A method for transmitting a signal to a receiver by a transmitter in a wireless communication system is disclosed. The method includes transmitting information about a first non-precoded pilot signal and information about a second non-precoded pilot signal to the receiver, transmitting the first non-precoded pilot signal the second non-precoded pilot signal to the receiver, and transmitting one or more transmission streams to the receiver through first logical antenna ports and second logical antenna ports, wherein the number of the first logical antenna ports is less than or equal to the number of the second logical antenna ports, the first non-precoded pilot signal is a pilot signal for measuring channel state information at the receiver, and the second non-precoded pilot signal is a pilot signal for determining the number of the first logical antenna ports.