Question

Collision prevention in 802.15.4 standard is provided by means of:

Answer 1

Answer is - CSMA/CA

Carrier-sense multiple access with collision avoidance or CSMA/CA is a network multiple access method which uses carrier sensing. The nodes try to avoid collisions by transmitting only when the channel is sensed to be 'idle'. They transmit their packet data in its entirety.

CSMA/CA is very useful in a wireless LAN because multiple stations are able to see the Access Point but not each other. This is known as the hidden node or hidden station problem.