Abstract: A cyclic delay diversity (CDD) technique in a multiple-antenna broadband wireless communication system is provided. An apparatus in the multiple-antenna broadband wireless communication system includes: a controller for selecting at least one sub-carrier to which CDD is applied; at least one shifter for shifting a phase of a signal mapped to the at least one selected sub-carrier; and an operator for converting the signal, which is mapped to the at least one selected sub-carrier and whose phase is shifted, and other signals mapped to the remaining sub-carriers into time-domain signals.

Abstract: A method and an apparatus apply an adaptive weight in a wireless communication system. In the method, channel estimation is performed. A weighting factor that reduces a Mean Square Error (MSE) is determined with respect to a channel in a specific section. A channel estimate value is multiplied by the weighting factor.

Abstract: An apparatus and a method for determining a multi-antenna transmission mode at a base station in a multi-antenna system are provided. The method for determining the multi-antenna transmission mode includes when using a Multiple Input Multiple Output (MIMO) transmission mode as a multi-antenna transmission mode, determining a reference set point; updating a set point for transmit power control of a terminal according to an error occurrence of a signal received from the terminal; determining whether a channel to the terminal is a channel for applying the MIMO transmission mode by comparing the updated set point with the reference set point; and when the channel to the terminal is not a channel for applying the MIMO transmission mode, changing the multi-antenna transmission mode to a fixed transmission mode.

Abstract: Uplink power control in a broadband wireless access system is provided. A Base Station (BS) includes a controller, a first generator, a second generator, and a modulator/demodulator (modem). The controller determines to apply one of a first power control which is slot-periodic and a second power control which is frame-periodic. The first generator generates a first power control command at a slot period using a channel quality premising a rake receiver according to the first power control. The second generator generates a second power control command at a frame period using a channel quality premising an equalizer according to the second power control, and generates a third power control command according to a predefined pattern at a slot not being able to use the channel quality. The modem transmits at least one of the first, second, and third power control commands.

Abstract: A Multiple Input Multiple Output (MIMO) wireless communication system is provided. A receiving end apparatus includes an estimator for estimating a channel between a plurality of Transmit (Tx) antennas of a transmitting end and a plurality of Receive (Rx) antennas of a receiving end; a filter for extracting a sum between interference and noise included in an Rx signal by using the estimated channel value and for computing a covariance matrix for the sum between the interference and the noise; and a detector for detecting a Tx signal by using a signal processing matrix generated from the covariance matrix.

Abstract: A method and apparatus for scheduling downlink packets in a mobile communication system are provided, in which a BS prioritizes MSs, while accounting for types of services provided to the MSs, generates one single-user candidate transmission format and M multi-user candidate transmission formats corresponding to a DRC value received from an MS with a highest priority level, estimates per-slot effective data rates for the single-user candidate transmission format and all of the multi-user candidate transmission formats, and transmits a downlink packet in a candidate transmission format having a maximum per-slot effective data rate.

Abstract: A method for determining a scaling factor in a communication system. The method includes calculating an average power for each of an input signal and an output signal of a channel predictor; calculating a noise variance using the calculated average power; normalizing the noise variance with an average power of the channel predictor's output signal; and determining a scaling factor using the normalized noise variance.

Abstract: Method of estimating a channel in a wireless communication system by obtaining a channel impulse response from a pilot signal included in a received signal; estimating a timing offset with a maximum peak power value for the channel impulse response; and performing a phase compensation using the estimated timing offset and estimating a channel which is applied with the compensated phase.

Abstract: An apparatus and a method for estimating a channel in a mobile communication system are provided. The apparatus includes a channel estimation unit for determining a channel estimation value using a channel power for each of a plurality of fingers, and a noise estimation unit for selecting a scheme for estimating a thermal noise power according to a channel environment among schemes for determining a plurality of thermal noise powers, and for estimating a noise using the channel estimation value in the selected scheme.

Abstract: A method and an apparatus for receiving a Minimum Mean-Squared-Error (MMSE) in a Single-Carrier Frequency Division Multiple Access (SC-FDMA) system is provided. The method includes, transforming a signal in a time domain received through an antenna into a signal in a frequency domain, and discriminating between bands respectively allocated to terminals in a frequency domain, estimating a channel and computing a weight value from the signal transformed into the frequency domain, and detecting an MMSE, computing a time-domain bias from the weight value and a channel estimation value of the signal transformed into the frequency domain, normalizing the detected MMSE by using the computed time-domain bias, and transforming the normalized signal into a normalized signal in a time domain, decoding the normalized signal transformed to the time domain, and transmitting the decoded normalized signal transformed into the time domain to each of the terminals.

