Description: <p> Carrier Sense Multiple Access with Collision Avoidance is the physical layer access control method used in IEEE 802.11 (Wi Fi) wireless LANs. The wireless nodes cannot transmit and receive at the same time and due to the very nature of the wireless medium, all the nodes cannot receive all the packets on the medium. Due to these two main limitations, CSMA/CD access control protocol cannot be used in wifi technology. </p> <p>This video talks about necessity of new protocol and explains CSMA/CA access control in detail. Collision avoidance is used to improve the performance of CSMA by attempting to be less "greedy" on the channel. If the channel is sensed busy before transmission then the transmission is deferred for a "random" interval. This reduces the probability of collisions on the channel. </p>CSMA/CA can be supported with Request to Send (RTS) and Clear to Send (CTS) packets optionally to reserve the channel. This kind of access control method is called as Virtual Carrier Sensing method, and it is implemented at MAC layer.
