Acknowledgement procedure in WLAN

1. A method for a first station (STA) to transmit an acknowledgement (ACK) signal to a second STA in a wireless local area network (WLAN), the method comprising:

receiving a first type frame, not including a quality of service (QoS) control field, from the second STA;

transmitting an ACK signal for the first type frame to the second STA based on an ACK policy of a QoS control field of a second type frame, when the first type frame had been received as aggregated with the second type frame including the QoS control field; and

transmitting the ACK signal for the first type frame to the second STA through resources allocated by a third type frame, when the first type frame had been received with the third type frame including resource allocation information,

wherein the first STA does not transmit the ACK signal for the first type frame, when the first frame had been received without the second type frame and the third type frame.

2. The method of claim 1 , wherein the first type frame includes a management frame.

3. The method of claim 1 , wherein the second type frame includes a QoS data frame.

4. The method of claim 1 , wherein the third frame includes one of a trigger frame or a frame including UL MU (uplink multi-user) response scheduling A control (aggregated control) field.

5. The method of claim 1 , further comprising:

receiving a specific management frame including information on the ACK policy; and

transmitting an ACK signal for the specific management frame to the second STA based on the ACK policy of the specific management frame.

6. The method of claim 1 , further comprising:

receiving a MU PPDU (Multi User Protocol Data Unit) from the second STA;

receiving a BAR (Block Ack Request) frame from the second STA; and

transmitting a Multi-STA Block ACK frame for the MU PPDU, when a BA (Block Ack) type field of the BAR frame has a predetermined value.

7. The method of claim 6 , wherein the BAR frame includes the BA type field followed by a Multi-STA Block Ack Request variant, when the BA type field has the predetermined value.

8. A first STA configured to transmit an acknowledgement (ACK) signal to a second STA, the first STA comprising:

a transceiver configured to receive a first type frame, not including a quality of service (QoS) control field, from the second STA; and

a processor configured to control the transceiver to:

transmit an ACK signal for the first type frame to the second STA based on an ACK policy of a QoS control field of a second type frame, when the first type frame had been received as aggregated with the second type frame including the QoS control field;

transmit the ACK signal for the first type frame to the second STA through resources allocated by a third type frame, when the first type frame had been received with the third type frame including resource allocation information,

wherein the processor determines not to transmit the ACK signal for the first type frame, when the first frame had been received without the second type frame and the third type frame.

9. The first STA of claim 8 , wherein the first type frame includes a management frame.

10. The first STA of claim 8 , wherein the second type frame includes a QoS data frame.

11. The first STA of claim 10 , wherein the third type frame includes one of a trigger frame or a frame including UL MU (uplink multi-user) response scheduling A control (aggregated control) field.

12. The first STA of claim 8 , wherein, when the transceiver receives a specific management frame including information on the ACK policy, the processor is configured to control the transceiver to transmit an ACK signal for the specific management frame to the second STA based on the ACK policy of the specific management frame.

13. The first type STA of claim 8 , wherein, when the transceiver receives a MU PPDU (Multi User Protocol Data Unit) followed by a BAR (Block Ack Request) frame from the second STA and when a BA (Block Ack) type field of the BAR frame has a predetermined value, the processor is configured to control the transceiver to transmit a Multi-STA Block ACK frame for the MU PPDU.

14. The first type STA of claim 13 , wherein the BAR frame includes the BA type field followed by a Multi-STA Block Ack Request variant, when the BA type field has the predetermined value.