802.11 ac networks define an operating band made of an ordered series of 20 MHz channels and authorize a restricted number of possible composite channel configurations to be used for data transmission. A method of transmitting data between a source and a receiver in such a wireless network may comprise, at the source: sending, to the receiver, RTS frames to request reservation of a composite channel, the RTS frames including a flag signalling the source supports transmission over un-authorized composite channels, for instance over sub-channels not contiguous within the operating band; receiving, from the receiver in response to the RTS frames, CTS frames acknowledging reservation of un-authorized composite channel configuration, for instance of non-contiguous sub-channels; and then transmitting, to the receiver, data frames on the reserved sub-channels of the un-authorized configuration, for instance on the reserved non-contiguous sub-channels within the operating band.