[STDS-802-11-TGM] Oh, *that* energy detect?!
--- This message came from the IEEE 802.11 Task Group M Technical Reflector ---
Hello Mark,
So let me see if I've now grokked this:
- CS/CCA includes both a "sniff the PHY header" mode and a "do
energy detect" mode. The latter asserts CCA if the power is at
least -62 dBm (assuming 20 MHz). These modes are both mandatory
- There's a *separate* "do energy detect" mode called CCA-ED
which is the same as the "do energy detect" mode of CS/CCA
except the threshold is -72 dBm. This mode is only used in some
regdoms, namely the 3 GHz band in the USA (a.k.a. 11y)
If so, this is a very confusing way to describe it for a
simple MAC person like me and I will raise a comment on D1.0!
Bonus questions:
- Is CCA-ED only required of the OFDM (11a) PHY? Or is it also
required for PHYs which incorporate the OFDM PHY by reference
(using the San Antonio wording)? What about 11n in GF mode,
should this ever be done in a regdom where CCA-ED is mandatory?
- Why is the CCA-ED threshold in a MIB variable
(dot11OFDMEDThreshold)? The other energy detect mode's
threshold is not in any variable (or is this dot11EDThreshold
(but this is only for the DSSS PHY) or even dot11TIThreshold
(deprecated and in the dot11PhyOFDMTable though its description
seems generic enough)?)
- What's the difference between "CCA-ED", "CCA-EnergyDetect",
"CCA-Energy Detect", "CCA energy detect" and "CCA-EDBehavior"?
Are the second and fourth just typos for the third, and the
first just an abbreviation of the third; the fourth being the
behavio(u)r associated with regdoms which require CCA-ED?
Mark
--
Mark RISON, Systems Architect, Wi-Fi English/Esperanto/Français
Samsung Cambridge Solution Centre Tel: +44 1223 434600
Innovation Park, Cambridge CB4 0ZT Fax: +44 1223 TBCTBC
ROYAUME UNI WWW: http://www.samsung.com/uk
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