Figure 584 Infrastructure Wlan - ZyXEL Communications ZyWALL USG 100 Series User Manual

Figure 584 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 cannot "hear" each other, that is they do not know if the channel is currently being
used. Therefore, they are considered hidden from each other.
ZyWALL USG 100/200 Series User's Guide
Appendix E Wireless LANs
843