Abstract: A method and apparatus for supporting mobility of a mobile terminal in a Visible Light Communication (VLC) system. The method includes searching, by the VLC device, for a first mobile terminal in a plurality of cells; locating the first mobile terminal in a first cell among the plurality of cells; exchanging data with the first mobile using a light source of the first cell; determining whether a response signal corresponding to data reception is received from the first mobile terminal in the first cell; searching for the first mobile terminal in a neighboring cell of the first cell, if the response signal is not received; and determining the neighboring cell as a second cell for visible light activation, if the first mobile terminal is located in the neighboring cell.

Abstract: A system and method for transmitting and receiving a signal in a communication system using a relay scheme. A base station receives a first signal in a first time interval from a first mobile station which is at least one mobile station located in a third region which is a region where a first region which is a region of the base station itself overlaps with a second region which is a region of a relay station. The relay station receives a second signal in the first time interval from a second mobile station which is at least one mobile station located in a fourth region which is a region not overlapping with the first region in the second region, and receives the first signal from the first mobile station. The relay station transmits a third signal including the first signal and the second signal to the base station in a second time interval. The base station receives the third signal in the second time interval, and cancels the first signal from the third signal to detect the second signal.

Abstract: A ranging apparatus in a communication system is provided. A terminal generates a ranging code for ranging with a base station, maps the ranging code to at least one sub-carrier so the ranging code is repeated in a time domain, generates a ranging signal so the mapped ranging code has a size of one symbol interval, and transmits the generated ranging signal to the base station. The base station receives a ranging signal, extracts a half signal of a valid symbol interval of the ranging signal, generates a valid symbol interval signal by repeating the extracted half signal of the valid symbol interval, restores a ranging signal using the valid symbol interval signal, and performs ranging using the ranging signal.

Abstract: An apparatus and method for reducing MAP channel overhead in a broadband wireless communication system. In a Base Station (BS), a traffic classifier classifies transmission data into a first group and a second group according to user channel information and packet sizes of the transmission data. A MAP channel configure configures a MAP channel to include information about users of the first group and positions of data for the users, information indicating whether users of the second group have succeeded in random access in a second uplink data region of a previous frame, and information about resource reservation for a current frame for the second group. A channel mapper maps the first group to a first downlink data region and maps the second group to a second downlink data region according to the MAP channel.

Abstract: Provided is an apparatus and method for estimating an uplink frequency offset in a wireless communication system. In a receiving apparatus of a wireless communication system using a random access channel composed of two equivalent sequences, the apparatus includes a channel receiver which extracts samples corresponding to the two sequences from an input random access channel signal; a correlator which computes first and second correlation values by correlating preceding and trailing samples among the samples output from the channel receiver with a predetermined sequence; and a frequency offset estimator which estimates a frequency offset by using a ratio of the second correlation value to the first correlation value output from the correlator.

Abstract: A method and an apparatus are provided for guaranteeing terminal mobility in a time division visible light communication system. In resource assignment in a position where the visible light communication terminal changes a cell, the terminal is assigned a resource to be used in a next cell in a cell boundary area from a communication coordinator, thereby guaranteeing the continuous mobility. The visible light communication system informs the terminal of cell boundary notice information for easily informing the terminal of the cell definition so that the terminal can recognize that the terminal is currently located in the cell boundary and is necessary to change the resource.

Abstract: An apparatus and method for cooperative maximal ratio transmission in a BWA communication system are provided, in which a BS transmits a signal directed to a user terminal to an RS in a first time slot, the RS transmits the signal received from the BS to the user terminal in a second time slot, and the user terminal receives the signal from the RS.

Abstract: A method is provided for controlling power in a communication system. The power control method includes allocating a first data transmission region and a second data transmission region corresponding to a first communication scheme and second communication scheme; providing a communication service to a receiver through the first data transmission region, and receiving power control information from the receiver through the second data transmission region while providing the communication service; and adjusting a level of transmission power used for providing the communication service according to the received power control information, and providing the communication service to the receiver using the adjusted transmission power.

Abstract: A method and apparatus for joint unicast using multi-user superposition coding in a wireless relay system are provided. A BS superposition-encodes first and second data messages directed to first and second MSs, respectively, scheduled at a current scheduling instant. The first and second data messages carry first and second information bit streams for the first and second MSs, respectively. The first MS has a relatively good direct link to the BS, and the second MS has a relatively bad direct link to the BS. The superposition-coded data is transmitted to the first MS and an RS connected between the BS and the first and second MSs. The RS receives the superposition-coded data from the BS, extracts the second information bit stream by decoding the superposition-coded data, and transmits a third data message carrying the second information bit stream to the first and second MSs.

Abstract: A method is provided for transmitting/receiving data in a communication system. The method includes measuring, by a Mobile Station (MS), states of channels which are allocated in a scheme prearranged with a Base Station (BS), and encoding measured channel state information in a scheme corresponding to an allocation scheme of the allocated channels; and configuring a message including the encoded channel state information, and transmitting the configured message to the BS.

Abstract: A method and apparatus for supporting mobility of a mobile terminal in a Visible Light Communication (VLC) system. The method includes activating only necessary light sources for VLC considering the mobility of the mobile terminal, instead of using total light sources for VLC. Consequently, power consumption can be significantly reduced.

