Abstract: Disclosed is a method for transmitting a reference signal for identification of each cell in a communication system including a plurality of cells each of which is identified by a cell identifier. The method includes receiving a cell identifier, and generating a block code corresponding to the cell identifier using a predetermined block code generator matrix, and generating a first part sequence using the block code; selecting a second part sequence in accordance with the cell identifier; generating a reference signal of a frequency domain using the first part sequence and the second part sequence; converting the reference signal of the frequency domain to a reference signal of a time domain through an Inverse Fast Fourier Transform operation and transmitting the reference signal of the time domain in a predetermined reference signal transmission interval.

Abstract: A method and apparatus are provided for calculating a log-likelihood ratio (LLR) for decoding in a receiver for a mobile communication system, wherein the method and apparatus determine selection bits for distinguishing four quadrants in a constellation representing signal points of transmission symbols, determine domain bits for distinguishing the signal points in each domain of the four quadrants according to a modulation order of the transmission symbols, repeat an operation of dividing a received signal into a real component and an imaginary component according to the number of determined domain bits, calculate and origin-shift absolute values of the real component and the imaginary component, and calculate LLRs for the selection bits. Further, the method and apparatus can subsequently calculate LLRs for corresponding domain bits each time the origin-shifted received signal is received.

Abstract: Disclosed is a method for receiving a signal by a receiver in a communication system, the method includes receiving a signal; estimating a first noise value by using a reference signal included in the received signal; estimating a second noise value by using at least one subcarrier which has been unused for a transmission of data and the reference signal; and when a difference between the estimated first noise value and the estimated second noise value is greater than a threshold value, demodulating the data by using an interference removal algorithm.

Abstract: A method of allocating sub-channel signal interleaving patterns to BSs forming a wireless communication system that divides a frequency band into a plurality of sub-carriers and including a plurality of sub-channels, which are a set of predetermined adjacent sub-carriers. The method includes: creating a basic orthogonal sequence having a length identical to a number of the sub-carriers forming the sub-channel; creating a plurality of sequences having a same length as the basic orthogonal sequence by cyclic-shifting the basic orthogonal sequence a predetermined number of times or performing a modulo operation based on a number of the sub-carriers forming the sub-channel, after adding a predetermined offset to the cyclic-shifted basic orthogonal sequence; selecting a predetermined number of sequences corresponding to a number of the BSs from among the plurality of sequences; and allocating the selected sequences as the sub-channel signal interleaving patterns for the BSs.

Abstract: Provided is an apparatus and method for compensating a timing offset in a broadband wireless communication system. A receiving apparatus for the timing offset compensation includes a selector, a first calculator, and a second calculator. The selector groups two or more adjacent tiles into one or more tile groups and selects one or more pilot pairs, each including adjacent pilot signals, from each tile group. The first calculator calculates an average phase difference between the pilot pairs. The second calculator calculates a timing offset using the average phase difference.

Abstract: An uplink (UL) power control apparatus and method in a broadband wireless communication system are provided. The Mobile Station (MS) includes a power controller for calculating a power compensation value using a last transmit power in a previous closed loop power control when a power control mode is changed to an open loop power control, and determining a transmit power according to the open loop power control using the power compensation value; and a transmitter for adjusting and transmitting the transmit power of a UL signal under control of the power controller.

Abstract: An apparatus and method for transmitting/receiving channel quality information (CQI) in a communication system having a frame including subchannels corresponding to the same frequency reuse factor or different frequency reuse factors. A base station (BS) allocates at least one of the subchannels in the frame to a subscriber station (SS), and sends a transmission request for a CQI for a subchannel desired to be received, to the SS. The SS measures channel quality for individual subchannels requested by the BS in response to the CQI request, and transmits the measured channel quality to the BS.

Abstract: Disclosed is a hard handover method and system for use in a Broadband Wireless Access (BWA) communication system. The method and system includes dividing a data transmission field for mobile stations (MSs) into a handover field and a normal user field, allocating at least one subchannel in the normal user field to non-handover MSs located in a non-handover region, allocating at least one subchannel in the handover field to handover MSs located in a handover region, and performing communication through the allocated at least one subchannel.

Abstract: A method and apparatus are provided for calculating a log-likelihood ratio (LLR) for decoding in a receiver for a mobile communication system, wherein the method and apparatus determine selection bits for distinguishing four quadrants in a constellation representing signal points of transmission symbols, determine domain bits for distinguishing the signal points in each domain of the four quadrants according to a modulation order of the transmission symbols, repeat an operation of dividing a received signal into a real component and an imaginary component according to the number of determined domain bits, calculate and origin-shift absolute values of the real component and the imaginary component, and calculate LLRs for the selection bits. Further, the method and apparatus can subsequently calculate LLRs for corresponding domain bits each time the origin-shifted received signal is received.

