Various communication systems benefit from suitable allocation. For example, system for vehicle to X communication may benefit from semi-persistent resource allocation mechanisms, for example, for uplink semi-persistent scheduling. A method can include configuring at least one main semi-persistent scheduling occasion to a user equipment. The method can also include configuring at least one subsequent semi-persistent scheduling occasion to the user equipment. The at least one subsequent semi-persistent scheduling occasion can depend on usage of the at least one main semi-persistent scheduling occasion.