cheaper solution
AP92 with ANT-2x2-D607 to AP92 also with ANT-2x2-D607 configured as mesh portal and point and then a AP105 connected on it's second ethernet port.
I'll power the remote AP92 with a poweradapter and connect its ethernet port to an AP105 powered by a POE power inserter so I don't need to provide an additional switch.

Looking at the antenna patterns, there appears to be a pretty hefty downwards angle on the ANT-2x2-D607. At a mere ~50m I should be able to safely ignore this and just mount them flat on the wall facing each other right?
Koen (ACMX #351 | ACDX #547 | ACCP)

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-- Problem Solved? Click "Accept as Solution" in a post.
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