Wireless USB adapters not roaming in Cisco Wireless Environment

[JR Harper]

I have recently upgraded a hospital wireless network and am running into roaming issues with wireless USB adapters.  I have a Cisco 5508 WLC running 7.4.121.0 code with around 225 Cisco 2602 APs.  Before the environment was running on WiSM2's running 7.0.240.0 and a mix of 1252, 1242, and 1131 APs. The hospital has several carts on wheels with iGel thin clients installed and wireless USB adapters with external antennas. I am 99.9% sure this was an issue before the upgrade but never seen it myself because it wasn't brought to my attention until the upgrade was 99% completed.  In the new upgrade I had the legacy data rates disabled causing smaller cell size than in the old environment with lower data rates enabled just making the cell size larger and more or less hiding the issue that the clients weren't roaming between APs.  I believe clients still got disconnect but it was way less frequent since the cell size was large enough that most of them never traveled outside of the cell it resided in and went unreported because of that.  The wireless adapters they use are Hawking USB 2.4Ghz b/g/n adapters and do have roaming aggressiveness settings in the provided utility.  When clients come to a cell edge, they just drop and rejoin to the closest AP at the time instead of handing off with roaming.  Debugs from the WLC of the client clearly show new association request instead of re-associations.  I initially chalked this up to a client issue with this adapter but have since tried 3 other wireless USB adapters on multiple laptops with all the same result.  I have also tried a wireless adapter specifically for the iGel thin client model in question that is just an expansion module that connection to the thin client with a serial connection but still get the same result.  The thin client recognizes the wireless card as a USB adapter also though.  I have tried updating drivers for the USB adapters but no change.  I have had a few cases open with TAC on the issue and they feel it is a client issue also but I am finding it odd that I am coming up with some many  different clients that all have the same issue but all appear to be USB wireless adapters.   I have been able to duplicate this issue in a lab environment with a vWLC running 7.4.100.0 and 1602 APs.  I have also tested successful roaming in both of these environments with an iPhone 4, Samsung Galaxy 5, Windows 8.1 laptop with intel adapter, Windows 7 laptop with intel adapter, and cisco 7925 wireless phone.  Has anyone had similar issues or know if any kind of resolution?  If this just appears to be a client issue that is somehow just related to USB adapters, does anyone have an suggestions on devices I can use to attach to thin clients on mobile  carts to provide wireless access that roams.  Thanks in advance.

[abwahid]

Hello JR

Check Intra-Controller Roaming on the following link.

http://www.cisco.com/c/en/us/td/docs/wireless/controller/7-0/configuration/guide/c70/c70ccfg.html#pgfId-1098553

[Francesco Pettene]

Hi

legacy data rates disabled ---> smaller cells

Did you perform a survey after moving to 2602 APs? There's a chance

you dont have enough signal or a good SNR for WiFi adapters not to try

roaming away from some cells.

Check the result of TPC, what power are those new APs transmitting at?

You might want to create and RF group to use different TPC thresholds,

in order to balance the smaller cells.

fp