Reduction of average-to-minimum power ratio in communications signals
First Claim
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1. A method of reducing the average-to-minimum magnitude ratio (AMR) of a communications signal having a sequence of symbols, comprising:
- obtaining a digital message for generating the communications signal having a sequence of symbols;
applying a pulse-shaping technique to an instance of a pulse of a given form to generate a communications signal s(t);
obtaining a minimum value ρ
(tmin) of the magnitude of the generated communication signal s(t) at a time instant t_min in a time interval between two distinct time instants t1 and t2 (t1<
t2);
generating, in the time interval between the time instants t1 and t2, a correction signal with a predetermined impulse response r(t−
tmin) which is obtained based on the minimum value and the predetermined signal envelope minimum if it is determined that ρ
(tmin) is smaller than a predetermined signal envelope minimum; and
adding the correction signal to the communications signal to generate a modified communications signal, whereinthe communications signal is represented within a signal plane having an origin denoting a signal of zero magnitude;
the minimum value of the magnitude of the communications signal is calculated from a distance from the origin to a first straight line spanning a coordinate of the communications signal s(t1) and a coordinate of the communications signal s(t2), and the method further comprises;
determining the first straight line spanning the coordinate of the communications signal s(t1) and the coordinate of the communications signal s(t2) and a second straight line passing through the origin and being orthogonal to the first straight line; and
calculating the minimum value ρ
(tmin) of the magnitude of the communications signal from a distance from the origin to an intersection point of the first straight line and the second straight line.
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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).
28 Citations
9 Claims
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1. 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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obtaining a digital message for generating the communications signal having a sequence of symbols; applying a pulse-shaping technique to an instance of a pulse of a given form to generate a communications signal s(t); obtaining a minimum value ρ
(tmin) of the magnitude of the generated communication signal s(t) at a time instant t_min in a time interval between two distinct time instants t1 and t2 (t1<
t2);generating, in the time interval between the time instants t1 and t2, a correction signal with a predetermined impulse response r(t−
tmin) which is obtained based on the minimum value and the predetermined signal envelope minimum if it is determined that ρ
(tmin) is smaller than a predetermined signal envelope minimum; andadding the correction signal to the communications signal to generate a modified communications signal, wherein the communications signal is represented within a signal plane having an origin denoting a signal of zero magnitude; the minimum value of the magnitude of the communications signal is calculated from a distance from the origin to a first straight line spanning a coordinate of the communications signal s(t1) and a coordinate of the communications signal s(t2), and the method further comprises; determining the first straight line spanning the coordinate of the communications signal s(t1) and the coordinate of the communications signal s(t2) and a second straight line passing through the origin and being orthogonal to the first straight line; and calculating the minimum value ρ
(tmin) of the magnitude of the communications signal from a distance from the origin to an intersection point of the first straight line and the second straight line. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A PAM generator, comprising:
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a baseband modulator for applying a pulse-shaping technique to instance of a pulse of a given form to generate a communications signal; an analyzer connected to an output end of the baseband modulator for obtaining a minimum value ρ
(tmin) of the magnitude of the communications signal at a time instant tmin in a time interval between two distinct time instants t1 and t2 (t1<
t2);a pulse-shaping filter connected to an output end of the analyzer for generating, in the time interval between the time instants t1 and t2, a correction signal by multiplying a correction weight C, based on the minimum value ρ
(tmin) and a predetermined signal envelope minimum, by a predetermined impulse response r(t−
tmin), which is based on the time instant tmin, if it is determined that there exists a time instant tin the time interval between the time instants t1 and t2 where the magnitude of the communications signal at the time instant t is smaller than the predetermined signal envelope minimum; andan adder for adding the correction signal to the communications signal s(t) to generate a modified communications signal, wherein the communications signal is represented within a signal plane having an origin denoting a signal of zero magnitude; the minimum value ρ
(tmin) of the magnitude of the communications signal is calculated from a distance from the origin to a first straight line spanning a coordinate of the communications signal s(t1) and a coordinate of the communications signal s(t2);the first straight line spanning the coordinate of the communications signal s(t1) and the coordinate of the communications signal s(t2), and a second straight line passing through the origin and being orthogonal to the first straight line are determined; and the minimum value ρ
(tmin) of the magnitude of the communications signal from a distance from the origin to an intersection point of the first straight line and the second straight line is calculated. - View Dependent Claims (8, 9)
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Specification