Abstract: Disclosed is an apparatus and a method for transmitting/receiving synchronization mode information in a wireless communication system. A transmission apparatus in the wireless communication system includes a mode information creating unit for creating operation mode information based on a determined utilized bandwidth, and a preamble generating unit for outputting a frequency domain preamble signal including the created operation mode information. A reception apparatus includes a signal receiving unit for receiving a frequency domain preamble signal, a bandwidth determining unit for determining a utilized bandwidth, and a mode information detecting unit for detecting operation mode information from the frequency domain preamble signal according to the determined utilized bandwidth.

Abstract: Disclosed is a method for transmitting a reference signal for identification of each cell in a communication system including a plurality of cells each of which is identified by a cell identifier. The method includes receiving a cell identifier, and generating a block code corresponding to the cell identifier using a predetermined block code generator matrix, and generating a first part sequence using the block code; selecting a second part sequence in accordance with the cell identifier; generating a reference signal of a frequency domain using the first part sequence and the second part sequence; converting the reference signal of the frequency domain to a reference signal of a time domain through an Inverse Fast Fourier Transform operation and transmitting the reference signal of the time domain in a predetermined reference signal transmission interval.

Abstract: Disclosed is a method for providing a pilot symbol for base station identification in a Multiple-Input Multiple-Output (MIMO) communication system having one or more transmission antennas, wherein the pilot symbol is comprised of a first sequence having a good cell identification characteristic and a second sequence for reducing a peak-to-average power ratio (PAPR) for all of pilot symbols.

Abstract: An apparatus and method for processing received signals in a handover of a MS in a BWA communication system including a plurality of BSs capable of providing a service to the MS. According to the method, the MS receives signals of different BSs and detects preambles for each BS from the received signals. Further, the MS measures channel quality information corresponding to each of the detected preambles and compares the measured channel quality information with a preset threshold value. Further, the MS processes the signals received from the different BSs based on a result obtained by comparing the measured channel quality information with the preset threshold value.

Abstract: Disclosed is a method for supporting a serving BS currently providing an MS with a communication service to perform handover in a broadband wireless access communication system which includes the MS, the serving BS and a target BS to which handover of the MS is directed. In such a method, the serving BS allocates the same sub-channel as that allocated to the MS in a specific time period by the target BS in the same time period, and information about the allocated sub-channel is transmitted to the MS.

Abstract: A system and method for allocating an adaptive modulation and coding (AMC) subchannel in a communication system for transmitting and receiving data through at least one antenna. A receiver examines at least one channel received from a transmitter, selects antenna transmission mode based on the examined at least one channel, selects an optimum frequency band based on the selected mode, and sends feedback information including selection information to the transmitter. The transmitter receives the feedback information from the receiver and allocates a frequency band to the receiver according to the received feedback information.

Abstract: A method for transmitting/receiving operation mode information in a broadband wireless access (BWA) communication system is disclosed. A transmission side maps a predetermined preamble pattern to an operation mode, and upon a change in operation mode, transmits a preamble pattern corresponding to the changed operation mode. A reception side receives the preamble pattern, detects an operation mode and a preamble code mapped to the preamble pattern, and acquires information from a frame section received according to the operation mode.

Abstract: A method of allocating sub-channel signal interleaving patterns to BSs forming a wireless communication system that divides a frequency band into a plurality of sub-carriers and including a plurality of sub-channels, which are a set of predetermined adjacent sub-carriers. The method includes: creating a basic orthogonal sequence having a length identical to a number of the sub-carriers forming the sub-channel; creating a plurality of sequences having a same length as the basic orthogonal sequence by cyclic-shifting the basic orthogonal sequence a predetermined number of times or performing a modulo operation based on a number of the sub-carriers forming the sub-channel, after adding a predetermined offset to the cyclic-shifted basic orthogonal sequence; selecting a predetermined number of sequences corresponding to a number of the BSs from among the plurality of sequences; and allocating the selected sequences as the sub-channel signal interleaving patterns for the BSs.

Abstract: A method for allocating a frequency to a subscriber station (SS) in handover operation in an Orthogonal Frequency Division Multiple Access (OFDMA) system. In the method, the SS checks safety channel frequencies for a target base station (BS), generates a safety channel frequency request message for requesting allocation of the checked safety channel frequencies, and transmits the safety channel frequency request message. Upon receiving the safety channel frequency request message from the SS, a serving BS allocates frequencies for a requested channel, and transmits an allocation message with the frequency allocation information to the SS. The serving BS transmits a channel allocation request message to the target BS according to the frequency allocation information. Upon receiving the channel allocation request message, the target BS allocates the safety channel frequencies to the SS.

Abstract: A device and method of displaying images using an afterimage caused by an optical illusion is disclosed In the device, a controller processes image data output from an image processing unit, thus generating an image display control signal and a motor control signal. A drive motor unit rotates a rotary display assembly at a speed in response to the motor control signal. A plurality of display units, individually designed to emit light beams at multi-angles, are orderly mounted on the rotary display assembly. The display assembly is rotated at a speed by the drive motor unit in response to the motor control signal while displaying images on the display units at multi-angles in response to the image display control signal, thus forming desired images due to an afterimage caused by an optical illusion.