1. Carrier sense multiple access with collision resolution
IEEE communications letters
Hyun-Ho Choi, Jung-Min Moon, In-Ho Lee, and Howon Lee

2. CSMA/CD
A transmitting station can detect a collision while transmitting
However, the CSMA/CD protocol is only possible in a wired network
A wireless network has deafness problem (the receiver of the transmitting station is overwhelmed by its own transmission power)

3. Wireless CSMA/CD (WCSMA/CD)
Each station allocates a short CD slot randomly within a fixed CD period
Senses the channel at the selected CD slot to determine whether a collision occurs or not

4. CSMA/CR It extends the WCSMA/CD protocol
CSMA/CR protocol identifies a collision by additional sensing after data transmission starts
One station that first detects a collision transmits a jam signal

5. CSMA/CR
No collision occurs

6. CSMA/CR
A collision is detected

7. Cases of a collision is not detected in CSMA/CR

8. Cases of a collision is not detected in CSMA/CR

9. Implementation issue
standard defines a slot time (aSlotTime) as a basic time unit required for the channel sensing and accessing
For the CSMA/CR, a CD slot time (aCDSlotTime) should satisfy

10. Throughput analysis
From theh Bianchi’s CSMA/CA analysis, - the probability that in a slot time there is at least one transmission - the probability that a transmission is successful - the probability that a transmission is collided

11. Throughput analysis
The collision probability of - WCSMA/CD CSMA/CR

12. Throughput analysis The collision detection probability of WCSMA/CD
The collision resolution probability of CSMA/CR

13. Normalized throughput