Redeploy Wireless APs

Unanswered Question
Oct 16th, 2007

My building is about 70 years old and made of block and concrete. Like a hospital or a school.

We have two hallways that run parrallel and are about 100 feet long, and are about 40 ft apart with a corridor that connects them to for basically an H. Under once section of the "H" there is a basement level.

I have 4 Cisco Aironet 1100s and 6 Cisco Aironet 1200s.

I am looking to spread them out evenly down each hallway to provide good coverage for each office.

What I am wondering is:

1. Is that overkill?

2. What channels should each go on?

3. What power level should they be set to?

4. How far apart should they be?

My attachment is my proposed locations for these APs.

Thank you for any input

I have this problem too.
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Overall Rating: 4.3 (4 ratings)
ericgarnel Wed, 10/17/2007 - 05:14

Why not just do a survey with the APs if you already have them?

You will want to avoid placing APs with the same channels adjacent to each other

1,6,11 hall1


11,1,6 hall2

As far as power levels go, I have seen surveys in which the power was maxed out at the start, then reduced as needed and also where the power was set really low, then bumped up where needed

It is hard to say what exactly you will need as far as power & placement. Are you using both B & G? all rates,etc...

rob.huffman Wed, 10/17/2007 - 05:21

Hi Ken,

These type of questions are very hard to answer without doing the requisite site survey :) I do like the fact that you have staggered these but this may be overkill. I might start without the AP's @ C7 and A7 (wire the drops anyways) and also fire this up initially without the AP's @ C3 and A3.

The non-overlapping b/g channels are 1,6 and 11 so try to stagger these as well.

Hope this helps, a good site survey would really clear this up.


EDIT: Eric, you are too fast for this one fingured typist (thats using the term typist very loosely :)

wirlessmd Wed, 10/17/2007 - 05:59

Thank you both for your input. I do have a survey that was done with Ekahau. Which I will upload. I really don't know how to Interpret the findings, other than to look at the colors and combine that with my knowledge of where signal strength is poor.

We have B/G and have limited data rates to help boost performance and roaming. Mostly we have eliminated B in areas that don't have wireless printers (they have jetdirect cards that are b)

dennischolmes Wed, 10/17/2007 - 12:10

If these are autonomous as I believe they are, it appears you only need one additional AP in the center of A5. Of course you would have to reassign channels so as to avoid cochannel interference but it should, and I stress should, work. The only way to know for sure is to site survey with the new design. Did you ever consider a WLC and converting these APs to LWAPP?

Scott Fella Wed, 10/17/2007 - 13:17

The site survey is hard to read, since it doesn't show what color is what. What was the requirements of the survey that was done. Was there a minimum of a certain dBm?

wirlessmd Wed, 10/17/2007 - 13:52

Did you ever consider a WLC and converting these APs to LWAPP?

-I dont know what WLC and LWAPP are. I will do some research.

I have contracted with someone to come out and pull cables for 4 in each hallway, but will only use three as per the recommendations. The upside is I will have the option to add 1 more at my option.

My trouble is mainly with the concrete/cinderblock walls. The rooms that get the best coverage are the ones that currently have an AP right outside their doors.

Thanks again for the input. I am very new to wireless deployment.

dennischolmes Wed, 10/17/2007 - 14:12

Imagine if you will, a world where Access Points configure themselves for power, channel assignment, and load balancing. Then they tell you when you have coverage holes and intruders trying to break into your system. Then imagine being able to shut those intruders down, locate them, and if necessary have the forensic evidence required to prosecute. A world where Voice over IP for wireless works flawlessly and your latency based applications never fail. You my friend, have entered the LWAPP zone. LWAPP, the lightweight access point protocol, allows you to set a controller (WLC) that dictates exactly how each AP will work and then you don't have to mess with such trivial things as channel and power assignments. It keeps an eye out for wireless intrusions. In short, it's a wireless engineer in a box and all this can be yours if the price is right.

wirlessmd Wed, 10/17/2007 - 17:28

That is quite funny. I keep my desktop support guy in a box, so I guess it is not a stretch to stuff a wireless engineer in one too ;)

Alas the quite bit of research I have done shows me that my 1100s and 1200s can infact enter this fantastic zone.

Ebay here I come :) Any recommendations on a model? (I have approximately 30 APs in various buildings all connected to a fiber backbone)

dennischolmes Wed, 10/17/2007 - 18:52

I would suggest a WLC4402-50. It supports 50 APs and gives you the growth you will need if you add more APs. You will also need a gig port for the sfp slot. It can be either copper or fiber. Lastly, download the autonomous to lwapp conversion tool and guide under the download pages for you models of APs. This will allow you to update the 1100 and 1200 series APs to lwapp.

rob.huffman Thu, 10/18/2007 - 05:06

Hey Dennis,

Loved the " Wireless Engineer in a Box" reference :) as well as many helpful ideas here. 5 points for your good work!

Take care,



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