CSMA/CA

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Used by WiFi (IEEE 802.11)

Nodes (computers or other devices) listen before sending. If the medium is busy they wait for a random time and try again. Once sending, a whole frame is sent. If the frame is received successfully the receiver sends an acknowledgment back to the sender. If the sender does not receive an acknowledgement it retransmits the frame.

RTS/CTS (Request to Send/Clear to Send) – Optionally can be used to mediate a access. Node will issue RTS before transmitting. Access point only issues CTS to one noted at a time. Helps with the problem of hidden nodes. Often only used on packets over a certain size because the overhead is too great for small packets.

See WiFi, IEEE 802.11