MIMO Precoding in a QAM system

A method for transmitting broadcast signals, the method comprising, demultiplexing Physical Layer Pipe,PLP data into first and second input signals, Quadrature Amplitude Modulation, QAM, mapping the first and second input signals onto constellations, Multi-input Multi-Output, MIMO, processing the QAM mapped first and second input signals, wherein the MIMO processing includes pre-coding processing and phase hopping processing, wherein the pre-coding processing is performed by using a pre-coding matrix which is carried out on pairs of normalized QAM symobls, wherein the phase hopping processing is performed by using a phase hopping matrix, building at least two signal frames by mapping the MIMO processed first and second input signals and modulating data in the at least two signal frames by an Orthogonal Frequency Division Multiplexing, OFDM, method and transmitting at least two broadcast signals having the modulated data by at least two transmit antennas.