Abstract: A multiple-input multiple-output (MIMO) wireless communication system. A transmitter that includes a plurality of transmit antennas selects one of a spatial multiplexing scheme and a spatial diversity scheme, processes a signal in the selected transmission scheme, and transmits the signal through the plurality of transmit antennas. A receiver that includes a plurality of receive antennas processes a signal in a reception scheme mapped to a transmission scheme of the transmitter. The transmission schemes include a transmission scheme for maximizing diversity gain and a transmission scheme for maximizing spectral efficiency. The MIMO communication system using an adaptive transmission mode switching technique performs switching between MIMO transmission modes using spatial selectivity of a channel, thereby obtaining maximum gain in a signal to noise ratio (SNR) and spectral efficiency according to channel state.

Abstract: A multiple-input multiple-output (MIMO) communication system is provided for communication between a transmission apparatus having a plurality of transmission antennas and a reception apparatus having a plurality of reception antennas. The reception apparatus performs singular value decomposition (SVD) on channel information for a channel established to the transmission apparatus, and feeds back the SVD-decomposed channel information to the transmission apparatus. The transmission apparatus receives the SVD-decomposed channel information from the reception apparatus, performs QR decomposition on the received SVD-decomposed channel information, and sets multiple transmission antennas to be allocated to the channel, thereby performing beamforming.

Abstract: Disclosed is a method and an apparatus for transmitting/receiving signals in an multiple input multiple output (MIMO) wireless communication system. The method and apparatus including beam forming of a reference signal while predetermined codes are mapped on a one-to-one basis to each of a plurality of beams available for the transmitter and thereafter transmitting the beam-formed reference signal to a receiver. Also, if information representing an optimum beam, which maximizes reception performance, is received from the receiver, beam forming of data signals is performed by means of a beam corresponding to the information on the optimum beam and the beam-formed data signals are transmitted to the receiver. Therefore, it is possible to apply a beam forming scheme having minimum operation complexity and maximizing reception performance.

Abstract: A bit/power loading method in an adaptive modulation-based multicarrier communication system computes ratios of modulation mode values to transmission power values sub-channel-by-sub-channel, selects a combination of sub-channels in which a sum of the ratios is maximized for a total number of bits to be simultaneously transmitted, and transmits signals in modulation modes corresponding to ratios of modulation mode values to transmission power values associated with the selected sub-channels. Because the bit/power loading method selects a combination of sub-channel modulation modes with the minimum total transmission power for a given number of bits on the basis of transmission power in each sub-channel modulation mode, the bits can be transmitted at the minimum transmission power in a given environment.

Abstract: An apparatus and method for performing beamforming or transmitting a plurality of bit streams output through Adaptive Modulation and Coding (AMC) via a plurality of transmission antennas in a base station using a multi-antenna scheme. The apparatus and method include classifying the plurality of transmission antennas into a plurality of transmission antenna groups; selecting one of the transmission antenna groups depending on a group selection signal being fed back from a mobile station; and outputting each of the bit streams to its associated transmission antenna among the transmission antennas constituting the selected transmission antenna group.

Abstract: A multiband antenna system is provided. The system includes a substrate; an antenna which is disposed on a first side and a second side of the substrate, and produces a resonance in a plurality of frequency bands; a plurality of feeders which are disposed on the first side of the substrate; and a filter which is disposed on the first side of the substrate, is coupled to an end of the antenna, and transfers signals of the plurality of frequency bands output from the antenna to respective feeders of the plurality of the feeders.

Abstract: A communication apparatus and a method for generating a signal thereof are provided. The communication apparatus adjusts a bandwidth or central frequency of an oscillating signal which is generated from a chaotic signal to be used in the modulation, or adjusts both the bandwidth and the central frequency. Accordingly, it is possible to transform the oscillating signal generated from the chaotic signal more diversely and thus to modulate an information signal more diversely and more adaptively.

Abstract: A multiband antenna system is provided. The system includes a substrate; an antenna which is disposed on a first side and a second side of the substrate, and produces a resonance in a plurality of frequency bands; a plurality of feeders which are disposed on the first side of the substrate; and a filter which is disposed on the first side of the substrate, is coupled to an end of the antenna, and transfers signals of the plurality of frequency bands output from the antenna to respective feeders of the plurality of the feeders.

Abstract: A multiple-input multiple-output (MIMO) communication system is provided for communication between a transmission apparatus having a plurality of transmission antennas and a reception apparatus having a plurality of reception antennas. The reception apparatus performs singular value decomposition (SVD) on channel information for a channel established to the transmission apparatus, and feeds back the SVD-decomposed channel information to the transmission apparatus. The transmission apparatus receives the SVD-decomposed channel information from the reception apparatus, performs QR decomposition on the received SVD-decomposed channel information, and sets multiple transmission antennas to be allocated to the channel, thereby performing beamforming.

