Page 268 - Antennas for Base Stations in Wireless Communications

7
Chapter

Antennas for WLAN

(WiFi) Applications

Zhi Ning Chen, Wee Kian Toh, Shie Ping See, Xianming Qing
Institute for Infocomm Research

7.1 Introduction

7.1.1 WLAN (WiFi)
Wireless Local Area Networks (WLANs) provide wireless network com-
munications, in particular, between computers and other portable devices
with fixed access points over a short distance, typically in the order of
tens of meters. WLAN’s rapidly increasing popularity in consumer elec-
tronics is primarily due to its convenience, mobility, easy deployment and
expandability, and cost efficiency, as well as its ease of integration with
other networks and devices. WLANs include Wireless Fidelity (WiFi,
1
IEEE 802.11a/b/g/n) and High Performance Radio LAN (HIPERLAN).
A typical WLAN is connected to stations equipped with wireless net-
work interface cards (WNICs). The wireless stations are categorized
into fixed base stations, namely access points (APs) and clients, or cus-
tomer premises equipment (CPE), or subscriber unit (SU). These include
mobile devices such as laptops, personal digital assistants, IP phones,
or fixed devices such as desktops and workstations that are equipped
with a wireless network interface. WLAN communication can be peer-
to-peer, bridge, or via wireless distribution. Peer-to-peer communica-
tion is achieved through an ad-hoc network without a base station and
permission to talk. In other words, peer-to-peer communication allows
wireless devices to talk directly to each other without any access points.
Typically, two computers can be connected to form a network. A bridge in

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