Signal transmission method using CDM against the effect of channel estimation error in transmit diversity system

A method of transmitting a signal, the method performed by a transmitter using a plurality of antennas and comprising:

• code division multiplexing input symbols using codes according to a predetermined spreading matrix;
• and
• transmitting the code division multiplexed input symbols via the plurality of antennas according to an Alamouti scheme,
• wherein the predetermined spreading matrix is a matrix obtained by multiplying one of four columns of a 4*4 Hadamard matrix by an imaginary unit to set a product of a first column and a second column of the Hadamard matrix to a real number and a product of a third column and a fourth column of the Hadamard matrix to an imaginary number, or to set a product of a first column and a second column of the Hadamard matrix to an imaginary number and a product of a third column and a fourth column of the Hadamard matrix to a real number.