ZyXEL Communications Corporation NWD271N 用户手册

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 Appendix B Wireless LANs
NWD271N User’s Guide
101
Figure 70   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.