SMC Networks SMC2890W-AN Management Manual page 73

Note: Enabling the AP to communicate with 802.11b/g clients in both 802.11b/g/n
Mixed and 802.11n modes also requires that HT Operation be set to HT20.
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Preamble Length — The radio preamble (sometimes called a header) is a
section of data at the head of a packet that contains information that the
wireless device and client devices need when sending and receiving packets.
You can set the radio preamble to long or short. A short preamble improves
throughput performance, whereas a long preamble is required when legacy
wireless devices are part of your network.
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Beacon Interval — The rate at which beacon signals are transmitted from the
access point. The beacon signals allow wireless clients to maintain contact with
the access point. They may also carry power-management information. (Range:
40-3500 TUs; Default: 100 TUs)
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Data Beacon Rate (DTIM) — The rate at which stations in sleep mode must
wake up to receive broadcast/multicast transmissions.
Known also as the Delivery Traffic Indication Map (DTIM) interval, it indicates
how often the MAC layer forwards broadcast/multicast traffic, which is
necessary to wake up stations that are using Power Save mode. The default
value of 2 indicates that the access point will save all broadcast/multicast
frames for the Basic Service Set (BSS) and forward them after every second
beacon. Using smaller DTIM intervals delivers broadcast/multicast frames in a
more timely manner, causing stations in Power Save mode to wake up more
often and drain power faster. Using higher DTIM values reduces the power used
by stations in Power Save mode, but delays the transmission of broadcast/
multicast frames. (Range: 1-255 beacons; Default: 1 beacon)
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RTS Threshold — Sets the packet size threshold at which a Request to Send
(RTS) signal must be sent to a receiving station prior to the sending station
starting communications. The access point sends RTS frames to a receiving
station to negotiate the sending of a data frame. After receiving an RTS frame,
the station sends a CTS (clear to send) frame to notify the sending station that it
can start sending data.
If the RTS threshold is set to 1, the access point always sends RTS signals. If set
to 2346, the access point never sends RTS signals. If set to any other value, and
the packet size equals or exceeds the RTS threshold, the RTS/CTS (Request to
Send / Clear to Send) mechanism will be enabled.
The access points contending for the medium may not be aware of each other.
The RTS/CTS mechanism can solve this "Hidden Node Problem. " (Range: 1-2346
bytes: Default: 2346 bytes)
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Short Guard Interval — The 802.11n draft specifies two guard intervals: 400ns
(short) and 800ns (long). Support of the 400ns GI is optional for transmit and
receive. The purpose of a guard interval is to introduce immunity to
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Chapter 6
| Wireless Settings
Radio Settings