Chung Nam Electronics Co. Ltd. WLANTUBGR ユーザーズマニュアル
Q72WLANTUBGR 802.11b/g WLAN USB User Manual
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Appendix A: Glossary
802.11b - The 802.11b standard specifies a wireless networking at 11 Mbps using
direct-sequence spread-spectrum (DSSS) technology and operating in the unlicensed
radio spectrum at 2.4GHz, and WEP encryption for security. 802.11b networks are also
referred to as Wi-Fi networks.
802.11g - specification for wireless networking at 54 Mbps using direct-sequence
spread-spectrum (DSSS) technology, using OFDM modulation and operating in the
unlicensed radio spectrum at 2.4GHz, and backward compatibility with IEEE 802.11b
devices, and WEP encryption for security.
DSSS (Direct-Sequence Spread Spectrum) - DSSS generates a redundant bit pattern
for all data transmitted. This bit pattern is called a chip (or chipping code). Even if one or
more bits in the chip are damaged during transmission, statistical techniques embedded in
the receiver 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. However, to an intended receiver (i.e. another wireless
LAN endpoint), the DSSS signal is recognized as the only valid signal, and interference
is inherently rejected (ignored).
FHSS (Frequency Hopping Spread Spectrum) - FHSS continuously changes (hops)
the carrier frequency of a conventional carrier several times per second according to a
pseudo-random set of channels. Because a fixed frequency is not used, and only the
transmitter and receiver know the hop patterns, interception of FHSS is extremely
difficult.
Infrastructure Network - An infrastructure network is a group of computers or other
devices, each with a wireless adapter, connected as an 802.11 wireless LAN. In
infrastructure mode, the wireless devices communicate with each other and to a wired
network by first going through an access point. An infrastructure wireless network
connected to a wired network is referred to as a Basic Service Set (BSS). A set of two or
more BSS in a single network is referred to as an Extended Service Set (ESS).
Infrastructure mode is useful at a corporation scale, or when it is necessary to connect the
wired and wireless networks.
Spread Spectrum - Spread Spectrum technology is a wideband radio frequency
technique developed by the military for use in reliable, secure, mission-critical
communications 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).