Oki Electric Industry Co., Ltd.

Naoki Minato

Takeshi Kamijoh

Satoko Kutsuzawa

Akihiko Nishiki

Hideyuki Iwamura

Saeko Oshiba

Takashi Ushikubo

In a passive optical communication network system, an optical signal OCDM-coded is transmitted from an OLT to a first port of a circulator, which in turn transfers the signal from its second port to one end of a first SSFBG. The first SSFBG then decodes the signal of one channel to output the decoded signal from its one end to the second port of the circulator, which in turn transmits the decoded signal from its third port to an ONU. When the ONU transmits an optical signal to the third port of the circulator, the circulator transfers the signal from its fourth port to one end of a second SSFBG, which in turn encodes the signal to output the encoded signal from its one end to the fourth port of the circulator. The circulator then transmits the encoded signal from its first port to the OLT.

Passive optical communication network system extendable with codec modules

An OCDM communication system and a method for correcting failure of the same are provided. In the system, encoders and decoders are provided respectively for channels. Each encoder, including an SSFBG, encodes an optical signal using a code value determined according to distance between adjacent unit fiber Bragg gratings in the SFFBG. Each decoder, including an SFFBG, generates a received optical signal by decoding the encoded signal using a code value determined in the same manner. A set temperature of each encoder and decoder is calculated and a corresponding control signal is generated based on average power and error rate detection signals of each received optical signal. The temperature of each encoder or decoder is individually adjusted according to the control signal, which makes equal the code values of an encoder and decoder of a channel in which average power of a received signal has changed or error rate thereof is excessive.

Optical code division multiplexing communication system and method for correcting failure of the same

An OCDM signal generation section generates an encoded optical pulse signal by encoded an optical pulse signal. The encoded optical pulse signal is then inputted to a wavelength disperser and the time waveform of the encoded optical pulse signal is shaped to be outputted as a shaped and encoded optical pulse signal. A WDM signal generation section generates an optical wavelength division multiplexing signal. A OCDM signal extraction section then decodes the OCDM reception signal by using the same code as the time-spreading/wavelength-hopping code for each channel and generates a decoded OCDM reception signal.

Optical division multiplexing transmission and reception method and optical division multiplexing transmission and reception device

The present invention is an optical multiplex communication system in which an optical wavelength division channel and an optical code division channel can coexist, wherein a WDM channel sectionhas a wavelength demultiplexerand WDM channels Wto W. An optical pulse string-is demultiplexed by the wavelength demultiplexer, and for channel W, an optical pulsewith wavelength &#x3bb;is input to an intensity modulatorand converted into an optical pulse signal of channel W, and is output as a wavelength division optical pulse signal, where transmission information of channel Wis reflected. An optical delay unitprovides a required time delay to a wavelength division optical pulse signal, so as to not match a position of an optical pulse constituting a wavelength division optical pulse signalon a time base, and a position of a chip pulse constituting an encoded optical pulse signal which comes from an OCDM channel, and has a same wavelength as this optical pulse, on a time base.

Optical multiplex communication system and delay quantity adjustment method

An object of the present invention is to provide an OCDM transceiver with which the reduction amount of the intensity of the correlation waveform signal is smaller than that of a conventional device of the same type in the decoding step that comprises a time gate processing step. Hence, in the OCDM transceiver of the present invention that comprises an encoding portion and a decoding portion, the decoding portion is constituted comprising a decoder, clock extractor, and time gate. The decoder decodes an encoded optical pulse signal and separates the encoded optical pulse signal into a clock signal extraction signal and an optical pulse signal playback signal. The clock extractor extracts a clock signal from the clock signal extraction signal. Further, the time gate removes only the auto-correlation waveform component from the optical pulse signal playback signal. The auto-correlation waveform component is converted to an electrical signal by means of an optical receiver and generated as a reception signal.

Optical code division multiplexing transmission and reception method and optical code division multiplexing transceiver

An optical modulating circuit realizing a PPM is constituted by circuit parts having a frequency band equal to a data rate to provide a technique which increase the data rate. A first light source generates a first single wavelength signal serving as a continuous light having a first wavelength &#x3bb;as a wavelength of a carrier wave. A second light source generates a second single wavelength signal serving as a continuous light having a second wavelength &#x3bb;different from &#x3bb;as a wavelength of a carrier wave. For the first single wavelength signal and the second single wavelength signal, according to a transmission electric signal having information 0 or 1, an optical switch outputs a first single wavelength signal as an input optical signal when the information is 0. On the other hand, when the information is 1, the optical switch outputs the second single wavelength signal as an input optical signal. An optical modulator generates an optical pulse signal obtained by arranging optical pulses having &#x3bb;or &#x3bb;as a wavelength of a carrier wave at predetermined time intervals from the input optical signal. A delaying unit delays the optical pulse having the wavelength &#x3bb;and the optical pulse having the wavelength &#x3bb;by different delay time &#x394;t to obtain a PPM signal.

