A method for processing a broadcast signal in a transmitter, the method comprising: performing Forward Error Correction, FEC, encoding on Physical Layer Pipe, PLP, data; performing bit interleaving on the FEC-encoded PLP data; performing Multi-input Multi-Output, MIMO, encoding on first data cells and second data cells of the bit-interleaved PLP data; time interleaving the MIMO encoded first data cells and the MIMO encoded second data cells; building a first frame including the time interleaved first data cells and a second frame including the time interleaved second data cells; frequency interleaving the data cells of the first frame and the data cells of the second frame; inserting a first symbol and a second symbol at a beginning of the first frame, wherein the first symbol is located before the second symbol in the first frame; inserting a first symbol and a second symbol at a beginning of the second frame, wherein the first symbol is located before the second symbol in the second frame, wherein the first symbol of the first frame or the second frame includes a front portion, an effective portion, and an end portion, wherein each of the front portion and the end portion is generated by applying a first frequency shift to a part of the effective portion, wherein the second symbol of the first frame or the second frame includes a front portion, an effective portion, and an end portion, wherein each of the front portion and the end portion is generated by applying a second frequency shift to a part of the effective portion, and wherein a value of the first frequency shift is equal to that of the second frequency shift, but opposite in sign; and transmitting a first broadcast signal through at least one of first and second transmission antennae and transmitting a second broadcast signal through at least one of the first and second transmission antennae, the first broadcast signal including the first frame into which the first symbol and the second symbol are inserted and the second broadcast signal including the second frame into which the first symbol and the second symbol are inserted. performing Forward Error Correction, FEC, encoding on Physical Layer Pipe, PLP, data; performing bit interleaving on the FEC-encoded PLP data; performing Multi-input Multi-Output, MIMO, encoding on first data cells and second data cells of the bit-interleaved PLP data; time interleaving the MIMO encoded first data cells and the MIMO encoded second data cells; building a first frame including the time interleaved first data cells and a second frame including the time interleaved second data cells; frequency interleaving the data cells of the first frame and the data cells of the second frame; inserting a first symbol and a second symbol at a beginning of the first frame, wherein the first symbol is located before the second symbol in the first frame; inserting a first symbol and a second symbol at a beginning of the second frame, wherein the first symbol is located before the second symbol in the second frame, wherein the first symbol of the first frame or the second frame includes a front portion, an effective portion, and an end portion, wherein each of the front portion and the end portion is generated by applying a first frequency shift to a part of the effective portion, wherein the second symbol of the first frame or the second frame includes a front portion, an effective portion, and an end portion, wherein each of the front portion and the end portion is generated by applying a second frequency shift to a part of the effective portion, and wherein a value of the first frequency shift is equal to that of the second frequency shift, but opposite in sign; and transmitting a first broadcast signal through at least one of first and second transmission antennae and transmitting a second broadcast signal through at least one of the first and second transmission antennae, the first broadcast signal including the first frame into which the first symbol and the second symbol are inserted and the second broadcast signal including the second frame into which the first symbol and the second symbol are inserted.