Apparatus and method for providing digital broadcasting service based on multiple broadcasting sites and frequency bands

An apparatus for transmitting data in a digital broadcasting system is disclosed. The apparatus includes: a source encoding unit for encoding data to be transmitted and generating source-coded data; a capacity managing unit for dividing the source-coded data into divided data for a plurality of channels in case that an available data capacity for transmitting the source-coded data does not exist in one channel but sum of available data capacities of the multiple channels can accommodate the source-coded data, and adding header information to the divided data; a channel encoding unit for encoding the divided data according to channel environment and generating channel-coded data; and a transmitting unit for multiplexing, modulating and transmitting the channel-coded data through multiple frequency bands and multiple broadcasting sites.