Request to Send/Clearto Send (RTS/CTS) is a mechanism for accessing the medium and distributing the NAV vector, Network Allocation Vector, in WLANs according to 802.11. This mechanism reduces the collision probability. Once the RTS/CTS mechanism of a WLAN station is activated, it must transmit the RTS/CTS before the normal data transmission through the frames
. When transmit
tingdata from a WLAN station, it first sends an RTS frame. Both frames, the RTS and the CTS frame, are transmitted at a lower data rate and are therefore received by all stations. The time value of the RTS frame resets the NAV timers of all listening WLAN stations until the transmitted data and the acknowledgement (ACK) have been transmitted. After that, the receiving station transmits Clear to Send (CTS). All stations receiving the CTS frame delay their access by the time
requested by the CTS frame.