A method that includes providing to multiple inverse fast Fourier transform (IFFT) and polyphase circuits multiple baseband channels so that different IFFT and polyphase circuits receive different sets of baseband channels; applying IFFT operations and the polyphase filtering operations by the multiple IFFT and polyphase circuits to provide multiple converted channels; wherein different IFFT and polyphase circuits output different sets of converted channels that at least partially populate different IFFT grids that comprise different frequency bins; wherein frequency bins of a same IFFT grid of the different IFFT grids are spaced apart from each other by a first spacing; frequency shifting one or more sets of the converted channels to provide an output set of sub-channels; wherein the output set of sub-channels at least partially populates an output frequency grid in which output sub-channels originating from different sets of converted channels are of interleaving frequencies and in which the spacing between adjacent output frequency bins is smaller than the spacing between frequency bins of each IFFT grid; and combining the sub-channels of the output set of sub-channels to provide an interleaved output channel.