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WLAN features two-fold protection in security. On the hardware side, as with Direct
Sequence Spread Spectrum technology, it has the inherent security feature of
scrambling. On the software side, WLAN offers the encryption function (WEP) to
enhance security and access control.
6. What is WEP?
WEP is Wired Equivalent Privacy, a data privacy mechanism based on a 64-bit or
128-bit shared key algorithm, as described in the IEEE 802.11 standard.
7. What is infrastructure mode?
When a wireless network is set to infrastructure mode, the wireless network is
configured to communicate with a wired network through a wireless access point.
8. What is roaming?
Roaming is the ability of a portable computer user to communicate continuously
while moving freely throughout an area greater than that covered by a single access
point. Before using the roaming function, the workstation must make sure that it is the
same channel number with the access point of dedicated coverage area.
To achieve true seamless connectivity, the wireless LAN must incorporate a number
of different functions. Each node and access point, for example, must always
acknowledge receipt of each message. Each node must maintain contact with the
wireless network even when not actually transmitting data. Achieving these functions
simultaneously requires a dynamic RF networking technology that links access points
and nodes. In such a system, the user’s end node undertakes a search for the best
possible access to the system. First, it evaluates such factors as signal strength and
quality, as well as the message load currently being carried by each access point and
the distance of each access point to the wired backbone. Based on that information,
the node next selects the right access point and registers its address. Communications
between end node and host computer can then be transmitted up and down the
backbone. As the user moves on, the end node’s RF transmitter regularly checks the
system to determine whether it is in touch with the original access point or whether it
should seek a new one. When a node no longer receives acknowledgment from its
original access point, it undertakes a new search. Upon finding a new access point, it
then re-registers, and the communication process continues.
9. What is ISM band?
The FCC and their counterparts outside of the U.S. have set aside bandwidth for
