A user equipment receives physical downlink shared channel data on a PDSCH in a second subframe from a second serving cell to the user equipment. The second serving cell is activated by the first serving cell, and the second serving cell does not map the PDSCH data to a second RE corresponding to a first resource element of the first subframe mapped with the CRS. The CRS is generated from a pseudo random sequence that is initiated by a cell identifier of the first serving cell and the PDSCH is indicated by an enhanced physical downlink shared channel of the second subframe, and the second RE of the second subframe and the first RE of the first subframe overlap in a time domain and in a frequency domain.