Method and apparatus for receiving frame
Disclosed are a method and an apparatus for receiving a frame. A method for receiving a frame in a wireless LAN comprises the steps of: an AP transmitting, to a plurality of STAs, a downlink PPDU including downlink data for each of the plurality of STAs, through a plurality of channels; and the AP receiving, from each of the plurality of STAs, a plurality of block ACK frames transmitted based on a block ACK transmission control field, wherein the downlink PPDU includes the block ACK transmission control field, and wherein each of the plurality of block ACK frames may include ACK information related to downlink data.
1. A method for receiving a frame in a wireless local area network (WLAN), the method comprising:
transmitting, by an access point (AP), a plurality of downlink physical layer protocol data units (DL PPDUs) including a plurality of downlink data for a plurality of stations (STAs) to the plurality of STAs based on orthogonal frequency division multiple access (OFDMA),
wherein the plurality of DL PPDUs are transmitted based on a plurality of first subbands on a primary channel and a plurality of second subbands on a secondary channel,
wherein the plurality of DL PPDUs include a plurality of block acknowledgement (ACK) transmission control fields for the plurality of STAs,
wherein each of the plurality of block ACK transmission control fields includes a transmission resource field and an ACK policy field,
wherein the transmission resource field includes information on whether an uplink channel allocated for a block ACK frame to be transmitted by a corresponding STA is the primary channel or the secondary channel, and
wherein the ACK policy field includes information on whether the block ACK frame to be transmitted by the corresponding STA is set to an immediate block ACK transmission policy or a delayed block ACK transmission policy; and
receiving, by the AP, from the plurality of STAs a plurality of block ACK frames that are transmitted based on the plurality of block ACK transmission control fields, wherein each of the plurality of block ACK frames includes ACK information for the plurality of downlink data.
2. The method of claim 1 , wherein the uplink channel is fixed to one channel among the primary channel and the secondary channel.
3. The method of claim 1 , wherein the step of receiving the plurality of block ACK frames comprises:
receiving, by the AP, an immediate block ACK frame from a first STA, the first STA having received an indication for the immediate block ACK transmission policy based on the ACK policy field, among the plurality of STAs;
transmitting, by the AP, a block acknowledgement request (BAR) frame to a second STA, the second STA having received an indication for the delayed block ACK transmission policy based on the ACK policy field, among the plurality of STAs; and
receiving, by the AP, a delayed block ACK frame from the second STA as a response to the BAR frame,
wherein the plurality of block ACK frames include the immediate block ACK frame and the delayed block ACK frame,
wherein the immediate block ACK frame is transmitted within a predetermined period of time after a reception of at least one downlink PPDU for the first STA, and
wherein the delayed block ACK frame is transmitted within the predetermined period of time after a reception of the BAR frame by the second STA.
4. The method of claim 1 , wherein the step of receiving the plurality of block ACK frames comprises:
transmitting, by the AP, a first block acknowledgement request (BAR) frame to a first STA, the first STA having received an indication for the delayed block ACK transmission policy based on the ACK policy field, among the plurality of STAs; and
in case the AP fails to receive a first delayed block ACK frame from the first STA within a threshold time period as a response to the first BAR frame, transmitting, by the AP, a second BAR frame to a second STA, the second STA having received an indication for the delayed block ACK transmission policy based on the ACK policy field, among the plurality of STAs.
5. The method of claim 4 , wherein the threshold time period is determined based on a time for transmitting a first delayed block ACK frame after receiving the first BAR frame of the first STA.
6. An access point (AP) for transmitting a frame in a wireless local area network (WLAN), the AP comprising:
a transceiver configured to transmit or receive radio signals; and
a processor operatively connected to the transceiver,
wherein the processor is configured to:
control the transceiver to transmit a plurality of downlink physical layer protocol data units (DL PPDUs) including a plurality of downlink data for a plurality of stations (STAs) to the plurality of STAs based on orthogonal frequency division multiple access (OFDMA),
wherein the plurality of DL PPDUs are transmitted based on a plurality of first subbands on a primary channel and a plurality of second subbands on a secondary channel,
wherein the plurality of DL PPDUs include a plurality of block acknowledgement (ACK) transmission control fields for the plurality of STAs,
wherein each of the plurality of block ACK transmission control fields includes a transmission resource field and an ACK policy field,
wherein the transmission resource field includes information on whether an uplink channel allocated for a block ACK frame to be transmitted by a corresponding STA is the primary channel or the secondary channel, and
wherein the ACK policy field includes information on whether the block ACK frame to be transmitted by the corresponding STA is set to an immediate block ACK transmission policy or a delayed block ACK transmission policy, and
control the transceiver to receive from the plurality of STAs a plurality of block ACK frames that are transmitted based on the plurality of block ACK transmission control fields,
wherein each of the plurality of block ACK frames includes ACK information for the plurality of downlink data.
7. The AP of claim 6 , wherein the uplink channel is fixed to one channel among the primary channel and the secondary channel.
8. The AP of claim 6 , wherein the processor is further configured to:
control the transceiver to receive an immediate block ACK frame from a first STA, the first STA having received an indication for the immediate block ACK transmission policy based on the ACK policy field, among the plurality of STAs,
control the transceiver to transmit a block acknowledgement request (BAR) frame to a second STA, the second STA having received an indication for the delayed block ACK transmission policy based on the ACK policy field, among the plurality of STAs, and
control the transceiver to receive a delayed block ACK frame from the second STA as a response to the BAR frame,
wherein the plurality of block ACK frames include the immediate block ACK frame and the delayed block ACK frame,
wherein the immediate block ACK frame is transmitted within a predetermined period of time after a reception of at least one downlink PPDU for the first STA, and
wherein the delayed block ACK frame is transmitted within the predetermined period of time after a reception of the BAR frame by the second STA.
9. The method of claim 6 , wherein the processor is further configured to:
control the transceiver to transmit a first block acknowledgement request (BAR) frame to a first STA, the first STA having received an indication for the delayed block ACK transmission policy based on the ACK policy field, among the plurality of STAs, and
in case the processor fails to receive a first delayed block ACK frame from the first STA within a threshold time period as a response to the first BAR frame, control the transceiver to transmit a second BAR frame to a second STA, the second STA having received an indication for the delayed block ACK transmission policy based on the ACK policy field, among the plurality of STAs.
10. The AP of claim 9 , wherein the threshold time period is determined based on a time for transmitting a first delayed block ACK frame after receiving the first BAR frame of the first STA.