Abstract: Benes networks include an input stage having a plurality of input ports, an input connection stage configured to connect output signals of the input stage, an add connection stage configured to connect outputs of the input connection stage and to connect inputs of add ports corresponding in number to the number of the plurality of input ports, a drop connection stage configured to connect outputs of the add connection stage, to output some outputs to a next stage, and to output some outputs to drop ports, an output connection stage configured to connect the some outputs of the drop connection stage to an output side, and an output stage configured to output the outputs of the output connection stage to output ports.

Abstract: Provided is a failure recovery method in a non-revertive mode of an Ethernet ring network. In an Ethernet ring network, link priorities between nodes or node priorities are determined based on media access control (MAC) addresses and the nodes having blocked ports are determined after failures are recovered from based on the priorities so that the blocked ports can be distributed.

Abstract: Apparatuses and methods are provided which suppress a surge component occurring at an optical amplifier on an optical path through which an optical burst signal is transmitted. An optical amplifier may experience a surge due to the power variation of the optical burst signal that is fed to the optical amplifier. To suppress such a surge component, a power corresponding to a number of wavelengths of an optical burst signal to be input is calculated. The optical amplifier is instructed to generate an optical signal with a power corresponding to a difference between a set value and the calculated power. The generated optical signal and the optical burst signal to be input are coupled and output according to the instruction. Thus, the optical amplifier can receive the optical signal with the constant power and the surge component at the optical amplifier can be suppressed.

Abstract: A timestamping apparatus and method are provided. The timestamping apparatus implements timestamping on a synchronization message at a physical layer when the synchronization message is transmitted to the physical layer. At an application layer of the timestamping apparatus, a bit stream including a start indicator bit informing a start of a pseudo random number sequence, the pseudo random number sequence, and an end indicator bit informing an end of the pseudo random number sequence is generated to check whether or not a message received from the physical layer is the synchronization message, and is inserted as signature information of the synchronization message. At the physical layer of the timestamping apparatus, the signature information included in the synchronization message is detected, and timestamping information is generated when the signature information is detected.

Abstract: The present invention, in preferred aspects, provides a communication method using a network coding packet in a wireless network, with reduced occurrence of negative acknowledgements, between a access point and plural mobile terminals.

Abstract: The present invention provides a method and apparatus for multicast transmission of a transmitting station in a wireless network. The method according to the present invention transmits a plurality of data packets to a plurality of receiving stations, receives information on loss of the plurality of the data packets from at least one of the plurality of the receiving stations, codes the plurality of the data packets into a single coded data packet based on the information on the loss of the plurality of the data packets and transmits an error control frame including the coded data packet to the plurality of the receiving stations. Therefore, when an error occurs at a data packet that a transmitting station transmits to a plurality of receiving stations by a multicast transmission, a number of retransmission of the data packet can be reduced.

Abstract: A method and apparatus for processing a timestamp using signature information on a physical layer is provided. The timestamp processing terminal uses a pseudo-random binary sequence to assign signature information to a message which is to be sent to another terminal, and verifies the signature information on a physical layer. The signature information is used to identify the message as a sync message. Accordingly, it is possible to precisely process the timestamp.

Abstract: An apparatus and method for effectively transmitting a packet data and a control data of path information about the packet data in an optical packet data switching network. The method includes grouping a plurality of wavelengths into at least two wavelength bandwidths, each wavelength bandwidth being composed of neighboring wavelengths, and transmitting the optical packet data and the control data with wavelengths of different wavelength bandwidths respectively. Since the wavelength to transmit the optical packet data and the wavelength to transmit the control data has a difference from each other, a node receiving optical data easily divides the packet data and the control data.

Abstract: Provided is an apparatus for transferring optical data in an optical switching system using time synchronization. The apparatus performs time synchronization on optical data to input the optical data at regular intervals through fiber delay line for time synchronization respectively disposed on input ports. Therefore, the apparatus can efficiently reduce a data blocking rate in comparison with a conventional optical switching system using an asynchronous electric buffer without a synchronous process, and achieve the same performance as conventional asynchronous technology despite using fewer wavelength converters and buffers, thus reducing system cost. In addition, using dynamic time synchronization modules, the apparatus performs time synchronization for minute time variation due to an environment such as temperature.

Abstract: Provided is a protection switching method via forwarding table correction in an Ethernet ring network. Upon detecting a failure in a link, a node generates a protection switching frame including an address list of a forwarding table corresponding to a port connected to the link, and transmits the protection switching frame to a port at an opposite direction of the link. A node that receives the protection switching frame deletes its own address from the address list included in the protection switching frame, and changes a port number of an address in the address list of the protection switching frame from among addresses of the forwarding table corresponding to a port that received the protection switching frame to a port number in an opposite direction of the port that received the protection switching frame or deletes the port number of the address in the address list.

Abstract: Disclosed are a forward discrete/inverse-discrete Fourier transform device and method for optical orthogonal frequency division multiplexing (OFDM) communication and a transmitting and receiving apparatus.The forward inverse-discrete Fourier transform device includes N 1:N splitters for splitting subcarrier signals received from N inputs corresponding to the number of optical frequencies of subcarriers, a phase shift delay array module for shifting phases of the split signals from the 1:N splitters, N N:1 power couplers for coupling signals output from the phase shift delay array module, a time delay array module for performing time delay on optical OFDM symbols from the N:1 power couplers, and an N:1 power coupler for coupling signals output from the time delay array module.

