difference between csma cd and csma ca
Carrier Sense Multiple Access is the channel access technique in which the carrier is first listened or checked (sensed) on the channel before sending the data. It is used in the Ethernet LANs with modification as Collision Detection. i.e. Carrier is listened before sending on the channel and continue to listen the channel for any collision due to the simultaneous data send by another node. If collision is there, it can be detected immediately (CD) and data is sent again.
Now, in Wireless channel, specifically WLANs, since the node can either Tx or Rx at one moment of time, collision detection is not possible when data send is in progress. The node can not listen while Tx at the same time so the Carrier Avoidance(CA) is used. That means, the channel is listened before Tx and if it is free, data can be sent. In case, the collision occurs, the sending node defer the Tx for a random time to Avoid Collision (CD).
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