Channel access method in wireless communication system and apparatus therefor
A channel access method in a wireless communication system and an apparatus for supporting the same are disclosed. Particularly, the method comprises the steps of: transmitting a beacon frame containing a traffic indication map (TIM); and receiving a power pave (PS)-poll frame within a PS-Poll section set in a station (STA), to which downlink data is designated by the TIM, from the STA, wherein the PS-Poll section can be set differently for each STA within the entire PS-Poll section set in all STAs, to which downlink data is designated by the TIM.
1. A channel access method for supporting channel access of a station (STA) in a wireless communication system, the method comprising:
transmitting, by an access point (AP), a beacon frame comprising a traffic indication map (TIM),
wherein the beacon frame further comprises information for determining a start time and an order of a PS-Poll interval, set differently for each STA among a plurality of STAs,
wherein the plurality of STAs are assigned with downlink data as indicated by the TIM;
receiving, by the AP, Power Save (PS)-Poll frames from the plurality of STAs,
wherein a PS-Poll frame corresponding to each STA is transmitted within the PS-Poll interval set for each STA; and
transmitting, by the AP, data frames in response to the PS-Poll frames after a total PS-Poll interval,
wherein the total PS-Poll interval comprises PS-Poll intervals set for the plurality of STAs.
2. The channel access method according to claim 1 , further comprising the step of transmitting an acknowledgement (ACK) frame to each STA within the PS-Poll interval set for each STA in response to the PS-Poll frame corresponding to each STA.
3. The channel access method according to claim 1 , further comprising the steps of:
transmitting a short training field (STF) to each STA within the PS-Poll interval set for each STA in response to the PS-Poll frame corresponding to each STA; and
transmitting, after the total PS-Poll interval, an acknowledgement (ACK) frame containing a bitmap indicating whether or not the PS-Poll frames from the plurality of STAs have been received.
4. The channel access method according to claim 1 , further comprising the step of transmitting, when the PS-Poll frame corresponding to each STA is not received from each STA within the PS-Poll interval set for each STA, an unsolicited acknowledgement (ACK) frame or a short training field (STF) to each STA within the PS-Poll interval set for each STA.
5. The channel access method according to claim 1 , further comprising the step of transmitting, when a delay sensitive data frame is transmitted to each STA, the delay sensitive data frame to each STA without a random backoff procedure after the total PS-Poll interval.
6. The channel access method according to claim 1 , wherein the information comprises at least one of offset information of each PS-Poll interval and duration information of each PS-Poll interval.
7. A channel access method for a station (STA) to perform channel access in a wireless communication system, the method comprising:
receiving, by the STA, a beacon frame comprising a traffic indication map (TIM) from an access point (AP),
wherein the beacon frame further comprises information for determining a start time and an order of a PS-Poll interval, set differently for each STA among a plurality of STAs,
wherein the plurality of STAs are assigned with downlink data as indicated by the TIM;
transmitting, by the STA, when downlink data is assigned to the STA as indicated by the TIM, a Power Save (PS)-Poll frame within a PS-Poll interval set for the STA; and
receiving a data frame from the AP in response to the PS-Poll frame after a total PS-Poll interval,
wherein the total PS-Poll interval comprises PS-Poll intervals set for the plurality of STAs.
8. The channel access method according to claim 7 , further comprising the step of maintaining a sleep state in an interval within the total PS-Poll interval other than the PS-Poll interval set for the STA.
9. The channel access method according to claim 7 , further comprising the step of receiving an acknowledgement (ACK) frame within the PS-Poll interval set for the STA in response to the PS-Poll frame.
10. The channel access method according to claim 7 , further comprising the step of receiving, when the STA is assigned with a last PS-Poll interval within the total PS-Poll interval a data frame from the AP, in response to the PS-Poll frame.
11. The channel access method according to claim 7 , further comprising the steps of:
receiving a short training field (STF) within the PS-Poll interval set for the STA, in response to the PS-Poll frame; and
receiving, after the total PS-Poll interval, an acknowledgement (ACK) frame containing a bitmap indicating whether or not the PS-Poll frames from every STA have been received.
12. The channel access method according to claim 7 , further comprising the step of receiving, when the STA is assigned with a last PS-Poll interval within the total PS-Poll interval, an acknowledgement (ACK) frame from the AP in response to the PS-Poll frame.
