Considerations on Inter-PPDU Based Preemption Scheme in IEEE 802.11-23

In this document, considerations are presented for a preemption scheme in IEEE 802.11-23, focusing on issues such as coordination, ACK transmission timing, and channel access fairness. The proposed inter-PPDU based preemption scheme aims to improve the transmission of low latency traffics within the TXOP, addressing challenges related to preemption coordination and collision avoidance. Various aspects of implementing this scheme are discussed, highlighting the need for precise timing coordination and resource management to enhance the efficiency of preemption operations.

• Preemption Scheme
• IEEE 802.11-23
• Inter-PPDU
• Coordination
• ACK Transmission

adnan Follow

Uploaded on Jul 23, 2024 | 1 Views

Download Presentation

Please find below an Image/Link to download the presentation.

The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. Download presentation by click this link. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.

Presentation Transcript

1. August 2023 doc.: IEEE 802.11-23/1242r1 Considerations on Inter-PPDU based Preemption Scheme Date: 2023-08-12 Authors: Name Juseong Moon Affiliations Address KNUT Phone email jsmoon0211@a.ut.ac.kr ronnykim@ut.ac.kr Ronny Yongho Kim Kyumin Kang KNUT kmkang@etri.re.kr ETRI shwang@etri.re.kr Sunghyun Hwang Woojin Ahn ETRI woojin.ahn@krri.re.kr KRRI Submission Slide 1 Juseong Moon, KNUT

2. August 2023 doc.: IEEE 802.11-23/1242r1 Abstract In UHR SG, there were some discussions on pre- emption schemes[1]-[4]. However, some issues, such as channel access scheme, fairness control and ACK mechanism in preemption operation are not fully discussed. In this contribution, considerations on preemption scheme for UHR will be discussed. Submission Slide 2 Juseong Moon, KNUT

3. August 2023 doc.: IEEE 802.11-23/1242r1 Background: Inter-PPDU based Preemption Scheme In [3]-[4], inter-PPDU based preemption scheme was proposed With the proposed scheme, low latency traffics of other STAs or AP can be transmitted within the TXOP. [3]: 23/0092r0 Submission Slide 3 Juseong Moon, KNUT

4. August 2023 doc.: IEEE 802.11-23/1242r1 Issues In order to support the proposed inter-PPDU based preemption scheme, the followings should be considered: 1. How to coordinate preemption? STAs need to be coordinated for the timing to perform preemption. 2. When TXOP responder should transmit ACK? It s not clear when TXOP responder should transmit ACK during inter-PPDU based preemption procedure. 3. How to access channel in XIFS? A channel access scheme for preemption performing STA is not defined. Fairness between preemption performing STA and preemption allowing STA(AP) should be considered . Submission Slide 4 Juseong Moon, KNUT

5. August 2023 doc.: IEEE 802.11-23/1242r1 Issues (Cont d) When a TXOP responder should transmit ack? Collision and resource management method is needed IFS IFS IFS AP DL PPDU to STA 1 DL PPDU to STA 1 (TXOP holder) STA 1 BA (TXOP responder) ? ? ? UL PPDU (Preemption) STA2 STA 2 does not know on which IFS opportunity it can transmit low latency frame Submission Slide 5 Juseong Moon, KNUT

6. August 2023 doc.: IEEE 802.11-23/1242r1 1. Preemption coordination A STA which intends to transmit using preemption scheme may not know whether it can transmit or not during IFSs. This lack of knowledge of transmission timing may lead to collision in a TXOP AP: TXOP Holder / STA 1: TXOP responder / STA 2: Preemption performing STA IFS IFS IFS AP DL PPDU to STA 1 DL PPDU to STA 1 DL PPDU to STA 1 (TXOP holder) STA 1 BA BA (TXOP responder) ? ? ? STA2 Indication method and additional preemption channel access rule are needed STA 2 does not know on which IFS opportunity it can transmit low latency frame Submission Juseong Moon, KNUT

