Nippon Telegraph and Telephone Corporation

Nissan Motor Company Limited

Honda Motor Co., Ltd.

Renault S.a.s.

Ntt Electronics Corporation

Sumitomo Electric Industries, Limited

Nippon Hoso' Kyokai

Renault S.a.s. Societe Par Actions Simplifiee

Sekisui Chemical Co., Ltd.

Kyushu University

Masanori Nakamura

Katsuo Suga

Yoshiaki Kisaka

Hironori Wakamatsu

Kazuyuki Shiratori

Seiji Okamoto

Fukutaro Hamaoka

Shuto Yamamoto

Hirofumi Yasuda

Etsushi Yamazaki

Kengo Horikoshi

Tetsuro Naito

Hiroto Kikuchi

Masahito Tomizawa

Toru Sekiba

Yutaka Miyamoto

Takayuki Kobayashi

Mitsuteru Yoshida

Kenichi Machida

Akira Masuda

Kazuhito Takei

Takeru Abe

Yukihiro Asada

Ryo Sato

Munehiko Nagatani

Hiroshi Yamazaki

Yoshiaki Tanaka

Koichi Ishihara

Hideyuki Nosaka

Katsuya Tanaka

Dai Arai

Kenji Tamaki

Akira Hirano

Akira Nakasuga

Shogo Yamanaka

Shoichiro Kuwahara

Kensaku Takata

Junji Ito

Takashi Tetsuka

Shoji Nozato

Hiroshi Iwakami

Hiroto Kawakami

Yasunari Hanaki

Hideki Nishizawa

Takeshi Yanagisawa

Asuka Matsushita

Jun Ikezawa

Hiroki Taniguchi

Toshiharu Miyamura

Takeo Sasai

Tomohiro Takamuku

Katsuichi Oyama

Yasuharu Onuma

Akihiro Yamagishi

Takasumi Yamanaka

Hiroyuki Sasazawa

Makoto Aoyama

Takeshi Kakizaki

Masashi Nagayama

Masato Nagata

Atsushi Hoki

Masahiro Takaya

Kazushige Yonenaga

Yutaka Aikyo

Osamu Kobayashi

Yoshitaka Kubota

Kenji Yamauchi

Tomoyoshi Kataoka

Ryohei Kitamura

Tohru Kashiwagi

Michio Atsuchi

Shigeki Nomura

Katsuyuki Okubo

Yoshiaki Hiramoto

Takeshi Kitajima

Tetsuro Hosoda

Shiro Kokubu

Hideaki Morisaka

Yuichi Kawasaki

Atsuro Takeno

Kuniharu Takizawa

Toshiya Sugimoto

Yasuo Shinde

Maki Shimada

Masahiro Kishida

Takamasa Nakagawa

Hideaki Nakagawa

Kyosuke Inada

Kenji Uesugi

Morihiko Katsuda

Naoki Kachi

Eisuke Tsuchiya

Hideo Fujikake

Shimpei Shimizu

Tatsuro Kato

Emi Shida

Kotaro Miki

Hiroshi Tachikawa

Misaki Fujimoto

According to an aspect of the present invention, there is provided an optical signal demodulator including an optical reception unit, an AD conversion unit, a digital signal processing unit, and a signal determination unit, in which the signal determination unit includes: a spectrum shaping filter processing unit that receives a reception signal sequence of the digital signal from the digital signal processing unit and outputs a value obtained by performing a convolution operation on the reception signal sequence which is received; a transmission line simulation filter processing unit that outputs a value obtained by performing a convolution operation on a candidate signal sequence which is determined based on a symbol transition of the reception signal; an error information acquisition unit that acquires error information between the value output from the spectrum shaping filter processing unit and the value output from the transmission line simulation filter processing unit; and a bit determination unit that determines a value of a bit included in the symbol transmitted by a transmission unit based on the error information acquired by the error information acquisition unit.

Optical signal demodulator, control method and program

The symbol determination device generates the plurality of estimated reception symbol sequences on the basis of the estimated transfer function of the transmission line represented by the tap gain value applied to each tap of the nonlinear filter including the plurality of taps and the plurality of candidate symbol sequences, determines the transmission symbol by the maximum likelihood sequence estimation on the basis of the determination target reception symbol sequence obtained from the reception signal sequence and each of the plurality of estimated reception symbol sequences, identifies the estimated transmission symbol corresponding to the determination target reception symbol sequence, calculates the new tap gain values on the basis of the determination target reception symbol sequence and the identified estimated transmission symbol sequence, updates the estimated transfer function by applying the calculated tap gain values to the taps of the transmission line estimation unit, and selects the tap to be used on the basis of the magnitude of the calculated new tap gain value and the predetermined tap gain threshold value.

