Abstract: A method of detecting a frame boundary for a multi-band orthogonal frequency division multiplexing mode is comprised of: calculating an autocorrelation value of a reception signal; estimating an error of the autocorrelation value; and detecting a frame boundary with reference to the error, a sign of the autocorrelation value, and a sign of an autocorrelation value of a previous reception signal. The method is able to substantially exactly detect the frame boundary even when the frequency error rate of all band groups of the UWB spectrums defined by the WiMedia PHY specification is conditioned over ±70 ppm.

Abstract: Disclosed herein are an Arabidopsis gene (AtLEJ1), acting as an inhibitor of the biosynthesis of the phytohormones jasmonic acid and ethylene, and a method for producing a male sterile transgenic plant using the same. The gene guarantees stable male sterile strains which need no maintainers for the maintenance thereof. Also, the transgenic plants comprising the gene can be readily restored to a fertile phenotype merely through hormonal treatment. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Abstract: A receiver performing an adaptive overlap and add (OLA) function in a multi band orthogonal frequency division multiplexing (OFDM) scheme and a method using the receiver. The receiver performing the OLA function in the multi band OFDM includes a channel estimator to estimate a delay spread from a digital input signal; a signal-to-noise ratio (SNR) estimator to estimate an SNR from the digital input signal; and an overlap and add (OLA) module to determine an OLA length based on the estimated delay spread and the estimated SNR and to perform an OLA according to the determined OLA length, wherein the OLA module adds, to header samples of an OFDM symbol, tail samples corresponding to the estimated delay spread of the OFDM symbol corresponding to the digital input signal.

Abstract: A multiband Orthogonal Frequency Division Multiplexing (OFDM) receiver, and more particularly, a receiver and method for effectively compensating for a frequency offset of a received signal in a multiband OFDM scheme. The receiver for compensating for a frequency offset of a received signal in an OFDM scheme includes: a numerically controlled oscillator (NCO) which generates a first compensation signal by processing an input signal in a time domain based on a first carrier frequency offset estimated in the time domain, and a second carrier frequency offset estimated in a frequency domain; a sampling frequency offset tracking (SFOT) unit which generates a second compensation signal by estimating a sampling frequency offset from frequency domain pilot symbols contained in the first compensation signal; and a carrier frequency offset tracking (CFOT) unit which estimates the second carrier frequency offset by using pilot symbols contained in the second compensation signal.

Abstract: A clear channel assessment CCA method implemented in a multi-band orthogonal frequency division multiplexing (OFDM) system, the method including: estimating an energy of a received signal in each window at predetermined intervals of two moving-average windows; detecting a peak value according to a difference of energies estimated in relation to the two moving-average windows, and accumulating a number of detected peak values; and reporting a channel status to a medium access control (MAC) according to the number of the accumulated peak values.

Abstract: A DCM demapper and a DCM demapping method are provided. The DCM demapper includes: a basic signal generation unit generating a plurality of basic signals using a signal and channel information of two subcarriers; a soft decision generation unit generating a plurality of soft decisions using the plurality of basic signals; and a soft decision selection unit selecting a soft decision corresponding to each bit of the two subcarriers among the generated soft decisions.

Abstract: A sampling frequency offset tracking method in an orthogonal frequency division multiplexing (OFDM) system includes determining a search direction of maximum likelihood estimation (MLE) using a carrier frequency offset estimated using pilot subcarriers of a received signal; calculating a size of a MLE search region using a maximum sampling frequency offset of the OFDM system and a resolution of the MLE; calculating a range of the MLE search region for each OFDM symbol based on the size of the MLE search region; and tracking the sampling frequency offset by calculating a maximum correlation between the pilot subcarriers and reference pilot subcarriers within the MLE search region each OFDM symbol. Accordingly, the search region of the MLE is reduced according to the sign of the estimated carrier frequency offset. Therefore, the sampling frequency offset can be easily tracked and the estimation error can be reduced.

Abstract: A sampling frequency offset estimation apparatus and method to be applied to an OFDM (orthogonal frequency division multiplexing) system are provided. The apparatus includes an ADC (analog-to-digital converter) sampling a received signal based on a predetermined sampling frequency; a FFT (Fast Fourier Transform) unit transforming the sampled received signal into a frequency domain; a phase calculator calculating phase shifts of pilot subcarriers of the sampled received signal which has been transformed into the frequency domain; a determiner calculating phase shift reaching times at which samples of the pilot subcarriers shift due to the phase shift; a time offset calculator calculating a sampling time offset using the pilot subcarriers, and a frequency offset calculator calculating a sampling frequency offset based on the phase shift reaching times and the sampling time offset.

Abstract: An apparatus and method applied to an OFDM receiver performs symbol timing synchronization by correlation between channel impulse responses. The apparatus applicable to an orthogonal frequency division multiplexing (OFDM) receiver, includes a channel impulse response (CIR) estimator for estimating a CIR of a present symbol from which a symbol timing is to be detected, using a previous symbol received prior to the present symbol; a matched filter for computing the CIR using the present symbol; a correlation calculator for calculating correlation between the estimated CIR and the CIR computed at the matched filter; and a peak detector for detecting the symbol timing by obtaining a timing offset between the estimated CIR and the computed CIR based on a maximum value of the calculated correlation.

Abstract: A signal acquisition apparatus and method for reducing a false alarm rate are disclosed. The apparatus includes a comparator for detecting a first peak by comparing a correlation value of a received signal with a first threshold and detecting second peaks in a sample interval of the detected first peak based on a second threshold which is different from the first threshold. Thus, a signal is acquired based on a number of the detected second peaks. Accordingly, the false alarm rate due to the noise can be reduced while the detection probability is maintained even at a high SNR.

Abstract: Disclosed is a matched filter and a method for performing cross correlation thereof. The matched filter includes a demultiplexer for demultiplexing an input sample signal into a predetermined number of signals; and cross correlators that perform a cross correlation of each of the demultiplexed sample signals with a predetermined sequence. Therefore, when the matched filter of the present invention is applied to a UWB system having a high sampling rate, the cross correlation operation can be performed at a high rate simply by using low-rate multipliers.

Abstract: A synthesis filter for an MPEG audio decoder, and a decoding method thereof. The synthesis filter for an MPEG audio decoder includes a butterfly computation part which performs a butterfly computation with respect to an input MPEG audio subband sample by a predetermined unit, a matrix computation part which performs a matrix computation using a result of the butterfly computation, a first buffer which stores a result of the matrix computation according to a predetermined address, a window computation address generation part which generates first and second addresses with respect to the first buffer to use for each cycle of the window computation, a window computation part which outputs the matrix computation result stored to the first and second addresses to perform the window computation, and an output part which outputs a result of the window computation.