The present invention relates to wireless communications, and in particular although not exclusively, to networks of indoor collocated or overlapping wireless coverage areas especially those intended for operation in unlicensed spectrum such as the Industrial Scientific and Medical (ISM) bands. The present invention provides a method of controlling the transmission power associated with an air interface channel, the method comprising determining a quality of service measure for a signal to be transmitted on a second air interference channel; determining an interference measure corresponding to the interference on said second air interface channel which will be caused by transmissions on said first air interface channel; requesting the changing of the transmission power associated with the first air interface channel when the signal is to be transmitted on the second air interface channel, when the quality of service measure is above a predetermined value and when the interference measure is above a predetermined value for said quality of service value.