Abstract: A frame configuration method and apparatus for sending data via an RS in a broadband wireless communication system are provided. In the reception mode, the RS monitors reception of data in an (n?1)th frame from an MS and reception of data in an nth frame from a BS. The RS classifies the data received from the MS and the data received from the BS as combinable data to be sent in combination or as non-combinable data to be sent separately, and stores the classified data distinguishably. When the RS transitions to a transmission mode, it determines whether to XOR-operate or mask the stored data. If the stored data can be masked, the RS XOR-operates the stored data and sends the masked data to the BS and the MS.

Abstract: A base station PDCCH (Packet Data Control Channel) apparatus for scrambling transmission packet data to prevent other terminals from recognizing the transmission packet data in a base station including a packet data channel device for transmitting packet data to a terminal and a packet data control channel device for transmitting control information needed for demodulation of the packet data to the terminal. In the apparatus, an encoder encodes the control information and generates a coded control information stream comprised of a stream of a plurality of bits. A scrambler generates a scrambling sequence using unique information known to only the terminal and the base station, and scrambles the coded control information stream with the scrambling sequence.

Abstract: A system for performing cell acquisition in a frequency overlay communication system having a first frequency band and a second frequency band including the first frequency band. A base station (BS) generates a reference signal used for identifying a cell using a specific sequence in a predetermined frequency band, and transmits the reference signal. A mobile station (MS) receives the reference signal to determine whether the BS uses the first frequency band or the second frequency band, determines a reference signal having a maximum correlation value through correlation calculation with at least one predefined sequence, and detects a BS identifier (ID) corresponding to the determined reference signal.

Abstract: A method for transmitting a signal by a transmitter in a frequency overlay communication system. The method includes generating y first signal groups by shuffling input information data with a length yN on an N-by-N grouping basis according to a first shuffling scheme; generating y second signal groups by performing N-point IFFT on each of the first signal groups; generating y third signal groups by multiplying each of the second signal groups by preset values; generating N fourth signal groups by de-shuffling the third signal groups on a y-by-y grouping basis according to a de-shuffling scheme; generating N fifth signal groups by performing y-point IDFT on each of the fourth signal groups; generating y sixth signal groups by shuffling the fifth signal groups according to a second shuffling scheme, and serial-converting the sixth signal groups; and performing a transmission RF process on the serial-converted signal and transmitting the RF-processed signal to a receiver.

Abstract: Provided is a method and apparatus for transmitting/receiving data in a frequency overlay communication system. A transmitter generates a data stream for data transmission, and performs Inverse Fast Fourier Transform (IFFT) on the generated data stream according to a predetermined first frequency band before transmission. Upon receiving a particular signal, a receiver performs Fast Fourier Transform (FFT) on the received signal according to a predetermined second frequency band, and restores the received signal.

Abstract: A frequency resource operating apparatus and method for transmitting and receiving data at a different hopping pattern speed according to a CSI in a BWA communication system are provided. In a method of transmitting and receiving data using CSI in a mobile communication system, a BS sets the CSI of an MS to an initial CSI and sends data to the MS according to the initial CSI. The MS sends a downlink CSI to the BS. The BS groups the MS based on the downlink CSI and sends data to the MS according to a hopping pattern for the group of the MS among hopping patterns preset for predetermined groups.

Abstract: An apparatus and method for retransmitting data using an RS in a multi-hop network are provided. When retransmitting data in a BS, the BS transmits data and activates a timer therefor. The BS monitors receipt of a response message for the data until the timer expires. The BS receives the response message and, if it is a Non-Acknowledgement (NACK), determines whether an RS has successfully received the data with a BSN associated with the NACK. If the RS has not successfully received the data, the BS retransmits the data. If the RS has successfully received the data, the BS determines a retransmission entity. If the retransmission entity is the RS, the BS transmits a control message commanding retransmission to the RS, and if the retransmission entity is the BS, the BS retransmits the data.

Abstract: Provided are an apparatus and method for transmitting/receiving a pilot code pattern used to identify a base station. In the base station, a pilot code pattern determiner determines a code set that includes a number of spreading codes based on a specific ID of the base station. A first spreader spreads a pilot symbol mapped onto an FC with a corresponding spreading code according to the determined code set, and controls gain so as to transmit the pilot symbol at a higher signal level than data. A second spreader spreads data symbols mapped onto the FC with spreading codes of the code set except for the spreading code used for the pilot spreading. A mapper groups a spread signal from the first spreader and spread signals from the second spreader on a TFC basis, and outputs signals that constitute each TFC to points of sub-carriers. An IFFT unit performs an IFFT operation on signals output from the mapper. Because the pilot as well as the data is spread, it is easy to implement the base station.

Abstract: Disclosed are the design and implementation of a CSI feedback channel in a multi-carrier wireless communication system. An apparatus and a method for channel state feedback using arithmetic coding are provided to ensure efficiency and reliability of a system by transmitting the CSI while compressing the CSI with a predetermined compression rate selected depending on a channel state. The apparatus for CSI feedback in a wireless communication system performing channel estimation at a transmitter or a receiver by using a communication channel includes a transmitter terminal transmitting a signal for CSI measurement by using the communication channel, and a receiver terminal receiving the signal from the transmitter terminal, checking a channel state based on the received signal, and transmitting the signal to the transmitter terminal after compressing the signal according to the channel state.