Abstract: Disclosed is an optical packet communication system using a wavelength-offset polarization-division multiplexing labeling. An optical signal transmitter which is provided at an ingress node positioned at a sending end in an optical packet switching network, generates and combines packet data and a label, and transmits the combined packet data and label to a core node, wherein the packet data and label have polarization directions perpendicular to each other and maintain a predetermined wavelength interval. A label swapping device detects the label from the combined packet data and label received from the optical signal transmitter, detects next moving position information of the packet data, for generating a new label, substitutes the detected label by the new label, combines the new label with the packet data, and transmits the combined packet data and new label to a next moving position.

Abstract: An apparatus for transforming a polarization and a method thereof are provided. The apparatus includes a polarization rotator for rotating a polarization plane of an input optical signal by a specified rotating angle, a polarization beam splitter for dividing the polarization of the optical signal output from the polarization rotator into first and second polarization components, a first monitoring unit for monitoring the first polarization component, a second monitoring unit for monitoring the second polarization component, and a controller for controlling a rotating angle of the polarization rotator so that strengths of the optical signals output from the first and second monitoring unit become equal to each other. Accordingly, a desired polarization component having a constant strength can be obtained by controlling only the rotating angle of the polarization rotator.

Abstract: Provided is a method of creating an address forwarding table in an Ethernet ring network. The method includes the steps of: broadcasting, at each Ethernet node, a ring learning frame having information for measuring cost in the frame's payload in both directions; and receiving, at each Ethernet node, two ring learning frames transferred from different Ethernet nodes and recording a ring learning frame containing information having the minimum cost in the Ethernet node's address forwarding table. Accordingly, by creating an intelligent address forwarding table, it is possible to efficiently prevent a loop without conventionally using a closed loop, and to rapidly transfer a frame through an optimal path.

Abstract: Disclosed is a method of establishing a network topology capable of carrying out a relay transmission among sub-networks in a backbone network having the plural sub-networks composed of at least one device. The method includes each of sub-master devices controlling communications in the respective sub-networks transmitting an ID request message to other sub-master devices; transmitting a response message from the other sub-master devices to the sub-master device having transmitted the ID request message; each of the sub-master devices assigning an ID to the sub-master device having no ID among the sub-master devices having transmitted the response message; and forming a network topology in accordance with whether or not the response message has been transmitted, and in accordance with the order of ID assignments, after the ID is assigned to all the sub-master devices in the backbone network. The network topology enables reliable communications among the respective sub-networks.

Abstract: An apparatus and method for transferring optical data in an optical switching system are provided. When optical data input to a node are in contention, the optical data are converted from optical signals to electrical signals and temporarily stored. When an output resource is available, the stored optical data are converted to the available output resource and transmitted to a desired destination node. This overcomes the buffering depth limit that is observed when a conventional optical fiber delay line is used. Accordingly, an optical data loss rate can be reduced such that optical data can be efficiently transferred. Further, non-contending optical data are directly delivered to output resource by the switching unit, thereby reducing the cost of optical/electrical conversion and wavelength conversion and enabling the apparatus to be implemented at low cost.

Abstract: A method and an apparatus for transmitting a single-band orthogonal frequency division multiplexing (OFDM)-based ultra wideband (UWB) signal over a pipeline carrying a cable television broadcasting signal. The method includes transforming a multimedia signal transmitted from a multimedia device into a wireline UWB signal; transforming the wireline UWB signal into a single-band OFDM signal; and frequency-spreading the single-band OFDM signal according to a transmission rate. Thus, the apparatus can be robust to multi-path interference and extend transmission distance so as to increase transmission efficiency.

Abstract: A time and wavelength division multiplexed passive optical network where a central office has a downstream transmitter and an upstream receiver. The downstream transmitter multiplexes and transmits downstream optical signals in a time region. The upstream receiver de-multiplexes, in a wavelength region, an upstream optical signal. An optical network unit has a downstream receiver and an upstream transmitter, where the downstream receiver de-multiplexes, in the time region, the downstream optical signals from the central office. The upstream transmitter multiplexes the upstream optical signal in the wavelength region and transmits the signal to the central office. A remote node, having an optical distributor and a wavelength division multiplexer, is connected between the central office and the optical network unit. The optical distributor distributes the downstream optical signals from the central office.

Abstract: Disclosed is a wavelength-division-multiplexed (WDM) passive optical network which comprises an optical network unit (ONU) for receiving and transmitting an optical communication service; a remote node having an amplifier for amplifying wavelength of light as being transmitted from the optical network unit; and a central office for receiving the amplified light. In accordance with the WDM passive optical network described herein, it is possible to enhance the quality of the optical communication service provided by the optical network.

Abstract: A wavelength converter for generating a wavelength tunable laser optical source in itself is disclosed. The wavelength converter includes a first semiconductor optical amplifier for generating an optical noise, generating and outputting a first optical source by amplifying the generated optical noise if an external current is applied, first and second distributed Bragg reflectors for reflecting only a component of a specified wavelength range among components of the optical noise and applying the reflected component to the first semiconductor optical amplifier, and a second semiconductor optical amplifier for receiving an optical source divided from the optical source reflected by and outputted from the first distributed Bragg reflector and an input data optical source, generating and outputting a second optical source by changing a phase of the divided optical source according to a digital signal from the input data optical source.