CSMA is full-formed as Carrier Sense Multiple Access and it is a protocol that controls the data packets access between the transmitter and receiver. It prevents the data packets from loss and maintains the data integrity. It has been further modified as CSMA/CA and CSMA/CD.

CSMA/CA=> Carrier Sense Multiple Access operates on (Collision Avoidance).

CSMA/CD=>Carrier Sense Multiple Access operates on (Collision Detection).

Carrier sense multiple access (CSMA) works by sensing the state of the medium in order to prevent the data from the collision and recover the data. The question arises is that what is the collision then. The collision occurs when the multiple transmitters send the data at the same time and the receiver unable to extract the data from two scrambled data and this leads to loss of data. Thus, information needs to be resent again so that the receiver will retain it and this is done through the MAC protocol called Carrier sense multiple access.

The Differences between CSMA/CD and CSMA/CA are as follows:

Carrier Sense Multiple Access/CD

As it is clear from the name it will detect the collision of the information and then further applies the protocol for transmitting data.

It detects the occurrence of collision and immediately terminates the transmission of data and the last information is retransmitted again. Thus, time consumption is saved and recovery of information is done.

It is mostly used in wired installation as it is possible to detect the collision has occurred or not easily.

It works after the collision.

The best example for the CSMA/CD is Ethernet.

Carrier Sense Multiple Access/CA

As it also detects the collision but it avoids it and uses it for the maximum utilization of the medium.

It does not deal with the recovery of information after the detection of a collision. It mainly checks either the medium is in use or not. If it is busy then it waits for the medium to get idle before it starts transmitting the information.

It is mostly using the wireless installation.

It works before the collision.

It reduces the possibility of collision.

The best example for the CSMA/CA is WI-FI.


Thus the Carrier sense multiple access (CSMA) is a protocol that controls the nodes of the media for media access control and verifies the traffic of media before transmitting the data or information on transmitting media such as an electrical bus or a band of the electromagnetic spectrum. It is done through two modes of Carrier sense multiple access, (i) CSMA/CD (ii) CSMA/CA.

Also, read…

Download Difference between CSMA/CA and CSMA/CD? in pdf- Click here