Coherent communication system, communication method, and transmission method

Patent metadata

Field	Value
Publication number	US-9621299-B2
Application number	US-201414759329-A
Country	US
Kind code	B2
Filing date	Jan 15, 2014
Priority date	Jan 15, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

The estimation of an amount of chromatic dispersion using a training signal sequence is possible. A transmission method includes: a training signal sequence generation step of generating, as training signal sequences, a plurality of signal sequences having power concentrated in a plurality of frequency bands, the power concentrated at different frequency bands; a training signal sequence selection step of selecting at least one training signal sequence from among the plurality of training signal sequences generated in the training signal sequence generation step, a signal multiplexing step of generating a signal sequence obtained by time-division multiplexing the training signal sequence selected in the training signal sequence selection step with a transmission data sequence, and an electrical-to-optical conversion step of transmitting the signal sequence generated in the signal multiplexing step as an optical signal.

First claim

The invention claimed is:

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.

2. The coherent communication system according to claim 1 ,
wherein the training signal sequence generation unit generates a signal sequence in which an interval of frequencies at which power is concentrated is larger than a predetermined interval as a training signal sequence.

3. The coherent communication system according to claim 1 ,
wherein the training signal sequence selection unit selects a plurality of training signal sequences,
the signal multiplexing unit generates a signal sequence for each of the training signal sequences selected by the training signal sequence selection unit, and
the electrical-to-optical conversion unit transmits a plurality of signal sequences generated by the signal multiplexing unit in different polarization planes.

4. The coherent communication system according to claim 1 ,
wherein the signal multiplexing unit time-division multiplexes another training signal sequence before and after the training signal sequence to be time-division multiplexed with the transmission data sequence.

5. 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 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 at least one of frequency characteristics of the optical signal transmission apparatus or the optical signal reception apparatus, narrowing in a propagation path, frequency characteristics of a transmission channel of the propagation path, an amount of chromatic dispersion, a transmission distance, and estimation precision of the amount of chromatic dispersion.

6. 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;
a plurality of power calculation units that are provided so as to correspond to the plurality of frequency band

Assignees

• Nippon Telegraph & Telephone

Inventors

• Ishihara Koichi
• Mizoguchi Masato
• Murakami Tomoki
• Kataoka Tomoyoshi
• Kisaka Yoshiaki
• Nakagawa Tadao
• Yamazaki Etsushi
• Okamoto Seiji
• Horikoshi Kengo
• Tomizawa Masahito
• Kudo Riichi

Classifications

• H04J14/08 Primary

  Time-division multiplex systems · CPC title

• H04B10/697

  Arrangements for reducing noise and distortion · CPC title

• H04B10/0775

  Performance monitoring and measurement of transmission parameters · CPC title

• H04B10/516

  Details of coding or modulation · CPC title

• H04B10/6161

  Compensation of chromatic dispersion · CPC title