A synchronization source device includes a receiving circuit, a timing adjusting circuit and a transmitting circuit. The receiving circuit receives a first synchronization signal from an Evolved Node B (eNB). The timing adjusting circuit adjusts, according to a timing indicator, a timing of transmission of a second synchronization signal in response to the first synchronization signal, wherein a timing of the second synchronization signal is corresponding to a timing of the first synchronization signal. The transmitting circuit transmits the timing indicator as well as the second synchronization signal based on the adjusted timing of transmission.