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 apparatus and method for transmitting and receiving a symbol through a reverse control channel in a mobile communication system for providing packet data are provided. When reverse traffic is present, the apparatus and method can effectively demodulate and decode the reverse traffic. In a method for transmitting a reverse channel in the mobile communication system capable of discontinuously transmitting packet data, a transmission is performed by setting power of a Data Rate Indicator (DRI) channel to a predefined power when packet data is transmitted. When no packet data is transmitted, a transmission is performed by decreasing the power of the DRI channel.

Abstract: An apparatus and method for detecting a pilot signal in a mobile communication system are provided by which the processing time taken to demodulate a traffic channel based on a channel estimation result can be reduced, and thus, the size of a buffer for buffering signals until the presence of a secondary/auxiliary pilot signal is detected can also be reduced. The apparatus includes a first channel estimator for estimating a channel for a noise component of a pilot symbol received by a first receiver, a second channel estimator for adding a pilot symbol received by a second receiver and the pilot symbol received by the first receiver and estimating a channel for a noise component of the added pilot symbol, an energy detector for detecting an energy value of a pilot symbol using result values output from the first and second channel estimators, and a comparison and determination unit for determining whether or not there is a secondary/auxiliary pilot signal by using the detected energy values.

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 scheduling apparatus for a base transceiver system (BTS), determines a point of data transmission to mobile stations (MSs). The BTS includes buffers for storing data to be transmitted to the MSs. A scheduler determines a priority of each of the MSs taking into account a data rate determined depending on a channel condition between the BTS and the MSs, a required amount of transmission data, and an amount of data to be transmitted to the MSs, and determines an MS having the highest priority among the MSs, as a destination MS to which data is to be transmitted by the BTS. The scheduler increases the required amount of transmission data upon receipt of a retransmitted data packet, and decreases the required amount of transmission data after transmitting data to the MSs.

Abstract: An apparatus and a method for a base station or a sector to efficiently detect Channel Quality Indicator (CQI) information transmitted from a terminal in a wireless communication system are provided. A method of a base station for detecting CQI information in a wireless communication system includes determining a part or all of a CQI interval as a correlation interval based at least partly upon a presence of an interference power less than a threshold in a corresponding interval of the CQI interval; and determining correlations between a signal received over the determined correlation interval and possible codewords.

Abstract: A base station is capable of performing a method for velocity estimation in a mobile communication system. In the velocity estimation method, a received signal is delayed by a plurality of different sample intervals. A candidate maximum Doppler frequency for each of the delayed received signals is estimated. A maximum Doppler frequency in a reliable period is selected among the candidate maximum Doppler frequencies.

Abstract: An apparatus and a method for determining a multi-antenna transmission mode at a base station in a multi-antenna system are provided. The method for determining the multi-antenna transmission mode includes when using a Multiple Input Multiple Output (MIMO) transmission mode as a multi-antenna transmission mode, determining a reference set point; updating a set point for transmit power control of a terminal according to an error occurrence of a signal received from the terminal; determining whether a channel to the terminal is a channel for applying the MIMO transmission mode by comparing the updated set point with the reference set point; and when the channel to the terminal is not a channel for applying the MIMO transmission mode, changing the multi-antenna transmission mode to a fixed transmission mode.

Abstract: An apparatus and a method for simultaneously supporting Multiple-Input Multiple-Output (MIMO) and beamforming in a wireless communication system are provided. In the method, two data streams are mapped to each of all of 2N transmission antennas; the two data streams are multiplied by different Cyclic Delay Diversity (CDD) phase sequences; the two data streams multiplied by the different CDD phase sequences for each transmission antenna are added; and the added data stream is multiplied by a beamforming coefficient and transmitted for each transmission antenna.

Abstract: An apparatus and method for controlling a whitening function of a whitening Maximum Ratio Combining (MRC) in a receive end of a multiple antenna system are provided. The method includes identifying if there is interference from at least one neighbor cell, if there is interference, generating a weight of the whitening MRC using a pre-whitening inverse matrix, and, if there is no interference, generating a weight of the whitening MRC using a unit matrix, thus being capable of improving a reception performance of the receive end.