A broadcast transmitter and a method of processing broadcast data in the broadcast transmitter are disclosed. The method includes the steps of performing RS encoding and CRC encoding on mobile service data to build RS frames belonging to an ensemble, wherein each of the RS frames are mapped into data groups, wherein each of the data groups comprises known data sequences and a portion of FIC data including information for rapid mobile service acquisition, wherein the information for rapid mobile service acquisition includes transport stream identification information for identifying a mobile broadcast carrying a mobile service that includes the mobile service data and C/N indication information for indicating whether the FIC data are applicable to a current transmission frame or a next transmission frame, multiplexing data in the data groups and main service data, and transmitting a transmission frame including the multiplexed data.