Frequency division multiplexing with channel constraints

Modulation via Fourier transform division multiplexing (FTDM) has been suggested for transmission over channels whose signal-to-noise ratios, as functions of frequency, are far from flat. Original designs following the clasical water-pouring theorem left a large gap between the theoretical promise of the method and the actual rates achieved. The author presents heuristic input-power allocations for enhancing the performance of such schemes. He also considers FTDM under peak-power constraints.