# Energy Saving in Wireless Sensor Networks via LEACH-Based, Energy-Efficient Routing Protocols
## 5 Comparative Performance Evaluation
### Presentation and Evaluation of Simulation Tests  
In what follows in this section, the simulation tests conducted are described, while the results of these tests are both presented and discussed. Totally, five simulation scenarios were examined. The metrics evaluated in all of them are the number of sensor nodes remaining alive and the total number of data bits that are transmitted by the network nodes to the base station per simulation round. The parameters whose values remained unchanged in all scenarios examined are presented in Table 1, along with their corresponding values. Likewise, the parameters whose values varied in these scenarios examined are presented in Table 2 along with their corresponding values. In the first three scenarios simulated, the protocol performance was evaluated in denser and sparser network configurations, and the influence of the density of the nodes was investigated, as well as the location of the base station within the field of interest. Specifically, in the first scenario studied, it was supposed that the WSN under consideration comprises of a base station located at position (100, 100) along with 100 nodes. It was found that T-LEACH\({}_{\text{SAS}}\), considering the depletion of last living node, achieves an extension of network lifetime by 575% when compared to LEACH and by 51.3% when compared to T-LEACH. Figure 3 illustrates the number of the network nodes that remain alive per simulation round. \begin{table}
\begin{tabular}{c c} \hline
**Parameter** & **Value** \\ \hline Network size & 200 m \(\times\) 200 m \\ \hline Node initial energy & 0.5 J \\ \hline Tx/Rx circuitry dissipation (\(E_{Tx\text{-}dec}/E_{Rx\text{-}dec}\)) & 50 nJ/bit \\ \hline Multi-path amplifier energy (\(\varepsilon_{\text{mp}}\)) & 0.0013 pJ/bit/m\({}^{4}\) \\ \hline Free-space amplifier energy (E\({}_{\text{fs}}\)) & 0.01 nJ/bit/m\({}^{2}\) \\ \hline Data packet size & 4000 bits \\ \hline Data aggregation energy & 5 nJ/bit \\ \hline Desired percentage of cluster heads (\(P\)) & 0.1 \\ \hline \end{tabular}
\end{table} 
Table 1: Simulation characteristics that are common in all scenarios examined. \begin{table}
\begin{tabular}{c c c} \hline
**Scenario No.** & **No. of Nodes** & **Base Station Position** \\ \hline
1 & 100 & (100, 100) \\ \hline
2 & 50 & (100, 100) \\ \hline
3 & 200 & (100, 100) \\ \hline
4 & 100 & (0, 0) \\ \hline
5 & 100 & (100, 220) \\ \hline \end{tabular}
\end{table} 
Table 2: Simulation characteristics that are scenario-dependent. Also, it was found that the total volume of data transmitted to the base station by using T-LEACH\({}_{\text{SAS}}\) are increased by 198% and 14.5% when compared to that achieved when using LEACH and T-LEACH, respectively. Figure 4 illustrates the total volume of data transmitted per simulation round in the first simulation scenario. Similarly, in the second scenario studied, it was supposed that the WSN under consideration comprises of a base station located at position (100, 100) along with 50 nodes. It was found that T-LEACH\({}_{\text{SAS}}\), considering the depletion of last living node, achieves extension of network lifetime by 393% when compared to LEACH and by 46.3% when compared to T-LEACH. Figure 5 illustrates the number of the network nodes that remain alive per simulation round. Figure 4: Total data bits transmitted to the base station per round in the first scenario for LEACH, T-LEACH, and T-LEACH\({}_{\text{SAS}}\). Figure 3: Nodes alive per round in the first scenario for LEACH, T-LEACH, and T-LEACH\({}_{\text{SAS}}\). Moreover, it was found that the total volume of data transmitted to the base station by using T-LEACH\({}_{\text{SAS}}\) increased by 175% and 14.1% when compared to that achieved when using LEACH and T-LEACH, respectively. Figure 6 illustrates the total volume of data transmitted per simulation round in the second simulation scenario. Likewise, in the third scenario studied, it was supposed that the WSN under consideration comprises of a base station located at position (100, 100) along with 200 nodes.