Abstract: A method and apparatus for measuring a distance in a wireless environment are provided, in which a first device transmits a distance measurement signal to a second device and receives at least one response signal for the distance measurement signal from the second device, matches the received response signal with a reference signal to detect an earliest response signal, and calculates a time taken from the transmission of the distance measurement signal to the second device and the reception of the response signal from the second device using a peak value of the matched reference signal.

Abstract: A method for transmitting/receiving data in an orthogonal frequency division multiple access-time division duplex (OFDMA-TDD) scheme. A first uplink signal and a first downlink signal of a specific band are periodically transmitted/received within a time-divided section. A second uplink signal and a second downlink signal are periodically transmitted/received, and the second signal is of a band other than the specific band, within the time-divided section, wherein, during a time section in which the first downlink signal is transmitted, the second uplink signal is received.

Abstract: Disclosed is an RoF system providing an HD wireless communication service.

Abstract: A method, apparatus and system for increasing cell capacity through optional signal combining between Relay Stations (RSs) in a cellular system using wired RSs is disclosed.

Abstract: A photoelectric cross-connect system for an optical-communication system minimizes service recovery time when an error is generated. A plurality of nodes are connected by an optical-transmission line wherein each nodes automatically recognizes a data rate of an input signal and communicates over a redundant channel with an adjacent node when there is a certain type of error. An optical-receiving unit receives an optical signal performs O/E conversion. A main optical-transmitting unit recovers clock and data signals according to the converted signal and sets a data rate according to the converted signal for subsequent transmission; a redundant optical-transmitting unit recovers a clock and data according to the converted signal and sets a data rate according to the converted signal for subsequent transmission A switch provides selectively connection state between the optical-receiving unit and the main optical-transmitting unit and between the optical-receiving unit and the redundant optical-transmitting unit.

Abstract: Disclosed is a device for allocating transmission power using a symbol error rate (SER) for orthogonal space-time block codes (OSTBC) in a wireless communication system. The device includes: a plurality of antennas, which are distributed geographically and independently linked to a central processing unit; a receiver to select an optimum subset of the SER performance, using a preset power allocation to each of available antenna subset combinations, and sending the selected subset to a transmitter; and a central processing unit to allocate power by applying an OSTBC symbol having a unit average power to the optimum subset from the receiver.

Abstract: A method and apparatus for transmitting data to an Access Point (AP) and a Mobile Station (MS) in a Time Division Duplex (TDD) optical repeater. A main donor generates a control frame for controlling a remote, upon receipt of data from the AP, and transmits the control frame to the remote during a non-downlink transmission period. The remote analyzes the control frame received from the main donor, detects sync information about a downlink signal and an uplink signal, and remote control information from the analyzed control frame, performs a control operation according to the detected remote control information, and generates a status frame for notifying the main donor of the status of the remote upon receipt of data from the MS. The status frame is transmitted from the remote to the main donor during a non-uplink transmission period.

Abstract: Disclosed are a method and a system for generating switching control signal separating transmission signal on an access point and a mobile communication terminal in an optical repeater employing, for example, a TDD scheme. The method includes the steps of generating a control signal for generating a switching control signal in transmitting data from the AP and transmitting the control information to a remote during an idle time interval, detecting synchronization information on the downlink signal and time-delay information from the control information, delaying a time interval between the synchronization information and a starting point of the downlink signal, generating the switching control signal for the downlink signal according to the transmission time information of the downlink signal, and performing a switching operation according to the switching control signal and setting a downlink path.

Abstract: A method of assigning radio resources in a cellular system using wired Relay Stations (RSs) includes: a Base Station (BS) gathering feed-back control information of all Mobile Stations (MSs) via the RSs in a cell of the BS; a first process, wherein the MSs are divided into two groups according to a channel state of each MS; a second process, wherein sub-channels are dynamically assigned to MSs belonging to a group, in which a channel state of each MS is good, of the two groups; and a third process, wherein sub-channels are dynamically assigned to MSs belonging to a group, in which a channel state of each MS is bad, of the two groups by considering a resource state per RS and a channel gain between sub-channels.

Abstract: An apparatus that adaptively allocates transmission power for beam-forming combined with orthogonal space time block codes in a distributed wireless communication system, the apparatus including: sub-arrays for beam-forming, which are geographically distributed and each of which includes a plurality of distributed antennas placed in random groups. A central processing unit provides predetermined combinable power allocation schemes according to subsets in a plurality of the sub-arrays, identifying performances of the schemes by using information on large-scale fading of each of the sub-arrays fed back from a receiving party, setting a subset having best performance as an optimal subset according to the identified performances, and performing power allocation according thereto.

Abstract: An optical wireless communications network connects a plurality of communication cells, which are defined by dividing a local communication area, for enabling optical wireless communication in each of the communication cells. An optical signal transmitter is installed in each communication cell for irradiating the cell with a data-modulated optical signal to perform data transmission to a terminal located therein. The optical signal transmitter comprises an optical signal source for outputting the data-modulated optical signal, and an optical signal diffuser with a concave inside surface facing the output end of the optical signal source for diffusing and reflecting the data-modulated optical signal to irradiate the cell.

