Dual Band Wireless PCI-E Adapter -RWND-N9003PCE- User Manual
Appendix B: Glossary
802.11a - specification for wireless networking at 54 Mbps using OFDM modulation and
operating in radio band at 5GHz.
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
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.
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
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.
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 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