A method for and apparatus for performing a synchronization in a wireless communication system is provided. A wireless device checks a configuration including a resource relationship about reference signals (RSs) between a first cell and a second cell; receives a first reference signal (RS) from the first cell; determines a timing reference to receive a second RS based on the resource relationship; receives the second RS from the second cell based on the timing reference; performs a frequency tracking using the second RS; and decodes data signals from the second cell.