Abstract: Disclosed is a transmission scheme for a transmitter according to a channel state in a communication system where the transmitter has M transmit antennas and a receiver has N receive antennas. Upon the input of data, the transmitter processes the data in a transmission scheme selected from among a plurality of transmission schemes, and transmits the processed data to the receiver. The receiver estimates the channel state of the received signal, selects a transmission scheme according to a channel state corresponding to the channel state estimation result, and feeds back to the transmitter transmission scheme information indicating the selected transmission scheme. The transmitter determines the transmission scheme corresponding to the received transmission scheme information.

Abstract: A method for receiving a signal from a radio unit in a base station having at least one reception antenna is disclosed. The method includes receiving a reception signal via the reception antenna, and generating an output signal using the reception signal and a reception beam weight for a previous time; calculating a cost function using a desired reception signal transmitted from the radio unit among the reception signal and the generated output signal; calculating a trace vector using the calculated cost function and the reception signal; updating the reception beam weight using the trace vector for a next time; and generating a reception beam by applying the updated reception beam weight.

Abstract: Disclosed are a method and a system for transmitting/receiving signals in a mobile communication system using a multiple input multiple output adaptive antenna array scheme. A first receiver calculates a reception weight value by using a de-spread signal of a reception signal for creating a reception beam of the first receiver and calculates a transmission weight value by using the calculated reception weight value for creating a transmission beam of the second transmitter, thereby creating feedback information including the transmission weight value. A first transmitter transmits the feedback information to a second receiver. The second receiver receives the feedback information and the second transmitter detects the transmission weight value from the feedback information received in the second receiver, and creates the transmission beam corresponding to the detected transmission weight value in order to transmit a signal by applying the transmission beam to the signal.

Abstract: An apparatus and a method for cell search in an orthogonal frequency division multiplexing-based mobile communication system using a multiple access scheme. The method includes the steps of: detecting a symbol boundary of an input reception signal; detecting a frame cell boundary after synchronizing with the detected symbol boundary; detecting a reference signal for each symbol interval in a preset search interval; and detecting a pattern of the detected reference signals and detecting a base station to which the terminal belongs.

Abstract: In a wireless communication system that divides an entire frequency band into a plurality of subcarrier bands, transmits reference signals at the subcarrier bands, and transmits data signals at subcarrier bands other than the subcarrier bands at which the reference signals are transmitted, a base station assigns the subcarrier band at which the reference signals are transmitted as a frequency band dedicated to the reference signals; and transmits the reference signals through the assigned reference signal-dedicated frequency band.

Abstract: A pilot pattern set time interval of an OFDM communication system is divided into a plurality of sub-time intervals. Pilot patterns are generated considering a coherence bandwidth and a coherence time for each of the sub-time intervals, and pilot pattern sets are generated by combining the pilot patterns generated for each sub-time interval. Base stations included in the OFDM communication system are identified with the pilot pattern sets, thereby increasing the number of base stations that can be identified. Therefore, the limited radio resources, i.e., the limited pilot pattern resources, are grouped for efficient utilization, thereby contributing to improvement in system performance.

Abstract: In a radio communication system that transmits reference signals for identifying a plurality of base stations from the base station to mobile stations, base station identification patterns for identifying base stations are generated by providing a method for dividing a frequency domain in a frequency-time domain given with the frequency domain and a time domain into a plurality of sub-bands. Reference signal patterns are determined in a predetermined time domain within the time domain at each of the sub-bands. In this way, the number of base stations that can be identified is increased.

Abstract: A method for generating a preamble sequence in an orthogonal frequency division multiplexing (OFDM) communication system having A subcarriers in a frequency domain. The method comprises generating a length-2×M×N preamble sequence, where 2×M×N is less than A, by using a length-N Golay complementary sequence and a length-M Golay complementary sequence; and assigning elements constituting the preamble sequence to 2×M×N subcarriers among the A subcarriers on a one-to-one mapping basis, assigning null data to the remaining subcarriers excluding the 2×M×N subcarriers from the A subcarriers, and then IFFT-transforming the assigned result into time-domain data.

Abstract: A method for generating a preamble sequence for decreasing a peak-to-average power ratio (PAPR) through at least two antennas in an orthogonal frequency division multiplexing (OFDM) communication system. The method comprises generating a first preamble sequence in which odd data of the preamble sequence becomes null data and even data of the preamble sequence becomes data, the first preamble sequence being adapted to be transmitted via one of the two antennas; and generating a second preamble sequence in which even data of the preamble sequence becomes null data and odd data of the preamble sequence becomes data, the second preamble sequence being adapted to be transmitted via another one of the two antennas.

Abstract: A method for generating a preamble sequence in an orthogonal frequency division multiplexing (OFDM) communication system having A subcarriers in a frequency domain. The method comprises generating a length-M×N preamble sequence, where M×N is less than A, by using a length-N Golay complementary sequence and a length-M Golay complementary sequence; and assigning elements constituting the preamble sequence to M×N subcarriers among the A subcarriers on a one-to-one mapping basis, assigning null data to the remaining subcarriers excluding the M×N subcarriers from the A subcarriers, and then IFFT-transforming the assigned result into time-domain data.

Abstract: A transceiver system and method in an OFDM communication system which enables exact symbol synchronization acquisition and improves performance for frequency offset and channel estimation. In the apparatus, a guard interval filling unit copies data at a predetermined interval in an input data row inputted to be transmitted, and fills in the copied data in the preset guard interval in the input data row. A selection unit selectively receives an output data row outputted from the guard interval filling means and unique words having a constant amplitude and a non-periodic auto-correlation characteristic, and outputs the OFDM symbol in which the unique words are inserted in the output data row.

Abstract: A method and apparatus for allocating pilot carriers adaptively in an OFDMA communication system are disclosed. To improve phase error estimation performance and optimize the number of pilot carriers allocated to each sub-channel, an OFDMA transmitter changes the number of pilot carriers for a sub-channel according to the status of the sub-channel. Consequently, less pilot carriers are allocated to a sub-channel in a good state, reducing power consumption and more pilot carriers are allocated to a sub-channel in a bad state, improving channel estimation performance despite increased power consumption.