wlan.bssid eq 00:11:92:6e:cf:00
    only listen to one specific access point

wlan.fc.type_subtype != 0x08 
    hide beacon frames
    (see p35 of http://www.willhackforsushi.com/books/377_eth_2e_06.pdf for more information on the subtypes)

wlan.fc.type == 2
    data frames only

wlan.fc.type == 2 and wlan.fc.subtype != 4
    data frames only, exclude NULL frames

!wlan.fc.protected
    unencrypted frames only