iB-WPA300N
300M MIMO Wireless-N PCI-E Adapter
36
Appendix B: Glossary
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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.
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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.
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802.11n -
802.11n builds upon previous 802.11 standards by adding MIMO
(multiple-input multiple-output). MIMO uses multiple transmitter and receiver antennas to
allow for increased data throughput via spatial multiplexing and increased range by
exploiting the spatial diversity, perhaps through coding schemes like Alamouti coding.
The Enhanced Wireless Consortium (EWC) was formed to help accelerate the IEEE
802.11n development process and promote a technology specification for interoperability
of next-generation wireless local area networking (WLAN) products.
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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.
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DSSS -
(
D
irect-
S
equence
S
pread
S
pectrum)
-
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).
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FHSS -
(
F
requency
H
opping
S
pread
S
pectrum)
-
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.
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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
