Mimo-ofdm system using eigenbeamforming method

A MIMO-OFDM system comprising:

• a serial/parallel converter for converting continuously inputted symbols of the number of subcarriers to K parallel signals;
• a signal reproducer for reproducing K parallel signals outputted from the serial/parallel converter by the number of transmit antennas;
• an eigenbeam calculator for calculating an instantaneous channel covariance and a spatial covariance matrix by using the uplink channel information, providing Nf dominant eigenbeam forming vectors from the spatial covariance matrix, and providing the eigenvalue of the instantaneous channel covariance;
• an eigenmode selector for selecting an eigenmode of which the eigenvalue of the instantaneous channel covariance is maximum among Nf, whenever Nf eigenbeam forming vectors are inputted from the eigenbeam calculator and the instantaneous channel covariance is updated;
• and
• a plurality of inverse Fourier converter for receiving the signals outputted from the eigenmode selector, and generating an OFDM symbol.

A MIMO-OFDM system comprising a transmitter with L transmit antennas, a receiver with M receive antennas, and an uplink feedback device for providing information of the receiver to the transmitter, wherein the transmitter comprises:

• a serial/parallel converter for converting continuously inputted symbols of a number of subcarriers to K parallel signals;
• a signal reproducer for reproducing K parallel signals outputted from the serial/parallel converter by the number of transmit antennas;
• an eigenmode generator for generating one eigenbeam for each group of subcarriers, on the basis of long-term feedback information corresponding to Nf eigenbeam forming vectors and short-term feedback information corresponding to a group of subcarriers which are provided through the feedback device;
• and
• a plurality of inverse Fourier converters for receiving the signals outputted from the eigenmode generator and generating an OFDM symbol.

A beam forming method for a MIMO-OFDM system comprising a transmitter with L transmit antennas and a receiver with M receive antennas, comprising:

• (a) converting continuously inputted symbols of a number of subcarriers to K parallel signals;
• (b) reproducing K parallel signals by the number of transmit antennas;
• and
• (c) generating one eigenbeam for each group of subcarriers, on the basis of the long-term feedback information corresponding to Nf eigenbeam forming vectors and the short-term feedback information corresponding to the group of subcarriers.