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CWNP Certified Wireless Network Administrator CWNA-109 · Domain 3: WLAN protocols and devices

Medium access: CSMA/CA, DCF, physical carrier sense (CCA) and virtual carrier sense (NAV)

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Last reviewed September 25, 2026 · Leer en español

A Wi-Fi channel is a shared, half-duplex medium: only one radio in range can successfully transmit at a time, and a transmitting radio cannot listen for collisions while it transmits. Wired Ethernet historically used collision detection, but Wi-Fi uses CSMA/CA, Carrier Sense Multiple Access with Collision Avoidance. Its goal is to reduce collisions before they happen and to confirm delivery afterward.

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