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An Ad-hoc integrated wireless LAN is a group of computers, each has a Wireless LAN card,
Connected as an independent wireless LAN. Ad hoc wireless LAN is applicable at a
departmental scale for a branch or SOHO operation.
Infrastructure
An integrated wireless and wireless and wired LAN is called an Infrastructure configuration.
Infrastructure is applicable to enterprise scale for wireless access to central database, or
wireless application for mobile workers.
BSS ID
A specific Ad hoc LAN is called a Basic Service Set (BSS). Computers in a BSS must be
configured with the same BSS ID.
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.
TKIP
TKIP is a quick-fix method to quickly overcome the inherent weaknesses in WEP security,
especially the reuse of encryption keys. TKIP is involved in the IEEE 802.11i WLAN security
standard, and the specification might be officially released by early 2003.
AES
AES (Advanced Encryption Standard), a chip-based security, has been developed to ensure the
highest degree of security and authenticity for digital information, wherever and however
communicated or stored, while making more efficient use of hardware and/or software than
previous encryption standards. It is also included in IEEE 802.11i standard. Compare with
AES, TKIP is a temporary protocol for replacing WEP security until manufacturers implement
AES at the hardware level.
DSSS vs FHSS
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 is, the greater the probability that the original data can be
recovered. Even if one or more bits in the chip are damaged during transmission, 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.
Spread Spectrum
Spread Spectrum technology is a wideband radio frequency technique developed by the
military for use in reliable, secure, mission-critical communication 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).
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VigorN65 User's Guide
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