Wireless Station with QOS enabled
Observer has sensed station on air that has the QOS (Quality of Service) feature enabled. Wireless QOS (which is not supported by all vendors) allows you to prioritize traffic for devices such as wireless VoIP phones.
Possible reasons for the event:
A rogue station, or crosstalk from another network is being sensed by the analyzer.
An legitimate user on your network has inadvertently enable QoS.