Abstract: A terminal of a communication system includes a power amplifier, an open-loop power controller, a gain controller, a modulator, and a digital/analog converter. The power amplifier amplifies transmission power of a transmission signal. The open-loop power controller measures a received signal strength to control the transmission power, and increases a gain of the power amplifier according to the received signal strength. The gain controller sets a power concentration gain and applies the power concentration gain to the transmission signal when the gain of the power amplifier is maximized. The modulator modulates the transmission signal. The digital/analog converter converts an input signal to an analog signal. The gain controller applies the power concentration gain to the trans mission signal modulated by the modulator, and transmits the power concentration gain to the digital/analog converter.

Abstract: A timing synchronous detection device includes: a first autocorrelator that performs autocorrelation using a received signal and a first delay signal in which the received signal is delayed; a second autocorrelator that performs autocorrelation using the received signal and a second delay signal in which the received signal is delayed; an average-normalization device that obtains an average value of an output signal of the first autocorrelator and an output signal of the second autocorrelator; a comparator that compares the average value and a threshold value and that outputs, if the average value is larger than the threshold value, the average value; and a maximum value search device that searches for a maximum value of the average values that are output from the comparator.

Abstract: A device for detecting a cyclic prefix length according to the present invention includes: a plurality of cyclic prefix length searchers that receive a received signal from a transmitting apparatus to search different cyclic prefix lengths for the received signal; a normalizer that receives and normalizes a plurality of search results received from each of the plurality of cyclic prefix length searchers and outputs a plurality of normalization values; and a determining unit that determines any of the normalization values as the cyclic prefix length of the received signal.

Abstract: In a calibration apparatus in a communication system, a modulation unit calculates a reference signal by modulating a downlink signal, and a digital Intermediate Frequency (IF) unit converts the reference signal to an intermediate frequency signal. An up-converter converts the intermediate frequency signal to a Radio Frequency (RF) signal, and a down-converter generates a received signal for each of the paths from the RF signal to be transmitted through each path. A calibrator calculates a correction value for each path and a delay value by using the reference signal and the received signal for each path.

Abstract: Disclosed is a method and apparatus for composing a received symbol signal modulated with a bit reflected Gray code into bit information. According to an embodiment of the present invention, a positive integer of the received symbol signal having bits is assigned according to the Gray mapping rule, and a sign is determined. A value that is indicative of an arrangement of the bits constituting the received symbol signal is calculated. A boundary value in at least one bit group consisting of the bits constituting the received symbol signal is acquired, and a difference from an absolute value of the received symbol signal is calculated. The received symbol signal is converted into information per bit using a value of the received symbol signal based on the positive integer and the determined sign, the value that is indicative of the bit arrangement, and the difference from the absolute value.

Abstract: Disclosed is an apparatus for generating a ranging pseudo noise (PN) code used in a base station of a portable internet system of an orthogonal frequency division multiplexing access scheme, wherein a ranging pseudo noise mask value is generated using a cell ID number, and then the generated ranging pseudo noise mask value is stored in a memory. A final ranging PN code is generated using the stored ranging PN mask value and a status of a pseudo random binary sequence for generating a ranging PN code. With such a structure, the maximal 256-numbered ranging PN code values can be obtained simultaneously with each 144 bit-length.

Abstract: A method for signal detection using a log likelihood ratio in a multi-input multi-output communication system includes reconfiguring the signals received through the reception antennas on the basis of channel characteristics and acquiring candidate groups for each transmission symbol by acquiring a signal constellation of one quadrant with respect to signals generatable for each transmission symbol and signal constellations for the remaining quadrants on the basis of the reconfigured signals.

Abstract: Disclosed is a method of detecting signals at a receiver of a communication system with a multiple input multiple output antenna. With the signal detection method, a square of the distance between a received signal vector and a channel status-considered transmission symbol vector is calculated first, and the square of the distance is then classified into first and second components. The first component is minimized to calculate a plurality of first soft symbol estimates. A solution set of the first component is calculated on the basis of the plurality of first soft symbol estimates. The second component is minimized to calculate a plurality of second soft symbol estimates. A solution set of the second component is calculated on the basis of the plurality of second soft symbol estimates. A final solution set is calculated by doing the sum of the first component solution set and the second component solution.

Abstract: A downlink beamforming apparatus and a transmission apparatus including the same includes a subcarrier based user identifier for dividing subcarriers according to users, a beamforming weight buffer for storing first beamforming weights for the subcarriers by each of transmitting antennas, an interpolator for outputting second beamforming weights for each transmitting antenna by interpolating the first beamforming weights, and a signal reproducer for reproducing the signal for each transmitting antenna. Subcarriers are allocated to the signal by each user; and a complex multiplier multiplies the signal for each transmitting antenna by the second beamforming weights.

Abstract: The present invention relates to a method and apparatus for estimating a channel in a mobile communication network. In particular, the present invention relates to a method of estimating a channel under a channel environment where interference between neighboring base stations exists in a mobile communication network using an orthogonal frequency division multiplexing (OFDM) method. In order to estimate a channel, one cluster is divided into two sub-clusters, and pilot sub-carrier signals included in at least one sub-cluster in an OFDM symbol direction are used. Therefore, it is possible to further improve performance as compared to a method of estimating a channel by using pilot sub-carriers included in one cluster.

Abstract: The present invention relates to a method of calculating a log-likelihood ratio and a method of detecting a transmission signal. According to the present invention, when a transmission symbol candidate vector is detected on the basis of a received signal, a threshold value and an ML metric of each transmission symbol candidate vector are calculated and the ML metric that is larger than the threshold value is updated by the threshold value. Further, a log-likelihood ratio of the transmission signal bit is calculated using the updated ML metric and the threshold value, and a transmission signal is detected using the log-likelihood ratio.

