Specifications

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Cisco IOS Software Configuration Guide for Cisco Aironet Access Points
OL-5260-01
Chapter 6 Configuring Radio Settings
Disabling and Enabling Short Radio Preambles
Disabling and Enabling Short Radio Preambles
The radio preamble (sometimes called a header) is a section of data at the head of a packet that contains
information that the access point and client devices need when sending and receiving packets. You can
set the radio preamble to long or short:
• Short—A short preamble improves throughput performance. Cisco Aironet Wireless LAN Client
Adapters support short preambles. Early models of Cisco Aironet's Wireless LAN Adapter (PC4800
and PC4800A) require long preambles.
• Long—A long preamble ensures compatibility between the access point and all early models of
Cisco Aironet Wireless LAN Adapters (PC4800 and PC4800A). If these client devices do not
associate to your access points, you should use short preambles.
You cannot configure short or long radio preambles on the 5-GHz radio.
Beginning in privileged EXEC mode, follow these steps to disable short radio preambles:
Short preambles are enabled by default. Use the preamble-short command to enable short preambles if
they are disabled.
Configuring Transmit and Receive Antennas
You can select the antenna the access point uses to receive and transmit data. There are three options for
both the receive and the transmit antenna:
• Diversity—This default setting tells the access point to use the antenna that receives the best signal.
If your access point has two fixed (non-removeable) antennas, you should use this setting for both
receive and transmit.
• Right—If your access point has removeable antennas and you install a high-gain antenna on the
access point's right connector, you should use this setting for both receive and transmit. When you
look at the access point's back panel, the right antenna is on the right.
• Left—If your access point has removeable antennas and you install a high-gain antenna on the
access point's left connector, you should use this setting for both receive and transmit. When you
look at the access point's back panel, the left antenna is on the left.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface dot11radio 0 Enter interface configuration mode for the 2.4-GHz radio
interface.
Step 3
no preamble-short Disable short preambles and enable long preambles.
Step 4
end Return to privileged EXEC mode.
Step 5
copy running-config startup-config (Optional) Save your entries in the configuration file.