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III). These cards can be used for many functions, including memory storage, as landline modems and
as wireless LAN
.
Preamble Mode
– Preamble is a sequence of bits transmitted at 1Mbps that allows the PHY circuitry to reach
steady-state demodulation and synchronization of bit clock and frame start. Two different preambles and
headers are defined: the mandatory supported Long Preamble and header, which interoperates with the
1 Mbit/s and 2 Mbit/s DSSS specification (as described in IEEE Std 802.11), and an optional Short
Preamble and header (as described in IEEE Std 802.11b). At the receiver, the Preamble and header are
processed to aid in demodulation and delivery of the PSDU. The Short Preamble and header may be
used to minimize overhead and, thus, maximize the network data throughput. However, the Short
Preamble is supported only from the IEEE 802.11b (High-Rate) standard and not from the original IEEE
802.11. That means that stations using Short-Preamble cannot communicate with stations implementing
the original version of the protocol.
Roaming -
A function that allows one to travel with a mobile end system (wireless LAN mobile station, for
example) through the territory of a domain (an ESS, for example) while continuously connecting to the
infrastructure.
RTS Threshold
– Transmitters contending for the medium may not hear each other. The RTS (Request To
Send) Threshold defines the number of bytes used for the RTS/CTS (Clear to Send) handshake
boundary. The small setup value will cause the overhead during the transmission and too big setup
value will decrease the transfer reliability. So normally the value should be default in 2432 bytes. By
inconsistent data flow, try to minor the value. The RTS/CTS mechanism can solve this “ Hidden Node
Problem”.
WEP
– Wired Equivalent Privacy (Wep) is an encryption scheme used to protect wireless data communication.
Selecting “Disabled” will prevent you from sharing data with other computers if your network uses Wep.
If your network is Wep enabled, you must choose “64 bits” or “128 bits”. Consult your System
Administrator for more information about your network type. For more information about Wep, see the
chapter entitled “PRISM Configuration Utility” in this manual.
