A method of controlling Semi-Persistent Scheduling (SPS) for a user device, including: receiving, by the user device, sidelink (SL) SPS radio network temporary identifier (RNTI) from a base station; and receiving, by the user device, a SL grant including downlink control information (DCI from the base station with a Physical Downlink Control Channel (PDCCH). The DCI includes a SL SPS index field and an activation/release indication field if the DCI with Cyclic Redundancy Check (CRC) is scrambled with the SL SPS RNTI. A start subframe for Sidelink Control (SC) period is determined based on an offset value and a subframe in which the sidelink grant is received, and an index of a subframe for SC period is relative to System Frame Number (SFN) 0.