The IEEE 802.11a/b/g standards define the
general frequency bands (2.4 Ghz, 5 Ghz) and channel allocations
for operation, however it is up to individual countries to
decide if all channels are allowed based on their current
frequency spectrum use, and what maximum transmit power is
allowed.
For the
USA, the FCC is the regulating body, and
for Europe
it is ETSI. Equipment manufacturers must produce equipment that
conforms not only to worldwide IEEE standards, but that also
meet local FCC and ETSI requirements. Certified equipment will
have a sticker with FCC for FCC compliance, and a CE sticker
for ETSI compliance.
(*Note: Individual EU countries may further restrict limits
beyond ETSI definitions)
FCC Logo:
CE Logo:
802.11a
802.11a covers most of the
5 Ghz frequency spectrum. There are 24 non-overlapping channels
(20 Mhz each) for a total of 480 Mhz of useable spectrum.
802.11b/g has a total of
14 channels (20 Mhz each) within a 100 Mhz useable spectrum in
the 2.4 Ghz range. Only 3 of the 14 channels are
non-overlapping. The overlapping channels allow for home users
to fine tune their frequency, as other devices (cordless
phones, microwave ovens) also use the same frequency range and
can disturb WiFi transmissions.
