Joint Transmit Power and Filter Tap Allocation in DMT Transmitters With Per-Tone Pulse Shaping

Per-tone pulse shaping has been proposed as an alternative to time domain spectral shaping for Discrete Multi-Tone (DMT) transmitters, e.g. VDSL modems. This enables the transmitter to use more tones without violating the Power Spectral Density (PSD) mask constraint for data transmission. The computational complexity of the per-tone pulse shaping and transmit power is evenly distributed over tones, however, resources (computational complexity and power) can be better exploited by using different filter lengths for different tones and by resorting to power loading. For a fixed pulse shaping filter length, the contribution of a particular tone to the stop band energy depends on the power allocated to the tone and on the distance of the tone from the band edges.