Residual frequency, phase, timing offset and signal amplitude variation tracking apparatus and methods for ofdm systems

Abstract

An error tracking apparatus and method for tracking a residual frequency error, a phase error, a timing error, and a signal amplitude variation to enhance a phase error tracking performance and a tracking speed in an orthogonal frequency division multiplexing (OFDM) system is provided. The error tracking apparatus and method include: a frequency error corrector for correcting a frequency at a time domain by adding a tracking carrier error estimating value to an initial carrier frequency error estimating value; a signal amplitude tracking corrector for controlling a signal amplitude by multiplying an input signal converted by a fast Fourier transform (FFT) by an output value corresponding to a calculated power of a receive pilot signal; a channel corrector for outputting a channel correcting signal by multiplying the receive pilot signal by a complex conjugate of a frequency channel response of the receive pilot signal; a carrier frequency error estimator for estimating a carrier frequency error parameter using the channel-corrected pilot and providing the tracking carrier frequency error estimating value; a time offset estimator for estimating a time offset parameter using the channel-corrected pilot; and a carrier phase error estimator for estimating a carrier phase error parameter using the channel-corrected pilot.