IEEE 802.11-25 Receive Procedure Overview 2025

January 2025 doc.: IEEE 802.11-25/0109r0 UHR Receive Procedure Date: 2025-01-xx Authors: Name Affiliations Address Phone email Lin Yang Bin Tian Youhan Kim Alice Chen Qualcomm Submission Slide 1 Lin Yang (Qualcomm)

January 2025 doc.: IEEE 802.11-25/0109r0 Overview of Main Changes from EHT Receive Processing When to check ELR-MARK, if ELR capable? SIG is invalid including CRC fails in legacy preamble portion up to U-SIG Recommend parallel processing of 11a and ELR-MARK check or 11ax ER SU and ELR-MARK check ELR preamble parsing after ELR-MARK is detected, or U-SIG indicates ELR PPDU and 3 ELR validate bits are 111 or value of 7 plus matching STA-ID How to do deferral? If length from ELR-SIG is valid at Rx, defer based on ELR-length Otherwise, defer based on legacy modes processing rules Recommend to remove the support of forward-looking ER SU preamble (defined in EHT) starting from UHR UHR introduces ELR feature which is better replacement Can significantly simplify the receive state machine QBPSK check on the 2nd U-SIG symbol before decoding U-SIG Submission Slide 2 Lin Yang (Qualcomm)

January 2025 doc.: IEEE 802.11-25/0109r0 If SIG is Invalid in Legacy Preamble Portion up to U-SIG Parity check fails and not ELR capable: Set PHY_RXEND.indicati on(FormatViolation) RATE check failed and not ELR capable Receive L-SIG Combine L-SIG and RL-SIG. Decode, Parity check, RATE (6 Mb/s) check Case 1: Invalid SIGNAL SIGNAL invalid and ELR capable HT preamble Check HT-SIG CRC and content ELR-MARK detect D Invalid HT- SIG and ELR capable Valid HT-SIG or not ELR capable: Refer to 19.3.21 Case 2: detected as 11n but HT-SIG is invalid Valid VHT-SIG or not ELR capable: Refer to 21.3.20 D VHT preamble Invalid VHT-SIG and ELR capable Check VHT-SIG CRC and content D Case 3: detected as 11ac but VHT-SIG is invalid Valid HE-SIG or not ELR capable : Refer to 27.3.22 Invalid HE-SIG and ELR capable Case 4: detected as 11ax SU/MU or TB but HE- SIG is invalid Check HE-SIG CRC and content D HE-SIG-A2 is BPSK CRC fails and not ELR capable: Set PHY_RXEND.indication (FormatViolation) The 2nd symbol of U-SIG is QBPSK and CRC passes Parse the Version independent information in the U-SIG D E2 Receive U-SIG Evaluate the constellation of the 2nd symbol of U-SIG and test the CRC of U-SIG E2 CRC fails and ELR capable The 2nd symbol of U-SIG is BPSK and CRC Passes Case 5: detected as EHT and above but U-SIG is invalid Forward-looking ER SU preamble check defined in EHT is removed (QBPSK check on the 2nd U-SIG symbol) Other PHY Version ID numbers and not ELR capable PHY Version ID=0 Check PHY Version ID D EHT preamble Refer to 36.3.23 Other PHY Version ID numbers and ELR capable PHY Version ID=1 No intended BSS color or DL/UL or Reserved-Validate U-SIG Indication (if not ELR capable) etc., PPDU is filtered out. Evaluate U-SIG Determine if the PPDU is filtered out or not based on BSS color(s), DL/UL, PPDU Type and compression mode and CoBF/CoSR, etc. Submission Slide 3 Lin Yang (Qualcomm) U-SIG invalid and ELR capable PPDU is not filtered out D

January 2025 doc.: IEEE 802.11-25/0109r0 Recommended Parallel Processing of Legacy Mode and ELR-Mark Detection Non-HT preamble Refer to 17.3.12 Case 1 : detected as 11a due to valid SIGNAL and no RL-SIG and no QBPSK detected L-SIG parity check has high false positive probability at low SNR Need to parallelly check ELR-MARK while processing 11a data process DATA1,2,3 Parallel processing DATA4/DATA5 and if ELR capable D ELR-MARK not detected Continue Non-HT DATA processing ELR-MARK detected ELR Preamble parsing Case 2 : detected as 11ax ER SU due to HE-SIG- A2 being QBPSK Need to parallel processing of HE-SIG decoding and ELR- MARK check HE-SIG-A3 and HE-SIG-A4 are at the same symbol location as ELR-MARK HE ER SU preamble HE-SIG-A2 is QBPSK Parallel processing HE-SIG receiving and if ELR capable D ELR-MARK not detected, refer to 27.3.22 for HE ER SU ELR-MARK detected ELR Preamble parsing Submission Slide 4 Lin Yang (Qualcomm)

