11g revisions for backward
compatibility. (Original standard had an
insignificant installed base.)
1999 802.11b 2.4 GHz DSSS/CCK 1, 2, 5.5, 11 The first widely deployed WLAN hardware.
Added complementary Code Keying (CCK)
to original DSSS methods to achieve 5.5 and
11 Mbps rates.
1999 802.11b 2.4 GHz DSSS/PBCC 1, 2, 5.5, 11 Added Packet Binary Convolutional Coding
(PBCC) as an optional approach to achieving
5.5 and 11 Mbps data rates.
1999 802.11a 5.0 GHz OFDM 6, 9, 12, 18,
24, 36, 48, 54
Introduced Orthogonal Frequency Division
Multiplexing (OFDM) to achieve
significantly higher data rates. Ratified in
1999, but hardware was not available until
2002.
2003 802.11g 2.4 GHz DSSS/CCK 1, 2, 5.5, 11 Included for backward compatibility with
802.11b nodes operating in the same band.
2003 802.11g 2.4 GHz OFDM 6, 9, 12, 18,
24, 36, 48, 54
Pure 802.11g mode (no 802.11b nodes
present).
2003 802.11g 2.4 GHz DSSS/OFDM 6, 9, 12, 18,
24, 36, 48, 54
Optional hybrid mode using DSSS
preamble/header, OFDM payload.
2003 802.11g 2.4 GHz PBCC 22, 33 Optional additional PBCC data rates.
2.2.2 WLAN Regulation
In addition to official standards bodies such as IEEE and ISO, three other classes of entities
have an impact on wireless networks: regulatory agencies, industry groups, and major
vendors.
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