Billion 5100 Guía Del Usuario

 

33

 

This section introduces the wireless LAN and some basic configurations. Wireless LANs can 

be as simple as two computers with wireless LAN cards communicating in a peer-to-peer 

network or as complex as a number of computers with wireless LAN cards communicating 

through access points which bridge network traffic to the wired LAN. 

The range of radio frequencies used by IEEE 802.11b wireless devices is called a “channel”. 

Channels available depend on your geographical area. You may have a choice of channels 

(for your region) so you should use a different channel than 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. 

An Extended Service Set (ESS) is a group of access points or wireless gateways connected to 

a wired LAN on the same subnet. An ESS ID uniquely identifies each set. All access points or 

wireless gateways and their associated wireless stations in the same set must have the same 

ESSID. 

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.