Draytek Vigor2830 Series User Manual page 276

Long Preamble
Packet-OVERDRIVE
Vigor2830 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.
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