Method and system for OFDM symbol timing synchronization
AssigneeAfa Technologies, Inc.
InventorsTzu-Hsien Sang, Tsung-Liang Chen
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Abstract
A method includes converting a received time domain digital signal to a corresponding frequency domain digital signal, calculating phase angles of tones of at least one symbol of the frequency domain digital signal when a symbol timing offset exists, and calculating at least one differential phase offset (DPO). A DPO is the difference between two consecutive gaps, a gap being the difference between the phase angle of a tone of the symbol of the frequency domain digital signal when the timing offset of the symbol exists and a correct phase angle of the tone of the symbol of the frequency domain digital signal. The method estimates the symbol timing offset with at least one DPO.
Claims13
A method for symbol timing synchronization in an orthogonal frequency division multiplexing (OFDM) communication system, the method comprising:
- (a) converting a time domain digital signal to a corresponding frequency domain digital signal;
- (b) calculating phase angles of tones of at least one symbol of the frequency domain digital signal when a symbol timing offset exists;
- (c) calculating at least one differential phase offset (DPO), which is the difference between two consecutive gaps, wherein a gap is the difference between the phase angle of a tone of the symbol of the frequency domain digital signal when the timing offset of the symbol exists and a correct phase angle of the tone of the symbol of the frequency domain digital signal;
- and
- (d) estimating the symbol timing offset utilizing a histogram of a group of DPOs, wherein the histogram is obtained by dividing the interval 0 to 2π into a plurality of sub intervals, and counting the number of DPOs that fall into each sub interval.
A symbol timing synchronization system for an orthogonal frequency division multiplexing (OFDM) communication system, the symbol timing synchronization system comprising:
- a serial-to-parallel converter for performing serial-to-parallel conversion on an input time domain digital signal;
- a fast Fourier transform (FFT) module electrically connected to the serial-to-parallel converter for transforming the time domain digital signal into a frequency domain digital signal;
- and
- a demodulator electrically connected to the FFT module comprising:
- a symbol timing offset estimator comprising:
- a phase calculator electrically connected to the FFT module for calculating phase angles of tones of at least one symbol of the frequency domain digital signal output from the FFT module when a symbol timing offset exists;
- a phase offset calculator electrically connected to the phase calculator for calculating at least one differential phase offset (DPO), which is the difference between two consecutive gaps, wherein a gap is the difference between the phase angle of a tone of the symbol of the frequency domain digital signal when the timing offset of the symbol exists and a correct phase angle of the tone of the symbol of the frequency domain digital signal;
- and
- an estimating module electrically connected to the phase offset calculator for utilizing a histogram of a group of DPOs, wherein the histogram is obtained by dividing the interval 0 to 2π into a plurality of sub intervals, and counting the number of DPOs that fall into each sub interval;
- and
- a demodulation module for demodulating the frequency domain digital signal.
Dependencies are inferred from the claim text.