Reduction of average-to-minimum power ratio in communications signals
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Accused Products
Abstract
This invention, generally speaking, modifies pulse amplitude modulated signals to reduce the ratio of average power to minimum power. The signal is modified in such a manner that the signal quality remains acceptable. The signal quality is described in terms of the Power Spectral Density (PSD) and the Error Vector Magnitude (EVM).
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Citations
26 Claims
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1-21. -21. (canceled)
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22. A method of reducing the average-to-minimum magnitude ratio (AMR) of a communications signal having a sequence of symbols, comprising:
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specifying a time interval between which a low magnitude event of the communications signal is likely to occur, said time interval not dependent on a transition between a given symbol and a successive symbol in said sequence of symbols;
calculating a minimum magnitude of the communications signal within the specified time interval; and
if the calculated minimum magnitude of the communications signal is less than a desired minimum magnitude, adding a correction pulse to the communication signal to form a modified communications signal. - View Dependent Claims (23, 25)
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24. An apparatus, comprising:
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a baseband modulator operable to generate a baseband signal defined by;
where an is a symbol corresponding to the nth component of a digital message, p(t) is a pulse at time t, and T is the symbol period;
an analyzer operable to determine one or more perturbation instances tm and one or more perturbation values bm, at least one of said one or more perturbation instances tm occurring at an instance other than t=kT+T/2, where k is an integer;
a pulse-shaping filter operable to generate a perturbation sequence from the one or more perturbation instances tm and the one or more perturbation values bm; and
a summer operable to form a perturbed baseband signal defined by;
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26-27. -27. (canceled)
Specification