Nippon Telegraph and Telephone Corporation

Mitsuhiro Teshima

Katsuhiro Araya

Masamichi Fujiwara

Junichi Kani

Kenichi Suzuki

Hiroki Kawahara

Hiroto Takechi

Hideki Maeda

Masahiro Yokota

Yoshihiko Uematsu

Masatoshi Namiki

Toshiyuki Oka

Hiroshi Yamamoto

Daisaku Shimazaki

Masaaki Inami

Yasutaka Sugano

Hirokazu Kobayashi

Hiroo Suzuki

Katsumi Iwatsuki

Jun-ichi Kani

Noboru Takachio

Shingo Kawai

Takeshi Seki

Masumi Sakamoto

Koji Akimoto

Masafumi Ando

Masaki Shinkai

Genichi Nishio

Jun-Ichi Kani

A transmission side transmission device includes: a first transmitter including a first switch; and a second transmitter including a second switch. A main signal is input to either the first transmitter or the second transmitter. The main signal input to the first transmitter is a first main signal and the main signal input to the second transmitter is a second main signal. The first transmitter and the second transmitter are configured such that, when the first transmitter detects a fault in the input first main signal: the second transmitter outputs the input second main signal to the first transmitter; and the first transmitter outputs the input second main signal via a first selector.

Transmission side transmission device and redundancy method of transmission side transmission device

A transmission side transmission device includes a first transmitter including a first switch and a second transmitter including a second switch. When the first transmitter detects a fault in the first main signal, the second transmitter outputs a duplicated signal of the second main signal to the first transmitter. The first selector of the first transmitter selects and outputs a duplicated signal of the input second main signal. When the second transmitter detects a fault in the first switch, the second transmitter selects and outputs the second main signal.

Transmitting side transmission device, receiving side transmission device, redundancy method of transmitting side transmission device, redundancy method of receiving side transmission device, program, and transmission device

A monitoring control unit () of an OXC () stores a management table () in which pieces of information regarding a modulation mode, an FEC, and a frame mode of an optical signal are associated with each other, and sequentially changes the modulation mode, the FEC, and the frame mode according to the management table () upon an LOS alert from a relay-side optical input/output unit () or an LOF alert from a DSP () being input thereto. Upon successfully receiving an appropriate optical signal according to the change, the monitoring control unit () acquires transmission source information included in the optical signal, and detects an occurrence of erroneous connection of an optical transmission line in an OXC (), which serves as a relay apparatus, when the acquired transmission source information indicates an optical cross-connect apparatus that is a transmission source different from an original transmission source.

Optical cross-connect device, optical transmission system, and optical transmission line connection error detection method

A transmission device () includes a flow table () that stores identification information about an uninterruptible target flow; a transmission-side identification unit () that identifies whether a received packet is from the target flow or a non-target flow based on whether the received packet matches the identification information about the target flow stored in the flow table (); a tag application unit () that applies, to packets from the target flow, an uninterruptible identifier indicating that the packets are from the target flow and a sequence number for distinguishing the packets from other packets; and a branch unit () that branches the packets from the target flow processed by the tag application unit () into packets to be transferred to an active path () among redundant routes and packets to be transferred to a backup path () among the redundant routes.

Transmitting device, receiving device, packet transfer system,packet transfer method, and packet transfer program

[Problem] whether optical input interruption detected by an OXC device is due to an external failure from an upstream side or an internal failure of the OXC device in a transponder device connected to the OXC device using an optical transmission line, and this determination is implemented at low cost. [Solution] An optical transmission system (A) is configured by connecting a plurality of OXC devices (A) using optical fibers () between transponder devices (A) that relay optical signals transmitted to/from terminals (). The OXC device (A) includes an OSC part () and a monitoring control part (). The OSC part () outputs wavelength information on an optical signal in which optical input interruption has occurred and path information on a path of an optical fiber () in which the optical input interruption has occurred, at the time of detecting the optical input interruption from the optical fiber (). In accordance with the wavelength information and the path information that have been output as above, the OXC device (A) includes an AIS generation part () that generates an AIS signal including both pieces of information on the wavelength and the path of the optical signal relating to the optical input interruption and alarm information relating to both the pieces of information.

Optical transmission system and optical transmission method

[Problem] To deal with interference in cases where a plurality of business operators perform testing at the same time at different MEG levels. [Solution] A network deviceincludes a frame distinguishing unitthat, upon receiving a start instruction for a test from a control device, monitors whether or not an OAM frame of a preceding test of a different level from a MEG level of an own device has arrived at the own device, for a predetermined period, and a CPUthat, if the frame distinguishing unitdetects arrival of the OAM frame, and determination is made that its own test will affect the preceding test, notifies the result of the detection and determination.

