Wireless Networks
By Stephen Bucaro
A wireless LAN (WLAN or WiFi) provides network connectivity by using radio waves
rather than cable. Wireless devices can communicate with each other or they can
communicate through a wireless access point (WAP) to a wired network.
Wireless networks use the IEEE (Institute of Electrical and Electronics
Engineers) 802.11 standard. The first 802.11 standard, created in 1997, supported
a maximum bandwidth of only 2 Mbps (million bits per second). In July 1999 the IEEE
created the 802.11b standard, which supports a maximum bandwidth of 11 Mbps.
At the same time 802.11b was created, IEEE extended the original 802.11 standard
to support a maximum bandwidth of 54 Mbps, and called it 802.11a. But because
802.11b products were lower cost than 802.11a, 802.11b became much more popular
than did 802.11a.
Because 802.11a and 802.11b use different frequencies, the two technologies are
incompatible with each other. In the 2002 the 802.11g standard was developed.
802.11g supports a maximum bandwidth of 54 Mbps, and is backwards compatible
with 802.11b. That means 802.11g and 802.11b wireless products can communicate,
although at the lower 11 Mbps frequency.
A single IEEE 802.11 WAP can typically communicate with 30 client systems
located within a 100 meter radius. However, the range of communication can vary
a greatly, depending on such variables as placement, obstructions, and interference
from other electronic devices.
The 802.11b and 802.11g standards use the 2.40 gigahertz (GHz) band. 802.11b and
802.11g equipment can incur interference from microwave ovens, cordless telephones,
and other appliances which commonly use the same 2.4 GHz band. The 802.11a standard
uses the 5 GHz band.
Advantages of Wireless LANs
The major advantage of Wireless LANs is increased mobility. Each computer in a
wireless LAN is referred to as a station. Stations may be fixed, mobile, or portable.
A portable station can be move from point to point, but is fixed during use. A mobile
station can access the LAN during movement. For example, a mobile station might be
used to access a database as warehouse workers move inventory into the warehouse and
move products out of the warehouse to fill orders.
Another advantage of Wireless LANs is reduced cost for new installations or
locations that are difficult to cable. With a new installation, you can implement
wireless hubs, switches, and routers, avoiding the cost of having to install a cable
infrastructure. With locations that are difficult to cable you can implement a
wireless link to an existing cabled network.
A wireless link can function as bridge between two wired networks. For example
if you need to link networks in two separate buildings, rather than paying the
high cost to tear up the parking lot to lay a fiber optic cable, you can implement
a point-to-point wireless bridge to connect the two buildings.
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