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: An apparatus and a method are provided for detecting N number of TX signals in a MIMO wireless communication system. The apparatus includes an RF processor, a channel estimator, and a signal detector. The RF processor converts signals, received through multiple antennas, into baseband signals. The channel estimator estimates channel information of the respective antennas by using the received signals. The signal detector arranges the baseband signals of the respective antennas on the basis of the channel information, calculates a threshold value of each stage, and selects symbols with a cumulative metric smaller than or equal to the threshold value as candidates at each stage, to detect a TX signal vector with N number of symbols.

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: Provided are a network-coding apparatus and method which can increase a data communication capacity in a communication environment to which an error-correction code (ECC) is applied. The network-coding apparatus includes a received signal processing unit receiving at least two signals, and decoding the at least two received signals; and a transmission signal processing unit receiving the at least two decoded signals from the received signal processing unit, merging the at least two decoded signals, and generating a merged transmission signal.

Abstract: Provided is a burst scheduling method in an Optical Burst Switching (OBS) system in which a plurality of nodes are connected through a mesh-type network. When a TDB which has used many network resources via a plurality of nodes and an SHG burst generated in a previous node, among bursts including BCPs transmitted from the previous node, compete in a current node so as to occupy a specific output channel, scheduling is performed to cause the TDB to have a higher priority than the SHG burst such that the corresponding output channel is occupied. Therefore, it is possible to minimize a burst loss in a network node, thereby enhancing the overall system performance.

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: 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: A method for improving power saving performance of a mobile station in an IEEE 802.16e system is provided.

Abstract: Provided is a fine frequency synchronization method of a WiBro system, and particularly, a fine frequency synchronization method which measures a spread degree of a received signal of an adjacent subcarrier using orthogonality of PN sequences and thereby estimates a frequency offset, in a base station or a wireless repeater without using a GPS receiver. The fine frequency synchronization method includes: (a) performing despreading on received adjacent subcarrier sequences, using a PN sequence transmitted from a transmitting party; (b) obtaining ratios of correlative values obtained by the despreading; and (c) estimating a frequency offset on the basis of the ratio of correlative values. Accordingly, fine frequency offset estimation with relatively low complexity is possible without using a GPS receiver in a WiBro environment where interference signals of other base stations or repeaters exist.

Abstract: A method for improving power saving performance of a mobile station in an IEEE 802.16e system is provided.

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 method and apparatus for classifying applications in traffic easily and accurately by utilizing only statistical data of traffic at transport layer. A method of the present invention includes determining candidate applications by comparing at least one of smallest packet size, biggest packet size and average packet size of collected packets for a flow with corresponding reference data of potential applications; and comparing mode set of packet size for the collected packets with corresponding reference data of the candidate applications to identify the flow as an application which has identical elements in the same order, the number of the identical elements being equal to or more than a predetermined number.

Abstract: Disclosed are a multiband output impedance matching circuit having passive devices, an amplifier including a multiband input impedance matching circuit having passive devices, and an amplifier including a multiband input/output impedance matching circuit having passive devices, which can be miniaturized without a separate output terminal buffer and reduce current consumption by using the passive devices.

Abstract: Disclosed are a method and apparatus capable of reducing the computational complexity of encryption and decryption by encrypting only data of scalable video coding contents for each coding layer in terms of temporal, spatial, and SNR scalabilities to provide a service for protected scalable video coding contents, and capable of protecting contents by generating and distributing an encryption key for encryption and decryption depending on a class of a contents consumer.

Abstract: An optical printed circuit board having an optical waveguide of at least one channel formed therein is provided. The optical waveguide of the at least one channel is stacked in the optical printed circuit board, and has both ends exposed on a surface of the optical printed circuit board and a predetermined length. An optical module is provided which can be optically aligned with the optical printed circuit board or another optical component through guide pins inserted into guide holes.

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: Provided are a network-coding apparatus and method which can increase a data communication capacity in a communication environment to which an error-correction code (ECC) is applied. The network-coding apparatus includes a received signal processing unit receiving at least two signals, and decoding the at least two received signals; and a transmission signal processing unit receiving the at least two decoded signals from the received signal processing unit, merging the at least two decoded signals, and generating a merged transmission signal.

Abstract: Provided is a fine frequency synchronization method of a WiBro system, and particularly, a fine frequency synchronization method which measures a spread degree of a received signal of an adjacent subcarrier using orthogonality of PN sequences and thereby estimates a frequency offset, in a base station or a wireless repeater without using a GPS receiver. The fine frequency synchronization method includes: (a) performing despreading on received adjacent subcarrier sequences, using a PN sequence transmitted from a transmitting party; (b) obtaining ratios of correlative values obtained by the despreading; and (c) estimating a frequency offset on the basis of the ratio of correlative values. Accordingly, fine frequency offset estimation with relatively low complexity is possible without using a GPS receiver in a WiBro environment where interference signals of other base stations or repeaters exist.

Abstract: An apparatus and a method are provided for detecting N number of TX signals in a MIMO wireless communication system. The apparatus includes an RF processor, a channel estimator, and a signal detector. The RF processor converts signals, received through multiple antennas, into baseband signals. The channel estimator estimates channel information of the respective antennas by using the received signals. The signal detector arranges the baseband signals of the respective antennas on the basis of the channel information, calculates a threshold value of each stage, and selects symbols with a cumulative metric smaller than or equal to the threshold value as candidates at each stage, to detect a TX signal vector with N number of symbols.