Method and device for transmitting PPDU

1. A method for use in a station for transmitting a physical layer protocol data unit (PPDU), the method comprising:

receiving, from an access point (AP), a trigger frame, wherein the trigger frame includes a first duration field, a length field and a resource allocation field, the resource allocation field indicating a resource allocated for transmission of a high efficiency (HE) trigger-based (TB) PPDU; and

transmitting, to the AP, the HE TB PPDU in response to the received trigger frame,

wherein the HE TB PPDU includes a second duration field,

wherein a value of the second duration field is set based on a value obtained from the first duration field of the trigger frame minus a Short Interframe Space (SIFS) duration and a duration of the HE TB PPDU.

2. The method of claim 1 , wherein the duration of the HE TB PPDU is based on a value of the length field of the received trigger frame and a SignalExtension value.

3. The method of claim 1 , wherein the HE TB PPDU further includes a legacy signal field and a data field, wherein the legacy signal field represents a number of orthogonal frequency division multiplexing (OFDM) symbols used for the data field, and wherein the legacy signal field indicates the value of the length field in the trigger frame.

4. The method of claim 1 , wherein the SIFS duration is 10 μs when the station operates in a 2.4 GHz band and the SIFs duration is 16 μs when the station operates in a 5 GHz band.

5. The method of claim 1 , wherein the trigger frame further includes an association identifier field associated with the station.

6. The method of claim 1 , further comprising updating a network allocation vector (NAV) based on the first and second duration fields.

7. The method of claim 1 , wherein the first duration field is included in a medium access control (MAC) header of the trigger frame.

8. The method of claim 7 , wherein the second duration field is included in a MAC header of the HE TB PPDU.

9. The method of claim 1 , wherein the HE TB PPDU further includes a third duration field, wherein the third duration field is set based on a value obtained from the first duration field of the trigger frame minus the time equal to SIFS plus a duration of the HE TB PPDU in a unit of 8 μs or 128 μs.

10. The method of claim 9 , wherein the third duration field is included in a physical layer preamble of the HE TB PPDU.

11. The method of claim 1 , wherein the HE TB PPDU is a multi-user (MU) transmission that is transmitted at a same time as another HE TB PPDU transmitted from another station.

12. A device for transmitting a physical layer protocol data unit (PPDU) in a wireless local area network, the device comprising:

a transceiver configured to receive and transmit radio signals from an access point (AP); and

a processor coupled with the transceiver and configured to:

receive, from an access point (AP), a trigger frame, wherein the trigger frame includes a first duration field, a length field and a resource allocation field, the resource allocation field indicating a resource allocated for transmission of a high efficiency (HE) trigger-based (TB) PPDU; and

transmit, to the AP, the HE TB PPDU in response to the received trigger frame,

wherein the HE TB PPDU includes a second duration field,

wherein a value of the second duration field is set based on a value obtained from the first duration field of the trigger frame minus a Short Interframe Space (SIFS) duration and a duration of the HE TB PPDU.

13. The device of claim 12 , wherein the duration of the HE TB PPDU is based on a value of the length field of the received trigger frame and a SignalExtension value.

14. The device of claim 12 , wherein the HE TB PPDU further includes a legacy signal field and a data field, wherein the legacy signal field represents a number of orthogonal frequency division multiplexing (OFDM) symbols used for the data field, and wherein the legacy signal field indicates the value of the length field in the trigger frame.

15. The device of claim 12 , wherein the SIFS duration is 10 μs when the station operates in a 2.4 GHz band and the SIFs duration is 16 μs when the station operates in a 5 GHz band.

16. The device of claim 12 , wherein the trigger frame further includes an association identifier field associated with the station.

17. The device of claim 12 , wherein the processor is further configured to update a network allocation vector (NAV) based on the first and second duration fields.

18. The device of claim 12 , wherein the first duration field is included in a medium access control (MAC) header of the trigger frame.

19. The device of claim 18 , wherein the second duration field is included in a MAC header of the HE TB PPDU.

20. The device of claim 12 , wherein the HE TB PPDU further includes a third duration field, wherein the third duration field is set based on a value obtained from the first duration field of the trigger frame minus the time equal to SIFS plus a duration of the HE TB PPDU in a unit of 8 μs or 128 μs.

21. The device of claim 20 , wherein the third duration field is included in a physical layer preamble of the HE TB PPDU.

22. The device of claim 12 , wherein the HE TB PPDU is a multi-user (MU) transmission that is transmitted at a same time as another HE TB PPDU transmitted from another station.