CHAPTER 21
Wireless Local Area Networks
21.1 Introduction
With the success of wired local area networks (LANs), the local computing market
is moving toward wireless LAN (WLAN) with the
same speed of current wired
LAN. WLANs are fl exible data communication systems that can be used for appli-
cations in which mobility is required. In the indoor business environment, although
mobility
is not an absolute requirement, WLANs provide more fl exibility than
that achieved by the wired LAN. WLANs are designed to operate in industrial,
scientifi c, and medical (ISM) radio bands (see Table 21.1) and unlicensed-national
information infrastructure (U-NII) bands.
In the United States, the Federal Com-
munications Commission (FCC) regulates radio transmissions; however,
the FCC
does not require the end-user to buy a license to use the ISM or U-NII bands.
Currently, WLANs can provide data rates up to 11 Mbps, but the industry is mak-
ing a move toward high-speed WLANs. Manufacturers are developing WLANs to
provide data rates up to 54 Mbps or higher. High speed
makes WLANs a promising
technology for the future data communications market [7].
The IEEE 802.11 committee is responsible for WLAN standards. WLANs
include IEEE 802.11a (WiFi 5), IEEE 802.11b (WiFi), IEEE 802.11g and IEEE
802.11n (see Figure 21.1). The deployment of WLANs
can provide connectivity
in homes, factories, and hot-spots. The IEEE 802.16 group is responsible for wire-
less metropolitan area network (WMAN) standards.
This body is concerned with
fi xed broadband wireless access systems, also known as “last mile” access net-
works.
In this chapter, we focus on different types of WLANs and introduce IEEE
802.16 standards including WiMAX (high speed WLAN) [1,18,19]. Table 21.2
lists all subgroups of IEEE 802.11.
