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[STDS-802-11] Questions on MAC Figures in Draft P802.11REVmc_D5.0



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All,

I have questions on two MAC figures in Draft P802.11REVmc_D5.0 (and early versions). Any explanation is appreciated.

1) Figure 10-4: Some IFS relationships
In statement "Immediate access when Medium is idle >= DIFS or AIFS[i]", should >= be >? Because >= indicates two cases: > or =. The case > is no problem, but case = may violate backoff rule. Because with =, a STA can wait for DIFS or AIFS[i], then immediately access medium even after busy medium (since medium is already idle for DIFS or AIFS[i] time).

2) Figure 10-13: Example of exponential increase of CW
    Should the initial CW value (i.e., CWmin value) be 8 instead of 7?
Because if CW = 7 for initial attempt, it means CWmin = 7. Then for the first retransmission, CW should be CWmin x 2 - 1 = 7 x 2 - 1 = 13, and for the second retransmission, CW should be 7x2x2-1 = 27, ...

Jianlin Guo
Mitsubishi Electric Research Labs
Cambridge, MA, USA

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