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Appendix B: Glossary
802.11b - The 802.11b standard specifies a wireless product 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.
Ad-hoc Network - An ad-hoc network is a group of computers, each with a
Wireless N USB 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.
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 of 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 N USB 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.
