Clear to Send(CTS) is an interface control signal. It is part of the modem control in handshake operation as well as the access authorization in the CSMA/CA procedure. In this procedure, which is also used in WLANs according to 802.11, the station that has a transmission request sends a Ready to Send (RTS). If the transmission path to the receiver is free, it receives a CTS packet in response.
In WLANs 802.11, the Ready to Send (CTS) is usedin
previous Request to Send (RTS) by the base stationto
grant the requesting stationpermission to transmit.802.11g uses a corresponding procedure to ensure compatibility with devices according to 802.11b. A CTS packet is sent before the actual transmission, which the 802.11b clients can follow.