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All:

An 802.11 station is built to the specifications of one of six PHYs. Each PHY is described in one clause of the standard, clauses 14 through 19, although some clauses refer to and include parts of earlier clauses. Three clauses are included in the IEEE 802.11-1999 base document; three were introduced by way of amendments to that document - 802.11a, 802.11b, and 802.11g.

To say that a station is 802.11g is a common way of saying that its physical layer is built to the requirements of IEEE 802.11, clause 19, ERP, introduced by the 802.11g amendment. To say that a station is 802.11b is a common way of saying that its physical layer is built to the requirements of IEEE 802.11, clause 18, HR/DSSS, introduced by the 802.11b amendment.

Unfortunately, these are also common ways of describing how a station has been configured regardless of the PHY under the hood. Actually no amount of configuring an ERP station will make it an HR/DSSS station. Or put another way, no amount of configuring an 802.11g station will make it an 802.11b station.

For instance supporting only HR/DSSS rates in an ERP station will not prevent that station from receiving, decoding, deferring to, and/or in some ways acting upon frames transmitted from other ERP stations at ERP rates that are not also HR/DSSS rates.

In another example debated in recent years, supporting only ERP rates that are not also HR/DSSS rates in an ERP station will prevent that ERP station from using protection mechanisms that require HR/DSSS rates to operate, but will not prevent that ERP station from needing protection from nearby transmissions by HR/DSSS or DSSS stations. I say the result is not a "Pure G" station but a "Crippled ERP" station.

The IEEE 802.11n amendment will give us a seventh PHY described in a clause 20 and called HT (for High Throughput). HT stations will be backwardly compatible with DSSS, OFDM, HR/DSSS, and ERP stations in both the 2.4 and 5 GHz RF bands! No amount of configuring an HT station will either make it not an HT station, nor make it entirely unaffected by transmissions of at least some of those other four PHYs.

I urge all 802.11 professionals to be conversant with the PHYs by clause, full name, acronym name, and amendment.

I hope this helps. Thanks. /criss