# CSNOMA: Carrier Sense Non-Orthogonal Multiple Access
## 5 Numerical Results
On the other hand, proactive mode shows poor performance with small carrier sensing range. As the carrier sensing range increases, exposed node problem occurs frequently, and the performance of proactive mode is improved. The receiver protection mode shows acceptable performance with various carrier sensing range. Figure 10: The area spectral efficiency of CSNOMA and carrier sense multiple access (CSMA) as a function of the node density. The target SIR \(\beta\) is 3 dB and the transmission distance \(r_{t}\) is 5. As the network becomes dense, CSNOMA outperforms CSMA. Even though CSNOMA shows higher ASE performance, it may show poor success probability performance. Depending on applications, achieving high-level success probability is required. In that case, CSNOMA may be not preferred. Figure 13 shows the success probability of variants of CSNOMA and CSMA as a function of the carrier sensing range. The reactive mode shows superior performance than CSMA; the proactive and receiver protection modes do not. This is because the reactive mode utilizes the same amount of concurrent transmitting nodes. With small carrier sensing range, CSMA  
Figure 11: The area spectral efficiency of IC Only and CSNOMA as a function of the node density. The target SIR \(\beta\) is 3 dB and the transmission distance \(r_{t}\) is 5. Figure 12: The area spectral efficiency of variants of CSNOMA and CSMA as a function of the carrier sensing range (\(r_{t}=5\), \(\beta=3\) dB, \(\lambda=0.02\)). suffers the hidden node problem, while the reactive mode solves the problem and increases success probability. However, with wide carrier sensing range, hidden node problem rarely occurs, and the reactive mode operates like CSMA. Figure 14 shows the transmission node density as a function of the carrier sensing range. As shown in Figure 14, proactive and receiver protection modes utilize more transmitting nodes than reactive mode and CSMA. Therefore, the interference level increases and success probability decreases. Figure 14: Transmission node density of variants of CSNOMA and CSMA as a function of the carrier sensing range (\(r_{t}=5\), \(\beta=3\) dB, \(\lambda=0.02\)). Figure 13: The success probability of variants of CSNOMA and CSMA as a function of the carrier sensing range (\(r_{t}=5\), \(\beta=3\) dB, \(\lambda=0.02\)). In real wireless networks, the carrier sensing range is usually fixed as a factory setting. Because the transmitters and receivers move in the network, it is hard to optimize the carrier sensing range all the time. To simulate this situation, the carrier sensing range is fixed as 5. The transmission distance varies from 2 to 9. Node density \(\lambda\) is 0.02. The variable communication distance also makes the cancelable distance variable. Figure 15 shows a snapshot of the network topology. In Figure 15, the variable size of circles represent the cancellable regions. The arrow line means the transmission be in progress. Figure 16 shows ASE of CSNOMA and CSMA as a function of the carrier sensing range. As shown in Figure 16, the performance of CSNOMA is improved with receiver protection mechanism. Figure 16: The area spectral efficiency of CSNOMA and CSMA as a function of the carrier sensing range (\(\beta\) = 3 dB, \(\lambda\) = 0.02). The transmission distance varies from 2 to 9. Figure 15: A snapshot of the network topology. The transmission distance varies from 2 to 9. The carrier sensing range is fixed as 5. Node density is 0.02. The cancelable distance \(r_{c}\) varies (blue circles).