Hi. I noticed this problem with my WLC running 4.1.185.0 and 1242AG AP's. I have the SSID on both the BG and the A radio. With my Dell D820 (same 1490 card) I noticed that my 802.11A clients hung around at a blazing fast 6 MBPS. To counteract the problem I tried a driver update, but that didn't work. I'm using the A17 drivers from Dell. BG works flawlessly. The A radio works, but I noticed that sometimes the client loses a packet or two at 6 MBPS. To get around the problem I disabled all rates below 18 MBPS (set to mandatory) and then had the rest of the rates set to supported. This is merely a workaround since I see the card pegged at 18 MBPS. Interesting enough though I don't get the occasional packet loss with the higher data rate. Very odd indeed. I also noticed that the dell utility reports noise levels for A which are simply just wrong. I confirmed with my Airmagnet laptop. It detected a very minimal amount of noise in some areas on A, but not on the channels that I was using. I'm thinking this is related to Dell doing a crappy 802.11A driver. I guess the real way to confirm if it is indeed related to the driver would be to get for example a Dlink or a Linksys 802.11A AP and see how the card works on A with another AP. If the card pegs at 6 MBPS we'll have a good indication of whether the problem is with Dell or with Cisco. I'm leaning towards Dell though since my CB21AG cards love the A radio...

Thanks for your response.

I am runnig controller 5.1.151.0. I think the issues is with some of the DELL drivers not allowing the 802.11a cards to tune the upper channels of the A spectrum. The card is spec'd to be able to use channels 36, 40, 44, 48, 52, 56, 60, 64, 149, 153, 157, 161. I set up an AP and incremented the channel and watched for the client to associate. The lower 2 digit channels were fine. The 3 digit channels would not work so since our wireless is designed with all of these channels these clients were basically sitting in dead spots and reaching to another AP and since that AP was a bit out of reach the client would range down in speed to 6 MBPS.

I found this in driver version 4.100.15.5. I then loaded version 4.170.77.3 and this cured the problem.

On a side note when checking this with the old driver the card was able to talk to the AP on some of the Mid range channels of A (136,100 etc). This was also cleared up with the new driver. I am checking with the group that manages the PC images to see if they loaded the right country driver. My laptop runs a much older version of the driver and works fine. The Cisco card does outperform any of the Dell cards I have seen.

I have been working with Dell on this. They sent me a replacement Intel card and the problem goes away. It has to be a problem with the hardware I am thinking. They changed their tone when I mentioned that the SSID's that are problems are 802.11a only. They may be willing to change out all the 1490's with the Intel card but I have over 1000 PC's that have this card. Not an easy task. They are still checking on the fix but I am not hopeful.