ZyXEL Communications NWA 1121-NI User Manual page 71

Table 13 Wireless LAN > Wireless Settings: MBSSID (continued)
LABEL
Preamble Type
RTS/CTS
Threshold
Extension
Channel
Protection Mode
A-MPDU
Aggregation
Short GI
MCS Rate
Apply
Cancel
NWA1121-NI User's Guide
DESCRIPTION
Select Dynamic to have the AP automatically use short preamble when wireless adapters
support it, otherwise the AP uses long preamble.
Select Long if you are unsure what preamble mode the wireless adapters support, and to
provide more reliable communications in busy wireless networks.
(Request To Send) The threshold (number of bytes) for enabling RTS/CTS handshake.
Data with its frame size larger than this value will perform the RTS/CTS handshake.
Setting this attribute to be larger than the maximum MSDU (MAC service data unit) size
turns off the RTS/CTS handshake. Setting this attribute to its smallest value (1) turns on
the RTS/CTS handshake.
You can use CTS to self or RTS-CTS protection mechanism to reduce conflicts with other
wireless networks or hidden wireless clients. The throughput of RTS-CTS is much lower
than CTS to self. Using this mode may decrease your wireless performance.
This field is available only when 802.11 b/g/n is selected as the Wireless Mode.
Select to enable A-MPDU aggregation.
Message Protocol Data Unit (MPDU) aggregation collects Ethernet frames along with their
802.11n headers and wraps them in a 802.11n MAC header. This method is useful for
increasing bandwidth throughput in environments that are prone to high error rates.
This field is available only when 802.11 b/g/n is selected as the Wireless Mode. Select
Enabled to use Short GI (Guard Interval). The guard interval is the gap introduced
between data transmission from users in order to reduce interference. Reducing the GI
increases data transfer rates but also increases interference. Increasing the GI reduces
data transfer rates but also reduces interference.
The MCS Rate table is available only when 802.11 b/g/n is selected in the Wireless
Mode field.
IEEE 802.11n supports many different data rates which are called MCS rates. MCS stands
for Modulation and Coding Scheme. This is an 802.11n feature that increases the wireless
network performance in terms of throughput.
For each MCS Rate (0-15), select either Enabled to have the NWA1121-NI use the data
rate.
Clear the Enabled check box if you do not want the NWA1121-NI to use the data rate.
Turn on the Auto option to have the NWA1121-NI set the data rates automatically to
optimize the throughput.
Note: You can set the NWA1121-NI to use up to four MCS rates at a time.
Click Apply to save your changes.
Click Cancel to begin configuring this screen afresh.
Chapter 6 Wireless LAN
71