SCALANCE W1750D UI
Configuration Manual, 02/2018, C79000-G8976-C451-02
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Appendix
A
B.1
Terms
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 working 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 operate at radio frequencies in
the 5GHz band. The specification uses a modulation 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. Instead 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 inter-
ference. 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, compared with the 11 Mbps theo-
retical maximum of 802.11b. 802.11g operates in the 2.4 GHz band and employs orthogonal frequency
division multiplexing (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 determined 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 else-
where. 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 in-
trude into the network, obtain a free Internet connection, and possibly 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.
DHCP
The Dynamic Host Configuration Protocol (DHCP) is an auto- configuration protocol used on IP net-
works. Computers or any network peripherals that are connected to IP networks must be configured,
before they can communicate with other computers on the network.
DHCP allows a computer to be configured automatically, eliminating the need for a network administra-
tor. DHCP also provides a central database to keep track of computers connected to the network. This
database helps in preventing any two computers from being configured with the same IP address.
