Method for managing NAV in wireless LAN system and device for same
According to an embodiment of the present invention, a method of managing a network allocation vector (NAV) by a station (STA) in a wireless LAN system supporting a high efficiency physical layer protocol data unit (HE PPDU) includes: receiving a frame including duration information; selecting a predetermined NAV from a plurality of NAVs of the STA; and managing the predetermined NAV based on the duration information of the frame, wherein the predetermined NAV is selected based on whether the frame has been received from a basic service set (BSS) to which the STA belongs.
1. A method of updating a network allocation vector (NAV) timer by a station (STA) in a wireless local area network (LAN) system supporting transmission of a high efficiency physical layer protocol data unit (HE PPDU), the method comprising:
receiving, by the STA, a frame including a signal (SIG) field, wherein the SIG field includes a transmission opportunity (TXOP) duration subfield;
obtaining a TXOP duration value from the TXOP duration subfield of the SIG field;
selecting, by the STA, a NAV timer from a first NAV timer for an intra-basic service set (intra-BSS) frame and a second NAV timer for an overlapping BSS (OBSS) frame, based on whether or not the frame is the intra-BSS frame; and
updating, by the STA, the selected NAV timer based on the TXOP duration value,
wherein the obtaining the TXOP duration value comprises:
determining a scaling factor for the TXOP duration value based on a first part of the TXOP duration subfield;
determining a scaled duration value based on a second part of the TXOP duration subfield; and
determining the TXOP duration value based on the scaling factor and the scaled duration value,
wherein the frame includes a medium access control (MAC) header, and the MAC header includes a duration field for the frame,
wherein a granularity used for the duration field is 1 us, and
wherein a total number of the plurality of bits in the TXOP duration subfield is smaller than that of the duration field.
2. The method of claim 1 , wherein the selecting of the NAV timer comprises:
selecting the first NAV timer upon determining that the frame is the intra-BSS frame received from a BSS to which the STA belongs; and
selecting the second NAV timer upon determining that the frame is the OBSS frame received from a BSS to which the STA does not belong.
3. The method of claim 1 , wherein the second NAV timer is used for a frame through which a BSS cannot be identified.
4. The method of claim 3 , wherein the frame through which the BSS cannot be identified is an acknowledgement (ACK) frame or a clear-to-send (CTS) frame.
5. The method of claim 1 , wherein the STA defers channel access when any of the first NAV timer and the second NAV timer has a value greater than 0.
6. A station (STA) for updating a network allocation vector (NAV) timer in a wireless local area network (LAN) system supporting transmission of a high efficiency physical layer protocol data unit (HE PPDU), the STA comprising:
a receiver for receiving a frame including a signal (SIG) field, wherein the SIG field includes a transmission opportunity (TXOP) duration subfield; and
a processor for:
obtaining a TXOP duration value from the TXOP duration subfield of the SIG field,
selecting a NAV timer from a first NAV timer for an intra-basic service set (intra-BSS) frame and a second NAV timer for an overlapping BSS (OBSS) frame, based on whether or not the frame is the intra-BSS frame, and
updating the selected NAV timer based on the TXOP duration value,
wherein the processor obtains the TXOP duration value by:
determining a scaling factor for the TXOP duration value based on a first part of the TXOP duration subfield,
determining a scaled duration value based on a second part of the TXOP duration subfield, and
determining the TXOP duration value based on the scaling factor and the scaled duration value,
wherein the frame includes a medium access control (MAC) header, and the MAC header includes a duration field for the frame,
wherein a granularity used for the duration field is 1 us, and
wherein a total number of the plurality of bits in the TXOP duration subfield is smaller than that of the duration field.
7. The STA of claim 6 , wherein the processor selects the first NAV upon determining that the frame is the intra-BSS frame received from a BSS to which the STA belongs, and selects the second NAV upon determining that the frame is the OBSS frame received from a BSS to which the STA does not belong.
8. The STA of claim 6 , wherein the second NAV timer is used for a frame through which a BSS cannot be identified.
9. The method of claim 1 , wherein a granularity determined based on the scaling factor is larger than the granularity used for the duration field.
10. The STA of claim 6 , wherein a granularity determined based on the scaling factor is larger than the granularity used for the duration field.