Symbol determination device and tap selection method

An aspect of the present invention is an adaptive equalization filter for an optical transmission system, including: a main signal filter; and a coefficient computation unit that updates the filter coefficient of the main signal filter. The pre-stage filter and the post-stage filter receive a sample of the main signal as an input. The pre-stage coefficient computation unit obtains the filter coefficient of the pre-stage filter by feedback control using the gradient method. The post-stage coefficient computation unit obtains the filter coefficient of the post-stage filter by feedforward control. The convolution computation unit obtains the filter coefficient of the main signal filter by convolution computation of the filter coefficient of the pre-stage filter obtained by the pre-stage coefficient computation unit and the filter coefficient of the post-stage filter obtained by the post-stage coefficient computation unit.

Adaptive equalization filter and method for updating filter coefficients

An optical transmission system is an optical transmission system for transmitting a signal from an optical transmitter to an optical receiver via at least a transmission line among one or more optical nodes and the transmission line, wherein the optical transmitter includes a digital filter that compensates for, between ripple components that are micro-fluctuating components in a frequency region representing a transmission characteristic of the signal in the optical transmitter and the optical receiver and non-ripple components of the transmission characteristic, at least the ripple components of the transmission characteristic, and at least one of the optical node and the optical transmitter includes an optical filter that compensates for the non-ripple components of the transmission characteristic.

Optical transmission system, control apparatus, optical transmission method and program

An aspect of the present invention is a communication system including: an encoding unit configured to transform an input symbol sequence into an output symbol sequence, the input symbol sequence being a sequence of first symbols, the output symbol sequence being a sequence of second symbols; and a decoding unit configured to transform the output symbol sequence into the input symbol sequence in accordance with a decoding-side transformation mapping for transforming the output symbol sequence into the input symbol sequence that is a transformation source for the output symbol sequence, wherein the encoding unit transforms the input symbol sequence into the output symbol sequence in accordance with encoding-side transformation destination candidate information, the input symbol sequence, and a transformation probability, the encoding-side transformation destination candidate information being information indicating candidates of a transformation destination for the input symbol sequence, the transformation probability being a probability of transformation into the transformation destination indicated by the encoding-side transformation destination candidate information, and a probability of appearance of the second symbol conforms to a predefined prescribed probability distribution.

Communication system, communication method and program

An optical transmission system, in which an optical transmission apparatus and an optical reception apparatus are provided, includes a coefficient determination unit configured to optimize, based on a reception signal received by the optical reception apparatus, a coefficient to be used to compensate for deterioration according to characteristics of each device configuring a transmission path between the optical transmission apparatus and the optical reception apparatus, and a device characteristic estimation unit configured to estimate the characteristics of each device by using the optimized coefficient.

Optical transmission system and characteristic estimation method

A tentative decision is made for symbols on the basis of a received signal and a decision threshold, and a tentative decision signal including a sequence of the symbols is output. A scale value indicating a rate of increase or reduction of the received signal or a threshold change rate indicating a degree of change in the decision threshold is updated so that an appearance frequency of each of symbols included in the tentative decision signal matches an appearance frequency of each of symbols in a reference signal obtained by modulating a transmitted signal with a modulation method used in transmission which is shared between a transmitting side and a receiving side, and an SN ratio is calculated using the scale value or the threshold change rate when a degree of agreement between the appearance frequencies is within a predetermined permissible range. When the scale value is updated, a tentative decision is made for the symbols on the basis of the received signal increased or reduced by the updated scale value and the decision threshold, and when the threshold change rate is updated, the tentative decision for the symbols is made on the basis of the received signal and the decision threshold to which the updated threshold change rate is applied.

S/N ratio estimation circuit, and adaptive filter circuit

An optical transmitter generates symbols for transmission by applying a predetermined coding method to each of m-valued transmission symbols generated from transmission data, generates signal light by performing optical modulation on the basis of the symbols for transmission, and transmits the signal light. An optical receiver generates a series of digital signals from the received signal light, detects coded symbols by applying predetermined digital signal processing to the series of digital signals, decodes the m-valued transmission symbols from the detected coded symbols, and restores the transmission data from the decoded m-valued transmission symbols. An operation based on the predetermined coding method performs nonlinear coding that generates the coded symbols by generating m-valued intermediate symbols from the m-valued transmission symbols, the nonlinear coding restricting transitions between series of the coded symbols in time series by assigning bit information to a state transition between coded symbols adjacent in time series and making a number of states that each of the coded symbols can take on greater than a number of states of the m-valued transmission symbols.

