US Patent 10390319 Device to-device synchronization signal (D2DSS) resource management

An in-coverage (InC) user equipment (UE) device transmits a device-to-device synchronization signal (D2DSS) and device-to-device (D2D) discovery resource pool information message to an out-of-coverage (OoC) UE device. The D2DSS is based on timing information obtained directly from an eNB and based on at least one of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). The D2D discovery resource pool information message identifies a set of communication resources authorized for transmission of D2D discovery signals where the set of resources are identified in an eNB discovery resource pool message received at the InC UE device from the eNB. The OoC UE device selects communication resources from the set of communication resources to transmit a discovery signal.