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US 9,438,455 B2Granted
Modulation of signals
AssigneeUniversity of Pretoria
InventorsKahesh Dhuness, Bodhaswar Tikanath Jugpershad Maharaj
Life of this patent
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Abstract
An orthogonal frequency division multiplexing (OFDM) modulation method, which includes phase modulating both the real and imaginary components of an OFDM signal.
Claims14
A method of controlling peak to average power ratio (PAPR) of an orthogonal frequency divisional multiplexing (OFDM) signal, comprising:
- with a serial to parallel converter of an OFDM modulator, separating an input OFDM signal into real and imaginary components;
- with the OFDM modulator, scaling the real and imaginary components of the input OFDM signal to produce scaled real and scaled imaginary components of the input OFDM signal;
- with the OFDM modulator, adding an offset term to the scaled real component of the input OFDM signal to produce an adapted real component of the input OFDM signal;
- with the OFDM modulator, phase modulating the adapted real component and the scaled imaginary component to produce a phase modulated OFDM signal including a phase modulated real component and a phase modulated imaginary component;
- and
- with the OFDM modulator, subtracting a dominant frequency component of the phase modulated OFDM signal from the phase modulated OFDM signal to produce an output signal with a controlled PAPR for transmission;
- wherein:
- the offset term impacts a value of the dominant frequency component.
5 more elements
A method of demodulating an orthogonal frequency-division multiplexing (OFDM) signal, comprising, with an OFDM demodulator:
- receiving an input modulated signal;
- detecting a peak to average power ratio (PAPR) of the input modulated signal;
- determining a predefined dominant frequency component control factor and a constant division term of the input modulated signal at least in part by examining the detected PAPR of the input modulated signal;
- adding the predefined dominant frequency component to the input modulated signal to produce an input OFDM modulated signal;
- and
- demodulating the input OFDM modulated input signal.
3 more elements
An Orthogonal Frequency-Division Multiplexing (OFDM) modulator for controlling a peak to average power ratio (PAPR) of an OFDM transmission, comprising:
- a multiplier configured to scale imaginary and real components of a transformed OFDM input signal to produce a scaled real component and a scaled imaginary component;
- an offset term adder configured to add an offset term to the scaled real component of the transformed OFDM input signal, so as to produce an adapted real component;
- a phase modulator configured to phase modulate the adapted real component and the scaled imaginary component of the transformed OFDM input signal using a cosinusoidal to produce a phase modulated OFDM signal including a phase modulated OFDM imaginary component and a phase modulated OFDM adapted real component;
- a subtractor configured to subtract the phase modulated OFDM imaginary component from the phase modulated OFDM adapted real component;
- and
- a subtractor configured to subtract a predefined dominant frequency from the phase modulated OFDM signal to produce an output signal with a controlled PAPR for transmission.
3 more elements
An Orthogonal Frequency-Division Multiplexing (OFDM) demodulator, comprising:
- a Peak-to-Average Power Ratio (PAPR) detector configured to determine a PAPR of an input modulated signal;
- a memory comprising a lookup table referencing the PAPR against predefined values for a dominant frequency component control factor (γ), an offset term (Ψos), and a constant division term (ζ);
- a processor configured to determine a predefined dominant frequency component control factor value associated with said input modulated signal from the predefined values in the lookup table;
- an adder configured to add the predefined dominant frequency component control factor value to the input modulated signal to produce an input OFDM modulated signal;
- and
- an OFDM demodulator configured to demodulate the input OFDM modulated signal.
3 more elements
Dependencies are inferred from the claim text.