Abstract: A phase excursion/carrier wave frequency excursion compensation device has a signal dividing unit, a preprocessing compensation circuit, post-processing compensation circuits, a signal combination unit, a correction amount calculation unit, and a signal correction unit. The preprocessing compensation circuit and the post-processing compensation circuits calculate a phase compensation amount with respect to the input signal, and output the phase compensation amount, and a compensation circuit output signal such that the input signal can be compensated accordingly. The signal combination unit acquires compensation circuit output signals from the post-processing compensation circuits and, based on order of input to the signal dividing unit, outputs rearranged signals.

Abstract: An optical receiver according to the invention includes a polarization diversity unit receiving a polarization multiplexed optical signal obtained by multiplexing two optical signals having a same frequency band of carrier waves and polarization states orthogonal to each other, and a frequency domain equalization unit receiving signal components parallel to mutually orthogonal polarization axes from the polarization diversity unit, wherein the frequency domain equalization unit includes filters for which filter coefficients thereof are set for compensating degradation of transmission characteristics in one optical signal without polarization multiplexing by means of the frequency domain equalization.

Abstract: In order to appropriately demultiplex the polarization multiplexed BPSK signal without using a training sequence and decreasing the resistance to a frequency offset, an optical receiver includes a coherent optical detection unit receiving an optical signal in which BPSK modulated carrier waves are polarization-multiplexed, performing coherent detection by mixing the received optical signal with local light, and outputting first electrical signals corresponding to the carrier waves; a butterfly FIR filter receiving the first electrical signals and extracting second electrical signals corresponding to each of the carrier waves from the first electrical signals; and a coefficient control unit for calculating a sum of respective phases of the second electrical signals output from the butterfly FIR filter, adaptively controlling tap coefficients of the butterfly FIR filter so that the calculated phase sum may become equal to 0 or ?, and outputting tap coefficients after being controlled to the butterfly FIR filter

Abstract: In order to improve degradation of receiving sensitivity caused by analog characteristics degradation in an optical receiver, the optical receiver includes: the first coefficient computing unit for computing the first equalization filter coefficient for compensating the first waveform distortion caused and formed by an optical transmission path; the second coefficient calculating unit for predetermining the second equalization filter coefficient for compensating the second waveform distortion caused and formed by an analog characteristics degradation of components; a coefficient operating unit for performing operation to the first equalization filter coefficient and the second equalization filter coefficient and outputting the third equalization filter coefficient; and a waveform equalization processing unit including a waveform equalization filter for performing an equalization process to an input signal including the first waveform distortion and the second waveform distortion based on the third equalizatio

Abstract: Provided in the EoE technique are the node, the network, the correspondence relationship generating method and the frame transfer program to avoid traffic concentration on a specific link to improve throughput of the network as a whole by realizing optimum path transfer. The frame switching unit includes the frame analysis unit for analyzing an input frame kind and the like, the table search unit for obtaining frame rewriting information and output port information, the forwarding table storage unit for managing an output port of a frame, the MAC learning unit for executing MAC address learning, the EoE-MAC learning unit for learning a relationship between a MAC address and an EoE-MAC address, the STP control unit for executing processing of a spanning tree, and the like.

Abstract: In order to reduce influence of noise due to a phase deviation, and to estimate an amount of phase compensation with superior accuracy in a polarization multiplexing/demultiplexing optical communication system, a signal processing circuit includes: optical frequency deviation estimating unit for estimating a frequency deviation which is a difference between a frequency of local light and a frequency of the optical carrier wave which is included in a signal data which corresponds to the polarizations and are generated by mixing a plurality of the optical carrier waves with the local light, which optical carrier wave is phase-modulated and have polarizations able to be demultiplexed and for outputting the estimated frequency deviation as an estimated value; for outputting the estimated frequency deviation as an estimated value; optical frequency deviation compensation amount analyzing unit for calculating an amount of frequency compensation which is an amount of compensation to make a phase of the signal data r

Abstract: Provided is a polarization separation device which converges filter coefficients used in polarization separating process more quickly.

Abstract: In a polarization demultiplexing optical communication system (1000), an optical transmitter (100) provides a predetermined frequency deviation between carrier wave frequencies of optical signal to be transmitted, and provides a periodic fluctuation having a predetermined frequency to the light intensity of the optical signal to be transmitted. An optical receiver (300) extracts intensity information of a frequency component of the periodic fluctuation from the received optical signal, and calculates a wavelength dispersion value of the optical transmission line on the basis of the extracted intensity information. For this reason, it is possible to measure the wavelength dispersion value of the optical transmission line while operating the optical communication system.

Abstract: A coherent receiver 1 assigns a first transmission signal to first transmission polarization, assigns a second transmission signal to second transmission polarization, and receives a quadrature multiplexed signal formed by applying quadrature multiplexing to the first transmission polarization and the second transmission polarization.

Abstract: In a phase excursion/carrier wave frequency excursion compensation device, increasing compensation processing speed using parallel processing deteriorates the transmission property.

