ELSA AirLancer
1
English
Introduction
The advantages of wireless LANs are obvious: Notebooks and PCs can be set up where
they are wanted—problems with missing ports or construction alterations are a thing of
the past with wireless networking.
Network links in conferences or presentations, access to resources in adjacent buildings
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
L
ocal
A
rea
N
etwork (LAN). Because the standard network wiring belonging to a
conventional LAN is replaced by a radio connection in this LAN, these wireless networks
are also referred to as a
W
ireless
L
ocal
A
rea
N
etwork (WLAN).
All the functions of a wired network are available in a wireless network: 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
being the most well-known. IEEE 802.11 covers the operation of local wireless networks
on private and public property in the ISM frequency range (
I
ndustrial,
S
cientific,
M
edical:
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 (
D
irect
S
equence
S
pread
S
pectrum) 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
transmitter uses a broader section of the possible frequency band and so is less sensitive
to narrow-band interference. This process is also used by the military to make