# A Channel Measurement-Based Listen-Before-Talk Algorithm for LTE-LAA and WLAN Coexistence
## 4 Simulation Results
Given that fairness is assigned a high weight of 0.7 in the reward calculation, the results in Figure 4 are likely influenced by the fairness values shown in Table 4. Figure 5 shows that the reward values for both \(n_{t}=5\) and 15 are dramatically improved whenever the number of WLAN basic service sets in the CCA range, \(n_{c}\), is reduced. However, if the same number of WLAN basic service sets is included in the CCA range, the reward performance marginally depends on \(P_{cca}\), as shown in Figure 5.  
Figures 6 and 7 present the reward results of CM-LBT, F-LBT, and LB-LBT as \(q\) is varied, where \(W=2\) and \(q_{w}=0.01\). Our model represents the offered load of LTE-LAA eNB using \(q\), the probability that a packet will become available to the medium access control in a slot [9]. As noted earlier in this section, the packet arrival rates of LTE-LAA and WLAN systems are determined by Equation (22). Figure 6 shows that CM-LBT performs better than both F-LBT and LB-LBT. On average, when \(n_{t}=5\), the reward value of CM-LBT is 0.43 and 0.4 times higher than that of F-LBT with \(P_{cca}=-62\) and \(-82\) dBm, respectively, and 0.44 and 0.41 times higher than that of LB-LBT with \(P_{cca}=-62\) and \(-82\) dBm. The same phenomenon is observed when \(n_{t}=15\) as shown in Figure 7, where the reward value of CM-LBT is 0.41 and 0.21 times higher than that of F-LBT with \(P_{cca}=-62\) and \(-82\) dBm, respectively, and 0.42 and 0.22 times higher than that of LB-LBT with \(P_{cca}=-62\) and \(-82\) dBm, respectively. Note that CM-LBT guarantees the fairness between LTE-LAA and WLAN by adaptively adjusting \(W\) and \(P_{cca}\) parameters. Conversely, in both F-LBT and LB-LBT, when \(q\) increases, the WLAN throughput decreases, whereas that of the LTE-LAA system largely increases. As a result, the fairness in both F-LBT and LB-LBT decreases with an increase in \(q\). Meanwhile, when \(n_{t}=15\), the reward value is greater for \(P_{cca}=-82\) dBm than for \(P_{cca}=-62\) dBm in both F-LBT and LB-LBT, as shown in Figure 7. This can be attributed to the fact that when \(n_{t}=15\), the number of WLAN basic service sets in the CCA range is larger for \(P_{cca}=-82\) dBm than for \(P_{cca}=-62\) dBm. Consequently, in both F-LBT and LB-LBT, the fairness in the case of \(P_{cca}=-82\) dBm is improved because the gap between \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Parameter** & **Value** & **Parameter** & **Value** \\ \hline \(P_{a}\) & 20 dBm & \(P_{s}\) & 17 dBm \\ \(P_{e}\) & 30 dBm & \(P_{N}\) & \(-90\) dBm \\ \(W_{0}\) & 16 & \(m\) & 5 \\ \(R_{I}\) & 40 m & \(\kappa_{bw}\) & 0.6726 \\ \(\kappa_{c}\) & 0.75 & \(\kappa_{sint}\) & 1 \\ \(B\) & 20 MHz & \(DIFS\) & 34 μs \\ \(SIFS\) & 16 μs & \(\sigma\) & 9 μs \\ \(S_{\mu}^{E}\) & 150 Mbps & \(\epsilon\) & 0.3 \\ \(W_{min}\) & 1 & \(W_{max}\) & 32 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Parameters used in performance evaluation. Lastly, Figures 8 and 9 plot the reward results of CM-LBT, F-LBT, and LB-LBT under different offered loads per WLAN node, \(q_{uv}\). We assume \(q\) equals 0.1. We see from Figure 8 that CM-LBT can improve the reward values in F-LBT and LB-LBT. Specifically, when \(n_{t}=5\), the reward value in CM-LBT is increased on average by 0.1 and 0.01 times compared to F-LBT with \(P_{cca}=-62\) and \(-82\) dBm, respectively, and by 0.07 and 0.02 times as compared to LB-LBT with \(P_{cca}=-62\) and \(-82\) dBm. In the case of \(n_{t}=15\), CM-LBT outperforms F-LBT and LB-LBT. As shown in Figure 9, it improves the reward result of