A method of processing a broadcast signal in a transmitter, the method comprising: Forward Error Correction, FEC, encoding Physical Layer Pipe, PLP data interleaving bits of the FEC encoded PLP, data; dividing the interleaved bits of the PLP data into cells of the PLP data; mapping the divided cells of the 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 signal frame including the MIMO encoded second signal; inserting a preamble symbol and an additional preamble symbol at a beginning of the first frame; and inserting the preamble symbol and the additional preamble symbol at a beginning of the second frame, wherein the preamble symbol includes basic transmission parameters and the additional preamble symbol includes additional transmission parameters to identify the first frame and the second frame, wherein the additional preamble symbol is inserted right after the preamble symbol, wherein the preamble symbol includes a main part, afirst guard interval and a second guard interval, wherein the first guard interval carries a frequency shifted version of a part of the main part while the second guard interval conveys a frequency shifted version of the other part of the main part, wherein (fsh) of frequency shift is applied to the first and second guard interval, wherein the additional preamble symbol includes an additional main part, a third guard interval anda fourth guard interval, wherein the third guard interval carries afrequency shifted version of a part of the additional main part while the fourth guard interval conveys a frequency shifted version of the other part of the additional main part, wherein (-fsh) of frequency shift is applied to the third and fourth guard interval, wherein lengths of the first, second, third and fourth guard intervals are different from each other. Forward Error Correction, FEC, encoding Physical Layer Pipe, PLP data interleaving bits of the FEC encoded PLP, data; dividing the interleaved bits of the PLP data into cells of the PLP data; mapping the divided cells of the 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 signal frame including the MIMO encoded second signal; inserting a preamble symbol and an additional preamble symbol at a beginning of the first frame; and inserting the preamble symbol and the additional preamble symbol at a beginning of the second frame, wherein the preamble symbol includes basic transmission parameters and the additional preamble symbol includes additional transmission parameters to identify the first frame and the second frame, wherein the additional preamble symbol is inserted right after the preamble symbol, wherein the preamble symbol includes a main part, afirst guard interval and a second guard interval, wherein the first guard interval carries a frequency shifted version of a part of the main part while the second guard interval conveys a frequency shifted version of the other part of the main part, wherein (fsh) of frequency shift is applied to the first and second guard interval, wherein the additional preamble symbol includes an additional main part, a third guard interval anda fourth guard interval, wherein the third guard interval carries afrequency shifted version of a part of the additional main part while the fourth guard interval conveys a frequency shifted version of the other part of the additional main part, wherein (-fsh) of frequency shift is applied to the third and fourth guard interval, wherein lengths of the first, second, third and fourth guard intervals are different from each other.