Electronics and Telecommunications Research Institute

Samsung Electronics Co., Ltd.

Kt Corporation

Sk Telecom Company, Ltd.

Hanaro Telecom., Inc.

Ktfreetel Co., Ltd

Kyung-Yeol Sohn

Youn-Ok Park

Jun-Woo Kim

Hyeong-Sook Park

Young-Jo Bang

Dae-Ho Kim

Chang-Wahn Yu

Yong-Su Lee

Seung-Ku Hwang

Seung-Jae Bahng

Jae-Gun Jung

Se-Young Cho

There are provided a method of generating a ranging signal of a wireless terminal and a device for generating a ranging signal of a wireless communication system that can generate the ranging signal using one IFFT engine independently from a mode of the ranging signal transmitted in uplink in a wireless communication system in which a frequency interval of subcarriers used to generate an initial ranging signal and a frequency interval of subcarriers using periodic ranging are different. In this way, it is possible to decrease complexity of hardware and design of the wireless terminal, and decrease power consumption of the wireless terminal through hardware simplification.

Device for generating ranging signal of wireless communication system and method of generating ranging signal of wireless terminal

Provided are a device and method for estimating carrier frequency offset of OFDM signals transmitted and received through a plurality of polarized antennas that may accurately estimate carrier frequency offset used for carrier frequency synchronization acquisition when there is interference between polarized waves.

Device and method for estimating carrier frequency offset of OFDM signals transmitted and received through plurality of polarized antennas

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. As a result, an apparatus for estimating a channel can be easily achieved.

Apparatus and method of estimating channel based on channel delay spread in mobile communication system

Disclosed herein is a base station that extracts a ranging channel signal from a received signal partially correlates each of a plurality of ranging channel signals and each of ranging codes according to ranging modes, and selects a ranging channel signal greater than a first threshold value, the plurality of ranging channel signals being signals according to plurality of time delays of a ranging channel signal. In addition, the base station correlates each of the selected ranging channel signal and each of corresponding ranging code, selects a ranging channel signal having the maximum correlation value, and estimates receiving power by using a time delay corresponding to the selected ranging channel signal.

Apparatus and method for processing ranging channel of communication system

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.

Apparatus and method of compensating for frequency offset in OFDMA system

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.

Apparatus and method for generating ranging pseudo noise code

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. According to an exemplary embodiment of the present invention, a value obtained by regularizing a result of a cell search is compared with a reference value, and it is checked again whether an accurate start point of a frame is detected or not on the basis of a result of the comparison. Accordingly, false alarm rates can be reduced.

Apparatus and method of acquiring initial synchronization of terminal in mobile communication system

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.

Terminal and method for controlling transmission power

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.

Apparatus and method for calibration in a communication system

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.

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.

Downlink beamforming apparatus in OFDMA system and transmission apparatus including the same

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.

Growing community of inventors

Daejeon, South Korea

Kyung-Yeol Sohn