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Wireless Networks

Notes usage and scale of WLANs have increased. Originally, WLANs were deployed with the use of a
relatively simple architecture of standalone enterprise access points (AP). The early WLAN APs
were built to simply translate between the radio frequency (RF) media and Ethernet media.

1.2 IEEE Standards for Wireless Networks

Wireless networking hardware requires the use of underlying technology that deals with radio
frequencies as well as data transmission. The most widely used standard is 802.11 produced by
the Institute of Electrical and Electronic Engineers (IEEE). This is a standard defining all aspects
of Radio Frequency Wireless networking.
The Institute of Electrical and Electronic Engineers (IEEE) is a professional organization of
electrical engineers that has organized a highly successful and unique standards making activity.
Arguably the most successful of these standards making activities has been under the auspices
of the IEEE’s 802 Committee which is responsible for networking standards at the data link (the
Media Access Control or MAC) and physical (the PHYsical) network layers. Subcommittees of
the 802 Committee have been responsible for the major networking standards that we use every
day:
z z 802.3: The entire family of Ethernet standards, defining both local and wide area
communication on coaxial cable, twisted pair copper and optical fiber.

z z 802.5: The legacy standards of Token Ring for network communication over coaxial cable
and twisted pair copper and optical fiber..

z z 802.11: The entire family of wireless local area network standards. Commercially known
as Wi-Fi.
z z 802.16: The entire family of wireless metropolitan area network standards. Commercially
known as WiMAX.

In particular, the IEEE 802.11 Subcommittee is responsible for the family of evolving wireless
local area network (WLAN) standards:

z z 802.11: The original WLAN standard in 1997 using 1 and 2 Mbps PHY in the 2.4GHz band.
z z 802.11b: The enhanced standard for the 2.4 GHz band in 1999 providing 11Mbps PHY.
z z 802.11a: The enhanced PHY standard for the 5 GHz band providing 54 Mbps using OFDM
(Orthogonal Frequency Division Multiplexing) modulation in 1999.

z z 802.11g: The enhanced PHY standard for the 2.4 GHz band providing 54 Mbps using
OFDM with backwards compatibility to 802.11b in 2003.
The variants of 802.11 all use a common MAC protocol. Other auxiliary standards in the family
(c–f, h, I, j) are service enhancements and extensions or corrections to previous specifications.
The IEEE 802.11n subcommittee was chartered by its parent IEEE 802.11 committee in 2003
to develop high performance enhancements to these standards.Wi-Fi is a brand of the Wi-Fi
Alliance - a commercial organization that certifies interoperability of products implementing the
802.11 IEEE standard and promotes the standard though market education.

Did u know? IEEE 802.11n is the most significant change in the wireless LAN world since
the adoption of the original standard in 1997. 802.11n defines enhancements for both the
MAC and the PHY. The greatest impact of 802.11n is in the technology used for the PHY.
The ability to create low-cost radios in CMOS now allows the simultaneous use of multiple
radios and antennas in every client. Advanced signal processing enables 802.11n to
integrate multiple radios and a number of other PHY improvements to effectively increase
the burst transmission speed and the total system capacity by a factor of ten when all of the
new enhancements are used.

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