ELSA AirLancer
1
English
Introduction
The advantages of wireless LANs are obvious: Notebooks and PCs can be set up where
theyarewanted—problems with missing portsor construction alterations areathing of
the past with wireless networking.
Networklinksinconferencesor presentations, access toresourcesinadjacentbuildings
and exchanging data with mobile units are only a few of the options available with a
wireless LAN.
The base station plays the central role in enabling these options in an existing wired
network. All stations in the wireless network access the LAN via the base station.
What does a wireless network card really do?
WLAN
A wireless network card is used to link individual notebooks and PCs to a local network,
a Local Area Network (LAN). Because the standard network wiring belonging to a
conventionalLANisreplacedbyaradioconnection in this LAN,thesewirelessnetworks
are also referred to as a Wireless Local Area Network (WLAN).
Allthe functions of a wired network are available ina wirelessnetwork: Access to files,
servers, printers etc. is possible as is the integration of the mobile stations into an
internal company e-mail system.
Radio transmission
IEEE 802.11
Wireless network cards from ELSA operate under IEEE Standard 802.11. This standard
is a supplement to the current IEEE standards for LANs, with IEEE 802.3 for Ethernet
beingthemostwell-known. IEEE802.11coverstheoperationof localwirelessnetworks
onprivateandpublicpropertyintheISMfrequencyrange(Industrial,Scientific,Medical:
2.4 and 2.483 GHz).
Please note that not all frequencies are permitted in every country! A table of the
frequencies is given in the appendix.
2 Mbps
The maximum bandwidth for data transfer is 2 Mbps. The transfer range in the open is
up to 300 meters, in buildings it is typically around 30 meters.
DSSS
The wireless network cards from ELSA use the DSSS process (Direct Sequence Spread
Spectrum) to shield against interference from other transmitters that may be using the
same frequency range. A transmitter normally uses only a very narrow range of the
available frequency band for transfer. If precisely this range is also in use by another
transmitter, this will cause interference in the transfer. In the DSSS process the
transmitterusesabroadersectionofthepossiblefrequencybandandsoislesssensitive
to narrow-band interference. This process is also used by the military to make