7. August 2023 doc.: IEEE 802.11-23/1242r1 1. Preemption coordination (Cont d) A preemption indication should be defined to perform preemption in UHR The TXOP holder can indicate the timing for preemption. Preemption performing STAs can transmit frame(s) based on the indication. A preemption indication may further provide more hints for channel access For example, TXOP holder can indicate the following parameters: Preemption indication can indicate the final PPDU for the TXOP responder. The TXOP responder can transmit ACK after SIFS or XIFS of the final PPDU when it received the indication. Channel access parameters for preemption performing STAs can be transmitted in each PPDU(s). Preemption performing STAs can contend for the medium within XIFS using the parameters. Submission Slide 7 Juseong Moon, KNUT

8. August 2023 doc.: IEEE 802.11-23/1242r1 2. Ack in preemption The TXOP responder may not know when it should transmit ACK to the TXOP holder The TXOP holder can indicate ACK indication which includes information about whether the TXOP responder should transmit ack The TXOP responder can transmit response frame when it received ack indication from the TXOP holder Ack Indication (STA 1 shall not ack) Ack Indication (STA 1 shall ack) XIFS SIFS SIFS AP DL PPDU to STA 1 BA to STA 2 DL PPDU to STA 1 (TXOP holder) BA to AP STA1 UL PPDU (Preemption) STA2 TXOP responder can determine when it shall transmit ack Submission Slide 8 Juseong Moon, KNUT

9. August 2023 doc.: IEEE 802.11-23/1242r1 3-1. Multiple access in preemption If two or more STAs attempt to transmit without channel access, collisions may occur. Channel access operation for the preemption may be similar to the current EDCA or DCF operation UHR may adopt or develop another channel access operation for the preemption Collision occurs XIFS SIFS AP DL PPDU DL PPDU (TXOP holder) UL PPDU (Preemption) UL LL PPDU STA 1 Time UL PPDU (Preemption) STA 2 LL frame enqueued LL frame enqueued Submission Slide 9 Juseong Moon, KNUT

10. August 2023 doc.: IEEE 802.11-23/1242r1 3-2. Resource Control for preemption A STA may greedily utilize another STA s TXOP with preemption To address this issue, a control method is required to prevent abusing. For instance, the resource for the preemption operation could be restricted by the TXOP holder. Entire TXOP SIFS XIFS SIFS AP DL PPDU to STA 1 DL PPDU to STA 1 (TXOP holder) STA1 BA UL PPDU (Preemption) STA2 STA 2 occupied a large portion of the AP's TXOP Submission Slide 10 Juseong Moon, KNUT

11. August 2023 doc.: IEEE 802.11-23/1242r1 Summary In this contribution, some considerations on inter-PPDU based preemption scheme were discussed 1. Coordinating preemption 2. Response frame transmission in preemption 3. Channel access and resource management in preemption Current preemption operation is lack of some details: preemption coordination, ACK transmission timing, and channel access in XIFS UHR SG should address the ambiguity of the inter-PPDU based preemption scheme identified in this contribution and make some solutions if the preemption is adopted to UHR Submission Slide 11 Juseong Moon, KNUT

12. August 2023 doc.: IEEE 802.11-23/1242r1 References [1] 11-22/1393r0: Latency Reduction Scheme for UHR, https://mentor.ieee.or g/802.11/dcn/22/11-22-1393-00-0uhr-latency-reduction-scheme-for-uhr.pp tx [2] 11-22/1880r1: Latency and Reliability enhancements for UHR, https://me ntor.ieee.org/802.11/dcn/22/11-22-1880-01-0uhr-latency-and-reliability-en hancements-for-uhr.pptx [3] 11-23/0092r0: Preemption, https://mentor.ieee.org/802.11/dcn/23/11-23-00 92-00-0uhr-preemption.pptx [4] 11-23/0018r1: Low Latency Support in UHR, https://mentor.ieee.org/802. 11/dcn/23/11-23-0018-01-0uhr-low-latency-support-in-uhr.pptx Submission Slide 12 Juseong Moon, KNUT