CSMA/CD (Collision Detection)
CSMA/CD: carrier sensing, deferral as in CSMA
- collisions detected within short time
- colliding transmissions aborted, reducing channel wastage
- persistent or non-persistent retransmission
collision detection:
- easy in wired LANs: measure signal strengths, compare transmitted, received signals
- difficult in wireless LANs: receiver shut off while transmitting
human analogy: the polite conversationalist