Optical modulating circuit and optical modulating method

An object of the present invention is to implement optical multiplexing transmission and reception in which an OCDM channel is added without changing the used wavelength bandwidth of the existing WDM channel or without changing the time slot allocated to the existing OTDM channel. Hence, one of the embodiments of the present invention is constituted as follows. The OCDM signal generation section generates an encoded optical pulse signal by encoding an optical pulse signal. The encoded optical pulse signal is inputted to the wavelength disperser and the time waveform of the encoded optical pulse signal is shaped to be outputted as a shaped and encoded optical pulse signal. The WDM signal generation section generates an optical wavelength division multiplexing signal. The OCDM signal extraction section decodes the OCDM reception signal by using the same code as the time-spreading/wavelength-hopping code for each channel and generates a decoded OCDM reception signal. The shaped and encoded optical pulse signal component that is contained in the decoded OCDM reception signal is restored by the inverse-wavelength disperser and a reproduced optical pulse signal is generated. Only the autocorrelation waveform component of the optical pulse signal constituting the OCDM transmission signal is extracted from the reproduced optical pulse signal by the first threshold value judgment section. In the WDM signal extraction section, the second threshold value judgment section extracts the WDM signal of each channel from the WDM reception signal.

There is provided an optical receiver in which a time gate can be realized with a simple, low-cost configuration, and which has few aspects that require adjustment. The optical receiver of the present invention comprises a decoding circuit in which optical signals which are spread over time in accordance with a coding pattern are inputted and decoded in accordance with a decoding pattern; and a time gate circuit for generating a time gate signal that represents the interval of time in which a significant optical pulse is present in the decoded optical signal, and controlling the passage of the decoded optical signal. The time gate circuit comprises optical splitting means for splitting the decoded optical signal from the decoding circuit into two, optical/electric conversion means for converting one of the split optical signals into an electric signal, time gate signal generation means for generating a time gate signal whose frequency is the fundamental frequency component in synchronism with the electric signal, and gate means for controlling the passage of the other split decoded optical signal in accordance with the time gate signal.

Optical receiver

To resolve problems, with the invention, an optical transmitter comprises an encoder for generating an optical signal obtained by encoding multi-wavelength pulses corresponding to sending data by use of a method of time spread/wavelength hopping in accordance with an encoding pattern of the encoder itself. The encoder concurrently executes time delay for every wavelength component at encoding, and time delay due to pre-compensation processing to pre-compensate for difference in propagation time for every wavelength component, occurring due to chromatic dispersion characteristics of a transmission line by &#x3b1;%. An optical receiver comprises a decoder for decoding the optical signal transmitted by the optical transmitter in accordance with a decoding pattern of the decoder itself. The decoder concurrently executes time delay for every wavelength component at decoding, and time delay due to dispersion equalization processing to compensate for difference in propagation time for every wavelength component, occurring due to chromatic dispersion characteristics of the transmission line by &#x3b2;%.

Optical transmitter, optical receiver and optical transmission system using same

According to the present invention, a code selection device wherein, an unused spreading code, or one of a plurality of unused spreading codes, is selected for allocation to a new communication channel, comprises: a dummy spreading signal generator for despreading dummy original data by using the unused spreading code or codes available for employment, and generating dummy spreading signals; a superimposing unit for superimposing the dummy spreading signals and received signals and forming pseudo superimposed signals; a despreading unit for despreading the pseudo superimposed signals by using the unused spreading codes related to the corresponding pseudo superimposed signals, and the spreading codes already used for communication channels that previously have been established; and a spreading code selector for selecting an unused spreading code based on data for the communication channels reproduced for the pseudo superimposed signals and the reproduced dummy original data. With this configuration, a method can be provided whereby, in accordance with the usage condition of a network, a code sequence having a preferable correlation property can be selected, from among a number of code sequences that are generated, and allocated to a communication channel.

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Tokyo, Japan

Naoki Minato