CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) is a technology in networking when each node senses if anyone else is communicating. If the node senses that some one else is using the network, then it will wait and try again in a moment. CSMA/CD (Carrier Detection) is not used with wireless because a single antenna cannot send & receive at the same time and therefore can't detect collision.
Wikipedia
Carrier-sense multiple access with collision avoidance (CSMA/CA) in computer networking, is a network multiple access method in which carrier sensing is used, but nodes attempt to avoid collisions by beginning transmission only after the channel is sensed to be "idle" When they do transmit, nodes transmit their packet data in its entirety It is particularly important for wireless networks, where the collision detection of the alternative CSMA/CD is not possible due to wireless transmitters desensing their receivers during packet transmission CSMA/CA is unreliable due to the hidden node problemCSMA/CA is a protocol that operates in the Data Link Layer (Layer 2) of the OSI model