I found the answer here:
http://forums-archive.ruckuswireless.com/forums/8/topics/1278
NPS does not return AD group memberships back to the ZoneDirector without setting a vendor-specific attribute on NPS. A role has to be configured for each group on the ZoneDirector and a network policy has to be configured for each group on NPS.
This seems rather redundant as I've already got authorization and vlan assignment happening on NPS, why would the ZoneDirector also require a role to authorize access to the specified WLAN? Oh well at least it works now.
In the scenario you describe, you should definitely be looking at multiple access points, preferrably dual band APs.
While coverage may be sufficient, coverage alone is no longer the primary consideration when deploying a wirelss network. Client capacity, channel utilization, signal quality, and reliability are much more important and multiple access points will help with all of these.
By using 3 (or more) APs on multiple channels (1, 6, and 11), you will in effect triple the amount of airtime (bandwidth) available on your wireless network.
Additionally, proper placement of the APs will provide clients a closer AP with stronger signal, which will be more resistant to noise in the RF environment. This will allow better signal-to-noise (SNR) ratios which will translate to the use of higher data rates and this results in more data transmitted per "timeslot".
I would recommend placing them 2/3 to 3/4 of the way from the center to the perimeter, spaced roughly evenly. Try to get them in or as close to the highest user denisity locations as possible (i.e. conference rooms, etc).
Finally, the additional access points will provide increased reliability. With a single access point, if it were to fail or reboot for any reason, this would create a disruption in service. Having multiple access points should allow for coverage to overlap, allowing service to remain (if degraded) when you have an access point down.
Best Answer
You can download the 802.11-2012 standard from the IEEE web page. On page 429 you can find the the information contained in the probe request body, none of which contain a time stamp.
However, you will note that the final element is defined as "Vendor Specific." It would be possible to add a time stamp in this this element. This would typically require that you modify the code of the driver on the client device. Any device not running your customized driver would not be sending this time stamp.
If you want the access point to recognize this and act on it, then you would need to modify the access point as well. If it would suffice for your needs, you would be able to view the contents of this element if you were doing something like a packet capture as probe requests are not encrypted.