The apparatus, signaling method, and tangible machine-readable medium thereof for time synchronization procedure in a cellular network are provided, wherein the network comprising a plurality of femto base stations and relay stations. The source of providing time synchronization information to femto base stations and relay station could be macro base station, femto base station, relay station or mobile station. The apparatus comprises a clock module, a receiving module, a transmission module, and a determination module. The clock module is configured to generate clocks to synchronize with the network. According to the source of providing time synchronization information to femto base stations and relay stations, the receiving module is configured to receive the system synchronization and access information, or the ranging messages including the ranging request and ranging response messages, the transmission module is configured to transmit the system synchronization and access information, or the ranging messages including the ranging request and ranging response messages. The determination module is configured to determine the timing with respect to the system clock.