ZyXEL Communications NWD-270N Network Card User Manual


 
Appendix C Wireless LANs
NWD-270N User’s Guide
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ESS
An Extended Service Set (ESS) consists of a series of overlapping BSSs, each containing an
access point, with each access point connected together by a wired network. This wired
connection between APs is called a Distribution System (DS).
This type of wireless LAN topology is called an Infrastructure WLAN. The Access Points not
only provide communication with the wired network but also mediate wireless network traffic
in the immediate neighborhood.
An ESSID (ESS IDentification) uniquely identifies each ESS. All access points and their
associated wireless clients within the same ESS must have the same ESSID in order to
communicate.
Figure 30 Infrastructure WLAN
Channel
A channel is the radio frequency(ies) used by wireless devices to transmit and receive data.
Channels available depend on your geographical area. You may have a choice of channels (for
your region) so you should use a channel different from an adjacent AP (access point) to
reduce interference. Interference occurs when radio signals from different access points
overlap causing interference and degrading performance.
Adjacent channels partially overlap however. To avoid interference due to overlap, your AP
should be on a channel at least five channels away from a channel that an adjacent AP is using.
For example, if your region has 11 channels and an adjacent AP is using channel 1, then you
need to select a channel between 6 or 11.