Multi sub-carrier communication system and method providing improved frequency equalization performance

A multi sub-earner communication system, comprising:

• a frequency equalizer to use a frequency equalization vector to compensate for a channel distortion of each received signal outputted from a Fourier transformer;
• and
• a calculation unit for calculating the frequency equalization vector, wherein the calculation unit includes:
• a normalizer for normalizing each of the received signals from the frequency equalizer to a reference coordinate value;
• a buffer for storing the normalized received signals;
• a unit error correction vector calculator for calculating an average value of N number of the stored normalized received signals and calculating the unit error correction vector based on the average value;
• an error compensator for compensating the calculated unit error correction vector according to a predetermined compensation ratio;
• and
• a multiplier for updating the frequency equalization vector by multiplying the coefficients of a precedent frequency equalization vector with the corresponding coefficients of the compensated unit error correction vector
• wherein the normalizer detects the sign of a real number and the sign of an imaginary number of the received signal, swaps the real number and the imaginary number for each other when the real number sign is different from the imaginary number sign, rotates the coordinates of the received signal to an axis where the real number equals to the imaginary number, and shifts the rotated coordinate of the received signal to the reference coordinate value.

A method for calculating a frequency equalization coefficient vector of a frequency equalizer to correct a channel distortion of a received signal by using the frequency equalization coefficient vector, the method comprising the steps of:

• receiving for each frame a signal outputted from the frequency equalizer;
• normalizing the received signal with a predetermined coordinate value to a reference coordinate value;
• calculating an average value of N number of the received signals at the N-th frame;
• calculating a unit error correction vector based on the average value;
• and
• updating the frequency equalization coefficient vector with the calculated unit error correction vector
• wherein the step of normalizing the received signal includes the steps of:
• detecting the sign of a real number and the sign of an imaginary number of the received signal;
• swapping the real number and the imaginary number for each other when the real number sign is different from the imaginary number sign;
• rotating the coordinates of the received signal to an axis where the real number equals to the imaginary number;
• and
• shifting the rotated coordinate of the received signal to the reference coordinate value.