Deployment of IEEE 802.11 WLAN Systems
Let us now explore some of the deployment scenarios with
wireless LAN and some deployment considerations. Although the IEEE 802.11 family
was seen as an extension of wired LAN, in some cases for new locations, the
popularity of the IEEE 802.11 family has extended beyond applications such as
conferences. WLAN systems are gaining ground at residential applications to
create a wireless LAN without any cabling. Enterprise and industrial
applications, including manufacturing, retail, warehousing, hospitality, health
care, and education are some of the applications where WLAN finds its niche
success.
One of the newer applications of the IEEE 802.11 family is the
public WLAN system, due to the attractiveness of the lower cost and operation in
the unlicensed band. This would allow subscribers to access their corporate
networks or other systems using a high-speed wireless interface. This could be
in locations such as airports, coffee shops, and malls around the United States
or even international access, as the 2.4-GHz band is available throughout the
world.
One of the interesting contrasts with the increasing demand for
high-speed access is the WLAN deployments versus public cellular systems such as
GSM or CDMA IS-95 and especially the 3G systems.
11.9.1 Deployment Considerations
There are several items to consider when deploying a wireless
LAN. We shall highlight some of the key issues. Most of these deployment issues
vary based on the deployment scenario (such as home versus enterprise versus
public WLAN).
COST
The first deployment issue is simply cost. Although the prices
of the access points and the WLAN access cards have been dropping, cost still
needs to account for the number of these devices that are needed. As well,
connections to the existing wired network, additional software needed in the
access points, setting up shared key infrastructure, deploying enough access
points for adequate coverage, and so on are factors that indirectly add to the
cost of deployment.
THROUGHPUT
Another set of related factors is throughput. The appropriate
IEEE 802.11 system should be chosen that best meets the throughput needs. The
deployment should choose the various PHY layer options available in the IEEE
802.11 family for throughput, as well as consider future needs for higher data
rates. The nature of applications dictates the use of appropriate WLAN
technology as well. Retail and warehousing may work well with the IEEE 802.11
standard. Higher-speed data requirements may require the need for IEEE 802.11b
standards or even the IEEE 802.11a standard.
RANGE, COVERAGE, AND MOBILITY
Depending on the application scenario such as a home versus
enterprise, the range and coverage of the WLAN systems need to be carefully
considered. Mobility (mostly applicable in enterprise and public WLAN systems)
introduces newer wrinkles such as extended coverage, WEP key management,
billing, connectivity to wired networks, and other issues that need to be
considered when deploying WLANs.
INTERFERENCE
When deploying the 2.4-GHz IEEE 802.11 systems, a key
consideration is the amount of interference starting from microwave ovens to new
technologies like Bluetooth. Sufficient testing should be performed to minimize
or avoid these interferers and, with respect to Bluetooth, examine the
recommendations made by the IEEE 802.15.2 committee on the coexistence of
Bluetooth and IEEE WLAN systems in unlicensed spectrums.
SECURITY
Security, management of shared keys, and authentication
mechanisms need to be considered as one of the key requirements. Residential
applications may use simple authentication management mechanisms. Enterprise and
public WLANs may require different levels of security such as MAC address
filtering, IP security mechanisms, and application-layer security
mechanisms.
Security is one of the primary concerns when using IEEE
802.11WLAN systems. One of the more common methods to eliminate any security
risks is to only use virtual private network (VPN) applications that employ some
form of IP security. This ensures that the information is carried securely over
the wireless medium.
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