Jan 19 2010 doc IEEE 802 11 100064

Jan. 19, 2010 doc. : IEEE 802. 11 -10/0064 r 2 VHT Frame Padding Date: 2010 -01 -19 Authors: Submission 1 Yong Liu, Robert Stacey et al.

Jan. 19, 2010 doc. : IEEE 802. 11 -10/0064 r 2 Outlines • 802. 11 n (HT) frame padding • VHT frame padding • 802. 11 n (HT) A-MPDU • VHT A-MPDU • Early End-of-Frame indication • Conclusions Submission 2 Yong Liu, Robert Stacey et al.

Jan. 19, 2010 doc. : IEEE 802. 11 -10/0064 r 2 802. 11 n (HT) frame padding • A length field (16 bits) is included in HT-SIGs to indicate the end of PSDU • Tail bits and PHY Pad are appended to fill in the last symbol Submission 3 Yong Liu, Robert Stacey et al.

Jan. 19, 2010 doc. : IEEE 802. 11 -10/0064 r 2 VHT frame padding • VHT-SIG indicates PPDU duration only (number of symbols) – No per user length (number of octets) indication in preamble • Use A-MPDU structure to provide length information for individual MPDUs – Require that A-MPDU always be used with both SU and MU VHT frames • • MAC provides an A-MPDU that fills the frame to the last byte for each per-user stream PHY provides 0 -7 bits of padding Submission 4 Yong Liu, Robert Stacey et al.

Jan. 19, 2010 doc. : IEEE 802. 11 -10/0064 r 2 802. 11 n (HT) A-MPDU • Except when it is the last A-MPDU subframe in an A-MPDU, padding octets are appended to make each A-MPDU subframe a multiple of 4 octets in length. • Any subframe may be preceded by one or more zero-length delimiters to meet the minimum MPDU Start Spacing requirement, for example Submission 5 Yong Liu, Robert Stacey et al.

Jan. 19, 2010 doc. : IEEE 802. 11 -10/0064 r 2 VHT A-MPDU • • • VHT A-MPDU subframes have the same structure as the subframes of an 802. 11 n A-MPDU The QWord MAC Pad (0 -3 octets) is added to reach the next 32 -bit boundary of MAC octets, if such octets fit into the last PHY symbol (Note that normally, the LAST subframe is NOT padded) Zero or more Null subframes and a Final MAC Pad (0 -3 octets) are appended to extend the A -MPDU to the last octet of the last symbol of a VHT frame – Null subframes are absent if last PHY symbol is full with 0 -3 octets of Final MAC Pad after the QWord MAC Pad Submission 6 Yong Liu, Robert Stacey et al.

Jan. 19, 2010 doc. : IEEE 802. 11 -10/0064 r 2 Early EOF indication • • The Null subframes appended to the end of a VHT A-MPDU can be a special Padding Delimiter with an EOF flag When RX MAC detects the EOF Padding Delimiter, it may inform RX PHY to stop receiving to conserve power Submission 7 Yong Liu, Robert Stacey et al.

Jan. 19, 2010 doc. : IEEE 802. 11 -10/0064 r 2 Conclusions • VHT-SIG indicates PPDU duration only (number of symbols) • All VHT frames, including both SU and MU frames, use AMPDU structure • Zero or more Null subframes and a Final MAC Pad can be appended to a VHT A-MPDU to extend the A-MPDU to the last byte of the VHT frame • The Null subframes appended to the A-MPDU may include an EOF indication in the delimiter so that the receiver knows it can stop receive processing to conserve power Submission 8 Yong Liu, Robert Stacey et al.

Jan. 19, 2010 doc. : IEEE 802. 11 -10/0064 r 2 Reference • 11 -10 -0070 -00 -00 ac-802 -11 ac-preamble. ppt Submission 9 Yong Liu, Robert Stacey et al.

Jan. 19, 2010 doc. : IEEE 802. 11 -10/0064 r 2 Straw Poll • Do you agree to include the VHT frame padding concept introduced in 10/0064 r 2 -VHT-frame-padding as section 6 of Proposed Specification Framework edits for preamble structure and A-MPDU (IEEE 802. 1110/0113 r 0)? • Yes • No • Abstain Submission 10 Yong Liu, Robert Stacey et al.