Physical layer processing and procedures for device-to-device (D2D) discovery signal generation and transmission and scheduling of D2D discovery signals are described. Detection and measurement of a D2D discovery signal, D2D signal identity management, and monitoring by a wireless transmit/receive unit (WTRU) of PDCCH for D2D discovery scheduling is described, as is a WTRU that may be configured with a D2D-specific transmission/reception opportunity pattern. The discovery signal may carry a payload for explicit information about user and/or service identity, and may be mapped to physical resources in such a way as to decouple transmission/reception of the discovery signal from downlink operations. A WTRU may measure a D2D discovery signal quality and report to the network.