Downclocking and/or adaptive sub-carriers for single user, multiple user, multiple access, and/or MIMO wireless communications. Communication device operation within a wireless local area network (WLAN/WiFi) is effectuated in the frequency spectra typically associated with television broadcast channels. Operation is made on a secondary non-interfering basis to such television broadcast channels. Any desired channel bandwidth (e.g., 6 MHz, 7 MHz, 8 MHz, etc.) may be employed. Adaptation with respect to the number of data sub-carriers within different respective packets may be made in accordance with two or more respective operational modes. For example, modification of the number of data sub-carriers in different respective packets may be made to increase the signal bandwidth from a first band was to a second bandwidth. Also, appropriate frequency down-clocking of a first channel bandwidth may be performed to generate the desired channel bandwidth to be employed within an available television broadcast channel bandwidth.