A method and apparatus of controlling a transmit power in a wireless local area network is provided. A wireless device operated in a TV White Space transmits a white space map indicating a list of available channels, and transmits an extended power constraint indicating a plurality of transmission channels and a plurality of maximum transmit powers, wherein the plurality of transmission channels are selected among the list of available channels and each of the plurality of maximum transmit powers corresponds to a maximum transmit power for each of the plurality of transmission channels. Interference can be mitigated between wireless devices operated in the TV White Space.