The working principle of CSMA
|CSMA is an improvement over ALOHA because they ensure that no station begins to transmit when it senses the channel busy. Another improvement is for stations to abort their transmissions as soon as they detect the collision. If two stations sense the channel to be idle and begin transmitting simultaneously they will both detect the collision almost immediately. Rather than finish transmitting their frames, which are irretrievably garbled anyway, they should abruptly stop transmitting as soon as the collision is detected. Quickly terminating damaged frames saves time and bandwith. You can see an example of collision in CSMA/CD.
– fast, hardware-based detection collisions
– resolve collision by retransmission based on special backoff algorithms