Abstract: Disclosed is a method and an apparatus for transmitting/receiving signals in an multiple input multiple output (MIMO) wireless communication system. The method and apparatus including beam forming of a reference signal while predetermined codes are mapped on a one-to-one basis to each of a plurality of beams available for the transmitter and thereafter transmitting the beam-formed reference signal to a receiver. Also, if information representing an optimum beam, which maximizes reception performance, is received from the receiver, beam forming of data signals is performed by means of a beam corresponding to the information on the optimum beam and the beam-formed data signals are transmitted to the receiver. Therefore, it is possible to apply a beam forming scheme having minimum operation complexity and maximizing reception performance.

Abstract: A multiple-input multiple-output (MIMO) wireless communication system. A transmitter that includes a plurality of transmit antennas selects one of a spatial multiplexing scheme and a spatial diversity scheme, processes a signal in the selected transmission scheme, and transmits the signal through the plurality of transmit antennas. A receiver that includes a plurality of receive antennas processes a signal in a reception scheme mapped to a transmission scheme of the transmitter. The transmission schemes include a transmission scheme for maximizing diversity gain and a transmission scheme for maximizing spectral efficiency. The MIMO communication system using an adaptive transmission mode switching technique performs switching between MIMO transmission modes using spatial selectivity of a channel, thereby obtaining maximum gain in a signal to noise ratio (SNR) and spectral efficiency according to channel state.

Abstract: A bit/power loading method in an adaptive modulation-based multicarrier communication system computes ratios of modulation mode values to transmission power values sub-channel-by-sub-channel, selects a combination of sub-channels in which a sum of the ratios is maximized for a total number of bits to be simultaneously transmitted, and transmits signals in modulation modes corresponding to ratios of modulation mode values to transmission power values associated with the selected sub-channels. Because the bit/power loading method selects a combination of sub-channel modulation modes with the minimum total transmission power for a given number of bits on the basis of transmission power in each sub-channel modulation mode, the bits can be transmitted at the minimum transmission power in a given environment.

Abstract: An apparatus and method for performing beamforming for transmitting a plurality of bit streams output through Adaptive Modulation and Coding (AMC) via a plurality of transmission antennas in a base station using a multi-antenna scheme. The apparatus and method include classifying the plurality of transmission antennas into a plurality of transmission antenna groups; selecting one of the transmission antenna groups depending on a group selection signal being fed back from a mobile station; and outputting each of the bit streams to its associated transmission antenna among the transmission antennas constituting the selected transmission antenna group.

Abstract: A closed-loop transmitting antenna diversity method, and a base station and mobile station apparatus therefore in a next generation mobile telecommunications system, the closed-loop transmitting antenna diversity method having a plurality of antennas in a mobile telecommunications system, including the steps of (a) measuring the changed amount per unit time of the phase difference between antennas for each of the plurality of antennas which are used in a base station; (b) transmitting the result of measuring as feedback information for adjusting transmitting antenna diversity; (c) receiving and interpreting feedback information in the base station; (d) calculating the weighted value of array antennas for each antenna, using the interpreted feedback information; and (e) multiplying data which is to be transmitted from the base station to a mobile station by the array antenna weighted value, and outputting the result through a corresponding antenna.

Abstract: Acquisition of initial code synchronization in a receiving system for a code division multiple access (CDMA) signal is realized by producing a complex digital signal having K components by sampling an analog signal derived from the received CDMA-modulated signal. Components of the complex digital signal are correlated with N code phases. The energies of these correlated values are examined, in parallel, to determine whether the ratio of the maximum energy within the block to the average energy in the block equals or exceeds a predetermined threshold. If so, this is a valid maximum, and the code synchronization is complete. If not, further components of the complex digital signal are correlated with another set of N code phases, and are examined in the same manner. Accordingly, reliable determination as to whether code synchronization has been achieved can be realized with minimal influence of channel distortion in a CDMA received signal.

Abstract: An adaptive equalizer includes a recording density detector for calculating a recording density reference value by obtaining the track radius using input track information, a reference tap coefficient storage portion for storing the reference tap coefficient obtained according to the channel impulse response at the lowest density position, a tap coefficient controller for obtaining a tap coefficient according to the recording density using the recording density reference value on the basis of the reference tap coefficient stored in the reference tap coefficient storage portion, and a waveform equalizer for eliminating the interference of the signal adjacent to the input reproducing digital signal using the tap coefficient obtained from the tap coefficient controller, to output the reproducing information signal.