Enhancing HARQ Framing for IEEE 802.11 Standards
Hybrid-ARQ (HARQ) is a candidate topic for TGbe presentations in IEEE 802.11 standards. Despite previous unsuccessful attempts, there is renewed interest in enabling HARQ through framing support. This document discusses the importance of presenting HARQ framing, outlining the necessary information at both the transmitter and receiver sides for efficient operation. It emphasizes the need for proper encoding and decoding of HARQ control signals and feedback mechanisms for correct codeword decoding. Dual feedback options at codeword and MPDU levels are also explored for optimal feedback transmission. The aim is to improve the implementation of HARQ within the IEEE 802.11 standard.
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May, 2019 doc.: IEEE 802.11-19/0873r0 HARQ Framing Date: 2019-05-13 Authors: Name Affiliation Address Email Imran Latif Quantenna Communications 1704 Automation Parkway, 95131, San Jose, CA, USA ilatif@quantenna.com Sigurd Schelstraete sschelstraete@quantenna.com Debashis Dash ddash@quantenna.com Huizhao Wang hwang@quantenna.com Ambroise Popper apopper@quantenna.com Imran Latif (Quantenna) Submission Slide 1
May, 2019 doc.: IEEE 802.11-19/0873r0 Background Hybrid-ARQ is one of the candidate topics for TGbe HARQ presentations in previous meetings show clear interest [1] [9] HARQ has been proposed for previous 802.11 standards However, it has never been successful in securing its place in 802.11 standard despite its promised gains We believe it can have its chances with TGbe Therefore, we would like to go beyond showing results and discuss how HARQ can be enabled through framing support Imran Latif (Quantenna) Submission Slide 2
May, 2019 doc.: IEEE 802.11-19/0873r0 HARQ Framing In this presentation we stress on the fact that we need to present HARQ framing To enable HARQ, MPDU and/or codeword related information is required at PHY level on both Tx and Rx side At Tx Side: Tx needs to send the information about HARQ related parameters for each MPDU/codeword at the PHY level by encoding the PHY level HARQ control signal. HARQ-SIG DATA L-STF L-LTF L-SIG Legacy Preamble HARQ Control Information It is essential to decode HARQ-SIG in order to be able to decode the DATA portion of the received packet. At a minimum HARQ SIG needs a unique identifier for the MPDUs/Codeword contained in the DATA(retransmission or not) Imran Latif (Quantenna) Submission Slide 3
May, 2019 doc.: IEEE 802.11-19/0873r0 HARQ Framing At Rx Side: Rx obtains the information about HARQ related parameters at the PHY level by decoding the PHY level HARQ control signal which is essential for HARQ operation in the following DATA portion of the received packet. There is no CRC at the PHY level. So how do we get the decoding status of each codeword? One way is to check the status of decoded codeword with LDPC parity check matrix at PHY level. PHY can provide error information on per codeword basis MAC can provide CRC information on MPDU level Finally Rx needs to send the feedback to Tx about the wrongly decoded codewords/MPDUs. Imran Latif (Quantenna) Submission Slide 4
May, 2019 doc.: IEEE 802.11-19/0873r0 Dual Feedback For the feedback there can be two options, codeword level and/or MPDU level It should be able to send the feedback not only based on MPDU level bitmap but also with the codeword level information either appended to the existing BA or creating a new additional acknowledgement packet for codeword information. This information can be kept at PHY for indexing and keeping codewords/MPDUs in its memory for recombination on receiving re- transmissions. BA bit mask Codeword level Feedback Imran Latif (Quantenna) Submission Slide 5
May, 2019 doc.: IEEE 802.11-19/0873r0 Summary We have discussed the Framing for HARQ We presented a new PHY level signaling enabling HARQ at both Tx and Rx We have also discussed the feedback options for HARQ We proposed the dual granularity of doing feedback based on either the MPDU or both MDPU and Codeword. Imran Latif (Quantenna) Submission Slide 6
May, 2019 doc.: IEEE 802.11-19/0873r0 Reference [1] Shimi Shilo HARQ for EHT (DCN:1587) 13 Sep 2018 [2] Ron Porat Multi-AP-HARQ-for-EHT (DCN: 1116) 6 July 2018 [3] Bo Sun - Discussion on HARQ for EHT (DCN: 1963) 11 Nov 2018 [4] Tianyu Wu HARQ performance analysis (DCN: 1979) 11 Nov 2018 [5] Hongyuan Zhang HARQ Feasibility (DCN: 1992) 11 Nov 2018 [6] Sindhu Verma HARQ gain studies (DCN: 2031) 13 Nov 2018 [7] Bo Sun - Discussion on HARQ for EHT (DCN: 1963) 28 Nov 2018 [8] Jinmin Kim Consideration on HARQ (DCN: 354) 07 Mar 2019 [9] Kome Oteri - Effect of Preamble Decoding on HARQ in 802.11be (DCN: 390) 09 March 2019 Imran Latif (Quantenna) Submission Slide 7