Abstract: Disclosed is an apparatus and method for processing a ranging channel in an OFDMA system. The apparatus converts received ranging complex signals to polar coordinate signals having a signal magnitude and a phase, and the received converted signals are each represented by a signal magnitude component and a phase component. A predetermined phase component of a signal according to a phase rotation is used to estimate a time delay by an addition operation of the phase of the received signal and the phase according to the phase rotation. Accordingly, the time delay and the power of each reverse link user of the OFDMA mobile communication system can be calculated by arithmetic operations of addition components instead of multiplication components, resulting in the reduction of complexity.

Abstract: A terminal of a communication system includes a power amplifier, an open-loop power controller, a gain controller, a modulator, and a digital/analog converter. The power amplifier amplifies transmission power of a transmission signal. The open-loop power controller measures a received signal strength to control the transmission power, and increases a gain of the power amplifier according to the received signal strength. The gain controller sets a power concentration gain and applies the power concentration gain to the transmission signal when the gain of the power amplifier is maximized. The modulator modulates the transmission signal. The digital/analog converter converts an input signal to an analog signal. The gain controller applies the power concentration gain to the trans mission signal modulated by the modulator, and transmits the power concentration gain to the digital/analog converter.

Abstract: Disclosed is an apparatus for generating a ranging pseudo noise (PN) code used in a base station of a portable internet system of an orthogonal frequency division multiplexing access scheme, wherein a ranging pseudo noise mask value is generated using a cell ID number, and then the generated ranging pseudo noise mask value is stored in a memory. A final ranging PN code is generated using the stored ranging PN mask value and a status of a pseudo random binary sequence for generating a ranging PN code. With such a structure, the maximal 256-numbered ranging PN code values can be obtained simultaneously with each 144 bit-length.

Abstract: The present invention relates to an apparatus and method of acquiring initial synchronization of a terminal in a mobile communication system. According to an exemplary embodiment of the present invention, one or more auto-correlation values of a preamble constituting a signal that is received from a base station are calculated. Averages of the calculated auto-correlation values according to samples are calculated, and then a peak value is detected among the calculated values. Then, a cell search is performed on the basis of the detected peak value, and a peak value from the result of the cell search is regularized. Then, the regularized peak value is compared with a predetermined reference value such that it is checked whether synchronization of a signal that has been searched is accurate or not.

Abstract: The present invention relates to an apparatus and method of estimating a channel based on a channel delay spread in a mobile communication system. Pilot subcarriers are inserted between data subcarriers at predetermined intervals to estimate a channel at locations of the pilot subcarriers. An approximate channel delay spread value is estimated by using an autocorrelation value of a pilot signal. Then, a channel for data subcarriers between the pilot subcarriers is estimated by using a Wiener finite impulse response (FIR) filter that has a separate coefficient according to the estimated delay spread value. Accordingly, by changing the Wiener FIR filter coefficient according to the delay spread value of the channel, it is possible to estimate the channel so as to be adaptive for a change of the channel over time. Since the filter coefficients, which are calculated in advance, are used, it is possible to reduce the amount of calculation required when calculating the filter coefficients.

Abstract: The present invention relates to an apparatus and method of compensating for a frequency offset in an orthogonal frequency division multiple access system that is capable of efficiently estimating and compensating for the frequency offset. A receiver of the orthogonal frequency division multiple access system can individually estimate a fractional frequency offset and an integer frequency offset by using a downlink preamble signal. Further, the receiver can compensate for the frequency offset by adding the integer frequency offset once after completely compensating for the fractional frequency offset. Therefore, it is possible to efficiently compensate for the frequency offset.

Abstract: Disclosed is an apparatus for generating a ranging pseudo noise code used for a terminal of a portable internet system of an OFDM access scheme. The apparatus for generating ranging pseudo noise code detects a cell ID number using a preamble signal transmitted from a base station covering the terminal, detects a ranging pseudo noise code mask value using the detected cell ID number and system parameters input from the base station, and generates a ranging pseudo noise code using the detected cell ID number and the ranging pseudo noise code mask value. With the above structure, a constant initial value can be used irregardless of the cell ID number of the base station, and a desired ranging pseudo noise code can be generated as fast as possible so as to have a desired offset.

Abstract: An inspection device of a physical layer module connected between a terminal transmitting an Internet Protocol (IP)-packet and a physical layer module, the inspection device including an interface transmitting/receiving the IP-packet; a destination MAC address analyzing unit analyzing a destination MAC address to which the IP-packet transmitted from the interface is to be transmitted; a physical layer-packet/physical layer-frame generator converting the IP-packet and generating a physical layer-frame with a control header and an error-detecting code attached; a physical layer-frame transceiving unit transmitting/receiving a physical layer-frame to/from the physical layer module; and an IP-packet generator receiving a physical layer-frame with a control header and an error-detecting code attached from the physical layer module, determining the physical layer module based on the control header and the error-detecting code, converting the physical layer-frame into an IP-packet, and transmitting the IP-packet to

Abstract: In a calibration apparatus in a communication system, a modulation unit calculates a reference signal by modulating a downlink signal, and a digital Intermediate Frequency (IF) unit converts the reference signal to an intermediate frequency signal. An up-converter converts the intermediate frequency signal to a Radio Frequency (RF) signal, and a down-converter generates a received signal for each of the paths from the RF signal to be transmitted through each path. A calibrator calculates a correction value for each path and a delay value by using the reference signal and the received signal for each path.