Apparatus for demodulating broadcasting signal and method for transmitting and receiving broadcasting signal

An apparatus for demodulating a broadcasting signal and a method for transmitting/receiving a broadcasting signal are provided to process a signal which is subject to an orthogonal frequency division multiplexing(OFDM) scheme. A method for transmitting a broadcasting signal includes the steps that broadcasting data are made by multiplexing channel-coded data and system information in a frequency domain, the multiplexed broadcasting data are scrambled according to the sequence of a series of factors, the scrambled data are transformed into time-domain data, and the time-domain data are transmitted. The sequence of the factors is the sequence of 7, 5, 2, 2, 3, and 3. A method for receiving a broadcasting signal includes the steps of receiving the broadcasting signal including data scrambled in a frequency domain, performing synchronization in relation to frames of the received broadcasting signal, and descrambling data belonging to the frames while performing FFT for the data.