Wireless signal transmission and reception method and device in wireless communication system involving a cell group including unlicensed band cells

A device for use in a wireless communication system, the device comprising:

• a memory;
• and
• a processor, wherein the processor is configured to:
• monitor a known signal in an n-th time interval;
• perform a carrier sensing in the n-th time interval;
• and
• control a signal transmission in an (n+1)-th time interval based on a result of the carrier sensing in the n-th time interval,
• wherein, based on the known signal being detected in the n-th time interval, the carrier sensing is performed with regard to a signal that remains after the known signal is removed from a received signal in the n-th time interval,
• wherein, based on the known signal not being detected in the n-th time interval, the carrier sensing is performed with regard to the received signal in the n-th time interval, and
• wherein n is an integer, and each time interval includes a plurality of contiguous orthogonal frequency division multiplexing (OFDM)-based symbols.