27
26
Wireless Notebook Adapter
Appendix B: Glossary
802.11b - One of the IEEE standards for wireless networking hardware.
Products that adhere to a specific IEEE standard will work with each other,
even if they are manufactured by different companies. The 802.11b standard
specifies a maximum data transfer rate of 11Mbps, an operating frequency of
2.4GHz, and WEP encryption for security. 802.11b networks are also referred
to as Wi-Fi networks.
Adapter - Printed circuit board that plugs into a PC to add to capabilities or
connectivity to a PC. In a networked environment, a network interface card
(NIC) is the typical adapter that allows the PC or server to connect to the
intranet and/or Internet.
Ad-hoc Network - An ad-hoc network is a group of computers, each with a
wireless adapter, connected as an independent 802.11 wireless LAN. Ad-hoc
wireless computers operate on a peer-to-peer basis, communicating directly
with each other without the use of an access point. Ad-hoc mode is also
referred to as an Independent Basic Service Set (IBSS) or as peer-to-peer
mode, and is useful at a departmental scale or SOHO operation.
Auto fall-back - A feature provided by some wireless products to increase con-
nection reliability. Automatic fall-back enables a device to dynamically shift
between various data transfer rates. It works by decreasing the data transfer rate
when interference increases, distance increases, and other factors undermine
signal strength and quality.
Backbone - The part of a network that connects most of the systems and net-
works together and handles the most data.
Bandwidth - The transmission capacity of a given facility, in terms of how
much data the facility can transmit in a fixed amount of time; expressed in bits
per second (bps).
Bit - A binary digit. The value - 0 or 1-used in the binary numbering system.
Also, the smallest form of data.
Network Everywhere
™
Series
worldwide. This presents a truly revolutionary opportunity to place convenient
high speed wireless capabilities in the hands of users around the globe.
What is Spread Spectrum?
Spread Spectrum technology is a wideband radio frequency technique devel-
oped by the military for use in reliable, secure, mission-critical communica-
tions systems. It is designed to trade off bandwidth efficiency for reliability,
integrity, and security. In other words, more bandwidth is consumed than in the
case of narrowband transmission, but the trade-off produces a signal that is, in
effect, louder and thus easier to detect, provided that the receiver knows the
parameters of the spread-spectrum signal being broadcast. If a receiver is not
tuned to the right frequency, a spread-spectrum signal looks like background
noise. There are two main alternatives, Direct Sequence Spread Spectrum
(DSSS) and Frequency Hopping Spread Spectrum (FHSS).
What is DSSS? What is FHSS? And what are their differences?
Frequency Hopping Spread Spectrum (FHSS) uses a narrowband carrier that
changes frequency in a pattern that is known to both transmitter and receiver.
Properly synchronized, the net effect is to maintain a single logical channel. To
an unintended receiver, FHSS appears to be short-duration impulse noise.
Direct Sequence Spread Spectrum (DSSS) generates a redundant bit pattern for
each bit to be transmitted. This bit pattern is called a chip (or chipping code).
The longer the chip, the greater the probability that the original data can be
recovered. Even if one or more bits in the chip are damaged during transmis-
sion, statistical techniques embedded in the radio can recover the original data
without the need for retransmission. To an unintended receiver, DSSS appears
as low power wideband noise and is rejected (ignored) by most narrowband
receivers.
Would information be intercepted while transmitting on air?
WLAN features two-fold protection in security. On the hardware side, as with
Direct Sequence Spread Spectrum technology, it has the inherent security fea-
ture of scrambling. On the software side, the WLAN series offers the encryp-
tion function (WEP) to enhance security and access control. Users can set it up
depending upon their needs.
Can Instant Wireless
TM
products support file and printer sharing?
Instant Wireless
TM
products perform the same function as LAN products.
Therefore, Instant Wireless
TM
products can work with Netware, Windows
NT/2000, or other LAN operating systems to support printer or file sharing.
What is WEP?
WEP is Wired Equivalent Privacy, a data privacy mechanism based on a 40 bit
shared key algorithm, as described in the IEEE 802.11 standard.
