You need to enable the interface Dot11Radio1 to use the 5GHz band. In your configuration, you only have the 2.4GHz Band operational:
interface Dot11Radio0 (2.4 GHz Band)
no ip address
!
///////////////////////////
!
interface Dot11Radio1 (5 GHz Band)
no ip address
shutdown (assign an SSID to this interface and perform a no shut)
antenna gain 0
peakdetect
dfs band 3 block
packet retries 64 drop-packet
channel dfs
station-role root
bridge-group 1
bridge-group 1 subscriber-loop-control
bridge-group 1 spanning-disabled
bridge-group 1 block-unknown-source
no bridge-group 1 source-learning
no bridge-group 1 unicast-flooding
The commands for this are in the configuration guide for the version of IOS on your autonomous AP:
The full Configuration Guide can be found here:
http://www.cisco.com/en/US/docs/wireless/access_point/15_2_4_JB/configuration/guide/scg15_2_4_JB3a.pdf
Chapter 6 covers this.
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Charles Moreton