The present invention provides a method of processing data in digital broadcasting system. The method includes receiving a broadcast signal including mobile broadcast service data and main broadcast service data, wherein the mobile broadcast service data configures a data group, wherein the data group is divided into a plurality of regions, wherein N number of known data sequences are inserted in some regions among the plurality of regions, and wherein a transmission parameter is inserted between a first known data sequence and a second known data sequence, among the N number of known data sequences, detecting the transmission parameter from the mobile broadcast service data, controlling power based upon the detected transmission parameter, thereby receiving a data group including requested mobile broadcast service data, extracting video data from the mobile broadcast service data and decoding the extracted video data, the decoding step comprising performing overlap smoothing on the video data and performing loop filtering on the overlap-smoothed video data.