Abstract: An apparatus for controlling a gain of transmit antennas in a communication system. The transmit antenna gain control apparatus includes a controller for determining a gain of multiple transmit antennas on a basis of a transmit antenna having a minimum currently unused residual power among currently unused residual powers of the multiple transmit antennas used in the communication system.

Abstract: A calibration apparatus and method for controlling the phase and amplitude of a signal in a smart antenna multicarrier communication system are provided. A calibration signal is allocated to remaining carriers after allocating carriers to a data signal, prior to transmission. Thus, the efficiency of frequency resources for data transmission is increased.

Abstract: An apparatus and method for transmitting and receiving Channel Quality Information (CQI) in a communication system. A Base Station (BS) transmits, to a Subscriber Station (SS), a request for CQI of a resource region corresponding to a frequency reuse factor K, which is designated by the BS. The BS then receives, from the SS, the CQI of the resource region corresponding to a channel quality measured by the SS. The channel quality is measured by the SS by measuring a boosted reference signal and compensating the boosted reference signal for a non-boosted signal.

Abstract: In transmitting channel quality information (CQI) by a mobile station (MS) in a communication system, the mobile station receives from a base station (BS) information of an allocation of a CQI channel and information as to a modulation to be performed on the CQI. CQI channel signal is generated based on the CQI and the modulation information, where the CQI corresponds to a measured channel state. The CQI channel signal is transmitted to the BS over the allocated CQI channel.

Abstract: An apparatus and method for changing an uplink power control scheme according to mobile status in a TDD mobile communication system are provided. The communication system comprises a Subscriber Station (SS) for transmitting a power control change request message to a Base Station (BS) to change the power control scheme, and the BS for deciding to change the power control scheme between the open loop power control and closed loop power control, and transmitting a power control change response message the SS including the decided power control scheme.

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: A method for transmitting channel information in a multi-antenna system, the method includes calculating channel quality information (CQI) with respect to each mode, comparing the CQI with respect to each mode to a threshold value with respect to each mode, and transmitting CQI with respect to a mode having higher CQI than the threshold value as channel information. Good performance can be achieved regardless of the number of users or an SNR of users.

Abstract: Disclosed is a method and an apparatus for generating a preamble sequence for an adaptive antenna system supporting a space division multiple access in an OFDMA communication system. Particularly, disclosed is a method for forming a preamble sequence identifying each of a plurality of mobile subscriber stations located within a cell or a sector of a communication system which includes a plurality of sub-channels assigned to the mobile subscriber stations, each of the sub-channels including a plurality of bins each of which includes n number of contiguous subcarriers in a frequency domain, the preamble sequence being transmitted before each of the sub-channels is transmitted, the method including the step of generating a preamble sequence by phase-shifting a predetermined sequence according to a predetermined phase shift sequence in the frequency domain.

Abstract: An apparatus and method for changing an uplink power control scheme according to mobile status in a TDD mobile communication system are provided. A subscriber station transmits to a base station a power control change request message including information about a requested power control scheme. Upon receipt of the power control change request message, the base station selects a power control scheme for the uplink of the subscriber station and transmits to the subscriber station a power control change command message including information about the selected power control scheme. The subscriber station extracts, upon receipt of the power control change command message from the base station, the power control scheme information from the power control change command message and selects a power control scheme according to the extracted information.

Abstract: An apparatus and method for controlling a digital AGC in a communication system in which power changes significantly from frame to frame. In the digital AGC controlling apparatus, an SNR estimator estimates an uplink SNR of a next frame. A power measurer measures uplink received power of every frame. A gain calculator estimates uplink power of an nth frame using an SNR estimate of an (n?1)th frame received from the SNR estimator and a received power measurement of the (n?1)th frame received from the power measurer, and calculates a gain to be applied to the nth frame in the digital AGC using the uplink power estimate of the nth frame.

Abstract: An apparatus and method for Forward link Outer Loop Rate Control (FOLRC) using Hybrid Automatic Repeat reQuest (HARQ) in a mobile communication system are provided. The method includes receiving information, which indicates success or failure in receiving a packet transmitted in a previous frame, from Mobile Stations (MSs); and decreasing an offset value for changing a CINR value in a link table of each MS when Acknowledgement (Ack) is received as the information indicating success or failure in receiving the packet, and increasing the offset value when a signal received as the information indicating success or failure in receiving the packet is other than the Ack. Accordingly, there is an advantage in that a link table adaptive to a channel condition can be obtained.

