Abstract: A method for transmitting an orthogonal frequency division multiplexing (OFDM) signal in an optical network and apparatus therefor are provided. The method includes: converting a media access control (MAC) frame into an OFDM frame that contains a physical (PHY) level preamble, using the MAC frame which is transmitted from a MAC layer in a passive optical network (PON) to a PHY layer in an OFDM-PON; and transmitting the generated OFDM frame.

Abstract: A method and apparatus for transmitting a relay frame in a relay end are provided. The method includes: receiving a relay request frame requesting data transmission to a receive end from a transmit end; transmitting a relay response frame including information on data to be relayed to each of the transmit end and the receive end; receiving the data from the transmit end; and generating a relay frame including the data to transmit the relay frame to the receive end. According to the present invention, the data is transmitted to the receive end positioned outside a transmission coverage of the transmit end, such that a wireless LAN service coverage may be expanded, and an adjacent terminal connected to the receive end is used as the relay end, such that the transmit end that may not be connected directly to the receive end may communicate with the receive end.

Abstract: Provided is an apparatus and a method for partial monitoring of an optical fiber, wherein the optical fiber monitoring apparatus includes a monitoring light transmitter to continuously output a monitoring light to the optical fiber based on a number of measuring time sections generated by dividing an optical fiber monitoring time section, a monitoring light receiver to receive a monitoring light fed back from the optical fiber, measure a monitoring light received based on different measuring time sections for each monitoring light, and store a result of the measuring in a storage medium, and an optical fiber monitor to monitor a status of the optical fiber based on the result of the measuring stored in the storage medium.

Abstract: Provided is an optical transmission apparatus and method for uplink transmission in an orthogonal frequency division multiple access-passive optical network (OFDMA-PON), wherein the optical transmission apparatus includes a digital signal processor to output a baseband orthogonal frequency division multiplexing (OFDM) signal, a tone generator to generate a dithering tone, a synthesizer to synthesize the dithering tone and the baseband OFDM signal, and an optical source to output an output light in which a spectrum width is increased to be greater than a spectrum width of a carrier light based on the baseband OFMD signal synthesized with the dithering tone.

Abstract: An apparatus for cancelling an acoustic echo estimates power of a non-linear distortion component of a line amplifier from a signal generated by passing a far-end signal through the line amplifier, controls a gain of the line amplifier using a power estimate of the non-linear distortion component, generates an acoustic echo estimation signal from the far-end signal, and subtracts the acoustic echo estimation signal from a signal input through a microphone to cancel an acoustic echo signal.

Abstract: A method and an apparatus for a transmitter to transmit data in a wireless communication system are provided. This method includes: generating a first signal field including at least one symbol; generating a second signal field configured by repeating at least one symbol of the first signal field; and transmitting a frame including the first signal field, the second signal field, and a data field and a first symbol of the second signal field is modulated through binary phase shift keying (BPSK) and symbols from a second symbol of the second signal field are modulated through Q-BPSK. According to the present invention, a service filed can be extended while maintaining compatibility with a wireless communication system in the related art by transmitting a frame using symbol repetition.

Abstract: An apparatus for detecting a packet end point in a wireless communication system includes: a signal reception unit configured to receive a signal from an outside, convert the signal into a baseband signal, perform analog-digital conversion of the baseband signal, and perform a digital front end; a storage unit configured to store an output of the signal reception unit; a frequency offset estimation unit configured to estimate a frequency offset using the output of the storage unit; a frequency offset correction unit configured to compensate for a frequency error using the estimated frequency offset; an offset correlation unit configured to calculate correlation of the frequency offset and a cyclic prefix; an auto-correlation operation unit configured to calculate auto-correlation of the cyclic prefix; and a packet end detection unit configured to check a packet end point using the auto-correlation.

Abstract: An apparatus for acquiring synchronization in a multi-channel system includes a signal reception unit for receiving information about repetition patterns of signal streams for each channel and receiving the signal streams and data from the channel, an estimated synchronization point tracking unit for determining a estimated synchronization point for the channel from a point of time where the repetition patterns are ended by tracking a period where the signal streams are repeated based on the repetition patterns, and a synchronization acquisition unit for searching, based on the estimated synchronization point related to the channel, for a point where the repetition of the signal stream is ended or a point where new signal streams are started and acquiring a synchronization point based on the point.

Abstract: Disclosed is a loop-back apparatus in wireless communication systems, including: an MAC processing unit configured to transmit a user data and a control frame when a loop-back mode is established; a loop-back unit configured to generate a response frame of a receipt for the user data and the control message transmitted from the MAC processing unit and again feedbacks the generated response frame to the MAC processing unit.

