A signal transmitter and receiver are provided. The transmitter includes: a Multiple Input Multiple Output (MIMO) precoder configured to, in response to a first input signal and a second input signal, generate a first transmission signal and a second transmission signal by performing MIMO precoding by pre-phase shifting or pre-phase shifting/hopping the second input signal, and superposition encoding the first input signal and the pre-phase shifted or pre-phase shifted/hopped second input signal; and an Orthogonal Frequency Division Multiplexing (OFDM) modulator configured to OFDM modulate the first transmission signal and the second transmission signal.