Nippon Telegraph and Telephone Corporation

Ntt Electronics Corporation

Fujitsu Corporation

Shigeki Aisawa

Masahito Tomizawa

Takuya Ohara

Yoshiaki Kisaka

Yutaka Miyamoto

Masahiro Suzuki

Kazuhito Takei

Jun-ichi Kani

Tomoyoshi Kataoka

Tadashi Sakamoto

Yasuyuki Endoh

Masahiko Jinno

Seiji Norimatsu

Katsuyoshi Miura

Tetsuo Takahashi

Naoki Fujiwara

Hiroshi Yamazaki

Hiroshi Koizumi

Hideyuki Nosaka

Yoshiaki Yamada

Koichi Murata

Etsushi Yamazaki

Akira Hirano

Hiroyuki Uzawa

Munehiko Nagatani

Hiroyuki Fukuyama

Takashi Saida

Masahiro Shioda

Shin Kamei

Kei Kitamura

Kengo Horikoshi

Hiroto Kawakami

Mitsuhiro Teshima

Satoru Saitoh

Nobuhiro Kikuchi

Takashi Ono

Hiroyuki Honma

Hiroaki Katsurai

Toshihiro Itoh

Masafumi Nogawa

Masafumi Koga

Mikio Yoneyama

Yasuyuki Endo

Tadanobu Nikaido

Yves Bouvier

An optical modulator driver circuit () includes an amplifier (, Q, Q, R-R), and a current amount adjustment circuit () capable of adjusting a current amount of the amplifier () in accordance with a desired operation mode. The current amount adjustment circuit () includes at least two current sources (IS) that are individually ON/OFF-controllable in accordance with a binary control signal representing the desired operation mode.

Optical modulator driver circuit and optical transmitter

A transport apparatus includes: a client signal transceiving unit which transceives a client signal; a line signal transceiving unit which performs electric-optic conversion on a line signal to be transmitted, transmits an optical line signal, performs optic-electric conversion on a received line signal, and outputs an electrical line signal; and a plurality of signal processing units which perform signal processing on the client signal to generate the line signal to be transmitted and perform signal processing on the electrical line signal to generate the client signal. Each of the plurality of signal processing units includes a signal transceiving unit which performs transfer of a branched signal obtained by branching a signal to be transmitted and a merged signal obtained by merging received signals with another signal processing unit, and the signal transceiving unit of each of the plurality of signal processing units and the signal transceiving unit of the other signal processing unit are coupled via an inter-chip wiring.

Transport apparatus and transport method

A client signal mapping circuit for accommodating a client signal in a transmission frame, including: a buffer unit configured to temporarily store the client signal; a buffer used amount monitoring unit configured to report a used amount of the buffer unit; a stuff processing determination unit configured to compare the used amount of the buffer unit with a predetermined reference value, and a pseudo random sequence signal and the comparison result; an overhead insertion unit configured to add an overhead to the client signal read from the buffer unit to form a transmission frame; and a reading control unit configured to perform control for reading the client signal from the buffer unit based on determination by the stuff processing determination unit.

Client signal mapping circuit and mapping method

In an apparatus for accommodating and multiplexing asynchronous client signals in which an idle signal is defined, the transmission side transmits client signals after synchronizing the client signals by inserting or removing, with reference to a specific client signal, an idle signal to/from the same type of another client signal, and in the receiving side, a PLL part is shared by recovering a clock from a client signal and distributing the clock for another client signal.

Client signal accommodating multiplexing apparatus and method

An optical digital transmission system of the present invention newly defines one second negative stuff byte in an overhead area for accommodation of the client signals with multiplexing into the OTU frame, newly defines one third positive stuff byte in a corresponding tributary slot in a payload area for accommodation of client signals with multiplexing, newly defines stuff control bits that is used for decision of the use of the second negative stuff byte and the third positive stuff byte in three different places in the overhead area for client signal accommodation with multiplexing, performs control by using the newly defined stuff control bits when accommodation of the client signal with the third positive stuff byte or the second negative stuff byte is required, and performs stuff control without using the newly defined stuff control bits when accommodation of the client signal by the third positive stuff byte and the second negative stuff byte is not required.

Optical digital transmission system

A digital transmission system includes at least a client device and a transmission device, and rate-adjusts the client signal transmitted from the client device to the transmission device before accommodating/multiplexing the signal in a frame. The transmission device includes a rate adjusting unit and a frame processing unit. The rate adjusting unit encapsulates the client signal by using a predetermined frame structure, inserts an idle pattern if necessary, and performs rate adjustment into the bit rate which can be contained in the frame. The frame processing unit accommodates/multiplexes the signal after the rate adjustment. The digital transmission system inserts a bit string of the client signal directly in a payload area of the digital frame, or accommodates and multiplexes it. Alternatively, a specific pattern is accommodated in the payload area, or accommodated and multiplexed after performing a reversible digital signal processing.

Digital transmission system and digital transmission method

An optical transmission system for performing frequency synchronization even with a client signal with low frequency accuracy, and for transmitting thereof by accommodating/multiplexing without causing a bit slip. A new overhead is added to the entire client signal, and the signal including the new overhead being stuffed is transmitted in conjunction with a plurality of stuffing bits as an optical signal wherein a data storing bit for a negative stuffing, a stuffing information notification bit, and a stuff bits inserting bit for a positive stuffing in the payload are defined in plurality as stuffing bits for adjusting clock frequencies of the client signal in this new overhead.

Optical transmission system and method

A multiplexing transmission system for adding a management overhead to a client signal, and transparently accommodating or multiplexing the client signal to transmit it is provided. The multiplexing transmission system: accommodates a plurality of client signals of different bit rates including a client signal of a bit rate that is not an integral multiple or an integral submultiple of a bit rate of other client signal, and performs rate adjustment for a part or the whole of the plurality of client signals such that the bit rate of each client signal becomes an integral multiple or integral submultiple of the bit rate of other client signal.

Multiplexing transmission system and multiplexing transmission method

In a wavelength division multiplexed optical transmission system wherein the zero dispersion wavelength of the optical fiber transmission pathis in the 1550 nm region, among multiplexed optical signals, the wavelengths of either of at least two optical signals are allocated between 1450 nm and 1530 nm, or between 1570 nm and 1650 nm.

Wavelength division multiplex optical transmission system

In a wavelength division multiplexed optical transmission system wherein the zero dispersion wavelength of the optical fiber transmission path is in the 1550 nm region, among multiplexed optical signals, the wavelengths of either of at least two optical signals are allocated between 1450 nm and 1530 nm, or between 1570 mn and 1650 nm.

Wavelength division multiplexing optical transmission system

Growing community of inventors

Yokosuka, Japan

Shigeki Aisawa