RTS/CTS: (request to send/ clear to send)



It is the optional mechanism used by the 802.11 wireless networking protocol to reduce frame collisions introduced by the hidden node problem.

It is based on the principle that every message must be preceded by a short request. The message will only be sent after having received a positive answer (the clear to send message). Since all nodes receive these messages, they know when the channel is used and it reduces the amount of message collisions.