HP MSR SERIES Configuration Manual page 126

Item
A-MPDU
short GI
Figure 103 Configuring advanced settings for the radio
Table 60 Configuration items
Item
Preamble
Description
Selecting the A-MPDU option enables A-MPDU.
802.11n introduces the A-MPDU frame format. By using only one PHY header, each
A-MPDU can accommodate multiple Message Protocol Data Units (MPDUs) which
have their PHY headers removed. This reduces the overhead in transmission and the
number of ACK frames to be used, and thus improves network throughput.
IMPORTANT:
When 802.11n radios are used in a mesh WLAN, make sure that they have the same
A-MSDU configuration.
Selecting the short GI option enables short GI.
Delays may occur during receiving radio signals due to factors like multi-path
reception. Therefore, a subsequently sent frame may interfere with a previously sent
frame. The GI function is used to avoid such interference. It increases the throughput
by 10 percent.
The short GI function is independent of bandwidth and thus supports both 20MHz
and 40MHz bandwidths.
Description
Preamble is a pattern of bits at the beginning of a frame so that the receiver
can sync up and be ready for the real data. There are two different kinds of
preambles:
•
Short preamble. A short preamble improves network performance.
Therefore, this option is always selected.
•
Long preamble. A long preamble ensures compatibility between access
point and some legacy client devices. Therefore, you can select this option
to make legacy client devices support short preamble.
802.11a/802.11n (5 GHz) do not support this configuration.
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