Systems and methods for user equipment synchronization

Systems and methods for User Equipment (UE) synchronization for Device-to-Device (D2D) out-of-coverage communication are provided. In an embodiment, a method in an in-coverage (IC) UE for the IC UE to become a synchronization source for out-of-coverage UEs for D2D communication includes obtaining, by the IC UE scanning parameters; scanning, by the IC UE, for out-of-coverage synchronization signals; transmitting, by the IC UE, a measurement report to a Transmission Point (TP) in response to a report trigger, the measurement report comprising information of one or more received out-of-coverage synchronization signals; receiving, by the IC UE, a configuration command from the TP instructing the IC UE to become a synchronization source in response to a configuration command from the TP; and transmitting, by the IC UE, a D2D synchronization signal (SS) for a duration of time or until instructed not to do so by the TP.