Method for channel access in wireless communication system and apparatus for performing same
A method for performing channel access in an unlicensed band by a base station in a wireless communication system according to an embodiment of the present invention may comprise the steps of: sensing, in an unlicensed band, a carrier for transmitting a downlink signal; and transmitting the downlink signal when power detected by sensing the carrier is less than an energy detection threshold set by the base station, wherein the energy detection threshold is set to be equal to or less than a maximum energy detection threshold determined by the base station, and when another radio access technology (RAT) sharing the carrier exists, the maximum energy detection threshold is adaptively determined depending on the bandwidth size of the carrier, using the value, in decibels, of the ration between a reference bandwidth and the bandwidth of the carrier.
1. A method of performing channel access on an unlicensed band by a base station in a wireless communication system, the method comprising:
sensing a carrier of an unlicensed band for transmitting a downlink signal; and
transmitting the downlink signal when power detected by sensing the carrier is less than an energy detection threshold that is configured by the base station,
wherein the energy detection threshold is configured to be equal to or less than a maximum energy detection threshold determined by the base station,
wherein when a different radio access technology (RAT) sharing the carrier is able to exist, 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 base station set for the carrier.
3. The method of claim 2 , wherein the second power value is obtained by a second equation ‘min{T max , T max −T A +(P H +10*log 10(BWMHz/20 MHz)−P TX )} [dBm]’, where ‘T max ’ of the second equation corresponds to ‘10*log 10(3.16288*10 −8 /BWMHz)’, ‘T A ’ corresponds to a constant predefined according to a type of the downlink signal, ‘P H ’ 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 ‘P TX ’ corresponds to the maximum transmit power of the base station 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 downlink signal contains a physical downlink shared channel (PDSCH), the ‘T A ’ is configured as 10 dB and
wherein when the downlink signal contains a discovery signal but does not contain the PDSCH, the ‘T A ’ is configured as 5 dB.
6. The method of claim 3 , wherein when the different RAT sharing the carrier does not exist, the maximum energy detection threshold does not exceed T max +10 dB.
7. The method of claim 1 ,
wherein the downlink 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.
8. A base station performing channel access on an unlicensed band, the base station comprising:
a processor to sense a carrier of an unlicensed band for transmitting a downlink signal; and
a transmitter to transmit the downlink signal when power detected by sensing the carrier is less than an energy detection threshold that is configured by the base station,
wherein the energy detection threshold is configured to be equal to or less than a maximum energy detection threshold determined by the base station,
wherein when a different radio access technology (RAT) sharing the carrier is able to exist, 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.
9. The base station of claim 8 , 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 base station set for the carrier.
10. The base station of claim 9 , wherein the second power value is obtained by a second equation ‘min{T max , T max −T A +(P H +10*log 10(BWMHz/20 MHz)−P TX )} [dBm]’, wherein ‘T max ’ of the second equation corresponds to ‘10*log 10(3.16288*10 −8 /BWMHz)’, where ‘T A ’ corresponds to a constant predefined according to a type of the downlink signal, ‘P H ’ 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 ‘P TX ’ corresponds to the maximum transmit power of the base station set for the carrier.
11. The base station of claim 10 , 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.