12014-04-22 10:42:49ClauzClauzFrom: Channel numbering for 40MHz is defined in 20.3.15.3 by specifying 2 channels : a primary channel and a secondary channel. For instance : (36,40) or (36,+1), the last digit indicating : “secondary channel is above/below the primary channel”. This information is present in beacons as well in the HT IE and is properly decoded by Wireshark. From now on, it’s clear that “channel 36 ht40+” means : primary channel is 36 and secondary channel is 40. Since channel 32 is not authorized in Europe, we cannot have “channel 36 ht40-”. Let’s examine all channels available in Europe now. Annex J defines behavior limits set for all channels and behavior limits set (defined in Annex I) can be interpreted as follows : 13 means ht40+, 14 means ht40-.