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Considerations for early NAV indication. Authors:. Date: 2012-05-11. Abstract. This document discusses possibility of additional packet protection using NAV indication in the ACK indication field. Early ACK indication. ACK indication field (2 bits) In the SIG or SIGA field
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Considerations for early NAV indication Authors: • Date:2012-05-11 Sudheer Grandhi, InterDigital Communications
Abstract • This document discusses possibility of additional packet protection using NAV indication in the ACK indication field. Sudheer Grandhi, InterDigital Communications
Early ACK indication • ACK indication field (2 bits) In the SIG or SIGA field • Indicate whether an immediate response is requested right after the PPDU, and also the type of the response (00: ACK; 01: BA; 10: No ACK; 11: reserved) • If a STA decodes the SIG correctly, but 1) decides to skip the remaining fields after SIG for power saving, or 2) is not able to decode /verify the MAC header, it can determine whether to defer medium access for ACK protection based on the ACK Indication in SIG Sudheer Grandhi, InterDigital Communications
Issues in Packet Protection • Due to hidden node problem, a STA cannot always hear all packets in a packet exchange • Frames could have no ACK but contains NAV setting in the Duration Field of the MAC header • RTS • CTS Sudheer Grandhi, InterDigital Communications
Proposal: further NAV Indication using ACK Indication bits (1/2) • Use the reserved “11” in the ACK indication bits in SIG field as NAV setting indicator for NAV settings other than Normal ACK or BA • If there is NAV setting in the MAC header other than Normal ACK or BA, an unintended receiving STA should • decode the MAC header to obtain the Duration Field and set NAV accordingly • or if the STA cannot decode the MAC header, it candefer medium access by a default value (TBD) to prevent premature medium access that would interrupt ongoing packet transmission or receptions Sudheer Grandhi, InterDigital Communications
Summary • The current ACK Indication may be extended for additional packet/NAV protection other than ACK or BA • Proposal: • Use of “11” value of ACK Indication bits to offer packet/NAV protection for frames other than Normal ACK or BA Sudheer Grandhi, InterDigital Communications
Questions / Comments ? Thank You! Sudheer Grandhi, InterDigital Communications
Straw Poll 1 • Do you think that the use of the reserved “11” value of the ACK Indication in the SIG field should be further studied to allow additional packet/NAV protection? • Yes • No • Abstain Sudheer Grandhi, InterDigital Communications
References • [1] IEEE Std 802.11™-2012: Wireless LAN MAC and PHY Specifications • [2] IEEE 802.11-11/1482r4, “Preamble Format for 1 MHz,” Qualcomm and et. al. • [3] IEEE 802.11-12/0119r0, “Early ACK Indication,” Marvell and et. al. Sudheer Grandhi, InterDigital Communications