Appendix B Wireless LANs
EMG6726/8726-B10A User’s Guide
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Figure 189
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.
