Method for receiving broadcasting signal and broadcasting receiver

An apparatus for receiving a broadcast signal in a receiver, the apparatus comprising:

• a tuner configured to receive a broadcast signal in which main data and data groups of mobile data are multiplexed, wherein the receiver is turned on during slots, and the data groups are received during the slots which are basic time periods for multiplexing of the mobile data and the main data,
• wherein each data group includes the mobile data, signaling information and a plurality of known data sequences, at least two of the known data sequences having different lengths than each other, and
• wherein the main data is data encoded by a systematic Reed-Solomon (RS) encoding method, and the mobile data is data encoded by an additional forward error correction (FEC) process and a non-systematic RS encoding method;
• a demodulator configured to demodulate the received broadcast signal;
• a first decoder configured to decode the signaling information;
• and
• a second decoder configured to decode the mobile data in the demodulated broadcast signal, wherein an error detection for the mobile data is performed and an error correction for the mobile data is performed by RS decoding.