1. doc.: IEEE 802.11-12/0110r3 SubmissionLiwen Chu Etc.Slide 1 Frame Header Compression Date: 2012-01-16 Authors: Date: Jan, 2012

2. doc.: IEEE 802.11-12/0110r3 Submission MAC Frame Header The typical frame payload of Smart Grid is tens/hundreds bytes. –100 bytes payload frame with 3 MAC addresses has about 30/100=30% MAC header overhead! –300 bytes payload frame with 3 MAC addresses has about 30/300=10% MAC header overhead! The following parts of the MAC header can be compressed : –Some MAC address fields, –No HT Control field when Reverse Direction (RD) is used, –Do we need 2 bytes Sequence Control in a low rate Smart Grid BSS? Frame Control Duration/ ID Address 1Address 2Address 3Sequence Control Address 4QoS Control HT ControlFrame BodyFCS Octets: 2 26662 6 24Variable4 Frame Header Slide 2 Date: Jan, 2012

3. doc.: IEEE 802.11-12/0110r3 Submission Data/Management Frame Header Compression 1 MPDU type (Normal or compressed) should be identified by either the PHY or MAC header. –Bit15 in Duration field. –PHY PLCP SIG. –Other methods. BSSID and one AID are used to identify the transmitter and the receiver of the data and management frames. –BSSID field is used to identify whether the frame is in the same BSS. –When “From DS” is 1 and “To DS” is 0, BSSID is the transmitter identifier and AID is the receiver identifier. When “From DS” is 0 and “To DS” is 1, BSSID is the receiver identifier and AID is the transmitter identifier. –When both “From DS” is 1 and “To DS” is 1, compressed MPDU header is not used. –TDLS is not allowed, because two AIDs would be needed. Frame Control Duration/ID /RD/FHC BSSIDAID/DASA Identifier Sequence Control QoS Control HT ControlFrame Body FCS Octets: 2 262224Variable4 Slide 3 Date: Jan, 2012

4. doc.: IEEE 802.11-12/0110r3 Submission Data/Management Frame Header Compression 1 AID/DASA Identifier field are used for indicating AID and DA/SA. –Bit15~Bit13 is the DA Identifier (when “From DS” is 0 and “To DS” is 1) and SA (when “From DS” is 1 and “To DS” is 0). DASA Identification Request/Response action frames are used to match DASA identifier to DASA MAC address. –Bit12 ~ Bit0 are used to identify Duration or ID Frame Type/subtype can be used to differentiate which one it is. AIDDASA Identifier Bit0 Bit12Bit13 Bit15 AID/DA RA Identifier RD would be relocated from the HT control field into the Duration/ID/RD/FHC field of the compressed header. Bit14 is the “RDG/More PPDU” subfield. Bit12 to Bit0 are the AID indication. Frame Header Compression indication would be in the Duration/ID/RD/FHC field of the compressed header. Bit15 is the “FHC” (Frame Header Compression indication) subfield. FHC is 1 means that the frame header is compressed frame header. Duration/IDRDG/More PPDU FHC Bit0 Bit13Bit14 Bit15 Duration/ID/RD/FHC Slide 4 Date: Jan, 2012 Single Address frames are not allowed to use compressed frame format.

5. doc.: IEEE 802.11-12/0110r3 Submission Data/Management Frame Header Compression 2 MPDU type (Normal or compressed) should be identified by either the PHY or MAC header. –Bit15 in Duration field. –PHY PLCP SIG. –Other methods. Partial AID in PHY SIG is used to identify RA. –If two STAs in the BSS have the same Partial AID, the STAs that have the same Partial AID are not allowed to use compressed frame by AP (e.g. through management frame). MAC address is used to identify TA. DA/RA identifier identifies DA/SA. –RDG/More PPDU can be included in the same byte. Single Address frames are not allowed to use compressed frame format. Slide 5 Date: Jan, 2012

6. doc.: IEEE 802.11-12/0110r3 Submission Conclusion Frame header compression can decrease short frame overhead through: –AID replaces RA/TA MAC address in MAC header, –Partial AID RA MAC address in MAC header, –RD can be used without HTC/VHTC, –SA/DA identifier indentify SA/DA MAC address. Further optimization may include decreasing sequence number length etc. Slide 6 Date: Jan, 2012

7. doc.: IEEE 802.11-12/0110r3 Submission Straw Poll 1 Do you support to use Partial AID or AID to replace RA/TA MAC address? –Y –N –A Slide 7 Date: Jan, 2012

8. doc.: IEEE 802.11-12/0110r3 Submission Straw Poll 2 Do you support to use RD without HTC/VHTC? –Y –N –A Slide 8 Date: Jan, 2012

9. doc.: IEEE 802.11-12/0110r3 Submission Backup Slides Slide 9 Date: Jan, 2012

10. doc.: IEEE 802.11-12/0110r3 Submission DASA Identification Management A non-AP STA sends DASA Identification Request frame to the AP to indicate the mapping between DASA Identifier and DASA MAC Address. The AP sends DASA Identification Response frame to acknowledge the mapping between DASA Identifier and DASA MAC Address. CategoryAction Value Dialog Token DASA Identifier DASA MAC Address ……DASA Identifier DASA MAC Address Octets: 1 111616 At most 16 DASA Identifier and DASA MAC Address pairs IdentifierReservedDASA Indication Bit0 Bit2Bit3 Bit6Bit7 DASA Identification Request frame DASA Identifier field CategoryAction ValueDialog TokenStatus Code Octets: 1 112 DASA Identification Response frame Slide 10 Date: Jan, 2012