Apparatus and method for TWT operation for multi-link devices

1. A non-access point (AP) multi-link device (MLD) comprising:

a plurality of stations (STAs) that each comprise a transceiver configured to transmit and receive signals; and

a processor operably coupled to the transceivers, the processor configured to:

perform a multi-link (ML) setup operation with an AP MLD to set up links between the STAs affiliated with the non-AP MLD and corresponding APs affiliated with the AP MLD;

negotiate a broadcast target wake time (TWT) agreement over a first link between a first STA and a first AP of the AP MLD, wherein the broadcast TWT agreement is for a shared TWT session including a group of the links; and

after the broadcast TWT agreement is successfully negotiated, apply the broadcast TWT agreement to the group of links.

2. The non-AP MLD of claim 1 , wherein the processor is further configured to indicate to the AP MLD on the first link, via the first STA during the ML setup operation, that broadcast TWT operation is supported by the non-AP MLD.

3. The non-AP MLD of claim 1 , wherein the processor is further configured to indicate to the AP MLD on the first link, via the first STA during the negotiation of the broadcast TWT agreement, the group of links that are to be included in the broadcast TWT agreement.

4. The non-AP MLD of claim 1 , wherein the processor is further configured to:

generate a broadcast TWT parameter set that includes a broadcast TWT link identifier (ID) bitmap subfield, and a subfield indicating whether the broadcast TWT link ID bitmap subfield is present in the broadcast TWT parameter set, wherein a bitmap included in the broadcast TWT link ID bitmap subfield indicates whether each of the links is included in the group of links that are to be included in the broadcast TWT agreement; and

transmit the broadcast TWT parameter set to the AP MLD over the first link via the first STA during the negotiation of the broadcast TWT agreement.

5. The non-AP MLD of claim 1 , wherein the processor is further configured to:

receive from the AP MLD on one link of the group of links, via a corresponding one of the STAs, a broadcast TWT schedule and an indication that the broadcast TWT schedule is aligned across multiple links in the group of links; and

apply the broadcast TWT schedule to each of the multiple links, such that broadcast TWT service periods (SPs) begin and end at same times for each of the multiple links.

6. The non-AP MLD of claim 1 , wherein the processor is further configured to:

receive from the AP MLD on at least one link of the group of links, via a corresponding at least one STA of the STAs, a broadcast TWT schedule and an indication that the broadcast TWT schedule is an aligned broadcast TWT schedule; and

apply the aligned broadcast TWT schedule to each of the at least one link on which the broadcast TWT schedule was received, such that broadcast TWT service periods (SPs) begin and end at same times for each of the at least one link.

7. The non-AP MLD of claim 1 , wherein the processor is configured to indicate to the AP MLD on a link of the group of links, via a corresponding one of the STAs, a potential broadcast TWT schedule that indicates that the potential broadcast TWT schedule needs to be aligned across multiple of the links in the group of links, such that broadcast TWT service periods (SPs) begin and end at same times for each of the multiple links.

8. An access point (AP) multi-link device (MLD) comprising:

a plurality of APs that each comprise a transceiver configured to transmit and receive signals; and

a processor operably coupled to the transceivers, the processor configured to:

perform a multi-link (ML) setup operation with a non-AP MLD to set up links between the APs affiliated with the AP MLD and corresponding stations (STAs) affiliated with the non-AP MLD;

negotiate a broadcast target wake time (TWT) agreement over a first link between a first AP and a first STA of the non-AP MLD, wherein the broadcast TWT agreement is for a shared TWT session including a group of the links; and

after the broadcast TWT agreement is successfully negotiated, apply the broadcast TWT agreement to the group of links.

9. The AP MLD of claim 8 , wherein the processor is further configured to receive an indication from the non-AP MLD on the first link, via the first AP during the ML setup operation, that broadcast TWT operation is supported by the non-AP MLD.

10. The AP MLD of claim 8 , wherein the processor is further configured to receive an indication from the non-AP MLD on the first link, via the first AP during the negotiation of the broadcast TWT agreement, of the group of links that are to be included in the broadcast TWT agreement.

