## 5 Results and Discussion
Meanwhile, SWIPT is not used in Cluster 1 because the rate of the CH is higher than the rates of the other sensor nodes (i.e., \(R_{i}>\min_{j}\{R_{ij}\}\)), so Cluster 1 has a dissipated energy distribution similar to that in the non-SWIPT scheme. \begin{table}
\begin{tabular}{l l} \hline \hline
**Parameter** & **Value** \\ \hline Number of sensor nodes in WPSN & \(N=100\)\(\sim\)500 (default = 300) \\ Number of clusters & \(K=2\)\(\sim\)20 (default = 10) \\ Width of the square network & \(W=10\)\(\sim\)50 m (default = 30 m) \\ Transmission power of HAP & \(P=46\) dBm \\ EH efficiency & \(\zeta_{j}=0.8\), \(\forall j\in\mathcal{N}\) \\ Ratio of energy used for transmission in sensors & \(\eta_{j}=0.9\), \(\forall j\in\mathcal{N}\setminus\{i\}\) \\ Ratio of energy used for transmission in CH & \(\eta_{i}=0.7\) \\ Noise spectral density & \(-174\) dBm/Hz \\ Noise figure & \(9\) dB \\ Channel bandwidth & \(1\) MHz \\ Channel power gains & \(h_{i}=Gd_{i}^{-\gamma}\), \(g_{ij}=Gd_{ij}^{-\gamma}\) \\ Power attenuation at a reference distance of 1 m & \(G=-30\) dB \\ Path loss exponent & \(\gamma=2.5\) \\ Length of WET slot & \(T_{e}=5\) s \\ Length of SWIPT slot & \(T_{s}=0.1\) s \\ Length of WIT slot & \(T_{d}=0.1\) s \\ Number of simulation trials & \(1000\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Parameter Setup. Figure 4 depicts the achievable rate and energy dissipated in each cluster of Figure 3. In the case of LEACH, both the achievable rate and energy dissipated are the worst because the CH is selected randomly without considering each link rates (i.e., \(R_{ij}\) and \(R_{i}\)). In the K-means case, the performance is improved because \(R_{ij}\) is considered for clustering and CH selection. In the non-SWIPT case, the performances are better than in the K-means case because \(R_{i}\) is additionally considered for CH selection. In the case of the proposed ENO with PS/TS, the achievable rate is improved more than in the non-SWIPT case because SWIPT is performed while considering both \(R_{ij}\) and \(R_{i}\), and the energy dissipated in each cluster is close to zero except in Cluster 1. This result occurs because each sensor node in the cluster transfers the remaining energy to the CH using SWIPT. This energy is used by the CH to increase the achievable rate of the cluster. Figure 4: (**a**) Achievable rate and (**b**) energy dissipated in each cluster. Figure 3: Clustering results of an example case when \(N=300\), \(K=5\), and \(W=30\) m: (**a**) K-means, (**b**) non-SWIPT, (**c**) ENO with PS, and (**d**) ENO with TS. Figure 5 shows the average achievable rate in cluster and the total energy dissipated in network versus the number of clusters (\(K\)) when the number of nodes in network (\(N\)) is 300 and the width of the square network (\(W\)) is 30 m. As \(K\) increases, the achievable rate increases in all schemes. These increases occur because the distance between nodes decreases on average as \(K\) increases. The LEACH, K-means, and non-SWIPT schemes show better achievable rates in that order. The proposed ENO with PS and ENO with TS have similar performances and outperform the other conventional schemes. Moreover, as \(K\) increases, the amount of energy dissipated decreases in all schemes, because the average distance between nodes decreases and the variance of link rates becomes smaller as \(K\) increases. The three conventional schemes have similar dissipated energy, which is greater than that in the two proposed ENO schemes. Figure 6 shows the average achievable rate in cluster and the total energy dissipated in network versus the number of nodes in network (\(N\)) when \(K\) = 10 and \(W\) = 30 m. As \(N\) increases, the average achievable rate in cluster does not change much. This lack of variation occurs because the minimum rate that determines the rate of the cluster does not change significantly even if \(N\) increases. Likewise, the achievable rate improves in the order of LEACH, K-means, and non-SWIPT, and the proposed ENO with PS and TS shows the best performance.