Siemens SCALANCE W1750D UI, Руководство по настройке

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Appendix
B.3 Glossary
SCALANCE W1750D UI
566
Configuration Manual, 02/2018, C79000-G8976-C451-02
B.3 Glossary
The following table lists the terms and their definitions used in this document.
Term Definition
802.11 An evolving family of specifications for wireless LANs developed by a work-
ing group of the Institute of Electrical and Electronics Engineers (IEEE).
802.11 standards use the Ethernet protocol and CSMA/CA (carrier sense
multiple access with collision avoidance) for path sharing.
802.11a Provides specifications for wireless systems. Networks using 802.11a op-
erate at radio frequencies in the 5GHz band. The specification uses a mod-
ulation scheme known as orthogonal frequency-division multiplexing
(OFDM) that is especially well suited to use in office settings. The maximum
data transfer rate is 54 Mbps.
802.11b WLAN standard often called Wi-Fi; backward compatible with 802.11. In-
stead of the phase-shift keying (PSK) modulation method historically used
in 802.11 standards, 802.11b uses complementary code keying (CCK),
which allows higher data speeds and is less susceptible to multipath-
propagation interference. 802.11b operates in the 2.4 GHz band and the
maximum data transfer rate is 11 Mbps.
802.11g Offers transmission over relatively short distances at up to 54 Mbps, com-
pared with the 11 Mbps theoretical maximum of 802.11b. 802.11g operates
in the 2.4 GHz band and employs orthogonal frequency division multiplex-
ing (OFDM), the modulation scheme used in 802.11a, to obtain higher data
speed. Computers or terminals set up for 802.11g can fall back to speeds
of 11 Mbps, so that 802.11b and 802.11g devices can be compatible within
a single network.
802.11n Wireless networking standard to improve network throughput over the two
previous standards 802.11a and 802.11g with a significant increase in the
maximum raw data rate from 54 Mbps to 600 Mbps with the use of four
spatial streams at a channel width of 40 MHz. 802.11n operates in the 2.4
and 5.0 bands.
AP An access point (AP) connects users to other users within the network and
also can serve as the point of interconnection between the WLAN and a
fixed wire network. The number of access points a WLAN needs is deter-
mined by the number of users and the size of the network.
access point mapping The act of locating and possibly exploiting connections to WLANs while
driving around a city or elsewhere. To do war driving, you need a
vehicle, a computer (which can be a laptop), a wireless Ethernet card set to
work in promiscuous mode, and some kind of an antenna which can be
mounted on top of or positioned inside the car. Because a WLAN may have
a range that extends beyond an office building, an outside user may be
able to intrude into the network, obtain a free Internet connection, and pos-
sibly gain access to company records and other resources.
ad-hoc network A LAN or other small network, especially one with wireless or temporary
plug-in connections, in which some of the network devices are part of the
network only for the duration of a communications session or, in the case of
mobile or portable devices, while in some close proximity to the rest of the
network.
band A specified range of frequencies of electromagnetic radiation.