11. The AP MLD of claim 8 , wherein the processor is further configured to receive a broadcast TWT parameter set from the non-AP MLD over the first link via the first AP during the negotiation of the broadcast TWT agreement,

wherein the broadcast TWT parameter set includes a broadcast TWT link identifier (ID) bitmap subfield, and a subfield indicating whether the broadcast TWT link ID bitmap subfield is present in the broadcast TWT parameter set, and

wherein a bitmap included in the broadcast TWT link ID bitmap subfield indicates whether each of the links is included in the group of links that are to be included in the broadcast TWT agreement.

12. The AP MLD of claim 8 , wherein the processor is further configured to:

generate a broadcast TWT schedule and an indication that the broadcast TWT schedule is aligned across multiple links in the group of links;

transmit to the non-AP MLD on one link of the group of links, via a corresponding one of the APs, the broadcast TWT schedule and the indication; and

apply the broadcast TWT schedule to each of the multiple links, such that broadcast TWT service periods (SPs) begin and end at same times for each of the multiple links.

13. The AP MLD of claim 8 , wherein the processor is further configured to:

transmit to the non-AP MLD on at least one link of the group of links, via a corresponding at least one AP of the APs, a broadcast TWT schedule and an indication that the broadcast TWT schedule is an aligned broadcast TWT schedule; and

apply the aligned broadcast TWT schedule to each of the at least one link on which the broadcast TWT schedule was transmitted, such that broadcast TWT service periods (SPs) begin and end at same times for each of the at least one link.

14. The AP MLD of claim 8 , wherein the processor is further configured to receive an indication from the non-AP MLD on a link of the group of links, via a corresponding one of the APs, of a potential broadcast TWT schedule that indicates that the potential broadcast TWT schedule needs to be aligned across multiple of the links in the group of links, such that broadcast TWT service periods (SPs) begin and end at same times for each of the multiple links.

15. A method for facilitating broadcast target wake time (TWT) operation by a non-access point (AP) multi-link device (MLD), the method comprising:

performing a multi-link (ML) setup operation with an AP MLD to set up links between a plurality of stations (STAs) affiliated with the non-AP MLD and corresponding APs affiliated with the AP MLD;

negotiating a broadcast TWT agreement over a first link between a first STA and a first AP of the AP MLD, wherein the broadcast TWT agreement is for a shared TWT session including a group of the links; and

after the broadcast TWT agreement is successfully negotiated, applying the broadcast TWT agreement to the group of links.

16. The method of claim 15 , further comprising indicating to the AP MLD on the first link, via the first STA during the ML setup operation, that broadcast TWT operation is supported by the non-AP MLD.

17. The method of claim 15 , further comprising:

generating a broadcast TWT parameter set that includes a broadcast TWT link identifier (ID) bitmap subfield, and a subfield indicating whether the broadcast TWT link ID bitmap subfield is present in the broadcast TWT parameter set, wherein a bitmap included in the broadcast TWT link ID bitmap subfield indicates whether each of the links is included in the group of links that are to be included in the broadcast TWT agreement; and

transmitting the broadcast TWT parameter set to the AP MLD over the first link via the first STA during the negotiation of the broadcast TWT agreement.

18. The method of claim 15 , further comprising:

receiving from the AP MLD on one link of the group of links, via a corresponding one of the STAs, a broadcast TWT schedule and an indication that the broadcast TWT schedule is aligned across multiple links in the group of links; and

applying the broadcast TWT schedule to each of the multiple links, such that broadcast TWT service periods (SPs) begin and end at same times for each of the multiple links.

19. The method of claim 15 , further comprising:

receiving from the AP MLD on at least one link of the group of links, via a corresponding at least one STA of the STAs, a broadcast TWT schedule and an indication that the broadcast TWT schedule is an aligned broadcast TWT schedule; and

applying the aligned broadcast TWT schedule to each of the at least one link on which the broadcast TWT schedule was received, such that broadcast TWT service periods (SPs) begin and end at same times for each of the at least one link.

20. The method of claim 15 , further comprising indicating to the AP MLD on a link of the group of links, via a corresponding one of the STAs, a potential broadcast TWT schedule that indicates that the potential broadcast TWT schedule needs to be aligned across multiple of the links in the group of links, such that broadcast TWT service periods (SPs) begin and end at same times for each of the multiple links.