Hardware Reference
In-Depth Information
Wi-Fi
When the first 802.11b wireless networking products appeared, compatibility problems existed due
to certain aspects of the 802.11 standards being ambiguous or leaving loopholes. A group of
companies formed an alliance designed to ensure that their products would work together, thus
eliminating any ambiguities or loopholes in the standards. This was originally known as the Wireless
Ethernet Compatibility Alliance (WECA) but is now known simply as the Wi-Fi Alliance ( www.wi-
fi.org ). In the past, the term Wi-Fi has been used as a synonym for IEEE 802.11b hardware. However ,
because the Wi-Fi Alliance now certifies other types of 802.11 wireless networks, the term Wi-Fi
should always be accompanied by both the standards supported (that is 802.11a/b/g/n) as well as the
supported frequency bands (that is 2.4GHz and/or 5GHz) to make it clear which products work with
the device. Currently, the Alliance has certified products that meet the final versions of the 802.11a,
802.11b, 802.11g, and 802.11n standards in 2.4GHz and 5GHz bands.
The Wi-Fi Alliance currently uses a color-coded certification label to indicate the standard(s)
supported by a particular device. Figure 17.2 shows the most common versions of the label, along
with the official IEEE standard(s) that the label corresponds to: 802.11a (orange background);
802.11b (dark blue background); 802.11g (lime green background); 802.11n (violet background).
Figure 17.2. The Wi-Fi Alliance's certification labels for Wi-Fi-compliant 802.11 hardware.
IEEE 802.11b
IEEE 802.11b (Wi-Fi, 2.4GHz band-compliant, also known as Wireless-B) wireless networks run at
a maximum speed of 11Mbps, about the same as 10BASE-T Ethernet (the original version of IEEE
802.11 supported data rates up to 2Mbps only). 802.11b networks can connect to conventional
Ethernet networks or be used as independent networks, similar to other wireless networks. Wireless
networks running 802.11b hardware use the same 2.4GHz spectrum that many portable phones,
 
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