Network device and network test method

When separate service apparatuses that provide various communication services to users are connected by a wiring with communication functional units interposed, if there is a wiring abnormality, the location of the abnormality is easily identified. When a wiring connection is completed between separated service apparatuses X and Y that provide various communication services to user terminalsandwith communication functional units Aand Binterposed, a wiring management systemA includes a transmission network management apparatusA that identifies a wiring abnormality. The transmission network management apparatusA associates endpoint names of the service apparatuses X and Y and of the functional units Aand Bwith opposite endpoint names on the opposite sides, defines opposite endpoint IDs of the endpoints of the functional units Aand Bas expected values, and saves the end points in association with the opposite endpoint IDs in a DB. Upon completing the wiring connection between the service apparatuses X and Y, an opposite endpoint ID of each of the functional units Aand Band the service apparatuses X and Y opposite to predetermined functional units Aand Bis received as a received value via a wiring, and if the received value does not match the expected value, it is determined that the wiring is abnormal.

Wiring management system and wiring management method

[PROBLEM TO BE SOLVED] To uninterruptedly change a band of an optical transmission path in a line IF section, which relays a signal transmitted to an optical transmission path in a client IF section to which a communication terminal is connected, to the same band as a changed band in the client IF section without suspending the communication in the line IF section. [SOLUTION] An optical transmission systemA performs processing for changing a band of an optical fiberin a line IF section (L section) that relays a signal from an optical fiberin a client IF section (C section) to the same band as that in the C section. Line IF unitsA andB provided on both sides of the L section set a temporary evacuation lane p as an optical lane having a band different from those of a plurality of optical lanesto n in the optical fiberin the L section, selects either a change-target optical lane (for example, the optical lane) or the temporary evacuation lane p, the change-target optical lane being provided in the optical fiberin the L section and having a band to be changed to a same band as a band in the C section, while causing a buffer unitto absorb a delay difference between a signal received by the change-target optical lane and a signal received by the temporary evacuation lane p, and sets the optical lane not selected to have the same band as the band in the C section.

[Problem] It is possible to cancel out beat noises in a WDM signal to obtain a high-quality signal component, and a configuration thereof is achieved with low mounting costs. [Solution] An optical reception device converts a WDM signal rs(t) of an optical signal to electrical signals d(t)to d(t)n expressed as complex numbers of orthogonal phases, cancels out beat noises from the electrical signals, and then demodulates the signals to obtain signals Dto Dn of a transmission source. This optical reception device includes an absolute value calculation unitstothat generate a signal component including a beat noise component through absolute value squaring calculation processing for squaring an absolute value of the electrical signal, scaling unitstothat multiply the generated beat noise component by a proportional constant to restore beat noise associated with n types of wavelengths in the electrical signal, and subtraction unitstothat subtract the n type of beat noises restored from the electrical signal to cancel out then types of beat noises included in the electrical signal.

Optical reception device

Multi-wavelength light having a frequency band equal to or greater than the FSR of an AWG is demultiplexed into individual wavelength channels, and power level deviations between wavelength channels are suppressed. An optical demultiplexer includes a wavelength-group demultiplexer that demultiplexes multi-wavelength light into wavelength groups formed from wavelength channels, and channel demultiplexers that demultiplex each wavelength group into wavelength channels light. An optical multiplexer includes channel multiplexers that multiplex modulated signal light of each wavelength channel for each wavelength group, and a wavelength-group multiplexer that multiplexes, for each wavelength group, WDM signal light output from the channel multiplexers. The FSR of the wavelength-group multiplexer/demultiplexer is set to be equal to or greater than the frequency band of the multi-wavelength light. The channel multiplexer/demultiplexer is an AWG in which the FSR is approximately the full width at half maximum of the transmission characteristics of each port of the wavelength-group multiplexer/demultiplexer.

Multi-wavelength optical modulation circuit and wavelength-division multiplexed optical signal transmitter

With respect to the relative intensity noise (RIN) for inputs to an optical modulator or the signal-to-noise ratio (SNR) for outputs therefrom, the optical modulator modulating coherent lights of different wavelengths obtained by slicing a spectrum of the multi-wavelength light, the shape of a spectrum of a multi-wavelength light is controlled so that predetermined RIN and SNR can be obtained in accordance with transmission system parameters (the type and distance of optical fibers, the number of repeaters), thus enabling design meeting a performance specification for a conventional transmission section using semiconductor lasers.

Multi-wavelength generating method and apparatus based on flattening of optical spectrum

A multi-wavelength generating apparatus generates a wavelength division multiplexing (WDM) signal by modulating light with a single central frequency and with an electric signal having a particular pulse repetition frequency. The resulting optical spectrum configuration is controllable so that a Relative Intensity Noise (RIN) or Signal to Noise Ratio (SNR) requirement may be achieved. A modulated or pulsed light source is used to obtain a discrete spectrum with particular mode spacing, which is then modulated to permit dynamic power control for specific modes of the discrete spectrum.

Amulti-wavelength generating apparatus generates a wavelength division multiplexing (WDM) signal by modulating light with a single central frequency and an electric signal having a particular pulse repetition frequency. The resulting optical spectrum configuration is conntrollable so that a Relative Intensity Noise (RIN) or Signal to Noise Ratio (SNR) requirement may be achieved. A modulated or pulsed light source in used to obtain a descrete spectrum with particular mode spacing, which is then modulated to permit dynamic power control for specific modes of the discrete spectrum.

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Tokyo, Japan

Katsuhiro Araya