Abstract: Provided is a method of allocating a resource in a small cell system. The method includes: selecting a temporary base station for each user terminal; measuring a signal-to-noise ratio (SNR) through a downlink pilot in a small cell base station; transmitting the signal-to-noise ratio measured for each user terminal to the temporary base station; receiving base station selection and resource allocation information from the small cell base station; and selecting the small cell base station to which most frequency resource block are allocated as a home base station.

Abstract: An apparatus and method for controlling interference between small-cell base stations by using multi-antenna beamforming. The apparatus includes a channel state information (CSI) estimator, a non-optimal beamforming factor calculator, an optimal beamforming factor calculator, and an interference controller. The apparatus and method control interference between small-cell base stations by calculating an optimal beamforming factor assuming that information exchange between base stations is limited in a small-cell downlink system and each base station knows only a channel value sent by itself or a channel value received by itself.

Abstract: Provided is a method of allocating a resource in a small cell system. The method includes: selecting a temporary base station for each user terminal; measuring a signal-to-noise ratio (SNR) through a downlink pilot in a small cell base station; transmitting the signal-to-noise ratio measured for each user terminal to the temporary base station; receiving base station selection and resource allocation information from the small cell base station; and selecting the small cell base station to which most frequency resource block are allocated as a home base station.

Abstract: Provided is a method of forming a random access preamble structure for an extended cell radius in a cellular system, the method including: generating a cyclic prefix (CP), which is the sum of a maximum delay spread and the maximum round trip delay according to the extended cell; generating a preamble sequence part. The method is used to form a preamble structure for an extended cell radius from among random access preamble structures transmitted when initial synchronization is achieved, when synchronization is lost, or when a handover is performed, during a random access process of the cellular system.

Abstract: Disclosed are a receiving apparatus and a receiving method. More particularly, disclosed are a receiving apparatus and a receiving method in an OFDM system. The receiving apparatus in the OFDM system includes a receiver for receiving wireless signals transmitted through wireless channels, a transformer for transforming the wireless signals into signals of a frequency domain, an inverse transformer for inversely transforming reference signals into signals of a time domain based on a number of reference signals included in the signals of the frequency domain and an arrangement interval of the reference signals included in the signals of the frequency domain, and a determiner for determining a delay spread based on the inversely transformed signals of the time domain.

Abstract: A method and apparatus for estimating a channel in a frequency domain are provided. The apparatus acquires frequency selectivity information using a cell-specific reference signal, selects a channel estimation scheme using a user specific reference signal according to the acquired frequency selectivity information, and estimates a frequency channel using the selected channel estimation scheme. Accordingly, more accurate channel estimation with respect to a region to which a physical downstream shared channel is allocated can be performed.

Abstract: Disclosed are a receiving apparatus and a receiving method. More particularly, disclosed are a receiving apparatus and a receiving method in an OFDM system. The receiving apparatus in the OFDM system includes a receiver for receiving wireless signals transmitted through wireless channels, a transformer for transforming the wireless signals into signals of a frequency domain, an inverse transformer for inversely transforming reference signals into signals of a time domain based on a number of reference signals included in the signals of the frequency domain and an arrangement interval of the reference signals included in the signals of the frequency domain, and a determiner for determining a delay spread based on the inversely transformed signals of the time domain.

Abstract: The present invention relates to a packet data transmission method in an OFDMA system and an apparatus thereof. The present invention provides a user packet data transmission method including generating a RACH burst for channel information estimation, selecting a first antenna among a plurality of antennas, transmitting the RACH burst through the first antenna to a base station, receiving a data transmission acceptance signal from the base station, in response to the RACH burst, transmitting user packet data through the first antenna when receiving a signal indicating that the data transmission is allowed, and selecting a second antenna that is difference from the first antenna and transmitting a RACH burst through the second antenna when receiving a signal indicating that the data transmission is not allowed, and a transmitting apparatus of a mobile station having the plurality of antennas.

Abstract: Provided are a channel estimation method and apparatus in mobile communication system having dispersed pilot. The channel estimation apparatus includes an entire band channel estimation unit and an edge channel estimation unit. The entire band channel estimation unit performs channel estimation on an entire frequency band. The edge channel estimation unit performs channel estimation on an edge region. By separately performing the gating operation of the entire band channel estimation unit and the gating operation of the edge channel estimation unit, a channel frequency response is more accurately calculated even in an edge region.

Abstract: Provided are apparatus and a method for transmitting and receiving channel state information. The apparatus for transmitting channel state information includes a resource demapper configured to extract at least one of data, a user equipment (UE)-specific reference signal, and a cell-specific reference signal from an orthogonal frequency division multiplexing (OFDM)-demodulated signal, a channel estimation unit configured to estimate a downlink channel on the basis of at least one of the UE-specific reference signal and the cell-specific reference signal, and a channel state information producer configured to produce at least one of a cell-specific channel quality indicator (CQI), a UE-specific CQI, and switched beam selection information on the basis of information on the estimated downlink channel. Accordingly, it is possible to efficiently perform channel adaptive transmission and beamforming-mode transmission in consideration of an actually reflected beamforming gain and interference cancellation gain.

