Chapter 4 Wireless Lan; Wireless Lan Basis; Channel; Ess Id - ZyXEL Communications ZyAIR B-420 User Manual

ZyAIR B-420 Wireless LAN Ethernet Adapter and Bridge
Chapter 4
Wireless LAN
This chapter discusses how to configure Wireless LAN screens on the ZyAIR.
4.1

Wireless LAN Basis

This section provides basic background information on the wireless LAN screens.

4.1.1 Channel

A channel is the radio frequency(ies) used by IEEE 802.11b wireless devices. 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 ZyAIR 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.
The ZyAIR's "Scan" function is especially designed to automatically scan for a channel with the least
interference.

4.1.2 ESS ID

An Extended Service Set (ESS) is a group of access points connected to a wired LAN on the same subnet. An
ESS ID uniquely identifies each set. All access points and their associated wireless stations in the same set
must have the same ESSID.

4.1.3 WEP Encryption

WEP (Wired Equivalent Privacy) encrypts data frames before transmitting over the wireless network. WEP
encryption scrambles the data transmitted between the wireless stations and the access points to keep network
communications private. It encrypts unicast and multicast communications in a network. Both the wireless
stations and the access points must use the same WEP key for data encryption and decryption.

4.1.4 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
Wireless LAN 4-1