A method of transmission comprises receiving at a first destination, a transmission from a first source; determining from the transmission from the first source, the maximum permitted additional interference subject to which the first destination can still communicate; sending an acknowledgement of the transmission and including in the acknowledgement an indication of the determined maximum permitted additional interference. A second source determines whether it has received the transmission from the first source, or the acknowledgement from the first destination, at a power level lower than that of the maximum permitted additional interference given in the indication; and if so, the second source sends a transmission to a second destination, which at least partially overlaps in time, communication between the first source and first destination.