Lancom Systems LCOS 3.50 User Manual
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Chapter 11: Wireless LAN – WLAN
LANCOM Reference Manual LCOS 3.50
205
Wi
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transmission. If exactly this range is used by another transmitter, interferences
in transmission would be the result. With the DSSS procedure the transmitter
uses a broader spread of the possible frequencies and becomes more insensi-
tive to narrow-band disturbances then. This procedure is also used in military
range for increasing tap-proof security.
IEEE 802.11g: 54 Mbps
The IEEE 802.11g standard works likewise with up to 54 Mbps data transmis-
sion rate in the 2,4 GHz ISM-frequency band. Contrary to IEEE 802.11b, the
OFDM modulation is used for IEEE 802.11g, like already introduced for IEEE
802.11a. IEEE 802.11g contains a special compatibility mode that ensures a
downward compatibility to the popular IEEE 802.11b standard . However, in
this compatibility mode you encounter reduced transmission speeds. Due to
the different frequency bands, IEEE 802.11g can not be compatible to IEEE
802.11a. The transmission distances of IEEE 802.11g products are compara-
ble with those of IEEE 802.11b products.
Turbo mode
The 'Turbo Mode' increases the transfer rates to a maximum of 108 Mbps with
the 802.11g standard, too.
Transfer rates
The indicated transfer rates are always to be interpreted as gross data rates,
i.e. the entire protocol overhead - as for example the complex protocols to
secure the radio transmission - is included in the indicated transfer rates. The
net data transfer rate can be thus lower than the indicated gross data rates,
typically over up to the half for all IEEE 802.11 standards mentioned above.
Ranges
The actually obtained distances for radio transfers depend strongly on the
individual environment. In particular influences of noise and obstacles have
an effect on the range. Decisive is an optimal placement of the radio stations
(both network adapters and base stations). For further increase of the transfer
distance, we recommend the operation with additional antennas (e.g.
AirLancer Extender).
IEEE standards
In order to guarantee a maximum of compatibility, LANCOM Systems fully
complies with the industry standards of the IEEE
1
described in the preceding
paragraph. For this reason, your LANCOM base station operates without
problems and with reliably also with devices of other manufacturers.