Method and device for accessing channel in wireless LAN system
According to one embodiment of the present invention, a method for performing a channel access by a station (STA) in a wireless communication system comprises the steps of: transmitting a first frame for a channel access request to an access point (AP); and receiving a second frame, which is a response to the channel access request, from the AP, wherein the first frame includes information indicating whether or not uplink data of the STA is present.
1. A method for performing channel access by a Station (STA) in a wireless communication system, the method comprising:
transmitting a Power Save (PS)-Poll frame related to a channel access request to an Access Point (AP); and
receiving an ACK frame from the AP in response to the channel access request,
wherein the PS-Poll frame relates to power saving and includes an indicator indicating the presence or absence of uplink data in the STA,
wherein the ACK frame includes first information having a first value or a second value regarding transmission of the uplink data, and second information indicating a time period during which no frame transmission is expected from the STA when the first information has the first value.
2. The method according to claim 1 , wherein the PS-Poll frame is a Null Data Packet (NDP) PS-Poll frame.
3. The method according to claim 2 , wherein the indicator indicating the presence or absence of uplink data in the STA is included in a More Data (MD) field of the PS-Poll frame.
4. The method according to claim 1 , wherein the first and the second values of the first information are determined based on whether transmission of the uplink data is accepted.
5. The method according to claim 4 , wherein if the first information has the second value, the STA transmits the uplink data after a Short Inter-Frame Space (SIFS).
6. The method according to claim 4 , wherein if the first information has the first value, the second information includes one or more of start offset information and duration information.
7. The method according to claim 6 , wherein the STA transmits the uplink data after a time indicated by the start offset information.
8. The method according to claim 6 , wherein after receiving the ACK frame, the STA is maintained in a doze state for a time period indicated by the start offset information and is maintained in an awake state for a time period indicated by the duration information.
9. The method according to claim 6 , wherein the STA receives downlink data in a time period indicated by the duration information.
10. The method according to claim 7 , wherein if the STA activates a timer after transmitting the uplink data, the STA switches to a doze state even before a time period indicated by the duration information elapses, upon expiration of the timer.
11. A Station (STA) for performing channel access in a wireless communication system, the STA comprising:
a transceiver that transmits and receives wireless signals; and
a processor,
wherein the processor transmits a PS-Poll frame related to a channel access request to an Access Point (AP) and receives an ACK frame from the AP in response to the channel access request,
wherein the PS-Poll frame relates to power saving and includes an indicator indicating the presence or absence of uplink data in the STA, and
wherein the ACK frame includes first information having a first value or a second value regarding transmission of the uplink data, and second information indicating a time period during which no frame transmission is expected from the STA when the first information has the first value.
12. A method for supporting channel access of a Station (STA) by an Access Point (AP) in a wireless communication system, the method comprising:
receiving a PS-Poll frame related to a channel access request from the STA; and
transmitting an ACK frame to the STA in response to the channel access request,
wherein the PS-Poll frame includes an indicator indicating the presence or absence of uplink data in the STA, and
wherein the ACK frame includes first information having a first value or a second value regarding transmission of the uplink data, and second information indicating a time period during which no frame transmission is expected from the STA when the first information has the first value.
13. An Access Point (AP) for supporting channel access of a Station (STA) in a wireless communication system, the AP comprising:
a transceiver that transmits and receives wireless signals; and
a processor,
wherein the processor receives a PS-Poll frame related to a channel access request from the STA, and transmits an ACK frame to the STA in response to the channel access request,
wherein the PS-Poll frame relates to power saving and includes an indicator indicating the presence or absence of uplink data in the STA, and
wherein the ACK frame includes first information having a first value or a second value regarding transmission of the uplink data, and second information indicating a time period during which no frame transmission is expected from the STA when the first information has the first value.