Method and apparatus for ACK transmission in a WLAN
The present invention relates to a method and apparatus for acknowledgement (ACK) transmission in a WLAN. A station receives a plurality of data frames from a plurality of other stations and then transmits an ACK for the plurality of data frames to the plurality of stations. The ACK is a multi-user (MU) block ACK frame which includes a plurality of block ACKs for the plurality of stations. One block ACK includes at least one ACK for at least one data frame that is received from one station.
1. A method of transmitting acknowledgement (ACK) performed by an Access Point (AP) in a Wireless Local Area Network (WLAN), the method comprising:
transmitting a control frame used for uplink multi-user Multiple-Input Multiple-Output (UL MU-MIMO) transmission, wherein the control frame indicates a plurality of stations (STAs) participating in the UL MU-MIMO transmission and indicates a time duration for the UL MU-MIMO transmission;
in response to the control frame, receiving a plurality of response frames from the plurality of STAs, wherein the plurality of response frames are simultaneously received by the AP during the time duration; and
transmitting a single frame including a Multi-User (MU) ACK frame for the plurality of response frames to the plurality of STAs,
wherein the MU ACK frame comprises a Medium Access Control (MAC) header followed by a Block ACK (BA) control field followed by a plurality of BA information fields,
wherein the MAC header includes a frame control field, a duration/ID field, a receiver address (RA) field, and a transmitter address (TA) field which are used for the MU ACK frame,
wherein the BA control field is common to the plurality of STAs, and the BA information fields are corresponding to the plurality of STAs, respectively,
wherein the BA control field includes an ACK type field indicating that the MU ACK frame is used for the plurality of STAs,
wherein each BA information field includes an association ID (AID) field indicating a corresponding STA, a traffic ID (TID) field used for the corresponding STA, and a BA bitmap field indicating at least one ACK for a corresponding response frame of the corresponding STA.
2. The method of claim 1 , wherein
the BA control field comprises a BA policy subfield indicating an ACK policy of the MU ACK frame.
3. The method of claim 2 , wherein the BA control field further comprises
an MU BA duration indicating a size of each of the plurality of BA information fields.
4. The method of claim 2 , wherein the BA control field further comprises an MU number field indicating a number of the plurality of STAs.
5. An access point (AP) in a Wireless Local Area Network (WLAN), comprising
a transceiver transmitting a control frame used for uplink multi-user Multiple-Input Multiple-Output (UL MU-MIMO) transmission, wherein the control frame indicates a plurality of stations (STAs) participating in the UL MU-MIMO transmission and indicates a time duration for the UL MU-MIMO transmission, receiving a plurality of response frames from the plurality of STAs in response to the control frame, wherein the plurality of response frames are simultaneously received by the AP during the time duration, and transmitting a single frame including a Multi-User (MU) ACK frame for the plurality of response frames to the plurality of STAs; and
a data processor processing the plurality of response frames and controlling the transceiver,
wherein the MU ACK frame comprises a Medium Access Control (MAC) header followed by a Block ACK (BA) control field followed by a plurality of BA information fields,
wherein the MAC header includes a frame control field, a duration/ID field, a receiver address (RA) field, and a transmitter address (TA) field which are used for the MU ACK frame,
wherein the BA control field is common to the plurality of STAs, and the BA information fields are corresponding to the plurality of STAs, respectively, wherein the BA control field includes an ACK type field indicating that the MU ACK frame is used for the plurality of STAs,
wherein each BA information field includes an association ID (AID) field indicating a corresponding STA, a traffic ID (TID) field used for the corresponding STA, and a BA bitmap field indicating at least one ACK for a corresponding response frame of the corresponding STA.
6. The AP of claim 5 , wherein the BA control field comprises a BA policy subfield indicating an ACK policy of the MU ACK frame.
7. The AP of claim 6 , wherein the BA control field further comprises an MU BA duration indicating a size of each of the plurality of BA information fields.
8. The AP of claim 6 , wherein the BA control field further comprises an MU number field indicating a number of the plurality of STAs.