January 2025 doc.: IEEE 802.11-25/0109r0 U-SIG Processing PHY Version ID=1 Evaluate U-SIG No intended BSS color or DL/UL or Reserved-Validate U-SIG Indication (if not ELR capable) etc., PPDU is filtered out. Determine if the PPDU is filtered out or not based on BSS color(s), DL/UL, PPDU Type and compression mode and CoBF/CoSR, etc. U-SIG invalid and ELR capable PPDU is not filtered out Evaluate the PPDU Type and compression mode subfield and DL/UL subfield and CoBF/CoSR indication subfield in U-SIG D Determine the PPDU type. UHR_ELR UHR_TRIG UHR_MU B Receive UHR-SIG Receive UHR-SIG based on the UHR-SIG-MCS and Number of UHR-SIG symbols indicated in U-SIG ELR validation fails Check 3 ELR Validate bits D ELR validation passes Determine if STA ID matches Determine if a supported mode is indicated Not intended STA-ID STA-ID matches Based on UHR-MCS, Nss, UHR- LTF, STA-ID, BSS color indication, RU allocation, etc. ELR Preamble parsing Unsupported mode or Reserved-Validate UHR-SIG Indication, PPDU if filtered out E2 B Submission Slide 5 Lin Yang (Qualcomm)

January 2025 doc.: IEEE 802.11-25/0109r0 ELR-MARK and ELR Preamble Processing ELR processing D E1 Detect ELR- MARK ELR-MARK not detected Determine whether it is an ELR PPDU and it is from IN-BSS End of Wait Go back to earlier mode and cont. Deferral rules: If length from ELR-SIG is valid at Rx, defer based on ELR-length Otherwise, defer based on legacy modes processing rules Set PHY_CCA indication() in accordance with 36.3.20.6 ELR-MARK detected ELR Preamble parsing C Receive ELR-SIG-1 Check if earlier mode =HT or L- SIG not pass YES CRC fails test the CRC E2 CRC passes NO End of Wait Evaluate UL/DL E1 Determine if the PPDU is filtered out Set PHY_CCA.indication(IDLE) when predicted duration based on RXTIME Defined in equation (38- 109) has elapsed, unless PHY- CCARESET.request received; If the RXTIME cannot be predicted using equation (38-109): set PHY_CCA.indication(IDLE) when predicted duration based on RXTIME Defined in equation (38- 110) or equation (36-108) has elapsed. No intended UL/DL PPDU is not filtered out Receive ELR-SIG-2 CRC fails test the CRC CRC passes Evaluate STA-ID No intended STA-ID Determine if the PPDU is filtered out PPDU is not filtered out Note Eqn. 38-109 based on ELR-length E2 B Submission Slide 6 Lin Yang (Qualcomm)

January 2025 doc.: IEEE 802.11-25/0109r0 SP1 Do you agree to include the following into the 11bn SFD? Remove the requirement, for UHR STAs, to receive the forward-looking EHT ER SU preamble in the UHR RX procedure Submission Slide 7 Lin Yang (Qualcomm)

January 2025 doc.: IEEE 802.11-25/0109r0 SP2 Do you agree to include the following into the 11bn SFD? UHR receive procedure is illustrated by the attached PHY receive state machine diagram and the text document of UHR receive procedure UHR receive procedure UHR PHY receive state machine Submission Slide 8 Lin Yang (Qualcomm)

January 2025 doc.: IEEE 802.11-25/0109r0 Appendix Submission Slide 9 Lin Yang (Qualcomm)

January 2025 doc.: IEEE 802.11-25/0109r0 ELR and Legacy Preamble Formats L-STF L-LTF L-SIG Data 11a 11n - HT GF HT-STF HT-LTF1 HT-SIG1 HT-SIG2 HT-STF HT-LTFs Data L-STF L-LTF L-SIG LEN%3 = 0 HT-SIG1 HT-SIG2 HT-STF HT-LTFs Data 11n - HT MF L-STF L-LTF L-SIG VHT-SIG-A1 VHT-SIG-A2 VHT-STF VHT-LTFs Data 11ac - VHT LEN%3 = 0 L-STF L-LTF L-SIG LEN%3 = 1 HE-SIG-A1 HE-SIG-A2 HE-STF HE-LTFs Data PE RL-SIG 11ax - HE SU/TB L-STF L-LTF L-SIG LEN%3 = 2 HE-SIG-A1 HE-SIG-A2 HE-SIG-Bs HE-STF HE-LTFs Data PE RL-SIG 11ax - HE MU L-STF L-LTF L-SIG LEN%3 = 2 HE-SIG-A1 HE-SIG-A2 HE-SIG-A3 HE-SIG-A4 HE-STF HE-LTFs Data PE RL-SIG 11ax - HE ER SU L-STF L-LTF L-SIG LEN%3 = 0 Mark1 -1*L-SIG Mark2 -1*L-SIG OOK 11ba - WUR L-STF L-LTF L-SIG LEN%3 = 0 U-SIG1 PHY version = X1 EHT PPDU Type = Y1 U-SIG1 PHY version = X1 EHT PPDU Type = Y2 U-SIG1 PHY version = TBD1 U-SIG2 EHT-SIGs EHT-STF EHT-LTFs Data PE RL-SIG 11be - EHT MU L-STF L-LTF L-SIG LEN%3 = 0 U-SIG2 EHT-STF EHT-LTFs Data PE RL-SIG 11be - EHT TB BPSK modulated L-STF L-LTF L-SIG LEN%3 = 0 RL-SIG U U-SIG2 U-SIG3 ER SU QBPSK modulated L-STF L-LTF L-SIG LEN%3 = 0 U-SIG1 PHY version = TBD2 U-SIG2 RL-SIG Post-11be Variable modulation U-SIG2 RL-SIG ELR-Mark1 L-SIG U-SIG1 PHY version = 1 ELR-Mark2 ELR-LTFs ELR-SIG Data PE ELR-STF ELR PPDU L-STF 3~6dB+ L-LTF 3~6dB+ Submission Slide 10 Lin Yang (Qualcomm)