Method for transmitting or receiving frame in wireless LAN system and apparatus therefor
A method for an STA to transmit or receive a frame in a WLAN, according to one embodiment of the present invention, comprises the steps of: receiving a first HARQ trigger frame that triggers transmission of an A-PHDU into which PHDUs that are PHY data transmission units for a HARQ process are combined; transmitting at least one PHDU within the A-PHDU on the basis of the first HARQ trigger frame at the timing designated for the STA; and retransmitting the at least one PHDU or transmitting a new PHDU according to reception of a second HARQ trigger frame, wherein the first HARQ trigger frame includes timing offset information between the STA and another STA transmitting the PHDU within the A-PHDU, and the STA may determine the timing designated for the STA by using the timing offset information.
1. A method for transmitting/receiving frames by a receiving station (STA) in a wireless LAN (WLAN), the method comprising:
receiving a polling frame for a status report;
in response to the polling frame, transmitting a status report frame;
receiving a first trigger frame for triggering transmission of an aggregated physical layer data unit (A-PPDU) which includes an aggregate of hybrid automatic repeat request (HARQ) data units,
wherein the first trigger frame includes a common information field and a user info field, the common information field includes a bandwidth field related to a bandwidth of the A-PPDU and a power field related to a transmit power of the first trigger frame, the bandwidth field has a length of 2 bits, the power field has a length of 6 bits, the user info field includes an STA identifier (ID) field related to an ID of the receiving STA, a resource allocation field related to a frequency resource of the A-PPDU, and a modulation and coding scheme (MCS) field related to a MCS index of the A-PPDU, the STA ID field has a length of 12 bits, the resource allocation field has a length of 8 bits, and the MCS field has a length of 4 bits;
transmitting at least one of the HARQ data units at a timing designated for the receiving STA in the A-PPDU based on first trigger frame; and
retransmitting the at least one of the HARQ data units or transmitting a new A-PPDU upon reception of a second trigger frame,
wherein the first trigger frame includes information on a timing offset between the receiving STA and other STAs transmitting HARQ data units in the A-PPDU, and the receiving STA determines the timing designated for the receiving STA based on the timing offset, the timing offset is determined based on differences of timing of arrival of the status report frame of the receiving STA and status report frames of the other STAs at an access point (AP).
2. The method of claim 1 , wherein the APPDU includes a short training field (STF) and a long training field (LTF).
3. A receiving station (STA) in a wireless LAN (WLAN), the method comprising:
a transceiver; and
a processor coupled to the transceiver,
wherein the processor is configured to:
receive a polling frame for a status report;
in response to the polling frame, transmit a status report frame;
receive a first trigger frame for triggering transmission of an aggregated physical layer data unit (A-PPDU) which includes an aggregate of hybrid automatic repeat request (HARQ) data units,
wherein the first trigger frame includes a common information field and a user info field, the common information field includes a bandwidth field related to a bandwidth of the A-PPDU and a power field related to a transmit power of the first trigger frame, the bandwidth field has a length of 2 bits, the power field has a length of 6 bits, the user info field includes an STA identifier (ID) field related to an ID of the receiving STA, a resource allocation field related to a frequency resource of the A-PPDU, and a modulation and coding scheme (MCS) field related to a MCS index of the A-PPDU, the STA ID field has a length of 12 bits, the resource allocation field has a length of 8 bits, and the MCS field has a length of 4 bits;
transmit at least one of the HARQ data units at a timing designated for the receiving STA in the A-PPDU based on first trigger frame; and
retransmit the at least of the HARQ data units or transmitting a new A-PPDU upon reception of a second trigger frame,
wherein the first trigger frame includes information on a timing offset between the receiving STA and other STAs transmitting HARQ data units in the A-PPDU, and the receiving STA determines the timing designated for the receiving STA based on the timing offset, the timing offset is determined based on differences of timing of arrival of the status report frame of the receiving STA and status report frames of the other STAs at an access point (AP).
4. The receiving STA of claim 3 , wherein the APPDU includes a short training field (STF) and a long training field (LTF).