Data Rates
The default data rate setting on access points is generally auto, which allows radio cards to use
any of the data rates of the given physical layer. For example, 802.11b allows data rates of 1, 2,
5.5, and 11 Mbps. The 802.11g standard extends these data rates up to 54 Mbps. The radio card
usually attempts to send data frames at the highest supported rate, such as 11 Mbps for 802.11b
stations and 54 Mbps for 802.11g stations. When set to auto, the radio card automatically rate
shifts to the highest data rate that the connection can support. A lower data rate, for example, might
be necessary if the radio card encounters too many retransmissions.
It is possible to set the access point to a specific data rate, such as 1 Mbps, which forces the access
point to send all frames at 1 Mbps. This effectively increases the range of the access point, because
Wireless Configuration Parameters 805
802.11 stations can detect access points over longer ranges. In general, a radio card is able to
communicate successfully with lower data rates over longer ranges.
The access point data rate setting, though, does not affect the data rate of the radio cards. If the
radio card is set to auto data rates (the default setting), then the radio card can still use the highest
possible data rate when sending frames to the access point. To maximize the range with fewer
retransmissions, set the radio cards to lower, fixed data rates. These data rate settings impact only
the transmit data rate. The radio card will still receive frames at higher data rates if necessary.