Abstract: The present invention provides an OFDM symbol generating apparatus. The OFDM symbol generating apparatus generates a plurality of weight-applied symbol groups by applying a plurality of weights to a digital modulation symbol group, and generates a plurality of IFFT symbol groups by performing an IFFT operation on the plurality of weight-applied symbol groups. Subsequently, an IFFT symbol group having the minimum PAPR is selected from among the plurality of IFFT symbol groups such that a characteristic of a PAPR can be improved without reducing data transmission speed.

Abstract: A method and apparatus for estimating a channel in a frequency domain are provided. The apparatus acquires frequency selectivity information using a cell-specific reference signal, selects a channel estimation scheme using a user specific reference signal according to the acquired frequency selectivity information, and estimates a frequency channel using the selected channel estimation scheme. Accordingly, more accurate channel estimation with respect to a region to which a physical downstream shared channel is allocated can be performed.

Abstract: Provided are a channel estimation method and apparatus in mobile communication system having dispersed pilot. The channel estimation apparatus includes an entire band channel estimation unit and an edge channel estimation unit. The entire band channel estimation unit performs channel estimation on an entire frequency band. The edge channel estimation unit performs channel estimation on an edge region. By separately performing the gating operation of the entire band channel estimation unit and the gating operation of the edge channel estimation unit, a channel frequency response is more accurately calculated even in an edge region.

Abstract: Provided is a method of forming a random access preamble structure for an extended cell radius in a cellular system, the method including: generating a cyclic prefix (CP), which is the sum of a maximum delay spread and the maximum round trip delay according to the extended cell; generating a preamble sequence part. The method is used to form a preamble structure for an extended cell radius from among random access preamble structures transmitted when initial synchronization is achieved, when synchronization is lost, or when a handover is performed, during a random access process of the cellular system.

Abstract: An operation method of a base station which adaptively determines a downlink transmission mode is provided. The operation method of the base station including: adaptively determining a downlink transmission mode based on at least one of a state of a channel between the base station and a terminal, and a number of receiving antennas, the number of receiving antennas being at least one and the receiving antennas being mounted on the terminal; selecting one of at least one type of feedback information which is fed back by the terminal based on the determined downlink transmission mode; and reporting type information associated with the selected type to the terminal.

Abstract: An apparatus and method for detecting a space-time multi-user signal are disclosed. The apparatus includes: an RF/IF processing unit for converting received signals through an array antenna into digital baseband signals; a splitting unit for dividing the digital baseband signals into data signals and reference signals; a estimating unit for estimating a delay time information and a channel impulse response; a vector generating unit for receiving the reference signals and the delay time information of to thereby generate a beamforming weight vector; a matrix generating unit for receiving the channel impulse response and the beamforming weight vector to there by generate a system matrix; a filtering unit for receiving the data signals and the system matrix to multiply the system matrix to data per each antenna; a antenna combining unit for combining signals outputted from the filtering unit; and an interference cancelling unit for cancelling an interference signal.

Abstract: The present invention provides an OFDM symbol generating apparatus. The OFDM symbol generating apparatus generates a plurality of weight-applied symbol groups by applying a plurality of weights to a digital modulation symbol group, and generates a plurality of IFFT symbol groups by performing an IFFT operation on the plurality of weight-applied symbol groups. Subsequently, an IFFT symbol group having the minimum PAPR is selected from among the plurality of IFFT symbol groups such that a characteristic of a PAPR can be improved without reducing data transmission speed.

Abstract: The present invention relates to a packet data transmission method in an OFDMA system and an apparatus thereof. The present invention provides a user packet data transmission method including generating a RACH burst for channel information estimation, selecting a first antenna among a plurality of antennas, transmitting the RACH burst through the first antenna to a base station, receiving a data transmission acceptance signal from the base station, in response to the RACH burst, transmitting user packet data through the first antenna when receiving a signal indicating that the data transmission is allowed, and selecting a second antenna that is difference from the first antenna and transmitting a RACH burst through the second antenna when receiving a signal indicating that the data transmission is not allowed, and a transmitting apparatus of a mobile station having the plurality of antennas.

Abstract: Disclosed is a transceiver for a base station with a smart antenna having a plurality of antennas. The transceiver comprises: a multipath searching unit for searching multipath delay information for each demodulation channel; a demodulating unit for forming an adaptive beam for each demodulation channel by using the multipath delay information for each demodulation channel for receiving signals and performing demodulation to the received signals and outputting at least one adaptive beam weight vector; a controlling unit for selecting at least one downlink beam index for each channel; and a modulating unit for selecting the downlink switched beams and forming switching beam for modulating signals of each channel and outputting the modulated signals in downlink.

Abstract: An apparatus and method for detecting a space-time multi-user signal are disclosed. The apparatus includes: an RF/IF processing unit for converting received signals through an array antenna into digital baseband signals; a splitting unit for dividing the digital baseband signals into data signals and reference signals; a estimating unit for estimating a delay time information and a channel impulse response; a vector generating unit for receiving the reference signals and the delay time information of to thereby generate a beamforming weight vector; a matrix generating unit for receiving the channel impulse response and the beamforming weight vector to there by generate a system matrix; a filtering unit for receiving the data signals and the system matrix to multiply the system matrix to data per each antenna; a antenna combining unit for combining signals outputted from the filtering unit; and an interference cancelling unit for cancelling an interference signal.