CSMA (Carrier Sense Multiple Access) as the name suggests it is the protocol used to avoid collision by sensing the medium first before sending any data to the receiver.

Difference between CSMA/CA and CSMA/CD

CSMA/CD

CSMA/CD, carrier sense multiple access/collision detection, is performed at the media access control, MAC, layer. The collision is detected in CSMA/CD is through broadcast sensing. When the collision is detected, the transmission is stopped. Then the jamming signal is sent by the stations, upon which station wait for a random time and then transmits again. CSMA/CD is effective after the collision is detected. CSMA/CD is mostly used in wired networks. As it only detects the collision, so it only reduces the recovery time. In CSMA/CD, the data frame is set to resend after the collision is detected in the network. It is used in 802.3 standards. CSMA/CD is more efficient then CSMA, as it also has the collision detection feature.

CSMA/CA

CSMA/CA, carrier sense multiple access/collision avoidance, is also the network protocol used for carrier transmission and performed at the MAC layer. But unlike CSMA/CD, which only can detect the collision and after detection resends the packets, CSMA/CA has the ability to avoid the collisions. This is why CSMA/CA is effective before the collision occurs, as it can avoid the incoming collision.

CSMA/CA is mostly used in wireless networks. Due to its detection of the collision before the occurrence, CSMA/CA can minimize the possibility of collision. Unlike CSMA/CD, it first sends the intent for data transmission, and after a reply from the receiver, it starts the data transmission. It is used in 802.11 standards. It is mostly similar to CSMA.