I have found the answer.
So, You Want to Run at 11n Speeds?
Getting your network operating on 11n is so simple that it's strangely easy to get something wrong along the way. Let's review some important factors that affect 11n throughput to save you from wondering where you went wrong. None will prevent you from passing data, but it pays to take notes and do things right here to make sure you get the most out of your new installation.
Getting Up to Speed
First, 11n presents some new requirements for WLAN configuration. If you don't heed them, the standard requires that your higher rates not be supported. This is most common when upgrading an existing configuration to support 11n rates. In order for your clients to be able to realize 11n rates, necessary WLANs need to be enabled for WMM (either "allowed" or "required," depending on your needs and client support).
Also, 11n requires AES cryptography be performed on all encrypted links. This means that you can get away with an open WLAN, but if you flip on Layer 2 crypto functions, you need to have Wi-Fi Protected Access 2 AES-enabled (with either Pre-Shared Key or back-end authentication, authorization, and accounting) or that WLAN won't work at all for 11n rates. You can go for a mix of crypto types (WPA with Temporal Key Integrity Protocol or AES and WPA2 with TKIP), just as long as you have WPA2 with AES-enabled.
The easiest way to make sure that your clients are connected at these rates (after confirming your WLAN configuration) is to check the client records in the wireless LAN controller GUI. Do this by going to Monitor and then the Clients subheading.
The image below shows how to identify which clients are connected at 11n rates (in this example, the 11n client is using 5 GHz). You can see further details on clients by selecting them individually on the same page.
