Patent ID: 8505048

Claim:
An apparatus for transmitting a broadcast signal, the apparatus comprising: a pre-processor configured to perform error correction encoding on mobile service data and form data groups, each of the data groups having the mobile service data including video/audio service data and a plurality of sequences of known data, wherein at least two sequences of the known data have different lengths, and wherein each of the data groups is formed by steps comprising: inserting the mobile service data into a corresponding area of a data group, adding the known data and signaling data, wherein the signaling data is added between the at least two sequences of the known data, inserting place-holder data for main service data for reserving locations of the main service data in the data group, non-systematic Reed-Solomon (RS) parity and an MPEG header; deinterleaving data in the data group, removing the place-holder data for the main service data and the RS parity, replacing the place-holder data for the MPEG header with an MPEG header, and formatting mobile service data packets including the mobile service data and the MPEG header; and a transmitting unit configured to transmit the broadcast signal including the mobile service data packets, wherein the broadcast signal has a specific collection of data groups included in slots.