A first wireless device receives, from a base station, one or more radio resource control messages indicating a type of demodulation reference signal (DMRS). The first wireless device determines a length of the DMRS. The first wireless device determines a DMRS configuration of a physical sidelink shared channel (PSSCH) based on based on the type and the length of the DMRS. The first wireless device transmits, to a second wireless device, sidelink control information comprising the DMRS configuration of the PSSCH.