Networking
Guess first
Can Wi-Fi Detect Its Own Collisions?
Most students get this one wrong. Guess before I explain.
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Lesson notes
Key points
- A Wi-Fi radio cannot listen while it transmits, because its own signal drowns out everything else.
- So Wi-Fi uses CSMA/CA: wait a random backoff, send, then treat a missing acknowledgement as a collision.
Takeaway: Wi-Fi can't hear collisions, so it avoids them and relies on ACKs.
Quick check: How does a Wi-Fi device know its frame collided with another one?
- It hears the collision live
- The router sends a jam signal
- No ACK comes back
Wi-Fi avoids collisions with CSMA/CA and infers them from missing ACKs.
Half-duplex radioCSMA/CA
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