The access control method used in wireless LAN. A station checks that the channel is idle, waits an additional random time before sending, and confirms delivery with an ACK from the receiver, so as to avoid collisions as far as possible.
Japanese name: CSMA/CA
CSMA/CA appears in 1 practice question across 1 topic, including Computer Networking Basics.
Field: Computer Networking Basics
Answer: A. On a wireless channel it is hard to detect a collision by receiving other stations' weak signals while transmitting, so stations wait before sending to avoid collisions as far as possible
CSMA/CD is used on shared wired media such as old hub-based Ethernet: a station that detects a collision while sending stops and resends after a random time. On a wireless channel, a station's own signal is so strong that it is hard to receive a distant station's weak signal at the same time, and collisions between stations that cannot hear each other (hidden stations) are invisible to the sender. So with CSMA/CA, a station confirms the channel is idle and then waits a fixed time plus a random backoff before sending. The receiver returns an ACK when it receives the frame correctly, and if no ACK arrives the sender assumes a collision or similar and retransmits. In today's wired Ethernet, connected full duplex to switches, collisions do not occur and CSMA/CD is effectively unused.
So with CSMA/CA, a station confirms the channel is idle and then waits a fixed time plus a random backoff before sending.
What is the main reason wireless LAN uses CSMA/CA rather th…As an Amazon Associate I earn from qualifying purchases.
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