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 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: 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 network system for interworking a Wireless Local Area Network (W-LAN) and a 3rd-Generation (3G) mobile communication network through a Radio-over-Fiber(RoF) link and an authentication method in interworking in the network system are provided. The network system includes a 3G mobile communication network and a W-LAN system. The 3G mobile communication network includes a voice signal processing network connected to a Public Switched Telephone Network (PSTN) for voice call processing with respect to a predetermined mobile terminal, a packet data network for data communication with the predetermined mobile terminal, and a terminal device for communication with the predetermined mobile terminal. The W-LAN system is connected to the packet data network of the 3G mobile communication network to provide a W-LAN service to the predetermined mobile communication terminal.

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.

Abstract: A duobinary optical transmission device provides duobinary optical transmission with improved quality by a technique that does not require an electrical low pass filter LPF.A duobinary optical transmission device includes at least one semiconductor optical amplifier (SOA). A light source outputs a carrier wave as an optical signal. A precoder encodes an input of a non-return-to-zero (NRZ) electrical signal. An interferometer type semiconductor optical amplification unit modulates the carrier wave according to a change of an applied bias current coupled to the encoded signal. An optical band pass filter (OBPF) receives the phase-modulated optical signal from the semiconductor optical amplification unit, filters the received phase-modulated optical signal according to a designated band, and outputs an optical duobinary signal.

Abstract: Disclosed is a remote antenna unit and a wavelength division multiplexing network. The remote antenna unit includes: an optical circulator having a plurality of ports; an electric field absorption modulator having a first input/output end and a second reflective end, the electric field absorption modulator configured to demodulate an optical signal into a first data signal, and modulate the demodulated optical signal according to a second electric data signal; and a filter disposed between the optical circulator and the electric field absorption modulator, for the filter configured to transmit an optical signal having a particular wavelength from among optical signals input from a port of the optical circulator toward the electric field absorption modulator and reflecting the remaining optical signals into the port of the optical circulator, and inputting the optical signal from the electric field absorption modulator into the port of the optical circulator.

Abstract: A multi-wavelength bidirectional optical transceiver includes a plurality of optical transmitters for generating and outputting forward optical signals, a plurality of optical receivers for performing optoelectric conversion on reverse optical signals, a band splitter for outputting the forward optical signals that are input from the plurality of optical transmitters to outside the multi-wavelength bidirectional optical transceiver and for outputting reverse optical signals that are input from outside the multi-wavelength bidirectional optical transceiver to the plurality of optical receivers, a power splitter on an optical path between the plurality of optical transmitters and the band splitter for power-splitting the forward optical signals that are input from the plurality of optical transmitters and for outputting portions of the forward optical signals to the band splitter, and a plurality of monitors for performing optoelectric conversion on the remaining portions of the forward optical signals that are

Abstract: Disclosed is a duobinary optical transmission apparatus using a semiconductor optical amplifier (SOA). The duobinary optical transmission apparatus includes a light source for generating a carrier wave; a duobinary precoder for encoding an input (non return to zero) electric signal; a semiconductor optical amplification unit to amplify the encoded signal from the duobinary precoder, wherein the amplification unit receives an optical amplification gain difference that varies with a bias current combined with the encoded signal; and an optical band pass filter for receiving a phase-modulated optical signal from the semiconductor optical amplification unit, filtering the received optical signal to a prescribed bandwidth, and thereby generates a duobinary optical signal.

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: Disclosed is a duobinary optical transmission apparatus. The duobinary optical transmission apparatusenhances nonlinear and dispersion characteristics for an intermediate-long distance transmission at a high-speed transfer rate without the use an electric LPF. The duobinary optical transmission apparatus includes a light source for generating a carrier wave, a duobinary optical signal generator for receiving a Non Return to Zero (NRZ) signal and generating a modulated optical signal generated by modulating the carrier wave according to the NRZ signal, and a Return to Zero (RZ) signal generator for converting the NRZ signal into a RZ (Return to Zero) signal. Therefore, optical intensity and a phase are modulated using only a single interferometer-type optical modulator.

Abstract: A metro wavelength division multiplexing network is disclosed and includes a plurality of optical repeaters connected to each other through an optical fiber link, wherein each of the optical repeaters includes a Raman gain medium for Raman-amplifying inputted optical signals, an amplification medium having a center wavelength different from a gain center wavelength of the Raman gain medium and amplifying a Raman-amplified optical signals, and a pumping unit for pumping the Raman gain medium.

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 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.

Abstract: Disclosed is a remote antenna unit and a wavelength division multiplexing network. The remote antenna unit includes: an optical circulator having a plurality of ports; an electric field absorption modulator having a first input/output end and a second reflective end, the electric field absorption modulator configured to demodulate an optical signal into a first data signal, and modulate the demodulated optical signal according to a second electric data signal; and a filter disposed between the optical circulator and the electric field absorption modulator, for the filter configured to transmit an optical signal having a particular wavelength from among optical signals input from a port of the optical circulator toward the electric field absorption modulator and reflecting the remaining optical signals into the port of the optical circulator, and inputting the optical signal from the electric field absorption modulator into the port of the optical circulator.

Abstract: A network system for interworking a Wireless Local Area Network (W-LAN) and a 3rd-Generation (3G) mobile communication network through a Radio-over-Fiber(RoF) link and an authentication method in interworking in the network system are provided. The network system includes a 3G mobile communication network and a W-LAN system. The 3G mobile communication network includes a voice signal processing network connected to a Public Switched Telephone Network (PSTN) for voice call processing with respect to a predetermined mobile terminal, a packet data network for data communication with the predetermined mobile terminal, and a terminal device for communication with the predetermined mobile terminal. The W-LAN system is connected to the packet data network of the 3G mobile communication network to provide a W-LAN service to the predetermined mobile communication terminal.

Abstract: A Base Transceiver Station (BTS) for interworking a Wireless Local Area Network (W-LAN) and a mobile communication network through a Radio-over-Fiber (RoF) link is provided. The BTS having mobile and fixed wireless service distribution functions includes a Wireless Local Area Network Access Point (W-LAN AP), a wireless service function block, a Radio Frequency (RF) converter, and an optical transmitter. The wireless service function block performs transmission/reception to/from a predetermined mobile terminal via a connection for the voice call communication and data communication with an external Base Station Controller (BSC). The RF converter performs a data communication connection with the external BSC, up-converts data from the BSC into W-LAN frequency band data, and down-converts data to the BSC into baseband data. The optical transmitter transmits the up-converted data of the packet data RF converter to the W-LAN AP through a RoF link.