Weak iphone/android Wifi signal in rooms, APs in hallway

[mo shea]

Hi...

I am struggling with weak signal coverage inside rooms where APs are hung on the outer walls of the rooms i.e. on the hallway, one the sides, not on the cieling. Laptops work fine but mobile devices (iphones, androids, ipads) suffer the most. The hallaway is approximately 30m long, having 4 large rooms, two on either side of the hallway. The walls are made up of cinder blocks with concrete pillars. We have installed 4 2602 APsin the hallway, each with 4 external antennas, in an alternate fashion, i.e. first AP on the left side of the hallway, second on the right, third again on the left, fouth on the right again. The APs are approximately 4m apart.

We are using

WLC 5508 7.4.100.0

Cisco 2602 APs with 4 external antennas

I have read the Cisco document of Best practices for Apple devices and enabled all 'n' data rates. That helped a little bit but I know we can get better coverage. I am suspecting that RRM is reducing the Tx power levels since the APs are all in the line of site.

I have to admit that a precise site survey was not performed but I hope to get some advice on tweaking the Tx levels in my scenario.

I am attaching 2 screen shots of the hallway APs (circled) in b/g/n and a/n showing the Transmit levels. I have tweaked one AP tx level only (circled, changed form 4 to 3 under a/n) but didnt get the time to see the results.

All help is appreciated

[Leo Laohoo]

The walls are made up of cinder blocks with concrete pillars.

Move your APs into the rooms.  Nothing you can do about it.

[Scott Fella]

You tx power is too low. Try to hard set the TX power to 2 in that area. Also if your using external antennas, make sure all the antennas are in a vertical position.

If that doesn't work, then listen to Leo and move the AP's in the room.

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[mo shea]

Thanks for the replies,

Leo,

I have tried to convince our people to place the APs inside, but they rejected this based on health concerns. I tried to dig up something from the internet to alleviate their fears but was not successful. The view of four antennas is what scares them most. Maybe I will remove the antennas and then try to convince them again.

Scott,

You have mentioned to position the external antennas in a vertical fashion. We have 4 per AP. Shall I point all the four in vertical upward direction or the top two upwards and the bottom two downwards? Just to remind you again that our APs are not mounted on the ceiling but on the side walls of the hallway.

I will force the Tx levels to 2 on all the 4 APs and hope interference will not degrade performance further.

Thanks again

[Leo Laohoo]

I have tried to convince our people to place the APs inside, but they rejected this based on health concerns. I tried to dig up something from the internet to alleviate their fears but was not successful. The view of four antennas is what scares them most. Maybe I will remove the antennas and then try to convince them again.

ROFL!  They are concerned about an AP in the room but they are OK with holding a mobile phone close to their head.  Nice.

[mo shea]

Leo Laohoo wrote:
ROFL!  They are concerned about an AP in the room but they are OK with holding a mobile phone close to their head.  Nice.

I know...Once I saw the argument going in an endless direction, I decided to go ahead with the implementation in the Hallways

[Scott Fella · Accepted solution]

Yes.. All 4 antennas should be vertical. The too will be pointing up and the bottom pointing down. You can even set the TX power to 1 if you still don't have coverage with TX power of 2.

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[mo shea]

Great!! I changed the antenna orientation, changed power to 2 on almost all APs except one AP I move it to 1, and the Signal improved greatly. Thanks Scott.

I got some interference according to my scanner and it showed some channels that overlapped, but I think this might be due to the fact that some APs were mounted too close to the ceiling that I couldnt get the top antennas to be 100% vetical.

One last question, setting the power manually does not affect the controllers DCA function, right?

Thanks Again

[Scott Fella · Accepted solution]

Setting the power does affect DCA in the fact that it might change the channels because all your AP's in that area are in the hallways. Now will it actually make a change... Who knows, maybe not. You can always baseline that by capturing the info each day and see if the channel does change.

You only need to hard set the tx power of the four AP's in that area. You should also set the DCA to 24 hours and not leave it at the default. Give that a try as that should help. I usually will set the DCA to 24 hours

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[mo shea]

Thanks for the feedback...

Now we have implemented another 4 APs in a similar hallway but in the ground floor (the first hallaway is in the First Floor, just right above). On my scanner I find that in one room of the first floor there is persistent channel 11 overlap between one Ground Floor AP and a First Floor AP. The signal strength is fine (not as strong as other rooms) and I tested some ipad HD streaming  for 13 minutes and that was fine.

Just wondering what is the best approach to this problem or how to gauge its effect on the clients; whether it requires any attention or whether we can live with it.

Thanks again.

[Scott Fella]

Well you just need to get feedback from the users. You will always have channel overlap so that's not too much of an issue. Just see if they start complaining again. If not, then your issue is solved:)

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