Optical transmission system, optical transmitting apparatus and optical receiving apparatus

A communication device includes an amplitude conversion unit configured to generate a symbol sequence according to a bit sequence, a distribution matching unit configured to add redundant bits to the symbol sequence through probabilistic amplitude shaping (PAS) coding, an insertion unit configured to insert a pilot symbol into the symbol sequence to which the redundant bits have been added and transmit the symbol sequence into which the pilot symbol has been inserted to a transmission path, and a control unit configured to acquire information on the transmission path and change, according to the information on the transmission path, allocation of the redundancy of the PAS coding and the redundancy of the pilot symbol in a range of redundancy that is able to be allocated depending on a predetermined throughput.

Communication apparatus, and optical transmission system

A signal processing apparatus includes: a coefficient update unit configured to approximate a characteristic of a transmission line of an optical signal by a first tap coefficient vector of which an L0 norm is a predetermined value or less; a zeroing unit configured to generate a second tap coefficient vector by replacing, with 0, a tap coefficient of which an absolute value is less than a threshold among tap coefficients of the first tap coefficient vector; and an adaptive filter configured to perform, based on the second tap coefficient vector, adaptive equalization processing on a digital signal corresponding to an optical signal received via the transmission line.

Signal processing apparatus, signal processing method, and program

A computation unit uses an assumed chromatic dispersion amount to compensate for dispersion of a coherently received optical signal and performs arithmetic of a signal power of the optical signal that is dispersion compensated. The computation unit performs computation of an evaluation function when a signal power and a delayed signal power obtained by applying a predetermined delay to the signal power satisfy a threshold condition. The evaluation function is a function for evaluating whether the assumed chromatic dispersion amount is a chromatic dispersion amount of the optical signal using the difference between the signal power and the delayed signal power. The chromatic dispersion amount calculation unit calculates a chromatic dispersion amount of the optical signal based on the computation result of the evaluation function by the computation unit when each of a plurality of different assumed chromatic dispersion amounts is used.

Wavelength dispersion amount calculation apparatus and wavelength dispersion amount calculation method

There are provided an evaluation method and an evaluation device for an optical receiver capable of evaluating only a phase error between optical 90-degree hybrids with high accuracy even when there is a skew between channels in the optical receiver. In the evaluation method and the evaluation device for the optical receiver including optical 90-degree hybrids, a phase error between the optical 90-degree hybrids is calculated by calculation of decomposing a transfer function of the optical receiver into a product of matrixes to evaluate the optical receiver.

Optical receiver evaluation method and optical receiver evaluation apparatus

An optical reception device includes a coefficient update section which optimizes a dispersion coefficient used in compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and a phase rotation amount used in compensation of a nonlinear optical effect of the received signal, and a transmission characteristic estimation section which estimates a transmission characteristic of a transmission line by using the optimized dispersion coefficient and the optimized phase rotation amount.

Optical transmitting apparatus and transmission characteristics estimation method

An optical transmission system according to an embodiment includes: an optical transmission unit which modulates an optical signal into which a known signal is inserted and transmits the optical signal; and an optical reception unit which receives the optical signal from the optical transmission unit, wherein the optical reception unit includes: an optical receiver which performs coherent detection of a reception signal of the optical signal received from the optical transmission unit; a receiver transfer function estimation section which estimates a nonlinear response transfer function of the optical receiver based on the known signal included in the reception signal after the detection by the optical receiver; and a receiver compensation section which compensates nonlinear distortion of the reception signal after the detection based on the nonlinear response transfer function which the receiver transfer function estimation section estimates.

Optical transmission system and compensation method

A device generates a symbol sequence by performing adaptive equalization by an estimation inverse transfer function of a transmission line on a reception signal sequence extracted from the transmission line, and performing provisional determination on the symbol sequence generated; generates a plurality of the symbol sequences indicating transmission line states in a range of a provisional determination symbol provisionally determined and nearby symbols of the provisional determination symbol; generates, based on the plurality of the symbol sequences indicating the transmission line states generated and an estimation transfer function of the transmission line, an estimation reception symbol sequence for each of the transmission line states; calculates a metric between the symbol sequence obtained from the reception signal sequence and each of a plurality of the estimation reception symbol sequences; selects a most likelihood estimation reception symbol sequence of the plurality of the estimation reception symbol sequences, based on the calculated metric, the provisional determination symbol, and the nearby symbols of the provisional determination symbol; and determines a transmission symbol sequence.

Symbol judgement apparatus and symbol judgement method

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Yokosuka, Japan

Masanori Nakamura