Digital broadcasting system and data processing method

A method of transmitting a broadcast signal in a transmitter, the method comprising:

• encoding mobile data to build a Reed-Solomon (RS) frame according to an RS code mode;
• dividing the built RS frame into a plurality of portions;
• convolutional encoding the mobile data in the plurality of divided portions;
• forming data groups including the convolutional encoded mobile data,
• wherein each of the data groups include a plurality of regions in which data blocks including contiguous data segments of the convolutional encoded mobile data are categorized,
• wherein transmission parameters of the mobile data are inserted into the corresponding data group, and
• wherein the transmission parameters include information for the RS code mode and information about the plurality of regions in the corresponding data group;
• forming mobile data packets including data in the data groups;
• multiplexing the mobile data packets and main data packets including main data;
• and
• transmitting a broadcast signal including the multiplexed mobile data packets and main data packets,
• wherein a collection of the data groups are carried in specific time slots.