I do RF Surveys for the Oil Industry and have a facility that is very dense. To cover the required areas, it will call for 5 APs. Do to the locations, design and surroundings, there is no getting around the outcome. Cisco advises to use Channels 1, 6 and 11. This leaves me with 2 APs left to set up. Is there any problem in using any of the other channels in this overlapping scenerio.
I have used all eleven channels in setting up networks and have used several 3 APs overlapping setups without a problem.
I have the ability to use all types of antennas and NEMA enclosures.
Has anyone done any testing or real life setup using more than 3 APs in a overlapping scenerio?
What was the solution?
Thank you for the help.
How are all the access points laid out? Are all five overlapping? What kind of coverage do you require and can they be done in a more sectorized manner using antennas focused in a certain area as opposed to omnis?
You are not limited to channels 1, 6, and 11. You just have to watch for adjacent-channel interference if you use the ones in between.
You can also use multiple APs to load-balance within the same area.
The best way to describe the layout is, ONE in the North, South, West, East and one in the middle of those. As you move from the North AP clockwise, it touches the East AP and so on. These four do not touch in the middle, this is due to the refinery lay out. The one in the middle overlapps all of the other 4 APs.
I will be out at the refinery taking more readings with lower dBi antenna.
Have you ever used a block (metal etc.) to keep the signal from getting out of an area. I do this often but this scenario is a little different due to the items that need to be covered. If you have, what calculations do you use to configure the size of the block?
With the layout you described, you can still only use channels 1, 6, and 11 to get the job done. For example, configure the middle bridge as channel 1. Since all other bridges overlap this bridge, don't use channel one on these. Instead, use channel 6 for the bridges located in the North, and the one in the South. Then use channel 11 for the bridge in the East and the one in the West.
Since the coverage areas do not overlap for North, South, East and West, you will not be overlapping these channels.
If everything does overlap, let me know and we can go over other scenarios and how to make everything work.
I use WildPackets Airopeak for this type of close survey. Setup the AP's as described in the previous then us Airopeak to sniff the channels. By walking around and capturing with a 1,6&11 channel scan you can tell how strong the signal is and what AP's your capturing from. I then draw a diagram showing those results and start to tweak the power on the radios to limit the overlap.
Hope that helps.
If you need Wildpackets info, let me know.
one thing you ought to consider is using cisco's power output power option to decrease the size of your cells so that there is not overlap in the cells...but rather they just barely touch each other. this will also allow you some added flexibility.
The channel layout suggested above by Tony is the best option (and what I was going to suggest).
Rather than the AP cells (coverage areas) touching, they should overlap slightly (maybe 10%). This will help with roaming & provide better coverage in the 'edge' areas.
i agree! I did 35+ AP352s covering 2 attached buildings w/ 5floors and one basements. Did overlapping configuration but, NO two alike channels touches (horizontally and vertically). Gives the hospital roaming capability for there mobile medical application.
I recently had to place five APs on the same floor of a building (with four on the floor above and three on the floor below) because of the customer's subnetting requirements.
I placed those that were furthest apart on the same channels, used antennas with an appropriate coverage area (Cushcraft SQ2403PG), then ran the Carrier Test to make sure that the interference wasn't strong enough to cause problems - all this in about 7500 square feet.
I also used a corner reflector (Mobile Mark) on another floor to cover two 220 foot hallways at right angles. In a square building they can be very useful.