Device, system, and method for transmissions during a restricted target wake time (rTWT) service period (SP)

1. A device comprising:

a wireless network interface device implemented on one or more integrated circuits (ICs), wherein the wireless network interface device is configured to:

transmit a beacon on a first link that indicates a restricted Target Wake Time (rTWT) Service Period (SP) for the first link;

transmit a frame prior to a wake period of the rTWT SP, wherein the frame is transmitted during a first Transmission Opportunity (TXOP) that overlaps with the wake period; and

transmit low latency traffic on the first link during the wake period, wherein the first TXOP that overlaps with the wake period is at least one of ended and continued.

2. The device of claim 1 , wherein when the first TXOP is ended, the low latency traffic is transmitted during a second TXOP that starts at a beginning of the wake period.

3. The device of claim 1 , wherein when the first TXOP is continued:

the frame is ended at a beginning of the wake period; and

the low latency traffic is transmitted during the first TXOP that continues through the beginning of the wake period.

4. The device of claim 1 , wherein the first TXOP is ended by a non-access point (non-AP) station (STA) of a non-AP Multi-Link Device (MLD) associated with the device at a beginning of the wake period if at least one of:

the non-AP STA is a first non-AP STA associated with the device on the first link and is a member of the rTWT SP for the first link;

the non-AP STA is a second non-AP STA associated with the device on a second link and has an on-going TXOP on the second link, wherein the second non-AP STA is a TXOP holder; and

the non-AP MLD has Traffic Identifier (TID) to link mapping, wherein the low latency traffic is not mapped to the second link.

5. The device of claim 1 , wherein a frame exchange on a second link is ended by an access point (AP) that is associated with a non-AP STA of a non-AP MLD at a beginning of the wake period if at least one of:

the non-AP STA is a first non-AP STA associated with the device on the first link and is a member of the rTWT SP for the first link;

the non-AP STA is a second non-AP STA associated with the device on the second link and has an on-going TXOP on the second link, wherein the second non-AP STA is a TXOP responder; and

the non-AP MLD has TID to link mapping, wherein the low latency traffic is not mapped to the second link.

6. The device of claim 1 , wherein the first TXOP is continued by a non-AP STA of a non-AP MLD associated with the device at a beginning of the wake period if at least one of:

the non-AP STA is a first non-AP STA associated with the device on the first link and is a member of the rTWT SP for the first link;

the non-AP STA is a second non-AP STA associated with the device on a second link and has an on-going TXOP on the second link, wherein the second non-AP STA is a TXOP holder; and

the non-AP MLD has TID to link mapping, wherein the low latency traffic is mapped to the first link and the second link.

7. The device of claim 1 , wherein a frame exchange on a second link is continued by an AP that is associated with a non-AP STA of a non-AP MLD at a beginning of the wake period if at least one of:

the non-AP STA is a first non-AP STA associated with the device on the first link and is a member of the rTWT SP for the first link;

the non-AP STA is a second non-AP STA associated with the device on the second link and has an on-going TXOP on the second link, wherein the second non-AP STA is a TXOP responder; and

the non-AP MLD has TID to link mapping, wherein the low latency traffic is mapped to the first link and the second link.

8. The device of claim 1 , wherein:

the first TXOP is for low priority traffic; and

when the first TXOP is continued, the low latency traffic is transmitted during a remaining duration of the first TXOP.

9. The device of claim 1 , wherein the first TXOP is at least one of ended and continued when a backoff counter for an Access Category (AC) becomes zero within the rTWT SP.

10. The device of claim 9 , wherein when the first TXOP is continued, the low latency traffic is transmitted during a remaining duration of the first TXOP, where a Contention Window (CW) and a Quality of Service (QoS) Short Retry Counter (QSRC) of an AC are unchanged during the remaining duration of the first TXOP.

11. The device of claim 9 , wherein when the first TXOP is ended, the low latency traffic is transmitted during a second TXOP, where a CW and a QSRC of the AC are unchanged.

12. The device of claim 1 , wherein when a Target Beacon Transmission Time (TBTT) is within the rTWT SP, the device schedules another beacon transmission regardless of whether the low latency traffic has finished being transmitted.

13. The device of claim 1 , wherein when a Delivery TBTT (DTBTT) is within the rTWT SP, the device schedules a Delivery Traffic Indication Map (DTIM) beacon regardless of whether the low latency traffic has finished being transmitted.

14. The device of claim 1 , wherein the rTWT SP is at least one of a trigger enabled rTWT SP and a non-trigger enabled rTWT SP, and wherein a backoff counter of a TID becomes zero before the device transmits the low latency traffic.

15. The device of claim 14 , wherein when the backoff counter of the TID becomes zero and an STA still has the low latency traffic to transmit, the STA uses a current CW to start another backoff procedure for non-low latency traffic.

16. The device of claim 14 , wherein when the backoff counter of the TID becomes zero and an STA still has the low latency traffic to transmit, the STA suspends a backoff procedure for non-low latency traffic.

17. The device of claim 16 , wherein the STA resumes the suspended backoff procedure when the STA finishes transmitting the low latency traffic.

18. The device of claim 1 , wherein the beacon includes rTWT SP schedules of other APs that are at least one of:

in a same multiple Basic Service Set (BSS) Identifier (BSSID);

co-hosted APs; and

neighbor APs.

19. A system comprising:

a first wireless device, wherein the first wireless device includes a wireless network interface device implemented on one or more integrated circuits (ICs), wherein the wireless network interface device is configured to:

transmit a beacon on a first link that indicates a restricted Target Wake Time (rTWT) Service Period (SP) for the first link;

transmit a frame prior to a wake period of the rTWT SP, wherein the frame is transmitted during a first Transmission Opportunity (TXOP) that overlaps with the wake period;

transmit low latency traffic on the first link during the wake period, wherein the first TXOP that overlaps with the wake period is at least one of ended and continued; and

a second wireless device, wherein the second wireless device includes another wireless network interface device implemented on one or more other ICs, and wherein the other wireless network interface device is configured to receive the beacon, the frame, and the low latency traffic on the first link.

20. A method for transmissions during a restricted Target Wake Time (rTWT) Service Period (SP), the method comprising:

transmitting a beacon on a first link that indicates an rTWT SP for the first link;

transmitting a frame prior to a wake period of the rTWT SP, wherein the frame is transmitted during a first Transmission Opportunity (TXOP) that overlaps with the wake period; and

transmitting low latency traffic on the first link during the wake period, wherein the first TXOP that overlaps with the wake period is at least one of ended and continued.