Patent ID: 9621299
Date: 2017-04-11
CPC Classifications: H04B,H04J

Claim:
1. A coherent communication system comprising: an optical signal transmission apparatus; and an optical signal reception apparatus, wherein the optical signal transmission apparatus comprises: a training signal sequence generation unit that generates, as a plurality of training signal sequences, a plurality of signal sequences having power concentrated in a plurality of frequency bands, the power concentrated in different frequency bands; a training signal sequence selection unit that selects at least one training signal sequence from among the plurality of training signal sequences generated by the training signal sequence generation unit; a signal multiplexing unit that generates a signal sequence obtained by time-division multiplexing the training signal sequence selected by the training signal sequence selection unit with a transmission data sequence; and an electrical-to-optical conversion unit that transmits the signal sequence generated by the signal multiplexing unit as an optical signal, and the optical signal reception apparatus comprises: an optical-to-electrical conversion unit that converts the optical signal transmitted from the optical signal transmission apparatus into an electrical signal; an analog-to-digital conversion unit that converts the electrical signal converted by the optical-to-electrical conversion unit into a digital signal sequence; a plurality of frequency band pass filter units that correspond to the plurality of signal sequences and pass part of frequency band components of the digital signal sequence converted by the analog-to-digital conversion unit; and a plurality of power calculation units that are provided so as to correspond to the plurality of frequency band pass filter units and calculate power values of digital signal sequences output by the corresponding frequency band pass filter units, wherein the training signal sequence generation unit generates at least one signal sequence in which power is concentrated at a frequency lower than a cut-off frequency in a band limit filter in the optical signal transmission apparatus, the optical signal reception apparatus, or a propagation path as a training signal sequence, and the training signal sequence selection unit selects at least one training signal sequence from the plurality of the training signal sequences generated by the training signal sequence generation unit based on presence or absence of the band limit filter in the optical signal transmission apparatus, the optical signal reception apparatus, or the propagation path.