carrier sense multiple access

Carrier Sense Multiple Access (CSMA) is a random-access method used in broadcast networks to manage channel access and reduce the likelihood of data collisions. In CSMA, a node first listens to the communication channel to determine if it is busy before transmitting. If the channel is clear, the node transmits its data. However, due to propagation delays, a node might mistakenly sense an idle channel as busy, leading to a collision if another node also begins transmitting. When a collision is detected (typically because the intended recipient does not acknowledge receipt of a valid packet), each transmitting node waits a random amount of time before attempting to resend. A variation, CSMA with Collision Detection (CSMA/CD), allows a node to stop transmitting immediately upon detecting a collision, minimizing channel downtime. This method is common in packet networks, particularly those using radio links.1