as topic "Release Notes for Cisco Aironet Access Points for Cisco IOS Release 12.4(3g)JA" I read the following:
Some Client Devices Cannot Associate When QoS Is Configured
Some wireless client devices, including Dell Axim handhelds and Hewlett-Packard iPaq HX4700 handhelds, cannot associate to an access point when the access point is configured for QoS. To allow these clients to associate, disable QoS on the access point. You can use the QoS Policies page on the access point GUI to disable QoS, or enter this command on the CLI:
ap(config-if)#no dot11 qos mode
therefore, it is avaible command
#dot11 qos mode
The question is the same, about autonomous AP, is it support some kind of QoS ?