User Manual

Channel
Direct communication between an 802.11 radio card and an access point occurs over a
common channel frequency. The FCC allows channels 1 through 11 within the U.S.. An
important concept to note regarding channel assignments is that the channel actually
represents the center frequency that the transceiver within the radio and access point uses
(e.g., 2.412 GHz for channel 1 and 2.417 GHz for channel 2). There is only 5 MHz separation
between the center frequencies, and an 802.11b signal occupies approximately 30 MHz of the
frequency spectrum. The signal falls within about 15 MHz of each side of the center
frequency. As a result, an 802.11b signal overlaps with several adjacent channel frequencies.
This leaves you with only three channels (channels 1, 6, and 11 for the U.S.) that you can use
without causing interference between access points.
Bit rate
This allows you to set the bit rate in Mb/s. The bit rate is the speed at which bits are
transmitted over the medium. The user speed of the link is lower due to medium sharing and
various overhead.Use auto / best to select automatic bit rate mode (fallback to lower rate on
noisy channels), which is the default. Use fixed and a value to lock the card to a particular bit
rate. If you specify auto and a specific rate, the driver will use all bit rates lower and equal
than this value.
RTS threshold
RTS/CTS adds a handshake before each packet transmission to make sure that the channel
is clear. This adds overhead, but increases performance in case of hidden nodes or a large
number of active nodes. This parameter sets the size of the smallest packet for which the
node sends RTS; a value equal to the maximum packet size disable the mechanism. You may
also set this parameter to auto, fixed or off.
Fragmentation threshold
Fragmentation allows to split an IP packet in a burst of smaller fragments transmitted on the
medium. In most cases this adds overhead, but in a very noisy environment this reduces the
error penalty and allow packets to get through interference bursts. This parameter sets the
maximum fragment size; a value equal to the maximum packet size disable the mechanism.