Apparatus and methods for processing a signal are disclosed. Data coding and entropy coding are performed with interconnection, and grouping is used to enhance coding efficiency. A data structure for processing a signal includes a payload part having at least one of data coding information including pilot coding information per a frame and entropy coding information. The data structure includes data coding information having information for a data coding scheme and entropy coding information having information for an entropy coding scheme and a second data part having a reference value corresponding to a plurality of data, and a difference value generated using the reference value and the data.