Compex Systems 802.11N - Manual (Page 73)

Appendix III- Advanced Settings
This section provides more detail explanation on advanced setting for routing and wireless
settings.
The Advanced options page allows you to manage advanced settings that influence on the device
performance and behavior. The advanced wireless settings are dedicated for more technically
advanced users who have a sufficient knowledge about wireless LAN technology. These settings
should not be changed unless you know what effect the changes will have on your device.
Advanced Wireless Setting
The 802.11 data rates include 1, 2, 5.5, 11 Mbps for IEEE 802.11b mode and 6, 9, 12, 18, 24, 36,
48, 54Mbps for IEEE 802.11a/g mode. The Rate Algorithm has a critical impact on performance
in outdoor links as generally lower data rates are more immune to noise while higher rates are less
immune, but are capable of higher throughput.
Rate Aggressiveness :
Allows user to reduce or increase transmit rate while still remain in Fully Auto Algorithm. There
are 2 scenarios that Rate Aggressiveness is useful. Environment might be noisy at times. Lower
the throughput will ensure better stability. Rate Aggressiveness allows device to reduce the
transmit rate, so range or power can be higher. Choose a range of value from -3,-2,-1.
Environment might be free of interference. But the fully auto algorithm might give low throughput.
Increase Rate Aggressiveness will increase transmit rate in this case to get higher throughput.
Choose a range of value from +3, +2, +1.
Noise Immunity option increases the robustness of the device to operate in the presence of noise
disturbance which is usually generated by external 802.11 traffic sources, channel hopping signals
and other interferers.
RTS Threshold: determines the packet size of a transmission and, through the use of an access
point, helps control traffic flow. The range is 0-2347bytes, or word “off”. The default value is
2347 which means that RTS is disabled.
RTS/CTS (Request to Send / Clear to Send) is the mechanism used by the 802.11 wireless
networking protocol to reduce frame collisions introduced by the hidden terminal problem.
RTS/CTS packet size threshold is 0-2347 bytes. If the packet size the node wants to transmit is
larger than the threshold, the RTS/CTS handshake gets triggered. If the packet size is equal to or
less than threshold the data frame gets sent immediately.
System uses Request to Send/Clear to Send frames for the handshake which provide collision
reduction for access point with hidden stations. The stations are sending a RTS frame first while
data is send only after handshake with an AP is completed. Stations respond with the CTS frame to
the RTS which provides clear media for the requesting station to send the data. CTS collision
control management has time interval defined during which all the other stations hold off the
transmission and wait until the requesting station will finish transmission.