We are installing a WLC-4402 with 1252 APs connected; they have been working ok; but we have a problem with a Lenovo x61's wireless laptop card; the signal strength of this client fluctuate (up and down) each few seconds (sometimes it gets disconnected even though it is located very close - 20 feet - to the AP); has anyone experienced the same problem?
Check to see if you have any co-channel interference of some sort. You should see the "signal strength" meter flunctuate here and there. It's the wifi card that is negotiating best signal. If you see the signal drop to like 5.5mbps 2 mbps, usually it is noise around the area.
I checked the client and it seems to be some kind of conflict between the Lenovo's wireless manager sw and the Windows's wireless manager. I just disabled the manager from Lenovo and it resolved the problem..