Abstract: In a polarization demultiplexing optical communication system (1000), an optical transmitter (100) provides a predetermined frequency deviation between carrier wave frequencies of optical signal to be transmitted, and provides a periodic fluctuation having a predetermined frequency to the light intensity of the optical signal to be transmitted. An optical receiver (300) extracts intensity information of a frequency component of the periodic fluctuation from the received optical signal, and calculates a wavelength dispersion value of the optical transmission line on the basis of the extracted intensity information. For this reason, it is possible to measure the wavelength dispersion value of the optical transmission line while operating the optical communication system.

Abstract: With respect to a coherent optical receiving apparatus, a polarization multiplexing light signal, whereupon a first signal is placed upon a first polarized wave light and a second signal is placed upon a second polarized wave light, is polarization divided upon the transmitting side thereof, and the first signal and the second signal cannot be received in correspondence with the transmitting side. Accordingly, disclosed is a coherent optical receiving apparatus, comprising a coherent light receiving unit that detects coherent light, and a signal processing unit that carries out signal processing that is set with control coefficients. The coherent light receiving unit receives a first polarized light that is modulated with a first transmitted signal and outputs a first detected signal, and simultaneously receives the first polarized light with a second polarized light that is modulated with a second transmitted signal, and outputs a second detected signal.

Abstract: A coherent receiver 1 assigns a first transmission signal to first transmission polarization, assigns a second transmission signal to second transmission polarization, and receives a quadrature multiplexed signal formed by applying quadrature multiplexing to the first transmission polarization and the second transmission polarization.

Abstract: An optical receiver according to the invention includes a polarization diversity unit receiving a polarization multiplexed optical signal obtained by multiplexing two optical signals having a same frequency band of carrier waves and polarization states orthogonal to each other, and a frequency domain equalization unit receiving signal components parallel to mutually orthogonal polarization axes from the polarization diversity unit, wherein the frequency domain equalization unit includes filters for which filter coefficients thereof are set for compensating degradation of transmission characteristics in one optical signal without polarization multiplexing by means of the frequency domain equalization.

Abstract: For eliminating a reduction in throughput in a network as a whole according to optimum path transfer technique which is the expansion of spanning tree protocol, a frame switching unit of the network has an STP control unit for, when a port state of a spanning tree is changed, notifying a table control unit of an identifier of the spanning tree and a port number of a predetermined port among the respective ports, the table control unit for setting, in a forwarding table storage unit, a received port number of a predetermined port as an output port in an entry in which a node ID is equivalent to a spanning tree identifier, and a table search unit for determining an output destination from among output ports obtained by acquisition of received frame information from a frame analysis unit.

Abstract: In a ring network to which a plurality of nodes are connected, even though a failure occurs in a link between a node and a client apparatus (a user terminal) or a node itself, communication between the node and the client apparatus can be achieved. Nodes (105a) and (105b) are provided, so that, even though a failure occurs at either one of the nodes in the link between the node and the client apparatus (102), communication can be done between the other node and the client apparatus (102) through the link. When the node (105a) has a failure, the node (105b) succeeds in operation of the node (105a) while the node (105a) holds a state of the node (105a) to avoid a steering operation or a lap protection operation, a packet disappearance in the packet ring caused by the operation, influence of traffics a packet route change, etc., consumption of CPU and memory resources, and a ring transfer band reduction.

Abstract: Nodes 901 and 902 have the same address. Upon reception of a broadcast packet whose TTL value is not zero from a ringlet 910a, a forwarding circuit 51 of each of the nodes 901 and 902 copies and transits the packet, and an address table 60 of each node learns the address based on the copied broadcast packet. Upon reception of a unicast packet whose destination is an address common to the two nodes from the ringlet 910a, the forwarding circuit 51 of one node 901 copies and transits the packet, while the forwarding circuit 51 of the other node 902 strips the packet, and each address tables learns the address. A filter circuit of the node 902 prohibits the passage of the packet from the ringlet 910a.

Abstract: A topological information management frame is classified based on the contents stored in the topological information management frame, and information stored in a database is updated based on the contents stored in the topological information management frame depending on the classification of the topological information management frame.

Abstract: The present invention provides a node capable of preventing the problems caused by switching between traffic communication paths when a link failure occurs. According to an embodiment of the invention, among ports of a node 10, ports P1 and P2 connected to a link between the node 10 and a node 20 are registered in a virtual port VP1, and ports P3 and P4 connected to a link between the node 10 and the node 30 are registered in a virtual port VP2. The virtual ports VP1 and VP2 are registered in a virtual port VP3 allocated to a virtual LAG group. When one link between the node 10 and the node 20 is disconnected, the node 10 transmits frames, which have been transmitted from a physical port connected to the link, from the virtual port including the physical port, among the virtual ports belonging to the virtual port VP3 allocated to the virtual LAG group.

Abstract: Nodes 901 and 902 have the same address. Upon reception of a broadcast packet whose TTL value is not zero from a ringlet 910a, a forwarding circuit 51 of each of the nodes 901 and 902 copies and transits the packet, and an address table 60 of each node learns the address based on the copied broadcast packet. Upon reception of a unicast packet whose destination is an address common to the two nodes from the ringlet 910a, the forwarding circuit 51 of one node 901 copies and transits the packet, while the forwarding circuit 51 of the other node 902 strips the packet, and each address tables learns the address. A filter circuit of the node 902 prohibits the passage of the packet from the ringlet 910a.