OFDM Protection Mode

pcatiprodotnet · Apr 24, 2006, 3:10 AM

What is generally the best choice for wireless-g access points and ad-hocs:
"Off", "CTS to Self", or "RTS and CTS" ? Will this be compatable with clients?
Setting this seems like a good idea, but I have no knowledge or experience with this setting.
Thanks, -pc

lsf · Apr 25, 2006, 11:08 PM

It all depends on how you use it, like if you run in "pure-g" mode there is no need for this.
In general one would like CTS/RTS if you run in mixed mode (b/g) in most other scenarios you would have it "off".
What protection mode does is prefixing each OFDM data frame with a request to send/clear to send (RTS/CTS) complimentary code keying (CCK) frame sequence. The duration fields of the RTS and CTS frames should allow the IEEE 802.11b node to correctly set its network allocation vector and avoid collisions with the subsequent OFDM frames.
CTS to self wil lhave the effect of a 802.11g node telling a 802.11b node that it is going to transmit.
Basically this is used as a collision avoidence, since the G node can talk to a b node in DSSS but a B node can not understand OFDM.

Also note that Protection mode has a performance penalty because of overhead.