A method of processing broadcast data includes: performing RS encoding and CRC encoding on mobile service data to generate an RS frame belonging to an ensemble including a signaling information table including access information of the mobile service data and identification information for identifying a stream where keys to decrypt the mobile service data are obtained; mapping a portion of data in the RS frame to a group including known data sequences, FIC data, and TPC data, wherein the FIC data includes information for rapid mobile service acquisition, and the TPC data includes FIC version information for indicating an update of the FIC data; and transmitting a broadcast signal including the group. The group further includes data blocks. First, fourth, fifth and sixth known data sequences are inserted into third, fifth, sixth and seventh data blocks, respectively. Second and third known data sequences are inserted into a fourth data block.