Abstract: A method and apparatus for estimating a velocity of a Mobile Station (MS) in a mobile communication system are provided, in which a Base Station (BS) receives a Channel Quality Indicator (CQI) measured by the MS, calculates a decision metric by calculating variations in the CQI for a predetermined time period, and estimates the velocity of the MS based on the decision metric, referring to a velocity table in which decision metrics are mapped to mobile velocities.

Abstract: An apparatus and method for accurately measuring the thermal noise power of a silence period and increasing the control efficiency of reverse link load in a mobile communication system. In the received power measuring apparatus, a UPMB measures the received power of the reverse link, accumulates the measured received power, and outputs the accumulated received power as a received power value. A remover compensates the received power value using a time constant if the received power value is for a silence period. A controller provides a silence period signal to the remover when the silence period starts.

Abstract: The present invention relates to a handover in a broadband wireless communication system. In the broadband wireless communication system, a mobile station includes: a measuring unit for measuring a strength of a signal received from a serving Base Station (BS) or a neighboring BS; a determining unit for determining a scanning time period according to the strength of the signal received from the serving BS; and a scanning unit for scanning neighboring BSs after the determined scanning time period is over.

Abstract: An apparatus for controlling a gain of transmit antennas in a communication system. The transmit antenna gain control apparatus includes a controller for determining a gain of multiple transmit antennas on a basis of a transmit antenna having a minimum currently unused residual power among currently unused residual powers of the multiple transmit antennas used in the communication system.

Abstract: Provided is an apparatus and method for enhancing a demodulation performance of a receiver in a Broadband Wireless Access (BWA) system. A receiving apparatus in a broadband wireless communication system includes an estimator, a first calculator, and a second calculator. The estimator estimates a desired signal. The first calculator calculates a correlation matrix of a signal obtained by eliminating the estimated desired signal from a Received (RX) signal. The second calculator performs an interference elimination using the correlation matrix.

Abstract: Frequency and timing offsets compensation in a Multiple Input Multiple Output (MIMO) system are provided. A receiver includes one or more antennas for receiving one or more signals using the same radio resource; a channel estimator for estimating a channel using the received signals; a transmit signal candidate pre-compensator for compensating a frequency offset and a timing offset of transmit signal candidates by estimating a frequency offset and a timing offset of one or more transmit antennas; and a demodulator for demodulating the received signals using the estimated channel information and the transmit signal candidates of the compensated frequency and timing offsets. The service coverage of the cellular system can be expanded and the transmit power of the terminal can be saved by enhancing the demodulation performance by compensating for the offset influence of each transmitter.

Abstract: An apparatus and method for transmitting data in a communication system are provided. The method for transmitting the data includes determining data to be transmitted over a power boosting zone, generating a power boosting zone used for power-boosting and transmitting the data, allocating the data to the generated power boosting zone and power-boosting and transmitting the power boosting zone.

Abstract: An apparatus and method for receiving data by a receiver in a communication system are provided. The data reception method includes receiving data from a transmitter over a transmission region including multiple tiles and measuring noise of each of predetermined tiles among the multiple tiles, calculating a total variance of noises of the measured tiles and a variance of tiles according to the measured noises, comparing the calculated total variance with a first threshold, and comparing the variance of each tile with a second threshold, calculating a Log Likelihood Ratio (LLR) using a value according to the comparison result and performing decoding using the calculated LLR. Accordingly, the reception performance is improved by minimizing an influence of noises due to ICI in a communication system having a multi-cell configuration.

Abstract: A method for transmitting common control information from a Base Station (BS) to an Mobile Station (MS) in a wireless mobile communication system is provided, in which the BS generates a MAP Information Element (IE) using common control information to be transmitted to the MS, the common control information being resource allocation information and control information, converts the MAP IE to a MAP IE message, applies an Modulation and Coding Scheme (MCS) level corresponding to the channel status of the MS, and transmits the MAP IE message with data to the MS.