Wireless signals fluctaute across network

We have a wifi network spread across two buildings. We're using the Cisco Aironet series APs all powered via POE. What i'm noticing is that the signal is fluctuating from 4 bars, down to 1 bar randomly and maybe even 0 and drops the connection. I can't seem to find any reason as the PCs aren't on the move and are in a docking station. There isn't anything that stands out that would cause any interference (Phones, metal cabinets). Any idea's on where to start? This is affecting mulitple users and applications.
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Fred MarshallPrincipalCommented:
The first thing that comes to mind is that some users are in marginal locations.
"Marginal" could include locations where there are reflective paths that vary - like a metal-clad door that is sometimes open, sometimes closed or equipped with a on a door-closer ... even if both the access point and the computer in question are on the same side of the door.  The door could be a big reflector.

The next thing that comes to mind is "which channel are you using" and has there been any channel survey to determine if there are interfering WiFi signals .. much less any interfering other device types such as you mentioned.  You didn't mention wireless mice and keyboards.

Closely related is "automatic channel selection".  Some units (you didn't say which AP model(s) you are using exactly) have this feature to try to find a quiet channel.  I've seen situations where this makes it worse rather than better and you get the sort of behavior you're seeing.

The applications don't have much to do with signal strength or dropouts unless you are including the wireless interfacing software.  Most laptops have two and sometimes 3 such app's to choose from.  You may find that one works better than another.  Examples:
- the interface manufacturer's sofware.
- Microsoft Windows software
- Dell software

I've had bad luck with the Dell software and found it a bit difficult to learn how to get rid of it.

You didn't mention the type of antenna on the laptops.  That can make quite a difference.  

WohlsenITAuthor Commented:
I attached a file of what my wifi looks like on my laptop. Most of the laptops are equiped with factor Wifi (IBM T series). The model of the APs are AIR-LAP1042M-A-K9. Less than 6 months old. We have a pretty open layout with things that shouldn't cause this type of problem. For instance, the AP is about 4 feet above my head as we speak and it's still occuring.
Fred MarshallPrincipalCommented:
I think maybe you meant.... AIR-LAP1142N -A-K9???

In truth, I have little experience with MIMO technology.  In fact, over the years I've had my doubts because it relies on muliple transmission paths (read as "bounce paths").  In reality there is going to be "one best path" and other paths are unlikely to be nearly as good.  That's an opinion based on years of experience in communication propagation.  So, I can't prove it really.

I would do this:  

Put in some plain old wireless G router set up as an access point and see how it behaves...  4 feet away!! My goodness!!
You might have to consider

Power Injector
The power injector AIR-PWRINJ4= can be used to power
both Cisco Aironet 1250 Series and Cisco Aironet 1140
Series Access Points. This power injector contains an
integrated power supply that converts 100 to 240 volts
AC into 56 volts DC and then injects this power onto the
Category 5 Ethernet cable to power the access point
(Figure 1). This deployment option is ideal for customers
who are interested in getting the full benefits of 802.11n
with the dual-radio 1250 Series but do not have an
enhanced PoE switch. A power injector extends the
distance that an access point can be deployed away
from a power strip.

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