IEEE 802.11-20/0055r0 Multi-link Block Ack Architecture Overview
This document from January 2020 presents an overview of the IEEE 802.11-20/0055r0 Multi-link Block Ack architecture proposed by Rojan Chitrakar from Panasonic. It discusses the negotiation of block ack agreements between multiple MLDs, common sequence number assignment, transmit and receive buffers, scoreboard sizes, and considerations for different link data rates. The architecture aims to enhance Multi-link block ack operations for improved efficiency and performance in wireless communications.
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January 2020 doc.: IEEE 802.11-20/0055r0 Multi-link Block Ack Architecture Date: 2020-01-10 Authors: Name Rojan Chitrakar Company Address Phone Email 202 Bedok South Avenue 1, #02-11 Singapore 469332 rojan.chitrakar@sg.panasonic.com Panasonic Corporation Lei Huang Yanyi Ding Yoshio Urabe Submission Slide 1 Rojan Chitrakar (Panasonic)
January 2020 doc.: IEEE 802.11-20/0055r0 Overview In our previous contribution, we shared our thoughts on some aspects of Multi-link block ack operations [1]. The following aspects related to Multi-link block ack have been added to the 11be SFD : A single block ack agreement is negotiated between two MLDs for a TID that may be transmitted over one or more links. Sequence numbers are assigned from a common sequence number space shared across multiple links of a MLD, for a TID that may be transmitted to a peer MLD over one or more links. This contribution shares one possible architecture for Multi-link block ack. Other architectures are also possible and are discusssed in [2] and [3]. Submission Slide 2 Rojan Chitrakar (Panasonic)
January 2020 doc.: IEEE 802.11-20/0055r0 Originator MLD Distribtuion Service (DS) MAC-SAP Multi-link Device Common Sequence Number Assignment Common Transmit Buffer STA 1 STA 2 MAC MAC Block ack State Block ack State Aggregation Aggregation Channel Access Channel Access PHY PHY Link 1 Link 2 Submission Slide 3 Rojan Chitrakar (Panasonic)
January 2020 doc.: IEEE 802.11-20/0055r0 Recipient MLD Distribtuion Service (DS) MAC-SAP Multi-link Device Common Receive Reordering Buffer Common Scoreboard Duplicate Detection STA 1 STA 2 MAC MAC Per-link Scoreboard Per-link Scoreboard Deaggregation Deaggregation PHY PHY Link 1 Link 2 Submission Slide 4 Rojan Chitrakar (Panasonic)
January 2020 doc.: IEEE 802.11-20/0055r0 Scoreboard size Different links may have different data rates (e.g. due to different bandwidths, # of antennas etc.). Consequently, the recipient MLD can expect to receive more MPDUs on the faster link and may need to negotiate different Per-link Scoreboard sizes for different links during the setup of block ack parameters between two MLDs. Else, the scoreboard size of a slower link may constrain a faster link s throughput. The size of the BA Bitmap of BAs may also get restricted by the scoreboard sizes. f 4 5 6 7 8 9 10 11 12 13 14 15 0 0 0 1 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Link 2 6 GHz (160 MHz) 1 2 3 1 0 1 0 0 0 1 2 3 4 5 6 Link1 5 GHz (40 MHz) t DL PPDU (Same TID) 0 1 Block Ack bitmap Block Ack frame Legend: m n Submission Slide 5 Rojan Chitrakar (Panasonic)
January 2020 Example Recipient Implementation Recipient MLD may also maintain a common scoreboard to keep a longer term record of received MPDUs (not limited by TXOPs). Per-link scoreboard may be implemented as partial-state, while common scoreboard may be implemented as full-state. The common Scoreboard is updated regularly with the content of the per-link Scoreboards (e.g. every time the Per-link scoreboard is updated, or at a very minimum at the end of each link s TXOP). doc.: IEEE 802.11-20/0055r0 MAC-SAP Multi-link Device Common Scoreboard Receive Reordering Buffer 1 0 1 1 0 0 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Bitmap Consolidation Generate ML-BlockAck STA1 STA2 Data MB-BAR Per-link Scoreboard Per-link Scoreboard Data 0 0 0 1 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Generate BlockAck Generate BlockAck BAR Rx Parse BAR Rx Parse Link 1 Link 2 Rx Data Rx BAR Rx ML-BAR Rx Data Rx BAR 1 2 3 Tx BA Tx BA 4 5 6 7 8 9 10 11 12 13 14 15 Tx ML-BA Submission Slide 6 Rojan Chitrakar (Panasonic)
January 2020 doc.: IEEE 802.11-20/0055r0 Conclusion This contribution shared one possible architecture for Multi-link block ack operations. We proposed that the block ack agreement for a TID that may be transmitted over multiple links be allowed to maintain different buffer sizes for different links. We also proposed that a recipient MLD may maintain a common scoreboard to consolidate the receipt status of MPDUs of a TID received via different links. Submission Slide 7 Rojan Chitrakar (Panasonic)
January 2020 doc.: IEEE 802.11-20/0055r0 Reference 1) IEEE 802.11-19/1512r6 Multi-link acknowledgment 2) IEEE 802.11-19/1575r0 Multi-link BA Operation 3) IEEE 802.11-19/1856r0 A-MPDU and BA Submission Slide 8 Rojan Chitrakar (Panasonic)
January 2020 doc.: IEEE 802.11-20/0055r0 Straw Poll 1 Do you support that an MLD maintains a common Receiver Reordering Buffer for a TID that may be received over one or more links? Y/N/A Submission Slide 9 Rojan Chitrakar (Panasonic)
January 2020 doc.: IEEE 802.11-20/0055r0 Straw Poll 2 Do you support that different scoreboard sizes may be negotiated for different links during negotiation of a block ack agreement for a TID that may be received over one or more links? Y/N/A Submission Slide 10 Rojan Chitrakar (Panasonic)
January 2020 doc.: IEEE 802.11-20/0055r0 Straw Poll 3 Do you support that an MLD may maintain a common scoreboard to consolidate the receipt status of MPDUs of a TID received via different links? Y/N/A Submission Slide 11 Rojan Chitrakar (Panasonic)
