Patent ID: 8467687
Filing Date: 2013-06-18
Classification: H04B,H04J,H04L

Abstract:
1. An optical transmitter in an optical OFDM communication system in which the optical transmitter maps digital data to a plurality of subcarriers orthogonal to each other over a symbol time, modulates subcarrier signals, and transmits modulated subcarrier signals as optical signals through an optical fiber, and an optical receiver applies a photoelectric conversion to the optical signals propagated through the optical fiber by a photodiode to receive the optical signals by a direct detection, and demodulates the subcarrier signals to reproduce original digital data, the optical transmitter comprising: a modulator that maps the digital data to the plurality of subcarriers orthogonal to each other over the symbol time, modulates the subcarrier signals, and outputs the modulated subcarrier signals, a distortion generator that applies an inverse FFT computation to the subcarrier signals to generate a baseband OFDM signal, and squares an absolute value of the baseband OFDM signal to generate a distortion component caused by inter-subcarrier interference; a subtractor that subtracts the distortion component generated by the distortion generator from each of the subcarrier signals output from the modulator to obtain a transmission signal; an inverse FFT unit that applies the inverse FFT computation to the transmission signal which is subtracted the distortion component to convert the transmission signal into a time signal; and a transmitter unit that transmits the optical signal based on the transmission signal converted by the inverse FFT unit to the optical receiver through the optical fiber.