ZyXEL Communications NWA1120 Series User Manual page 189

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 93 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.
RTS/CTS
A hidden node occurs when two stations are within range of the same access point, but are not
within range of each other. The following figure illustrates a hidden node. Both stations (STA) are
within range of the access point (AP) or wireless gateway, but out-of-range of each other, so they
NWA1120 Series User's Guide
Appendix E Wireless LANs
189