Adaptive channel equalizer for use in digital communication system utilizing OFDM method

An adaptive channel equalizer for use in a digital communication system utilizing OFDM method, comprising:

• first complex multiplying means for outputting a first in-phase complex multiplication signal and a first quadrature phase complex multiplication signal by performing a complex multiplication for received in-phase and quadrature phase channel signals and the in-phase and quadrature phase coefficients;
• reference signal generating means for generating a reference signal;
• error calculating means for outputting an in-phase error signal and a quadrature phase error signal by calculating a phase error from the first in-phase and quadrature phase complex multiplication signals and the reference signal;
• delaying means for outputting an in-phase delay signal and a quadrature phase delay signal by delaying the in-phase and quadrature phase channel signals;
• gain controlling means for outputting an in-phase gain control signal and a quadrature phase gain control signal by controlling a gain of the in-phase and quadrature phase delay signals;
• second complex multiplying means for outputting a second in-phase complex multiplication signal and a second quadrature phase complex multiplication signal by performing a complex multiplication for the in-phase and quadrature phase error signals, and the in-phase and quadrature phase gain control signals;
• adding means for outputting updated in-phase and quadrature phase coefficients after adding respectively the second in-phase and quadrature phase complex multiplication signals and the in-phase and quadrature phase coefficients;
• address generating means for generating a write address signal and a read address signal;
• storing means for storing the updated in-phase and quadrature phase coefficients according to the write address signal, and outputting the updated coefficients stored according to the read address signal;
• initial coefficients generating means for generating an initial coefficients;
• selecting signal generating means for generating a selecting signal according to a symbol sync signal;
• and
• multiplexing means for selecting one of the initial coefficients from said initial coefficients generating means and the updated coefficients from said storing means according to the selecting signal, to supply said first complex multiplying means as the in-phase and quadrature phase coefficients.