Method and apparatus for mapping virtual antenna to physical antenna

A method in which a transmitter maps a plurality of virtual antenna ports to a plurality of physical antenna ports, the method comprising:

• generating a plurality of first shift sequences by circular shifting a first sequence having a constant magnitude in a time domain and a frequency domain;
• generating a plurality of second shift sequences by circular shifting a discrete Fourier transform (DFT) vector sequence;
• generating a plurality of precoding vectors for the plurality of virtual antenna ports using the plurality of first shift sequences and the plurality of second shift sequences;
• and
• mapping a plurality of first data streams for the plurality of virtual antenna ports to the plurality of physical antenna ports using the plurality of precoding vectors,
• wherein the generating of a plurality of precoding vectors comprises:
• randomly selecting one of the plurality of first shift sequences;
• randomly selecting one of the plurality of second shift sequences;
• and
• generating a first precoding vector of the plurality of precoding vectors for beamforming by using the selected first shift sequence and the selected second shift sequence.