CSMA/CA with RTS/CTS
—Step-1 When a sending station wants to transmit data, it
first sends (through contention) an RTS (request to send) frame and waits for
the destination to reply with a CTS (clear to send) frame.
—Step-2 If CTS is detected, then data is transmitted and
destination sends an ACK if the data was received completely and correctly.
—Step-3 If CTS is not detected, the sending station goes back to
compete for the media, in the CSMA/CA mode
—Step-4 All other stations that hear RTS or CTS would defer
transmission in the duration indicated in RTS or CTS.
—Step-5 Both RTS and CTS include the estimated transmission time in
the MAC header, so stations which hear either of them, know when the
channel is going to be free again, through the NAV mechanism.
CSMA/CA without RTS
CSMA/CA with RTS
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