[STDS-802-11-TGBN] P-EDCA open issues
Hi all,
Let us continue the discussion of today’s presentation on open issues of
P-EDCA in this thread.
[Dmitry]: "for the second part (resuming backoff counter). I think the question should be set in a bit different way (i.e. broader) - do we think it is beneficial to reuse AC_VO BK counter and simply maintain it thoughout EDCA and P-EDCA periods or isolate
one from another(ie. have separate non-overlapping counters) “.
[ML] Keeping one retry counter seems fine. Right now, I don’t see a case when this could lead to cheating or fairness issues. Moreover, this would greatly simplify the rules for switching between EDCA and P-EDCA operation.
[Reza]: " For the 1st part, I prefer that the duration is fixed for DS-CST (given its impact of the choice of scrambler sequence). The current
spec has it fixed at 97us. It'd be good to first converge if there is a problem before proposing a solution. Btw, does this problem occur during DL or UL case? Regarding the 2nd part, we've settled on counting each DS-CTS transmission as one P-EDCA opportunity
and have set the consecutive such opportunities to be 1 (the default value). We need to have more sim and analysis before deciding on your suggestion. Did you by any chance have such analysis e.g. the improvement for P-EDCA STAs and the impact on legacy devices?”
[ML]:
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That’s a valid point. However, all STAs in BSS would use same Duration value, so a chance of a collision of different DS-CTS frames isn't very high. Also, we haven’t seen any evidence that setting same scrambler sequence may improve reception at all.
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The problem is real: 24Mb/s RTSs are often used, NAV rules do not allow responding to an RTS until NAV expires.
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The problem occurs in both UL and DL
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We have another degree of freedom: implementation complexity, but let me get back to the tradeoff between P-EDCA and legacy performance, and bring some illustrative results shortly.
Thanks
Mikhail Liubogoshchev
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