Wireless Access

Hi All,

 

I really need advices for this one, we have installed around 24 APs in huge covered place, the length is around 900 meters and the width is approx. 70 meters, hieght is around 15-20 meters, the problem is  all the walls are made of metal :)))))) 

 

The APs are places in a zigzag mode on the walls, means if na AP is placed on the right hand side wall the 2nd nearest AP is placed around 50 to 70 meters away on the left side wall and so on, half of the AP is actually inside the wall and only the front half is showing outside, we are using AP225, i facing poor performance and i tried reducing the power to the minimum and even i have enabled "Mode Aware Arm" to change the Radios to AM mode is there is interference and i started to see lots of 2.4 radios changing to 2.4, but that causes also poor coverage, i have a doubt that the signals are getting bounced and reflected from the walls so the APs are hearing each other although they are really far away from each other.

 

Any solution or advices for this ?

 

Also client match is not kicking in and not steering the clients to the 5 GHz radios for better bandwidth :'( played with almost every setting and i even disable client match and enabled band steering and set it to force 5 ghz but still my phone was getting connected to the 2.4 radio although i'm in a seperate room which has only 1 AP and closed walls no other APs nearby at all (isolated room) but there is a door that opens to that huge covered hall, i feel like when i open the door the signals are getting bounced inside from the metal walls :smileylol:

 

Running 6.3.1.8, tried 6.3.1.7 and 6.4 same result.

 

HELP :'(

 

Kind Regards,

#AP225

Islam Soliman,

 

You probably need a consultant to look at your design and your building materials.  Your poor performance can be because of

 

- Metal

- Non-802.11 interference

- Poor access point placement

- Improper mounting height

- Broadcast or Multicast traffic

- High RF Utilization

- Poor Network Design

 

There is almost no way that we can determine what is wrong with your plan by guessing on this forum.  Your deployment is complicated enough that someone needs to take a look at what you are trying to do and work with you to achieve your goal.  Client Match and Mode Aware ARM and any knob that is in the Aruba controller cannot overcome a poor network design; it can only improve a good one.

 

Hi Colin,

 

Thanks for the quick reply, i didn't design this one :D i'm trying to make it work, i'm trying everything from software and config prespective since we cannot touch the APs nor change the places or the design unfortunetly, APs are mounted 7 meters height, no other Wifi nearby at all so might be non wifi interference for sure if this is the reason, mmmmm but what confuses me is that even in another room with no other things and AP is actually placed on the floor for testing still i'm not getting consistant results, APs it not mounted nor there is any other wifi device in the room, new site only the TV and lights nothing else no other lectronic devices nearby  and i'm setting like 5 to 10 meters away from the AP.

Islam Soliman,

 

You need a spectrum analyzer or turn one of the APs into a full spectrum monitor to see what is going on.  There may be interference that you cannot see.

 

You should leave the software on all of the defaults, so that you are not influencing anything.

Done that and found only wifi interference... am a beginner when it comes to reading the spectrum output but 90% sure the interference is wifi only which again supports my theory regarding the signal bouncing and reflecting from the walls and causing issues...

You need to look at the dashboard to see utilization, etc. to determine that. Metal by itself does not cause degradation, especially if the access point is not touching it and if it is not between the access point and the client.

yeah I know metal does not degrade the signal it reflects it as far as I know, the APs are mounted inside the metal wall half inside and half..
my theory is the signal from the APs bouncing everywhere.... the site is like a huge metal cage so inside it the signal keeps bouncing and I'm seeing APs more than 100 to 150 meters a way with very gd strength although I have set the max power to 12 and min to 6...

How high are the access points mounted and In what direction are they pointing. In open space it is very possible to see RF at that distance.

they are around 7 meters high facing the other wall... I have switched some APs to AM mode for now, I'm seeing -60 from APs configured with 12 dbm power placed more than 100 meters away :D ... will try to get AirMagnet spectrum and scan the whole place.

2nd thing is the client match is not steering the 5 Ghz clients to Radio 1... even disabled client match and configured band steering to "forced" mode still not steering and most of the time I connect to 2.4 ... finally I have reduced the 2.4 power dramatically so that the client doesn't have any choice but to connect to 5 Ghz radio...

At those distances it is possible that the 5ghz is not strong enough to steer clients.

At that height the AP 225 should be pointing down.

the 5 Ghz test was with an AP in a seperate room placed on the floor 3 meters far away from me :)

thanks for the info about placing the AP, we cannot placed it like this the AP shouldn't be out of the wall, we should have asked them to place it a little lower then... I think they are placed 5 meters from the ground, we are restricted to those places only by the customer unfortunately.


Thanks a lot Colin for the help and the useful info much appreciated (Y).

You should avoid situations where metal is between your clients and your AP.  In that situation, the signal strength could be high, but the frames would be corrupted.  This would make your throughput plunge.

 

You should first try to see what your performance is when you are in the same room as the access point, and start from there.

 Hi,

 

You should recommend customer to make sure that the access point and clients have a good line of sight to avoid many frames corruption as Colin said and also AP-225 have 6 Integrated downtilt OMNI directional antennas which mean that the RF propagation will be probably propagate if you use celling mount the access point must be horizontal and parallel to the celling, now you said you have a huge multipath environment so my recommendation that you use your power with the lowest match to the client power and also with a 7 meter with clean line of sight you may have a 15 meter to 20 meter diameter and also make sure to disable low rates to optimize your network as you know wireless is a half-duplex technology each user send and the other wait so imagine having 1 MB and 2 MB rates working you will find that the specified channel utilized and gives you a very bad throughput and to avoid that Disable 1,2,5.5 Mb and also make sure that the RF from each access point overlapped well to roam between users and always know your client devices well so in some cases you will need to enable some protocols and in another cases you need to disable it so you should look from the both sides to get the best solution in hand.

 

 

Hi Colin,

I understand the problem you are facing. Living in a metal building comes with difficulties too. But I guess the problem of wifi interference can be solved. I live in metal buildings colorado and had to face the same problem when installing wifi in my apartment. I called up my design engineer to look into the matters. There can be various things causing interference - metal, poor ap positions etc. Do yor have your ceiling of metal too? My ceiling wasn't completely a metal one so the consultant asked me to place my AP's near my ceiling and not near the metal walls for improved signal reception. Also he adjusted the way the AP's were mounted. The angle stuff and all.