Appendix B About Wireless Lans; Modes; Bss/Ess; Channels - TRENDnet TEW-435BRM User Manual

Appendix B
About Wireless LANs
This Appendix provides some background information about using Wireless
LANs (WLANs).

Modes

Wireless LANs can work in either of two (2) modes:
•
Ad-hoc
•
Infrastructure
Ad-hoc Mode
Ad-hoc mode does not require an Access Point or a wired (Ethernet) LAN. Wireless
Stations (e.g. notebook PCs with wireless cards) communicate directly with each other.
Infrastructure Mode
In Infrastructure Mode, one or more Access Points are used to connect Wireless Stations
(e.g. Notebook PCs with wireless cards) to a wired (Ethernet) LAN. The Wireless Stations
can then access all LAN resources.
Access Points can only function in "Infrastructure" mode,
and can communicate only with Wireless Stations which are
set to "Infrastructure" mode.

BSS/ESS

BSS
A group of Wireless Stations and a single Access Point, all using the same ID (SSID), form a
Basic Service Set (BSS).
Using the same SSID is essential. Devices with different SSIDs are unable to communicate
with each other.
ESS
A group of Wireless Stations, and multiple Access Points, all using the same ID (ESSID),
form an Extended Service Set (ESS).
Different Access Points within an ESS can use different Channels. In fact, to reduce
interference, it is recommended that adjacent Access Points SHOULD use different channels.
As Wireless Stations are physically moved through the area covered by an ESS, they will
automatically change to the Access Point which has the least interference or best performance.
This capability is called Roaming. (Access Points do not have or require Roaming
capabilities.)
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Wireless ADSL Router User Guide

Channels

The Wireless Channel sets the radio frequency used for communication.
•
Access Points use a fixed Channel. You can select the Channel used. This allows you to
choose a Channel which provides the least interference and best performance. In the USA
and Canada, 11 channel are available. If using multiple Access Points, it is better if
adjacent Access Points use different Channels to reduce interference.
•
In "Infrastructure" mode, Wireless Stations normally scan all Channels, looking for an
Access Point. If more than one Access Point can be used, the one with the strongest signal
is used. (This can only happen within an ESS.)
•
If using "Ad-hoc" mode (no Access Point), all Wireless stations should be set to use the
same Channel. However, most Wireless stations will still scan all Channels to see if there
is an existing "Ad-hoc" group they can join.

WEP

WEP (Wired Equivalent Privacy) is a standard for encrypting data before it is transmitted.
This is desirable because it is impossible to prevent snoopers from receiving any data which is
transmitted by your Wireless Stations. But if the data is encrypted, then it is meaningless
unless the receiver can decrypt it.
If WEP is used, the Wireless Stations and the Access Point must have the same settings
for each of the following:
WEP Off, 64 Bit, 128 Bit
Key For 64 Bit encryption, the Key value must match.
For 128 Bit encryption, the Key value must match
Open System or Shared Key.
WEP Authentication

WPA-PSK

WPA-PSK is another standard for encrypting data before it is transmitted. This is a later
standard than WEP (Wired Equivalent Privacy), and provides greater security for your data.
Data is encrypted using a 256Bit key which is automatically generated and changed often.
If all your Wireless stations support WPA-PSK, you should use this instead of WEP.
If WPA-PSK is used, the Wireless Stations and the Access Point must have the same
settings for each of the following:
Enter the same value on every station and the AP. The PSK
WPA PSK
(Pre-shared Key) must be from 8 to 63 characters in length. The 256Bit key
used for the actual encryption is derived from this key.
Encryption The same encryption method must be used. The most
common encryption method is TKIP, and in many
situations this is the only encryption method which can be
used.
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