It is provided a method for combining signal streams in a point-to-point transmitter comprising a plurality of frequency component inputs and a transmitter output. The method is performed in the point-to-point transmitter and comprises the steps of: receiving a first set of data subcarriers for a first signal stream on respective frequency component inputs, the first signal stream intended to be transmitted on a first carrier; receiving a second set of data subcarriers for a second signal stream on respective frequency component inputs, the second signal stream intended to be transmitted on a second carrier; combining all frequency component inputs to one output signal by performing an inverse fast Fourier transform of all frequency component inputs and a parallel to serial conversion; and providing the output signal on the output for transmission to a point-to-point receiver over a point-to-point medium.