and the wire. In a WLAN, they provide the interface between the network
operating system and an antenna to create a transparent
connection to the
network.
Access point
(
AP
)
:
The AP is the wireless equivalent of an LAN hub. It
receives, buffers, and transmits data between the WLAN and the wired
network, supporting a group of wireless user devices. An AP is typically
connected with the backbone network through a standard Ethernet cable,
and communicates with wireless devices by means of an antenna. The AP
or antenna connected to it is generally mounted
on a high wall or on the
ceiling. Like cells in a cellular network, multiple APs can support handoff
from one AP to another as the user moves from area to area. APs have a
range from 20 to 500 meters. A single AP can support between 15 to 250
users,
depending on technology, confi guration, and use. It is relatively
easy to scale a WLAN by adding more APs to reduce network conges-
tion and enlarge the coverage area. Large networks requiring multiple
APs deploy them to create overlapping cells for
constant connectivity to
the network. A wireless AP can monitor movement of a client across its
domain and permit or deny specifi c traffi c or clients from communicating
through it.
Outdoor LAN bridges:
Outdoor LAN bridges are used to connect LANs
in different buildings. When the cost of buying a fi ber
optic cable between
buildings is considered, particularly if there are barriers such as highways or
bodies of water in the way, a WLAN can be an economical alternative. An
outdoor bridge can provide a less expensive alternative to recurring leased-
line charges. WLAN bridge products support
fairly high data rates and
ranges of several miles with the use of line-of-sight directional antennas.
Some APs can also be used as a bridge between buildings of relatively close
proximity.
