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Maximizing MAC Throughputs by Dynamic RTS-CTS Threshold

Maximizing MAC Throughputs by Dynamic RTS-CTS Threshold. Woo-Yong Choi and Sok-Kyu Lee Electronics and Telecommunications Research Institute. Contents. Introduction Two Factors for Efficiency of RTS-CTS Method Dynamic RTS-CTS Threshold Control Method Throughput Analysis

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Maximizing MAC Throughputs by Dynamic RTS-CTS Threshold

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  1. Maximizing MAC Throughputs by Dynamic RTS-CTS Threshold Woo-Yong Choi and Sok-Kyu Lee Electronics and Telecommunications Research Institute Woo-Yong Choi, ETRI

  2. Contents • Introduction • Two Factors for Efficiency of RTS-CTS Method • Dynamic RTS-CTS Threshold Control Method • Throughput Analysis • Optimal RTS-CTS Threshold • Conclusions Woo-Yong Choi, ETRI

  3. Introduction • TGn has the target of 100Mbps at MAC SAP • MAC Protocol should be enhanced to meet this target • RTS-CTS threshold can be dynamically adjusted to increase the MAC throughput • More realistic assumption of data frame size distribution and hidden node situation is considered for the throughput analysis (cf. IEEE 802.11-03/0509r0) Woo-Yong Choi, ETRI

  4. Two Factors for Efficiency of RTS-CTS Method • Data Frame Length • RTS-CTS method is efficient in the case of transmissions of long data frames • But, inefficient with short data frames • Numbers of STAs and Transmission Attempts • Related with the number of retransmissions • Efficient in the case of many STAs and transmission attempts • But, inefficient with small numbers of STAs and transmission attempts Woo-Yong Choi, ETRI

  5. Dynamic RTS-CTS Threshold Control Scheme • Infrastructure BSS • AP periodically monitors the number of STAs connected to itself, the number of transmission attempts and the data frame size distribution • AP calculates the optimal dot11RTSThreshold • AP broadcasts the updated threshold value to be used by STAs • Detailed algorithm is needed • Independent BSS • For further research Woo-Yong Choi, ETRI

  6. Simulation Condition • n greedy STAs attempt to transmit data frames continuously using DCF protocol • The length of data frames is variable based on the experimental statistics from NLANR (National Lab. for Applied Network Research) (www.nlanr.net/NA/Learn/paketsizes.html) • p: the probability that a transmission attempt fails due to the hidden node problem (p = 0, 0.25, 0.5) • Optimal RTS-CTS threshold was obtained using computer simulations for maximizing MAC throughput Woo-Yong Choi, ETRI

  7. Payload Size Distribution Woo-Yong Choi, ETRI

  8. Throughput Analysis (p=0) Woo-Yong Choi, ETRI

  9. Throughput Analysis (p=0.25) Woo-Yong Choi, ETRI

  10. Throughput Analysis (p=0.5) Woo-Yong Choi, ETRI

  11. Optimal RTS-CTS Threshold (p=0) Woo-Yong Choi, ETRI

  12. Optimal RTS-CTS Threshold (p=0.25) Woo-Yong Choi, ETRI

  13. Optimal RTS-CTS Threshold (p=0.5) Woo-Yong Choi, ETRI

  14. Performance Improvements • Average 25 % throughput improvement in IEEE 802.11a • Average 28 % throughput improvement in IEEE 802.11b Woo-Yong Choi, ETRI

  15. Conclusions • Dynamic RTS-CTS threshold can improve MAC throughput • We analyzed the throughput with the consideration of realistic data frame size distribution and hidden node situation • We propose that the value of dot11RTSThreshold used by (Q)STAs in the (Q)BSS be broadcast via a new information field in beacon frame Woo-Yong Choi, ETRI

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