Abstract: A single wavelength bi-directional RoF link apparatus for signal transmission in a TDD wireless system includes a main donor for receiving an RF signal of downstream data from an upper layer, electrooptic converting the received RF signal to an optical signal, and transmitting the converted optical signal via an optical fiber in response to a TDD switching signal received from the upper layer, or receiving an optical signal of upstream data via the optical fiber, opto-electric converting the received optical signal to an RF signal in response to the TDD switching signal received from the upper layer, and transmitting the converted optical signal to the main donor; and a remote for receiving the optical signal of the downstream data via the optical fiber from the main donor, opto-electric converting the received optical signal to an RF signal, and emitting the converted RF signal to a terminal via an antenna in response to a TDD switching signal generated by a switch timing signal generation circuit, or receiv

Abstract: A multichannel bidirectional optical transceiver is disclosed. The transceiver includes an optical fiber transmitting downstream optical signals and receiving upstream optical signals, a plurality of vertical surface light-emitting sources that generate the downstream optical signals and a plurality of vertical surface light-receiving detectors that receive the upstream optical signals. The transceiver also includes an optical coupler that outputs the downstream optical signals and the upstream optical signals received through the optical fiber to the optical fiber and the vertical surface light-receiving detectors, respectively.

Abstract: Disclosed is a radio-over-fiber (ROF) system for supporting various services, the system comprising: a central access platform (CAP) for providing time division duplexing (TDD), frequency division duplexing (FDD), and broadcasting services, converting a TDD downward signal and FDD/broadcasting downward signals into optical signals, respectively, transmitting the converted optical signals to a remote access unit (RAU), converting a TDD upward signal and an FDD upward signal, which have been transmitted as optical signals from the RAU, into electric signals, respectively, and using an optical circulator in order to separate upward and downward signals from each other; and the RAU for converting the TDD downward signal and FDD/broadcasting downward signals transmitted from the CAP into electric signals, respectively, converting the TDD upward signal and FDD upward signal to be transmitted to the CAP into optical signals, respectively, and using an optical circulator in order to separate upward and downward signa

Abstract: A remote access unit (RAU) apparatus, coupled to a central station (CS) of an RoF network through at least one optical fiber, and which RAU apparatus includes at least one antenna, includes: first and second antenna ports coupled to the at least one antenna; first and second optical fiber ports coupled to the at least one optical fiber; a first coupler for decoupling a first downstream signal of a first duplexing method and a second downstream signal of a second duplexing method, which are input through the first optical fiber port; a circulator for outputting the first downstream signal input from the first coupler to the first antenna port and outputting a first upstream signal of the first duplexing method input from the first antenna port to the second optical fiber port; and a second coupler for outputting the second downstream signal input from the first coupler to the second antenna port and outputting a second upstream signal of the second duplexing method input from the second antenna port to the sec

Abstract: A method for correcting write strategy data of an optical disc may include setting initial values, measuring and storing the width of a generated write enable signal, and calculating an offset correction value. The initial values may include a data write rate, a number of write strategy data, a maximum number of steps of a time parameter to be applied to the write strategy data, step sizes of the steps in the time parameter, and a generated modulated signal. A write enable signal may be generated whenever the time parameter is varied by a step size, and a width thereof may be measured and stored. The offset correction may be determined by calculating an offset correction value corresponding to a difference between the stored width of the write enable signal and a predetermined value of the write enable signal.

Abstract: A radio over fiber (ROF) link apparatus capable of a stable TDD wireless service for a time division duplexing (TDD) baseband signal includes a central access platform (CAP) for receiving various kinds of data including the TDD baseband signal from upper layers, multiplexing the data, electro-optically converting the multiplexed data, and transmitting the converted data as downstream data through an optical fiber, and opto-electrically converting upstream data received through the optical fiber, demultiplexing the converted upstream data, and transmitting the demultiplexed upstream data to the respective upper layers, and a remote access unit (RAU) for receiving the downstream data through the optical fiber, opto-electrically converting the received downstream data to the multiplexed data, demultiplexing the multiplexed data, performing a wireless access process of the demultiplexed data, and transmitting the wireless access processed data to a wireless local area network (WLAN) service terminal through an an

Abstract: Disclosed is an ROF link apparatus for selecting an IF band in order to process various service signals through an MMF, which including transmitters for receiving the service signals, performing IF modulation for the service signals, and transferring the modulated IF signals, a first controller for scanning frequency characteristics of the MMF, searching for flat frequency bands, and transferring information regarding the flat frequency band, thereby controlling IF modulation to be performed, a link unit for combining the IF signals with output signals of the first controller, converting the combined signals into optical signals, transmitting the optical signals, converting the optical signals into electrical signals, and splitting the electrical signals, a second controller for receiving the output signals of the first controller, detecting information regarding the flat frequency band, and transferring the information to receivers, thereby controlling modulation to be performed, and the receivers for receiv

Abstract: Disclosed are an apparatus and a method for shortening a processing time at each node in an optical network. A transmission optical cross-connect (OXC) determines a transmission rate corresponding to the transmission speed of the signal to be transmitted. An optical receiver and an optical transmitter are stabilized by means of the transmission rate. In addition, a transmission OXC transmits the transmission rate to an OXC aligned between the transmission OXC and the receiving OXC, thereby stabilizing the OXC. Each of the OXCs detects the transmission speed of the optical signal to be received so that a time required for converting the transmission speed is reduced.

Abstract: Disclosed is a remote access unit for transmitting and receiving upstream and downstream data in which channels having different transmission scheme are multiplexed, and an optical network for bi-directional wireless communication using same. The remote access unit includes an antenna for receiving the downstream data and wirelessly transmitting same and for receiving the upstream data and providing same to the remote access unit, a switch for outputting downstream time division channels of the downstream data to the antenna and for receiving upstream time division channels of the upstream data from the antenna, and a controller for controlling the switch in order to prevent the upstream and downstream time division channels from overlapping.