Working with the notebook
A26391-K136-Z120-2-7619 47

Adhoc mode

A wireless LAN in the adhoc mode, also called peer-to-peer mode, consists of a si ngl e c losed cell.
Adhoc wireless networks result when a workgroup comes together with its systems and would like to
interconnect these for data exchange. Any number of systems can be added to this type of network
and can leave it again.
So that several adhoc wireless networks do not interfere with each other in radio traff i c , there is a
unique network name, the SSID (Service Set Identifier). The SSID is used f or addres sing so that a
data packet can always be assigned to a certain cell.
If you want to join an existing cell, you require the network name (SSID), which y ou enter in the
settings for the network card. The driver searches for a wireless network with t his ID during start-up.
When the driver has found a wireless network, it connects to it and you can communi c ate with the
systems in this wireless network. If two cells are very close together, the channels of these networks
should be 4 to 5 channels apart.

Infrastructure mode

In the infrastructure mode, a base station, referred to as an AccessPoint , exists in addition to the
mobile stations. In the infrastructure mode the AccessPoint as s umes the function of a "guard". In
contrast to the adhoc mode, each system must log on to the AccessPoint before it is allowed to
exchange data in the cell.
Another task of the AccessPoint is the connection of the cell s with a cable-connected Ethernet. As
due to the logon requirement, the AccessPoint knows at all times exact l y which stations are on the
radio side, it can decide exactly which data must be sent to it and which don't . This process is also
referred to as bridging.
The range of a wireless network can be increased with several AccessPoints. The A ccessPoints
have the same SSID for this purpose. When a system enters the wireless net, it searches among
the reachable AccessPoints for the one with the strongest signal and logs on t here. Two systems
logged on to different AccessPoints communicate with each other in thi s way, even when they are
not within direct radio reach. If a system also continuously monitors the radio situation after the
logon, it can detect how the signals from an AccessPoint become weaker and t hos e of another
become stronger, and can then log on to the stronger one without the user noticing. This procedure
is referred to as roaming.
Operating system requirements
Windows 2000 and Windows XP