A method for a wireless communication apparatus comprising a plurality of antennas to transmit and receive a wireless signal in an unlicensed band in a wireless communication system, the method comprising: performing CCA, Clear Channel Assessment, using the plurality of antennas for a predetermined time duration in the unlicensed band; wherein the performing of CCA comprises: obtaining a reference value based on energy sensing indicators, ESIs, measured through each of the plurality of antennas; and determining whether the unlicensed band is an idle state where the unlicensed band is unoccupied by other communication apparatuses, by comparing the reference value with a CCA threshold, when the unlicensed band is determined as the idle state, transmitting the wireless signal through the unlicensed band; and when the plurality of antennas is configured to a directional antenna, keeping a first difference the same as a second difference, wherein the first difference is a difference between a CCA range and an interference range when the wireless signal is transmitted and received using the directional antenna, wherein the second difference is a difference between the CCA range and the interference range when the wireless signal is transmitted and received using an omni - directional antennas. performing CCA, Clear Channel Assessment, using the plurality of antennas for a predetermined time duration in the unlicensed band; wherein the performing of CCA comprises: obtaining a reference value based on energy sensing indicators, ESIs, measured through each of the plurality of antennas; and determining whether the unlicensed band is an idle state where the unlicensed band is unoccupied by other communication apparatuses, by comparing the reference value with a CCA threshold, when the unlicensed band is determined as the idle state, transmitting the wireless signal through the unlicensed band; and when the plurality of antennas is configured to a directional antenna, keeping a first difference the same as a second difference, wherein the first difference is a difference between a CCA range and an interference range when the wireless signal is transmitted and received using the directional antenna, wherein the second difference is a difference between the CCA range and the interference range when the wireless signal is transmitted and received using an omni - directional antennas. obtaining a reference value based on energy sensing indicators, ESIs, measured through each of the plurality of antennas; and determining whether the unlicensed band is an idle state where the unlicensed band is unoccupied by other communication apparatuses, by comparing the reference value with a CCA threshold, when the unlicensed band is determined as the idle state, transmitting the wireless signal through the unlicensed band; and when the plurality of antennas is configured to a directional antenna, keeping a first difference the same as a second difference, wherein the first difference is a difference between a CCA range and an interference range when the wireless signal is transmitted and received using the directional antenna, wherein the second difference is a difference between the CCA range and the interference range when the wireless signal is transmitted and received using an omni - directional antennas. <EOS>