Method and device for transceiving wireless signal in wireless communication system

A user equipment (UE) for use in a wireless communication system, the UE comprising:

• a radio frequency (RF) module;
• and
• a processor,
• wherein the processor is configured to receive information about a contention-based resource pool, to select N contention-based resources from among a plurality of contention-based resources included in the contention-based resource pool, based on a size of data, and to transmit the data and a reference signal for the data to a base station (BS) in the N contention-based resources, and
• a contention-based resource is a unit in which one or more UEs perform contention-based transmission, N is a variable integer of 1 or more, and indicated by a seed value used for scrambling the reference signal transmitted along with the data.