Peak-to-average reduction with post-amplifier filter

1. A method for broadcasting a modulated signal, the method comprising:

detecting a plurality of peaks within a waveform envelope signal of the modulated signal;

constructing, for each of the plurality of peaks, a pulse having substantial spectral content that is outside of a passband of a high power filter, wherein constructing the pulse for each of the plurality of peaks comprises selecting a first peak and iteratively repeating the following until a termination event occurs:

scaling a selected wavelet to match a magnitude of the selected peak;

subtracting the scaled wavelet from the peak to provide an intermediate signal representing a location of the peak; and

selecting a new peak within the intermediate signal;

subtracting the constructed pulse for each peak from its associated peak to provide a peak-reduced signal;

amplifying the peak-reduced signal at a power amplifier to provide an amplified signal;

filtering the amplified signal at the high power filter to provide a filtered signal; and

broadcasting the filtered signal at an associated antenna.

2. The method of claim 1 , wherein constructing the pulse for each of the plurality of peaks comprises:

extracting a set of samples from the a waveform envelope signal around a location of the peak; and

determining weights for a basis set of wavelets, that, when applied to the basis set, approximate the extracted set of samples from around the location of the peak.

3. The method of claim 2 , wherein determining weights for the basis set of wavelets comprises determining, via an optimization algorithm, a vector of weights, w, representing an optimal solution to the relationship A·w=p, where A is a matrix representing the basis set of wavelets and p is a vector containing the extracted set of samples from the waveform envelope signal.

4. The method of claim 2 , wherein the basis set of wavelets comprises delayed, overlapping versions of a selected wavelet.

5. The method of claim 4 , wherein the selected wavelet is of the form 1−sin c(t).

6. The method of claim 1 , wherein detecting a plurality of peaks within the waveform envelope signal comprises:

applying a clipping function to the waveform envelope signal to provide a magnitude-limited signal; and

subtracting the magnitude-limited signal from the waveform envelope signal.

7. A transmitter system comprising:

a high power filter having a frequency passband;

a peak-to-average reduction component that detects a plurality of peaks within a waveform envelope signal of a modulated signal, constructs, for each of the plurality of peaks, a pulse having substantial spectral content that is outside of the passband of the high power filter, and subtracts the constructed pulse for each peak from its associated peak to provide a peak-reduced signal;

a power amplifier that amplifies the peak-reduced signal at a power amplifier to provide an amplified signal, the high power filter filtering the amplified signal to provide a filtered signal; and

an antenna that broadcasts the filtered signal;

wherein the peak-to-average reduction component constructs the pulse for each of the plurality of peaks such that the spectral content of the constructed pulse is divided between the passband of the high power filter and a stopband of the high power filter such that an in-band distortion of the filtered signal is substantially equal to a maximum allowable in-band distortion for a transmission protocol associated with the transmitter system.

8. The transmitter system of claim 7 , wherein the modulated signal is an orthogonal frequency division multiplexed (OFDM) signal, with a plurality of channels in the OFDM signal each carrying a signal utilizing quadrature amplitude modulation (QAM).

9. The transmitter system of claim 7 , further comprising:

a stored basis set of wavelets having spectral content that is substantially outside of the passband of the high power filter, the basis set of wavelets comprising delayed, overlapping versions of a selected wavelet;

a sample extractor that extracts a set of samples from the signal around a location of the peak; and

an optimization component that determines weights for the basis set of wavelets that, when applied to the basis set, approximate the extracted set of samples from around the location of the peak.

10. The transmitter system of claim 9 , wherein the selected wavelet is of the form 1−sin c(t).

11. The transmitter system of claim 7 , wherein the peak-to-average reduction component that constructs the pulse for each of the plurality of peaks by iteratively scaling a selected wavelet to match a magnitude of the peak, subtracting the scaled wavelet from the peak to provide an intermediate signal representing a location of the peak, and detecting a new peak within the intermediate signal until a termination condition occurs.

12. The transmitter system of claim 7 , the peak-to-average reduction component that applies a clipping function to the waveform envelope signal to provide a magnitude-limited signal and subtract the magnitude-limited signal from the waveform envelope signal.

13. A transmitter system comprising:

a high power filter having a frequency passband;

a peak-to-average reduction component that detects a plurality of peaks within a modulated signal, constructs, for each of the plurality of peaks, a pulse having substantial spectral content that is outside of the passband of high power filter, and subtracts the constructed pulse for each peak from its associated peak to provide a peak-reduced signal, the peak-to-average reduction component comprising:

a stored basis set of wavelets having spectral content that is substantially outside of the passband of the high power filter, the basis set of wavelets comprising delayed, overlapping versions of a selected wavelet;

a sample extractor that extracts a set of samples from the modulated signal around a location of the peak; and

an optimization component that determines weights for the basis set of wavelets that, when applied to the basis set, approximate the extracted set of samples from around the location of the peak;

a power amplifier that amplifies the peak-reduced signal to provide an amplified signal, the high power filter filtering the amplified signal to provide a filtered signal; and

an antenna that broadcasts the filtered signal.

14. The transmitter system of claim 13 , wherein the peak-to-average reduction component constructs the pulse for each of the plurality of peaks such that substantially all of the spectral content of the constructed pulse is outside of the passband of the high power filter.

15. The transmitter system of claim 13 , wherein the peak-to-average reduction component constructs the pulse for each of the plurality of peaks such that the spectral content of the constructed pulse is divided between the passband of the high power filter and a stopband of the high power filter such that an in-band distortion of the filtered signal is substantially equal to a maximum allowable in-band distortion for a transmission protocol associated with the transmitter system.

16. The transmitter system of claim 13 , wherein the optimization component determines, via an optimization algorithm, a vector of weights, w, representing an optimal solution to the relationship A·w=p, where A is a matrix representing the basis set of wavelets and p is a vector containing the extracted set of samples from the waveform envelope signal.

17. The transmitter system of claim 13 , wherein the modulated signal is an orthogonal frequency division multiplexed (OFDM) signal, with each channel of the OFDM signal utilizing quadrature amplitude modulation (QAM).