A method of receiving a broadcasting signal, the method comprising: receiving the broadcasting signal including a signal frame comprising a first pilot, P1, symbol, at least one second pilot, P2, symbol, and data symbols including service data, the P1 symbol being positioned at a beginning of the signal frame within each RF channel and including information of a guard interval and a Fast Fourier Transform, FFT, size for the at least one P2 symbol, and the at least one P2 symbol being positioned right after the P1 symbol and including Layer-1, L1, signaling data, wherein the L1 signaling data includes a field indicating that contents of the L1 signaling data will change, and the field is included in a dynamic part of the L1 signaling data; detecting synchronization information from the broadcasting signal; demodulating the received broadcasting signal by an Orthogonal Frequency Division Multiplexing, OFDM, method; compensating channel distortion of the demodulated broadcasting signal; obtaining the L1 signaling data included in the at least one P2 symbol from the signal frame of the demodulated broadcasting signal; deinterleaving the obtained L1 signaling data; and decoding the deinterleaved L1 signaling data, wherein a number of P2 symbols is equal to 8 when the FFT size corresponds to 2k, the number of P2 symbols is equal to 4 when the FFT size corresponds to 4k, the number of P2 symbols is equal to 2 when the FFT size corresponds to 8k, and the number of P2 symbols is equal to 1 when the FFT size corresponds to 16k or 32k, wherein the L1 signaling data further include information for indicating a number of physical layer channels, and wherein a guard interval and an FFT size for the P1 symbol are fixed and the guard interval and the FFT size for the at least - one P2 symbol are varied. receiving the broadcasting signal including a signal frame comprising a first pilot, P1, symbol, at least one second pilot, P2, symbol, and data symbols including service data, the P1 symbol being positioned at a beginning of the signal frame within each RF channel and including information of a guard interval and a Fast Fourier Transform, FFT, size for the at least one P2 symbol, and the at least one P2 symbol being positioned right after the P1 symbol and including Layer-1, L1, signaling data, wherein the L1 signaling data includes a field indicating that contents of the L1 signaling data will change, and the field is included in a dynamic part of the L1 signaling data; detecting synchronization information from the broadcasting signal; demodulating the received broadcasting signal by an Orthogonal Frequency Division Multiplexing, OFDM, method; compensating channel distortion of the demodulated broadcasting signal; obtaining the L1 signaling data included in the at least one P2 symbol from the signal frame of the demodulated broadcasting signal; deinterleaving the obtained L1 signaling data; and decoding the deinterleaved L1 signaling data, wherein a number of P2 symbols is equal to 8 when the FFT size corresponds to 2k, the number of P2 symbols is equal to 4 when the FFT size corresponds to 4k, the number of P2 symbols is equal to 2 when the FFT size corresponds to 8k, and the number of P2 symbols is equal to 1 when the FFT size corresponds to 16k or 32k, wherein the L1 signaling data further include information for indicating a number of physical layer channels, and wherein a guard interval and an FFT size for the P1 symbol are fixed and the guard interval and the FFT size for the at least - one P2 symbol are varied.