Patent ID: 8355637
Filing Date: 2013-01-15
Classification: H04B,H04L

Abstract:
1. A subcarrier separation circuit which receives an optical OFDM signal consisting of N subcarriers, N being an integer greater than or equal to 2, and separates a subcarrier component, the subcarrier separation circuit comprising: at least one system of optical reception circuits, received signal light and at least one system of local oscillator light being input to each optical reception circuit, each optical reception circuit converting the received signal light and the local oscillator light into a baseband electrical signal; at least one system of analog/digital conversion circuits, each analog/digital conversion circuit converting the baseband electrical signal into a digital signal; N systems of frequency shift circuits which shift the frequency of the converted digital signal so that a center frequency of a desired subcarrier becomes zero; N systems of band limiting filters which limit bands of signals which have been subjected to the frequency shifting by the N systems of the frequency shift circuits, respectively, so that signals in the same pass band as a signal bandwidth of the desired subcarrier are passed therethrough; and N systems of adders which add signals whose bands have been limited by the N systems of the band limiting filters to signals obtained by delaying the signals whose bands have been limited by ½ of a symbol time, to separate components of the N subcarriers.