Infrastructure Mode - ELSA LANCOM Wireless L-2 Manuel De L'utilisateur

R2 Technical basics
has a specific parameter—the name of a WLAN domain. From the viewpoint of the user,
the WLAN domain is a freely chosen string of up to 32 characters; at the radio level, this
name is converted to an additional addressing component that permits data packets to
be associated with a specific cell. To enter an existing wireless LAN, the name of the
WLAN domain must be entered in the advanced settings for the network adapter driver.
When initialized, the driver will then look for an existing wireless network with this
identification. If it finds one, it will then establish a connection, permitting you to
communicate with the computers in that wireless network. If it does not find an existing
network, it will establish a new cell of its own.
Even if the cells are logically separated in this manner, they can still interfere with one
another physically, as only one station can transmit at a time. In other words, none of
the cells would be able to take advantage of the full bandwidth in the event of an overlap.
This can be prevented by not only assigning different domain names, but also different
radio channels to the individual networks. Just as two radio transmitters can transmit
simultaneously on different frequencies, two wireless LANs can work simultaneously on
different channels without interference. If two cells are very close to one another, there
should be a difference of 4–5 channels between the channels used, as the cells also
partially use the neighboring channels.
Not all of the channels included in the IEEE standard are permitted in all countries!

Infrastructure mode

The actual strength of wireless networks based on the IEEE 802.11 standard is the ease
of interoperability with existing Ethernet networks. A wireless network can be used to
connect mobile stations to an existing wired network. Existing networks can also be
used to link multiple cells, thus increasing the range of the wireless network. This
requires all participants to operate in a different mode, the infrastructure mode.
In addition to the mobile stations, infrastructure mode uses a a base station, also known
as an access point or distribution system. The ELSA LANCOM Wireless units were
designed to serve as base stations. The base station handles monitoring functions in the
infrastructure mode. Domain names and radio channels are still required, and stations
entering a network still search for an existing cell. However, unlike ad hoc mode, the cell
is always established by the base station, and each station entering the network must
log onto to the base station before being permitted to exchange data in the cell. The base
station generally also fulfills the function of a "relay station" for data. While this reduces
the achievable data rate, careful positioning of the base station can increase the size of
a cell. The actual role of a base station, however, is the connection of a wireless cell to
a wired Ethernet. If the base station receives a data packet for a workstation that is not
logged onto it, it forwards the packet to the Ethernet. In the other direction, the base
station "listens" to the Ethernet for data intended for wireless stations and forwards it
accordingly. As all mobile stations must log onto the base station, the base station
ELSA LANCOM Wireless