OFDM RECEIVING SYSTEM AND METHOD OF ESTIMATING SYMBOL-TIMING OFFSET NOT AFFECTED BY JITTER

摘要

PURPOSE: An OFDM(Orthogonal Frequency Division Multiplexer) receiving system and method of estimating symbol-timing offset not affected by jitter is provided to make symbol-timing recovery possible, in spite of inferior channel conditions and low signal-to-noise ratio by setting up a threshold value to an offset value of an integral number part. CONSTITUTION: An OFDM receiving system comprises an ADC(Analog-to- Digital Conversion) unit(210), am FFT(Fast Fourier Transform) window control unit(220), an FFT-arithmetic and logic unit(230), a symbol timing offset estimation unit(240), an offset-processing unit(250), and a DPLL(Digital Phase Locked Loop) unit(260). The offset-processing unit comprises an integral number calculator(252), a former integral number reservoir(254), a comparator(256), and an offset producer(258). The ADC unit converts an analog-type OFDM signal into digital complex samples with sample rate of 9.14MHz. The FFT window control unit decides two transmission modes and four protective region modes among the digital complex samples and detects the boundary between a protective region and an effective symbol region. The FFT window control unit receives the integral numbers of the symbol timing offset, adjusts the start point of the FFT, removes the protective region, and inputs only the effective symbol region to the FFT-arithmetic and logic unit.