Wireless Access

Now lets say I have disable the low data rates for 2.4 GHZ (1,2,5.5 Mb) to get the best for airtime and I create a bandwidth contract fron specific vlan to be 1 Mbs now what will happen actully?

Wifi negotiated rates are not directly  related to throughput (bandwidth contracts).

ok great ,now lets say that I disabled the low data rates thats affect the signal level to  be reduced ?

Devices negotiate rates based on signal quality and signal strength.  If a device cannot send a frame through successfully at 54 X number of times, it will de-rate and try at 48, etc.

What exactly are you trying to do?

I'm not familiar with bandwidth contracts on VLANs - my options only show 'per role,' 'per user,' and 'per AP group.'

We have a guest role that limits bandwidth to 384 kbps up and down, on a per user basis. 

We typically see speed test results of 0.66 Mbps down and 0.70 Mbps up, so not exactly sure how the bandwidth contract actually works.

Bandwidth contracts on VLANs only control the rate of multicast traffic on those vlans.  http://www.arubanetworks.com/techdocs/ArubaOS_63_Web_Help/Web_Help_Index.htm#ArubaFrameStyles/1CommandList/interface_vlan_.htm

Bandwidth contracts on roles limits the rate of upstream or downstream traffic on those roles.  http://www.arubanetworks.com/techdocs/ArubaOS_63_Web_Help/Web_Help_Index.htm#ArubaFrameStyles/Firewall_Roles/User_Roles.htm