Method and apparatus for transmitting data frame in WLAN system

1. A method of transmitting a data frame by a station in a wireless local area network, the method comprising:

obtaining, by the station, a transmission opportunity (TXOP) for a bandwidth, the TXOP indicating an interval of time during which the station has a right to initiate frame exchange sequences onto a wireless medium;

selecting, by the station, a transmit bandwidth parameter of a non-initial data unit of a plurality of data units from available bandwidth parameters, wherein the available bandwidth parameters include a first available bandwidth parameter which is same as a transmit bandwidth parameter of a preceding data unit of the plurality of data units and a second available bandwidth parameter which is narrower than a transmit bandwidth parameter of the preceding data unit; and

transmitting, by the station during the TXOP, the non-initial data unit according to the transmit bandwidth parameter of the non-initial data unit.

2. The method of claim 1 , wherein the station is an Access Point (AP) station.

3. The method of claim 1 , wherein the station is a non-Access Point (non-AP) station.

4. The method of claim 1 , further comprising:

determining, by the station, whether a certain condition in the TXOP has been met to select the transmit bandwidth parameter of the non-initial data unit from the available bandwidth parameters.

5. The method of claim 1 , wherein the step of obtaining the TXOP comprises:

obtaining, by the station, the TXOP for a bandwidth greater than 20 MHz.

6. A station configured to transmit a data frame in a wireless local area network, the station comprising:

a transceiver; and

a processor operatively connected to the transceiver and configured to:

obtain a transmission opportunity (TXOP) for a bandwidth, the TXOP indicating an interval of time during which the station has a right to initiate frame exchange sequences onto a wireless medium;

select a transmit bandwidth parameter of a non-initial data unit of a plurality of data units from available bandwidth parameters, wherein the available bandwidth parameters include a first available bandwidth parameter which is same as a transmit bandwidth parameter of a preceding data unit of the plurality of data units and a second available bandwidth parameter which is narrower than a transmit bandwidth parameter of the preceding data unit; and

transmit, during the TXOP, the non-initial data unit according to the transmit bandwidth parameter of the non-initial data unit.

7. The station of claim 6 , wherein the station is an Access Point (AP) station.

8. The station of claim 6 , wherein the station is a non-Access Point (non-AP) station.

9. The station of claim 6 , wherein the processor is further configured to determine whether a certain condition in the TXOP has been met to select the transmit bandwidth parameter of the non-initial data unit from the available bandwidth parameters.

10. The station of claim 6 , when obtaining the TXOP the processor is further configured to:

obtain the TXOP for a bandwidth greater than 20 MHz.

11. A method of transmitting a data frame by a station in a wireless local area network, the method comprising:

obtaining, by the station, a transmission opportunity (TXOP) for a bandwidth, the TXOP indicating an interval of time during which the station has a right to initiate frame exchange sequences onto a wireless medium;

setting, by the station, a transmit bandwidth parameter of a non-initial data unit of a plurality of data units to be same or narrower than a transmit bandwidth parameter of a preceding data unit of the plurality of data units; and

transmitting, by the station during the TXOP, the non-initial data unit according to the transmit bandwidth parameter of the non-initial data unit.

12. The method of claim 11 , wherein the station is an Access Point (AP) station.

13. The method of claim 11 , wherein the station is a non-Access Point (non-AP) station.

14. The method of claim 11 , further comprising:

determining, by the station, whether a certain condition in the TXOP has been met to set the transmit bandwidth parameter of the non-initial data unit.

15. The method of claim 11 , wherein the step of obtaining the TXOP comprises:

obtaining, by the station, the TXOP for a bandwidth greater than 20 MHz.

16. A station configured to transmit a data frame in a wireless local area network, the station comprising:

a transceiver; and

a processor operatively connected to the transceiver and configured to:

obtain a transmission opportunity (TXOP) for a bandwidth, the TXOP indicating an interval of time during which the station has a right to initiate frame exchange sequences onto a wireless medium;

set, by the station, a transmit bandwidth parameter of a non-initial data unit of a plurality of data units to be same or narrower than a transmit bandwidth parameter of a preceding data unit of the plurality of data units; and

transmit, by the station during the TXOP, the non-initial data unit according to the transmit bandwidth parameter of the non-initial data unit.

17. The station of claim 16 , wherein the station is an Access Point (AP) station.

18. The station of claim 16 , wherein the station is a non-Access Point (non-AP) station.

19. The station of claim 16 , wherein the processor is further configured to determine whether a certain condition in the TXOP has been met to select the transmit bandwidth parameter of the non-initial data unit from the available bandwidth parameters.

20. The station of claim 16 , wherein when obtaining the TXOP, the processor is further configured to obtain the TXOP for a bandwidth greater than 20 MHz.