Harris Corporation

John W Pajunen

Christopher Douglas Moffatt

Anders S Mattsson

A system communicates data and includes a transmitter for transmitting a communications signal that carries communications data. It includes an efficient modulator for approximating the frequencies of sine/cosine basis waveforms using complex exponential functions and adding and subtracting the complex exponential functions to generate an Orthogonal Frequency Division Multiplexed (OFDM) communications signal as a plurality of N data subcarriers that carry communications data as data symbols. A receiver receives the OFDM communications signal and includes a demodulation circuit for demodulating the OFDM communications signal using logical shifts of multiples +/&#x2212;2based on complex exponential functions corresponding to sine/cosine basis waveform approximations to extract amplitude and phase values from a plurality of N data subcarriers as data symbols within the OFDM communications signal.

System and method for communicating data using efficient fast fourier transform (FFT) for orthogonal frequency division multiplexing (OFDM)

A communications device includes at least one memory device for storing complex exponential functions as approximations of sine and cosine basis waveforms. A logic circuit adds and subtracts the complex exponential functions to generate an Orthogonal Frequency Division Multiplexed (OFDM) communications signal as a plurality of N data subcarriers that carry communications data. The logic circuit provides efficient and accurate implementation of the IFFT for use as an OFDM modulator using additions of stored complex exponentials and modulation of the integer-valued QAM data symbols using logic shifts and sign changes (2's complement).

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Satellite Beach, FL, United States of America

John W Pajunen