Method for channel access in wireless communication system and apparatus for performing same

1. A method of performing channel access on an unlicensed band by a user equipment in a wireless communication system, the method comprising:

sensing a carrier of an unlicensed band for transmitting an uplink signal; and

transmitting the uplink signal when power detected by sensing the carrier is less than an energy detection threshold that is configured by the user equipment,

wherein the energy detection threshold is configured to be equal to or less than a maximum energy detection threshold determined by the user equipment,

wherein the maximum energy detection threshold is determined adaptively to a bandwidth of the carrier using a decibel value of a ratio between a reference bandwidth and the bandwidth of the carrier,

wherein the maximum energy detection threshold is configured to be equal to or greater than a first power value which is a sum of a lower bound of the maximum energy detection threshold for the reference bandwidth and the decibel value, and

wherein the first power value is obtained by a first equation ‘−72+10*log 10(BWMHz/20 MHz)[dBm]’, where ‘20 MHz’ of the first equation corresponds to the reference bandwidth, ‘BWMHz’ corresponds to the bandwidth of the carrier represented in a unit of MHz, ‘10*log 10(BWMHz/20 MHz)’ corresponds to the decibel value, and ‘−72’ corresponds to the lower bound of the maximum energy detection threshold for the reference bandwidth represented in a unit of dBm.

2. The method of claim 1 , wherein the maximum energy detection threshold is configured to be equal to or greater than a second power value which is determined in consideration of a difference between the decibel value and maximum transmit power of the user equipment set for the carrier.

3. The method of claim 2 , wherein the second power value is obtained by a second equation ‘min{Tmax, Tmax−TA+(PH+10*log 10(BWMHz/20 MHz)−PTX)}[dBm]’, where ‘Tmax’ of the second equation corresponds to ‘10*log 10(3.16288*10−8/BWMHz)’, ‘TA’ corresponds to 10 dB, ‘PH’ corresponds to 23 dBm, ‘20 MHz’ corresponds to the reference bandwidth, ‘BWMHz’ corresponds to the bandwidth of the carrier represented in a unit of MHz, ‘10*log 10(BWMHz/20 MHz)’ corresponds to the decibel value, and ‘PTX’ corresponds to the maximum transmit power of the user equipment set for the carrier.

4. The method of claim 3 , wherein the maximum energy detection threshold is determined to be a greater value among the first power value obtained by adding the decibel value to −72 dBm and the second power value.

5. The method of claim 3 , wherein when the different RAT sharing the carrier does not exist, the maximum energy detection threshold does not exceed Tmax+10 dB.

6. The method of claim 1 ,

wherein the uplink signal is transmitted via at least one licensed-assisted access secondary cell (LAA SCell) operating based on LAA and

wherein the sensed carrier corresponds to a carrier at which the at least one LAA SCell resides.

7. A user equipment performing channel access on an unlicensed band, the user equipment comprising:

a processor to sense a carrier of an unlicensed band for transmitting an uplink signal; and

a transmitter to transmit the uplink signal when power detected by sensing the carrier is less than an energy detection threshold that is configured by the user equipment,

wherein the energy detection threshold is configured to be equal to or less than a maximum energy detection threshold determined by the user equipment,

wherein the maximum energy detection threshold is determined adaptively a bandwidth of the carrier using a decibel value of a ratio between a reference bandwidth and the bandwidth of the carrier,

wherein the maximum energy detection threshold is configured to be equal to or greater than a first power value which is a sum of a lower bound of the maximum energy detection threshold for the reference bandwidth and the decibel value, and

wherein the first power value is obtained by a first equation ‘−72+10*log 10(BWMHz/20 MHz) [dBm]’, where ‘20 MHz’ of the first equation corresponds to the reference bandwidth, ‘BWMHz’ corresponds to the bandwidth of the carrier represented in a unit of MHz, ‘10*log 10(BWMHz/20 MHz)’ corresponds to the decibel value, and ‘−72’ corresponds to the lower bound of the maximum energy detection threshold for the reference bandwidth represented in a unit of dBm.

8. The user equipment of claim 7 , wherein the maximum energy detection threshold is configured to be equal to or greater than a second power value which is determined in consideration of a difference between the decibel value and maximum transmit power of the user equipment set for the carrier.

9. The user equipment of claim 8 , wherein the second power value is obtained by a second equation ‘min{Tmax, Tmax−TA+(PH+10*log 10(BWMHz/20 MHz)−PTX)} [dBm]’, wherein ‘Tmax’ of the second equation corresponds to ‘10*log 10(3.16288*10−8/BWMHz)’, where ‘TA’ corresponds to 10 dB, ‘PH’ corresponds to 23 dBm, ‘20 MHz’ corresponds to the reference bandwidth, ‘BWMHz’ corresponds to the bandwidth of the carrier represented in a unit of MHz, ‘10*log 10(BWMHz/20 MHz)’ corresponds to the decibel value, and ‘PTX’ corresponds to the maximum transmit power of the user equipment set for the carrier.

10. The user equipment of claim 9 , wherein the maximum energy detection threshold is determined to be a greater value among the first power value obtained by adding the decibel value to −72 dBm and the second power value.

11. The user equipment of claim 9 , wherein when the different RAT sharing the carrier does not exist, the maximum energy detection threshold does not exceed Tmax+10 dB.

12. A method of performing channel access on an unlicensed band by a base station in a wireless communication system, the method comprising:

receiving an uplink signal when power detected by sensing a carrier is less than an energy detection threshold that is configured by a user equipment,

wherein the energy detection threshold is configured to be equal to or less than a maximum energy detection threshold determined by the user equipment,

wherein the maximum energy detection threshold is determined adaptively to a bandwidth of the carrier using a decibel value of a ratio between a reference bandwidth and the bandwidth of the carrier,

wherein the maximum energy detection threshold is configured to be equal to or greater than a first power value which is a sum of a lower bound of the maximum energy detection threshold for the reference bandwidth and the decibel value, and

wherein the first power value is obtained by a first equation ‘−72+10*log 10(BWMHz/20 MHz) [dBm]’, where ‘20 MHz’ of the first equation corresponds to the reference bandwidth, ‘BWMHz’ corresponds to the bandwidth of the carrier represented in a unit of MHz, ‘10*log 10(BWMHz/20 MHz)’ corresponds to the decibel value, and ‘−72’ corresponds to the lower bound of the maximum energy detection threshold for the reference bandwidth represented in a unit of dBm.

13. An apparatus for a user equipment, the apparatus comprising:

at least one processor; and

at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations comprising:

sensing a carrier of an unlicensed band for transmitting an uplink signal; and

transmitting the uplink signal when power detected by sensing the carrier is less than an energy detection threshold that is configured by the user equipment,

wherein the energy detection threshold is configured to be equal to or less than a maximum energy detection threshold determined by the user equipment,

wherein the maximum energy detection threshold is determined adaptively to a bandwidth of the carrier using a decibel value of a ratio between a reference bandwidth and the bandwidth of the carrier,

wherein the maximum energy detection threshold is configured to be equal to or greater than a first power value which is a sum of a lower bound of the maximum energy detection threshold for the reference bandwidth and the decibel value, and

wherein the first power value is obtained by a first equation ‘−72+10*log 10(BWMHz/20 MHz) [dBm]’, where ‘20 MHz’ of the first equation corresponds to the reference bandwidth, ‘BWMHz’ corresponds to the bandwidth of the carrier represented in a unit of MHz, ‘10*log 10(BWMHz/20 MHz)’ corresponds to the decibel value, and ‘−72’ corresponds to the lower bound of the maximum energy detection threshold for the reference bandwidth represented in a unit of dBm.