Abstract: A channel sounding method in a wireless local area network (WLAN) system is provided. The method, performed by a transmitter, includes transmitting a null data packet announcement (NDPA) frame to a receiver to initiate a channel sounding procedure; transmitting a null data packet (NDP) to the receiver and receiving a feedback frame. The feedback frame includes a plurality of segment frames and a channel feedback report. The channel feedback report is split into a plurality of feedback segments. Each of the plurality of feedback segments is respectively included in each of the plurality of segment frames. The each of the plurality of segment frames includes a first-segment subfield indicating whether the each of the plurality of feedback segment included is a first segment and a remaining-segment subfield indicating the number of remaining feedback segments.

Abstract: A transmitter/receiver for a wireless communication system is provided. The transmitter for a wireless communication system includes: an external amplifier connected to a next stage of a power amplifier amplifying a signal to be transmitted to a required power level; a transmission selector configured to directly output the signal amplified by the power amplifier to an antenna or control the external amplifier to amplify the signal, based on a mode control signal; and a mode selector configured to compare a power level of a signal provided from a receiver with a predetermined power level to generate the mode control signal for determining whether or not to operate the external amplifier.

Abstract: A data communication method in a basic service set (BSS) of a wireless communication system using a carrier sense multiple access with collision avoidance (CSMA/CA) protocol includes: performing, by first and second nodes within the BSS, communication within a predetermined first time period; and transmitting, by a third node within the BSS, data to a fourth node within the first time period through a channel which is not used by the other nodes.

Abstract: Provided is a link adaptation method and apparatus in wireless communication system. The method, includes: amplifying a received signal; converting the amplified signal into a digital signal; calculating digital signal strength; and calculating the received signal strength based on the digital signal strength and a gain of said amplifying a received signal.

Abstract: A method and apparatus of selecting N metrics among M metrics is provided. The apparatus determines M metrics P(i), where i=1, . . . , M. Each P(i) is represented by B bits. The apparatus determines N metrics among M metrics. The complexity for configuring the circuit is decreased, and the length of the critical path is reduced.

Abstract: Provided are apparatus and method for transmitting and receiving data for a wireless communication system. The method includes generating a first aggregation packet by controlling the number of preambles or by controlling a size of a packet according to a channel state of a channel formed to at least one reception terminal or according to a state of the reception terminal, and transmitting the first aggregation packet to the reception terminal.

Abstract: Provided are an apparatus and method for compensating for a delay mismatch between an amplitude component signal and a phase component signal. The apparatus includes an amplitude path delay obtainer configured to obtain amplitude-delay information on a delay occurring in a propagation path of an amplitude component signal, a phase path delay obtainer configured to obtain phase-delay information on a delay occurring in a propagation path of a phase component signal, a delay controller configured to calculate and output a difference between the obtained amplitude path delay and the obtained phase path delay, and a variable delayer configured to compensate for a delay by changing a delay value on the basis of the delay difference output from the delay controller.

Abstract: Provided are a transmitter and receiver for a high throughput wireless communication system using a multiple antenna, a method thereof, and a digital intermediate frequency (DIF) transmission signal processing method for the same. The transmitter, includes: a baseband transmitting unit for processing a transmission signal by performing a Media Access Control (MAC) protocol process on transmission data and dividing the transmission data into n band signals where n is a predetermined natural number in a physical layer process; a DIF transmitting unit for integrating transmission signals of each band transmitted from the baseband transmitting unit and outputting m channels where m is a predetermined natural number; and a Radio Frequency (RF) transmitting unit for modulating each channel signal transmitted from the DIF transmitting unit into an RF signal and emitting the signal through the multiple antenna.

Abstract: Provided is an apparatus and method for encoding a Low Density Parity Check (LDPC) code using a message passing algorithm. The apparatus, includes: a parity calculating unit for operating a check node value on an input bit and a predetermined parity bit according to the message passing algorithm and calculating a parity bit; a parity correcting unit for correcting the calculated parity bit according to a parity check result of the calculated parity bit; and an output transform unit for combining the input bit and the corrected parity bit.

Abstract: A method for transmitting a frame in a wireless local area network system is provided. The method includes obtaining, by a station (STA), interference channel information of an interference channel between the STA and neighbor STA that is a frame transmission object of an access point (AP); determining, by the STA, a transmitting beam vector based on the interference channel information; and transmitting, by the STA, a data frame to a transmission target STA using a multiple input multiple output (MIMO) transmission based on the transmitting beam vector.

Abstract: An interleaving apparatus and method for an OFDM transmitter are provided. The interleaving apparatus comprises a memory unit, a memory write/read control unit, a memory access address generation unit, and a second permutation and output selection unit. The memory unit includes a plurality of memory banks, which are capable of being independently controlled so that data can be written or read in/from the memory banks, each having memory cells arranged in an N×M matrix structure. The memory write/read control unit generates control signals to write/read data in/from the memory unit. The memory access address generation unit generates a memory access address used to write/read data in/from the memory unit in response to the memory write/read control signals. The second permutation and output selection unit rearranges the positions of data bits output from the memory unit and outputs the position-rearranged data bits.