Method and apparatus for channel access in wireless communication system

A method for communication of a terminal, the method comprising:

• receiving data from a base station through an unlicensed band during a first channel occupying duration, in response to a determination that an unlicensed band channel of the unlicensed band is in an idle state during a first channel sensing duration;
• and
• receiving, when the first channel occupying duration is less than a maximum occupancy time possible for the base station or the terminal to continuously occupy the unlicensed band and the first channel occupying duration is equal to an actual occupancy time allowed for the base station or the terminal to continuously occupy the unlicensed band, the data from the base station through the unlicensed band during a second channel occupying duration, in response to a determination that the unlicensed band channel of the unlicensed band is in an idle state during a second channel sensing duration,
• wherein a sum of the first channel occupying duration, the second channel sensing duration, and the second channel occupying duration is equal to or less than a certain time determined based on a rounding up value of a result of a calculation between the maximum occupancy time and the actual occupancy time.

A base station comprising:

• a transceiver configured to transmit or receive a signal;
• and
• a controller configured to:
• determine whether an unlicensed band channel of an unlicensed band is in an idle state during a first channel sensing duration,
• control the transceiver to transmit data to a terminal through the unlicensed band during a first channel occupying duration, in response to a determination that the unlicensed band channel of the unlicensed band is in the idle state during the first channel sensing duration,
• determine, when the first channel occupying duration is less than a maximum occupancy time possible for the base station or the terminal to continuously occupy the unlicensed band and the first channel occupying duration is equal to an actual occupancy time allowed for the base station or the terminal to continuously occupy the unlicensed band, whether the unlicensed band channel of the unlicensed band is an idle state during a second channel sensing duration, and
• control the transceiver to transmit the data to the terminal through the unlicensed band during a second channel occupying duration, in response to a determination that the unlicensed band channel of the unlicensed band is in the idle state during the second channel sensing duration,
• wherein a sum of the first channel occupying duration, the second channel sensing duration, and the second channel occupying duration is equal to or less than a certain time determined based on a rounding up value of a result of a calculation between the maximum occupancy time and the actual occupancy time.

A terminal comprising:

• a transceiver configured to transmit and/or receive a signal;
• and
• a controller configured to:
• control the transceiver to receive data from a base station through an unlicensed band during a first channel occupying duration, in response to a determination that an unlicensed band channel of the unlicensed band is in an idle state during a first channel sensing duration, and
• control the transceiver to receive, when the first channel occupying duration is less than a maximum occupancy time possible for the base station or the terminal to continuously occupy the unlicensed band and the first channel occupying duration is equal to an actual occupancy time allowed for the base station or the terminal to continuously occupy the unlicensed band, the data from the base station through the unlicensed band during a second channel occupying duration, in response to a determination that the unlicensed band channel of the unlicensed band is in an idle state during a second channel sensing duration,
• wherein a sum of the first channel occupying duration, the second channel sensing duration, and the second channel occupying duration is equal to or less than a certain time determined based on a rounding up value of a result of a calculation between the maximum occupancy time and the actual occupancy time.