The client adapter can be used in a variety of network configurations. In
some configurations, APs provide connections to the wired network or act as
repeaters to increase the wireless communication range. The maximum
communication range is based on how the wireless network is configured.
Ad Hoc WLAN
An ad hoc, or peer-to-peer, WLAN is the simplest WLAN
configuration. It is shown in Figure
. In a WLAN using
an ad hoc network configuration, all devices equipped with a client adapter can
communicate directly with one another. It is also called an independent basic
service set (IBSS) or a microcell.
Operating systems such as Windows 98
and Windows 2000 have made this type of network very easy to set up. This
topology can be used for a small office or home office to allow a laptop to be
connected to the main PC, or for several people to simply share files.
The primary drawback for this type of network is coverage limitation.
Everyone must be able to hear everyone else.
Wireless Infrastructure
with Workstations Accessing a Wired LAN
A WLAN that is connected to a
wired infrastructure comprises a basic service set (BSS). Placing two or more
access points on a LAN can extend the BSS. Figure
shows
such an extended service set (ESS) microcellular network, with workstations
accessing a wired LAN through access points.
This configuration is
useful with portable or mobile stations because it allows them to be directly
connected to the wired network even while moving from one microcell domain to
another. This process is transparent and the connection to the file server or
host is maintained without disruption. The mobile station stays connected to an
access point as long as it can. Once the STA moves out of range the station
automatically searches for and associates to another AP. This process is
referred to as roaming.