Draytek Vigor2920n User Manual page 274

Long Preamble
Packet-OVERDRIVE
Rate Control
Vigor2920 Series User's Guide
This option is to define the length of the sync field in an 802.11
packet. Most modern wireless network uses short preamble with
56 bit sync field instead of long preamble with 128 bit sync
field. However, some original 11b wireless network devices
only support long preamble. Check it to use Long Preamble if
needed to communicate with this kind of devices.
This feature can enhance the performance in data transmission
about 40%* more (by checking Tx Burst). It is active only
when both sides of Access Point and Station (in wireless client)
invoke this function at the same time. That is, the wireless client
must support this feature and invoke the function, too.
Note: Vigor N61 wireless adapter supports this function.
Therefore, you can use and install it into your PC for matching
with Packet-OVERDRIVE (refer to the following picture of
Vigor N61 wireless utility window, choose Enable for
TxBURST on the tab of Option).
Note: * means the real transmission rate depends on the
environment of the network.
It controls the data transmission rate through wireless
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