11.9 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.