AML KDT750 Price Verification System - Manual (Page 39)

KDT750 User’s Guide
5 - 3
Interference and Coexistence
802.11 operates in a range of radio frequencies known as an "unlicensed" band (i.e., the
FCC does NOT require the use of a license in order to operate a radio transmitter in this
range). This means that commercially available radio devices other than wireless LAN
devices are permitted to use the same frequency band as 802.11. Consequently, these co-
existing radio devices can interfere or "jam" the wireless LAN (and vice versa). The most trou-
blesome devices are cordless telephones and microwave ovens.
Fortunately, higher quality cordless phones tend to "listen" for a clear channel before
becoming active and will thus avoid interfering with a wireless LAN (i.e., the cordless phone
seeks a clear channel for itself so naturally avoids being interfered with or being a source of
interference). Jamming from microwave ovens is more severe but is usually restricted to the
upper frequency range for 802.11 (it should be noted that 802.11b/g divides the available
frequency band into 11 channels [US]. The higher numbered channels are most susceptible
to microwave oven interference).
In each instance, jamming occurs only when the cordless telephone or microwave oven is
active.
Encryption and Authorization
Much has been publicized in the mass media recently about security problems with wireless
LANs. Although it cannot be denied that some encryption algorithms currently used in
802.11 are flawed, the fact is that security breaches of a wireless LAN require a deliberate
attempt to access the network by an intruder.
The primary issue is that many current users of wireless LAN have opted NOT to turn on secu-
rity features. If users were to enable the security features currently available (including only
allowing known systems access to the network and enabling WEP [Wired Equivalent Privacy]
or WPA [Wifi Protected Access]) on even the most basic access points, the intruder's work is
much harder. Much as a burglar will stray away from a house whose doors and windows are
securely locked, so too will an attacker tend to move past a wireless network when even
the simplest security measures are enabled.
Wireless Configuration
The optional 802.11b/g/n radio can be configured with the KDT750 Setup Utility under the
Network menu.