Method for deriving weight vectors to be used at the time of transmitting signals from a plurality of antennas, and transmitting apparatus and communication system utilizing said method

A method for deriving weight vectors, the method comprising:

• acquiring, per carrier, a channel matrix having elements the number of which is determined by the number of a plurality of transmitting antennas and the number of a plurality of receiving antennas provided in a receiving apparatus wherein values of the elements represent channel characteristics between the plurality of transmitting antennas and the plurality of receiving antennas, respectively;
• deriving a common autocorrelation matrix for the acquired channel matrix per carrier;
• deriving a steering matrix by eigenvalue-decomposing the derived common autocorrelation matrix;
• and
• deriving, per carrier, weight vectors in a manner such that an orthonormalization is performed respectively on matrices obtained by operating the steering matrix on the channel matrix per carrier.

A communication system, comprising:

• a transmitting apparatus which transmits multicarrier signals, composed of a plurality of streams, by a plurality of transmitting antennas;
• and
• a receiving apparatus which receives the multicarrier signals, composed of a plurality of streams, by a plurality of receiving antennas;
• said transmitting apparatus including:
• an acquisition unit which acquires, per carrier, a channel matrix having elements the number of which is determined by the number of the plurality of transmitting antennas and the number of a plurality of receiving antennas wherein values of the elements represent channel characteristics between the plurality of transmitting antennas and the plurality of receiving antennas, respectively;
• a first derivation unit including a means which derives a common autocorrelation matrix for the channel matrix acquired by the acquisition unit per carrier and a means which derives a steering matrix by eigenvalue-decomposing the derived common autocorrelation matrix;
• a second derivation unit which derives, per carrier, weight vectors for a plurality of streams in a manner such that an orthonormalization is performed respectively on matrices obtained by operating the steering matrix derived by the first derivation unit on the channel matrix per carrier;
• and
• a transmitter which transmits, from the plurality of transmitting antennas, the multicarrier signals composed of a plurality of streams by using the weight vectors derived by said second derivation unit.