Method for transmitting data in wireless communication system and apparatus therefor
A method for performing, by a station (STA) apparatus, uplink (UL) multi-user (MU) transmission in a wireless communication system according to an embodiment of the present invention includes performing carrier sensing on a channel, receiving a trigger frame including information for UL MU transmission and a carrier sense indicator indicating whether a result of the carrier sensing is to be reflected from an access point (AP), and transmitting an UL MU frame through the channel based on the information for UL MU transmission. The UL MU frame is transmitted through the channel based on a result of the carrier sensing if the carrier sense indicator indicates the reflection of a result of the carrier sensing. The UL MU frame is transmitted through the channel regardless of a result of the carries sensing if the carrier sense indicator does not indicate the reflection of a result of the carrier sensing.
1. A method for performing, by a station (STA) apparatus, uplink (UL) multi-user (MU) transmission in a wireless communication system, the method comprising:
receiving a trigger frame comprising information for the UL MU transmission and an indicator indicating whether or not to execute carrier sensing,
wherein the method further comprises:
if the indicator indicates executing the carrier sensing, executing the carrier sensing on a specific channel, considering a result of the carrier sensing, and transmitting a UL MU frame in response to the trigger frame; and
if the indicator indicates not executing the carrier sensing, transmitting the UL MU frame in response to the trigger frame without the carrier sensing,
wherein considering the result of the carrier sensing comprises:
if the specific channel is considered idle as a result of considering both a channel clear assessment (CCA) and a network allocation vector (NAV), transmitting the UL MU frame through the specific channel; and
if the specific channel is considered busy as the result of considering both the CCA and the NAV, not transmitting the UL MU frame through the specific channel,
wherein the NAV indicates idle when a NAV count value is nonzero and a non-bandwidth signaling transmitter address (TA) field is same as an address of a transmission opportunity (TXOP) holder, and
wherein the CCA indicates busy when a detected energy level through energy detection exceeds a threshold.
2. The method of claim 1 , wherein executing the carrier sensing comprises performing energy detection to check the CCA, during a short interframe space (SIFS) after receiving the trigger frame.
3. The method of claim 1 , wherein the specific channel corresponds to a channel allocated to the STA apparatus.
4. The method of claim 1 ,
wherein the specific channel is considered idle when both the CCA and the NAV indicate idle, and
wherein the specific channel is considered busy when at least one of the CCA or the NAV indicates busy.
5. The method of claim 4 , wherein the NAV indicates idle when the NAV count value is zero.
6. The method of claim 4 , wherein the CCA indicates idle when the detected energy level through the energy detection does not exceed the threshold.
7. The method of claim 1 , further comprising:
if an Access Point (AP) transmitting the trigger frame is a transmission opportunity (TXOP) holder setting the NAV of the STA apparatus, transmitting the UL MU frame without considering the NAV.
8. The method of claim 1 ,
wherein the trigger frame includes a common information field for all of STA apparatuses receiving the trigger frame and a user-specific information field for an individual STA apparatus of the STA apparatuses,
wherein the user-specific information field is included in the trigger frame as often as a number of the STA apparatuses,
wherein the common information field includes the indicator and the user-specific information field includes an allocated frequency resource for the individual STA apparatus, and
wherein whether the carrier sensing is executed is determined commonly among the STA apparatuses based on the indicator and the specific channel on which the carrier sensing is executed of the individual STA apparatus corresponds to the allocated frequency resource for the individual STA apparatus.
9. A station (STA) apparatus performing uplink (UL) multi-user (MU) transmission in a wireless communication system, the STA apparatus comprising:
a radio frequency (RF) unit configured to transmit/receive radio signals; and
a processor configured to control the RF unit,
wherein the processor is configured to:
receive a trigger frame comprising information for the UL MU transmission and an indicator indicating whether or not to execute carrier sensing,
wherein the processor is further configured to:
if the indicator indicates executing the carrier sensing, execute the carrier sensing on a specific channel, consider a result of the carrier sensing, and transmit a UL MU frame in response to the trigger frame; and
if the indicator indicates not executing the carrier sensing, transmit the UL MU frame in response to the trigger frame without the carrier sensing,
wherein, when considering the result of the carrier sensing, the processor is further configured to:
if the specific channel is considered idle as a result of considering both a channel clear assessment (CCA) and a network allocation vector (NAV), transmit the UL MU frame through the specific channel; and
if the specific channel is considered busy as the result of considering both the CCA and the NAV, not transmit the UL MU frame through the specific channel,
wherein the NAV indicates idle when a NAV count value is nonzero and a non-bandwidth signaling transmitter address (TA) field is same as an address of a transmission opportunity (TXOP) holder, and
wherein the CCA indicates busy when a detected energy level through energy detection exceeds a threshold.
10. The STA apparatus of claim 9 , wherein the processor is further configured to perform energy detection to check the CCA, during a short interframe space (SIFS) after receiving the trigger frame.
11. The STA apparatus of claim 9 ,
wherein the specific channel is considered idle when both the CCA and the NAV indicate idle, and
wherein the specific channel is considered busy when at least one of the CCA or the NAV indicates busy.
12. The STA apparatus of claim 11 , wherein the NAV indicates idle when the NAV count value is zero.
13. The STA apparatus of claim 11 , wherein the CCA indicates idle when the detected energy level through the energy detection does not exceed the threshold.
14. The STA apparatus of claim 9 , wherein the specific channel corresponds to a channel allocated to the STA apparatus.
15. The STA apparatus of claim 9 , wherein the processor is further configured to:
if an Access Point (AP) transmitting the trigger frame is a transmission opportunity (TXOP) holder setting the NAV of the STA apparatus, transmit the UL MU frame without considering the NAV.
16. The STA apparatus of claim 9 ,
wherein the trigger frame includes a common information field for all of STA apparatuses receiving the trigger frame and a user-specific information field for an individual STA apparatus of the STA apparatuses,
wherein the user-specific information field is included in the trigger frame as often as a number of the STA apparatuses,
wherein the common information field includes the indicator and the user-specific information field includes an allocated frequency resource for the individual STA apparatus, and
wherein whether the carrier sensing is executed is determined commonly among the STA apparatuses based on the indicator and the specific channel on which the carrier sensing is executed of the individual STA apparatus corresponds to the allocated frequency resource for the individual STA apparatus.