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## DMG Base MCS and Length Supplementary Slides

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**Hiroyuki Motozuka, Panasonic**DMG Base MCS and LengthSupplementary Slides Authors: • Date: 2016-05-17**Hiroyuki Motozuka, Panasonic**Abstract • The current text in draft D5.4 of REVmc defines the Base MCS and Length field in the PHY SC header for extended MCS. • But the formula for Length field value causes duration calculation error for some Ns (number of PSDU octets.) • The submission 11-16/0670r5 proposes modified text and formulae to fix it. • This submission includes supplementary slides for 11-16/0670r5.**Hiroyuki Motozuka, Panasonic**Duration calculation error • Base MCS and Length field value in SC Header should be set so that the duration calculated from Header equals to the actual duration. • The formula in D5.4 causes duration errors for some Ns (numbers of octets.) • Potential risks to fairness and interoperability on IFS/backoff procedures Extended MCS capable STA sees this duration example) Actual MCS, PPDU octets MCS9.1, N = 70 actual PPDU duration = 3.09 usec Header values Base MCS6, Length=40 (according to the formula in D5.4) duration calculated from Header = 2.80 usec -0.29 usec Extended MCS non-capable STA sees this duration Observed duration errors-0.29us ~ +0.58us**Hiroyuki Motozuka, Panasonic**Proposed Modification – Base MCS • Base MCSs (6 to 12) are mapped to Extended MCSs in natural order.**Hiroyuki Motozuka, Panasonic**Proposed Modification - Length • Proposed Length formula is based on NBLKS (number of symbol blocks) • Avoid errors caused by number of parity bits used for recovery of number of data octets (N) at receivers set according to given duration**Hiroyuki Motozuka, Panasonic**Proposed Modification – Length(cont’d)**Hiroyuki Motozuka, Panasonic**Proposed Modification - SI • Similar to 11-16/0220r3, two bits out of SI field are used for recovery of the actual number of octets at receiver STA. • Formula is as follows: =**Hiroyuki Motozuka, Panasonic**Verification • Duration error is eliminated with proposed formula. • Recovery of the number of data octets works. • We verified it throughout: MCS {9.1, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6} x Number of octets: 1-262143 example) Actual MCS, PPDU octets MCS9.1, N = 70 actual PPDU duration = 3.09 usec Header values Base MCS6, Length=68 duration calculated from Header = 3.09 usec Observed duration error0 usec**Hiroyuki Motozuka, Panasonic**References • [1] Draft P802.11REVmc_D5.3 • [2] 11-16/0220r3 Clause 20 SC MCS Extension • [3] 11-16/0233r0 Additional SC MCSs in clause 20 (DMG PHY) • [4] 11-16/0670r5 Base MCS and Length Calculation for Extended MCS Set