Apparatus and method for tracking symbol timing of OFDM modulation in a multi-path channel
First Claim
1. A wireless signal receiver to demodulate an OFDM signal having multipath components, said receiver comprising symbol timing logic to control the timing of a Fourier Transformation operation by Fast Fourier Transform (FFT) logic, wherein the symbol timing logic is to drive the Fast Fourier Transform logic to perform the Fourier Transformation operation on signal data synchronized to a first multipath component received earlier in time than a second multipath component, wherein the symbol timing logic adjusts a result of an autocorrelation operation by a fixed design constant to generate a signal used to drive the timing of the FFT logic, wherein the autocorrelation operation determines an amount of correlation between a cyclic prefix and a later portion of the OFDM signal that repeats the cyclic prefix, wherein the fixed design constant is predetermined based at least in part on a plurality of OFDM waveform parameters, the fixed design constant being independent of the multipath components.
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Abstract
Methods and Systems for tracking symbol timing of an OFDM signal are disclosed. In one embodiment, a wireless receiver includes signal tracking and timing logic to facilitate the timing of a demodulation operation such that the demodulation operation occurs on the proper symbol boundary, particularly when the OFDM signal has multipath components and the second component has greater power than the first.
17 Citations
16 Claims
- 1. A wireless signal receiver to demodulate an OFDM signal having multipath components, said receiver comprising symbol timing logic to control the timing of a Fourier Transformation operation by Fast Fourier Transform (FFT) logic, wherein the symbol timing logic is to drive the Fast Fourier Transform logic to perform the Fourier Transformation operation on signal data synchronized to a first multipath component received earlier in time than a second multipath component, wherein the symbol timing logic adjusts a result of an autocorrelation operation by a fixed design constant to generate a signal used to drive the timing of the FFT logic, wherein the autocorrelation operation determines an amount of correlation between a cyclic prefix and a later portion of the OFDM signal that repeats the cyclic prefix, wherein the fixed design constant is predetermined based at least in part on a plurality of OFDM waveform parameters, the fixed design constant being independent of the multipath components.
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9. In a wireless signal receiver, a method of tracking symbol timing in a received signal having multipath components, comprising:
setting FFT timing in the receiver near a leading edge of a portion of a nonzero autocorrelation operation due to a first multipath component by shifting a result of the autocorrelation operation based on a fixed design constant, the fixed design constant being predetermined based at least in part on a plurality of OFDM waveform parameters, the fixed design constant being independent of the multipath components of the received signal, the fixed design constant being predetermined to drive a tracking point of the autocorrelation operation to a leading edge of the first multipath component for a maximum power ratio of a second multipath component to the first multipath component. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
Specification