A method of processing a broadcast signal in a transmitter, the method comprising: mapping Physical Layer Pipe, PLP, data into a constellation using a Quadrature Amplitude Modulation, QAM; performing Multi-input Multi-Output, MIMO, encoding on a first signal and a second signal of the PLP data mapped into the constellation; building a first frame including the MIMO encoded first signal and a second frame including the MIMO encoded second signal; inserting a first preamble, P1, symbol and an additional first preamble, AP1, symbol at a beginning of the first frame; and inserting the first preamble, P1, symbol and the additional first preamble, AP1, symbol at a beginning of the second frame, wherein the P1 symbol includes a first prefix portion, a main part, a first postfix portion, wherein the first prefix portion carries a frequency shifted version of a part of the main part while the first postfix portion conveys a frequency shifted version of the other part of the main part, wherein a frequency shift of f sh is applied to the first prefix and postfix portions, wherein the AP1 symbol includes a second prefix portion, an additional main part, a second postfix portion, wherein the second prefix portion carries a frequency shifted version of a part of the additional main part while the second postfix portion conveys a frequency shifted version of the other part of the additional main part, wherein a frequency shift of -f sh is applied to the second prefix and postfix portions, wherein the first frame and the second frame each further includes a pilot signal of a specific pilot pattern and Layer 1-pre, L1-pre, signaling data, wherein at least one of the AP1 symbol and the L1-pre signaling data includes information for identifying the specific pilot pattern included in the corresponding frame, wherein the P1 symbol includes a transmission type information and essential transmission parameters, wherein the L1-pre signaling data are carried through at least one second preamble, P2, symbol within each frame, and wherein the P1 symbol is located right before the AP1 symbol and the at least one P2 symbol is located right after the AP1 symbol. mapping Physical Layer Pipe, PLP, data into a constellation using a Quadrature Amplitude Modulation, QAM; performing Multi-input Multi-Output, MIMO, encoding on a first signal and a second signal of the PLP data mapped into the constellation; building a first frame including the MIMO encoded first signal and a second frame including the MIMO encoded second signal; inserting a first preamble, P1, symbol and an additional first preamble, AP1, symbol at a beginning of the first frame; and inserting the first preamble, P1, symbol and the additional first preamble, AP1, symbol at a beginning of the second frame, wherein the P1 symbol includes a first prefix portion, a main part, a first postfix portion, wherein the first prefix portion carries a frequency shifted version of a part of the main part while the first postfix portion conveys a frequency shifted version of the other part of the main part, wherein a frequency shift of f sh is applied to the first prefix and postfix portions, wherein the AP1 symbol includes a second prefix portion, an additional main part, a second postfix portion, wherein the second prefix portion carries a frequency shifted version of a part of the additional main part while the second postfix portion conveys a frequency shifted version of the other part of the additional main part, wherein a frequency shift of -f sh is applied to the second prefix and postfix portions, wherein the first frame and the second frame each further includes a pilot signal of a specific pilot pattern and Layer 1-pre, L1-pre, signaling data, wherein at least one of the AP1 symbol and the L1-pre signaling data includes information for identifying the specific pilot pattern included in the corresponding frame, wherein the P1 symbol includes a transmission type information and essential transmission parameters, wherein the L1-pre signaling data are carried through at least one second preamble, P2, symbol within each frame, and wherein the P1 symbol is located right before the AP1 symbol and the at least one P2 symbol is located right after the AP1 symbol.