EHT EMLSR TWT operation in wireless communications

1 . A method, comprising:

enabling, by a processor of a non-access point (non-AP) multi-link device (MLD), an enhanced multi-link single-radio (EMLSR) mode by performing operations comprising:

establishing one or more target wake time (TWT) agreements comprising a concurrent TWT agreement with an access point (AP) MLD on a first link and a second link of multiple links such that data exchange between a first station (STA) affiliated with the non-AP MLD and a first AP affiliated with the AP MLD occurs on the first link during a TWT service period (SP) while an operation in the EMLSR mode is performed on the second link between the AP MLD and a second STA affiliated with the non-AP MLD; and

switching from operating in the EMSLR mode to operating in a single radio mode on the second link responsive to the first STA transmitting a TWT Teardown frame on the first link to terminate the concurrent TWT agreement;

wherein, prior to switching from the EMLSR mode to the single radio mode, the non-AP MLD transmits the TWT Teardown frame that selectively applies to one or more links to terminate the concurrent TWT agreement on the multiple links.

2 . The method of claim 1 , wherein the establishing of the one or more TWT agreements comprises transmitting a TWT request, and wherein a Link Identifier (ID) Bitmap subfield of a TWT element in the TWT request indicates one or more links of the multiple links for which the one or more TWT agreements are requested to be established.

3 . The method of claim 2 , wherein the establishing of the one or more TWT agreements further comprises receiving a TWT response, and wherein a Link Identifier (ID) Bitmap subfield of a TWT element in the TWT response indicates the one or more links of the multiple links for which the one or more TWT agreements are requested to be established.

4 . The method of claim 1 , further comprising:

negotiating, by the processor as the first STA, a wake target beacon transmission time (TBTT) and a wake interval with a second AP affiliated with the AP MLD; and

receiving, by the processor, one or more beacon frames on the second link.

5 . The method of claim 4 , further comprising:

ending, by the processor as a second STA affiliated with the non-AP MLD and operating in the EMLSR mode on the second link, a transmission opportunity (TXOP) on the second link before the first STA receives a beacon frame scheduled at the negotiated TBTT.

6 . The method of claim 5 , wherein the ending of the TXOP comprises ending the TXOP at least an EMLSR transition delay before the first STA receives the beacon frame scheduled at the negotiated TBTT, and wherein the EMLSR transition delay is indicated in an EMLSR Transition Delay subfield of an Enhanced Multi-Link (EML) Capabilities subfield in a Common Info field of a Basic Multi-Link element.

7 . The method of claim 1 , wherein the TWT Teardown frame comprises a TWT flow identifier comprising:

a first subfield indicating whether a link identification (ID) bitmap is present;

a second subfield indicating whether the TWT Teardown frame applies to all TWTs; and

a third subfield containing the link ID bitmap indicating one or more links to which the TWT Teardown frame applies, in an event that the first subfield indicating a presence of the link ID bitmap.

8 . An apparatus, comprising:

a transceiver configured to communicate wirelessly; and

a processor coupled to the transceiver and configured to perform, as a non-access point (non-AP) multi-link device (MLD), operations comprising:

enabling an enhanced multi-link single-radio (EMLSR) mode by performing operations comprising:

establishing, via the transceiver, one or more target wake time (TWT) agreements comprising a concurrent TWT agreement with an access point (AP) MLD on a first link and a second link of multiple links such that data exchange between a first station (STA) affiliated with the non-AP MLD and a first AP affiliated with the AP MLD occurs on the first link during a TWT service period (SP) while an operation in the EMLSR mode is performed on the second link between the AP MLD and a second STA affiliated with the non-AP MLD; and

switching from operating in the EMSLR mode to operating in a single radio mode on the second link responsive to the first STA transmitting a TWT Teardown frame on the first link to terminate the concurrent TWT agreement,

wherein, prior to switching from the EMLSR mode to the single radio mode, the non-AP MLD transmits the TWT Teardown frame that selectively applies to one or more links to terminate the concurrent TWT agreement on the multiple links.

9 . The apparatus of claim 8 , wherein the establishing of the one or more TWT agreements comprises transmitting a TWT request, and wherein a Link Identifier (ID) Bitmap subfield of a TWT element in the TWT request indicates one or more links of the multiple links for which the one or more TWT agreements are requested to be established.

10 . The apparatus of claim 9 , wherein the establishing of the one or more TWT agreements further comprises receiving a TWT response, and wherein a Link Identifier (ID) Bitmap subfield of a TWT element in the TWT response indicates the one or more links of the multiple links for which the one or more TWT agreements are requested to be established.

11 . The apparatus of claim 8 , wherein the processor is further configured to perform operations comprising:

negotiating, as the first STA, a wake target beacon transmission time (TBTT) and a wake interval with a second AP affiliated with the AP MLD; and

receiving, by the processor, one or more beacon frames on the second link.

12 . The apparatus of claim 11 , wherein the processor is further configured to perform operations comprising:

ending, by as a second STA affiliated with the non-AP MLD and operating in the EMLSR mode on the second link, a transmission opportunity (TXOP) on the second link before the first STA receives a beacon frame scheduled at the negotiated TBTT.

13 . The apparatus of claim 12 , wherein the ending of the TXOP comprises ending the TXOP at least an EMLSR transition delay before the first STA receives the beacon frame scheduled at the negotiated TBTT, and wherein the EMLSR transition delay is indicated in an EMLSR Transition Delay subfield of an Enhanced Multi-Link (EML) Capabilities subfield in a Common Info field of a Basic Multi-Link element.

14 . The apparatus of claim 8 , wherein the TWT Teardown frame comprises a TWT flow identifier comprising:

a first subfield indicating whether a link identification (ID) bitmap is present;

a second subfield indicating whether the TWT Teardown frame applies to all TWTs; and

a third subfield containing the link ID bitmap indicating one or more links to which the TWT Teardown frame applies, in an event that the first subfield indicating a presence of the link ID bitmap.