USER’S MANUAL OF WLAN BROADBAND ROUTER
Version: 1.0
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stations to establish and maintain communications in an orderly fashion.
Beacon Interval represents the amount of time between beacon transmissions. Before a
station enters power save mode, the station needs the beacon interval to know when to
wake up to receive the beacon (and learn whether there are buffered frames at the access
point).
4.13
What is Preamble Type?
There are two preamble types defined in IEEE 802.11 specification. A long preamble
basically gives the decoder more time to process the preamble. All 802.11 devices
support a long preamble. The short preamble is designed to improve efficiency (for
example, for VoIP systems). The difference between the two is in the Synchronization
field. The long preamble is 128 bits, and the short is 56 bits.
4.14
What is SSID Broadcast?
Broadcast of SSID is done in access points by the beacon. This announces your access
point (including various bits of information about it) to the wireless world around it. By
disabling that feature, the SSID configured in the client must match the SSID of the
access point.
Some wireless devices don't work properly if SSID isn't broadcast (for example the
D-link DWL-120 USB 802.11b adapter). Generally if your client hardware supports
operation with SSID disabled, it's not a bad idea to run that way to enhance network
security. However it's no replacement for WEP, MAC filtering or other protections.
4.15
What is Wi-Fi Protected Access (WPA)?
Wi-Fi’s original security mechanism, Wired Equivalent Privacy (WEP), has been
viewed as insufficient for securing confidential business communications. A longer-term
solution, the IEEE 802.11i standard, is under development. However, since the IEEE
802.11i standard is not expected to be published until the end of 2003, several members
of the WI-Fi Alliance teamed up with members of the IEEE 802.11i task group to
develop a significant near-term enhancement to Wi-Fi security. Together, this team
developed Wi-Fi Protected Access.
To upgrade a WLAN network to support WPA, Access Points will require a WPA
software upgrade. Clients will require a software upgrade for the network interface card,
and possibly a software update for the operating system. For enterprise networks, an