13. The channel access method according to claim 7 , wherein the information comprises at least one of offset information of each PS-Poll interval and duration information of each PS-Poll interval.
14. 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 a radio frequency signal; and
a processor that controls the transceiver to:
transmit a beacon frame comprising a traffic indication map (TIM),
wherein the beacon frame further comprises information for determining a start time and an order of a PS-Poll interval set differently for each STA among a plurality of STAs,
wherein the plurality of STA are assigned with downlink data as indicated by the TIM;
receive Power Save (PS)-Poll frames from the plurality STAs,
wherein a PS-Poll frame corresponding to each STA is transmitted within the PS-Poll interval set for each STA; and
transmit data frames in response to the PS-Poll frames after a total PS-Poll interval,
wherein the total PS-Poll interval comprises PS-Poll intervals set for the plurality of STAs.
15. The AP according to claim 14 , wherein the processor controls the transceiver to transmit an acknowledgement (ACK) frame to each STA within the PS-Poll interval set for each STA in response to the PS-Poll frame corresponding to each STA.
16. The AP according to claim 14 , wherein the processor controls the transceiver to:
transmit a short training field (STF) to each STA within the PS-Poll interval set for each STA in response to the PS-Poll frame corresponding to each STA; and
transmit, after the total PS-Poll interval, an acknowledgement (ACK) frame containing a bitmap indicating whether or not the PS-Poll frames from the plurality of STAs have been received.
17. The AP according to claim 14 , wherein the processor controls the transceiver to transmit, when the PS-Poll frame corresponding to each STA is not received from each STA within the PS-Poll interval set for each STA, an unsolicited acknowledgement (ACK) frame or a short training field (STF) to each STA within the PS-Poll interval set for each STA.
18. The AP according to claim 14 , wherein the processor controls the transceiver to transmit, when a delay sensitive data frame is transmitted to each STA, the delay sensitive data frame to each STA without a random backoff procedure after the total PS-Poll interval.
19. The AP according to claim 14 , wherein the information comprises at least one of offset information of each PS-Poll interval and duration information of each PS-Poll interval.
20. A station (STA) apparatus configured to perform channel access in a wireless communication system, the STA comprising:
a transceiver that transmits and receives a radio frequency signal; and
a processor that controls the transceiver to:
receive a beacon frame comprising a traffic indication map (TIM) from an access point (AP),
wherein the beacon frame further comprises information for determining a start time and an order of a PS-Poll interval, set differently for each STA among a plurality of STAs,
wherein the plurality of STA are assigned with downlink data as indicated by the TIM;
transmit, when downlink data is assigned to the STA as indicated by the TIM, a Power Save (PS)-Poll frame within a PS-Poll interval set for the STA and
receive a data frame from the AP in response to the PS-Poll frame after a total PS-Poll interval,
wherein the total PS-Poll interval comprises PS-Poll intervals set for the plurality of STAs.
21. The STA according to claim 20 , wherein the processor maintains a sleep state in an interval within the total PS-Poll interval other than the PS-Poll interval set for the STA.
22. The STA according to claim 20 , wherein the processor controls the transceiver to receive an acknowledgement (ACK) frame within the PS-Poll interval set for the STA in response to the PS-Poll frame.
23. The STA according to claim 20 , wherein the processor controls the transceiver to receive, when the STA is assigned with a last PS-Poll interval within the total PS-Poll interval a data frame from the AP, in response to the PS-Poll frame.
24. The STA according to claim 20 , wherein the processor controls the transceiver to:
receive a short training field (STF) within the PS-Poll interval set for the STA, in response to the PS-Poll frame; and
receive, after the total PS-Poll interval, an acknowledgement (ACK) frame containing a bitmap indicating whether or not the PS-Poll frames from every STA have been received.
25. The STA according to claim 20 , wherein the processor controls the transceiver to receive, when the STA is assigned with a last PS-Poll interval within the total PS-Poll interval, an acknowledgement (ACK) frame from the AP in response to the PS-Poll frame.
26. The STA according to claim 20 , wherein the information comprises at least one of offset information of each PS-Poll interval and duration information of each PS-Poll interval.