State about CSMA/CA
It belongs to a class of protocols known as multiple access methods. CSMA/CA stands for: Carrier Sense Multiple Access with Collision Avoidance. In CSMA, a station willing to transmit has to first listen to channel for a predetermined amount of time so as to check for any activity on channel. If channel is sensed "idle" then station is permitted to transmit. If channel is sensed as "busy" station has to defer its transmission. This is essence of both CSMA/CD and CSMA/CA. In CSMA/CA (Local Talk), once channel is clear, a station transmits a signal telling all other stations not to transmit, and then sends its packet. In Ethernet 802.3, station continues to wait for a time, and checks to see if channelis still free. If it is free, station transmits, and waits for an acknowledgment signal that packet was received.