Daewoo Electronics Co., Ltd.

Olivier Dejonghe

Young-Rok Park

Francois Langinieux

Yeong Sang Kim

Jae Hyeok Park

Jean Jacques Michel

An OFDM receiver system for performing precise OFDM demodulation is provided. The OFDM receiver system performs demodulation by sharing memories and operators in a time-divisional manner. FFT-processed data is separated into specific pilot signals and data according to the timing indicated by a controller to then be rearranged and stored, thereby facilitating extraction of corresponding pilot signals and data for various synchronization and equalization steps. Therefore, the demodulation system having an optimal structure can be realized in view of resource utilization efficiency and chip areas, the cost and time for fabricating and designing the system can be reduced, and verification of the system can be easily performed.

Orthogonal frequency division multiplexing receiver system

A method and an apparatus for estimating coarse frequency offset in OFDM receiver are disclosed. The method for estimating coarse frequency offset includes the steps of: a) performing differential decoding process for two adjacent OFDM symbols obtained by performing FFT on the OFDM signal; b) obtaining candidate offset values by using L number of differential decoded values at the same position from the reference signal among differential decoded values; and c) estimating a coarse frequency offset according to positions on which the first and the second maximum values among the 2S&plus;1 number of candidate offset values are present. The apparatus for estimating coarse frequency offset includes an input buffer, a complex multiplier, a storing unit, an address controller, a frequency offset acquisition unit and a frequency offset tracking unit. By the above construction, candidate offset values of constant range are directly obtained on the frequency domain posterior to the FFT processing by using the reference carrier signal inserted within OFDM frames and a coarse frequency offset is estimated within &plusmn;&frac12; range of intercarrier spacing. Accordingly, the stable and reliable frequency offset can be obtained.

Method for estimating coarse frequency offset in OFDM receiver and apparatus employing the same

The disclosure describes an apparatus for correcting a frequency offset in a OFDM receiving system. The apparatus comprises a loop filter for receiving a predetermined phase value, multiplying the phase value by a gain value, accumulating the multiplied values, and outputting the accumulated value; a voltage control oscillator for multiplying the accumulated value outputted from the loop filter by the gain value, feeding back the result, and adding the feedback values; a derotator for obtaining sine and cosine waves from the result outputted from the voltage control oscillator, multiplying the obtained value by an output signal from an A/D converter, and outputting the multiplied value to an OFDM demodulator; a correlation calculation unit for calculating a correlation value from a value outputted from the OFDM demodulator; and a frequency offset estimator for generating a phase signal according to a frequency offset outputted sequentially within a predetermined frequency offset range, outputting the phase signal to the loop filter, determining an approximate value of the frequency offset within 1/4 range of a carrier frequency interval by using a value outputted from the correlation calculating unit for a corrected symbol, and correcting the frequency offset according to a final determined frequency offset estimation value.

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Metz, France

Olivier Dejonghe