摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
A wireless mesh network system generates at least one virtual node within a transmission area of a specific mesh node when no mesh nodes exist in two or three continuous quadrants within the transmission area with reference to the specific mesh node. Also, the system performs routing by combining uplink and downlink routing methods so as to support unicast between the mesh nodes in a domain. Further, a channel access order of the mesh nodes is determined based on the potential values allocated to the mesh nodes forming the wireless mesh network according to the field theory. In this instance, the channel access order can be established by a central control method by a central processor for controlling the wireless mesh network or a distributed control method using contention per mesh node.
摘要:
A packet switching system includes a plurality of switch fabrics connected in cascade and a plurality of buffers respectively connected to the plurality of switch fabrics. In the event of packet competition, the plurality of switch fabrics buffer the competing packets to the corresponding buffers through buffer connection ports, and forward the competing packets in excess of the number of buffer connection ports to an adjacent switch fabric through switch connection ports.
摘要:
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.