## 5 Protocol Performance Evaluation
### Simulation Results Evaluation  
The depletion of nodes over time is a typical measure of the energy efficiency of a routing protocol. Simulation tests show that SHPER protocol is particularly better than the TEEN protocol in retarding the time of node depletion, no matter what the distance between the base station and the nodes is. More precisely, the total of the network nodes remain alive for a period which is considerably longer in SHPER than in TEEN when the base station is located relatively close to the WSN field. After this initial period, during which the energy load is shared among the whole of the nodes, the worn out nodes start to deplete until a new level of resistance is reached i.e., the routing is performed by other sets of nodes which belong to other levels of the network hierarchy. This is carried on until all nodes deplete. However, the overall network lifetime is prolonged when compared to TEEN. As distance between the base station and the network field increases, nodes get more rapidly exhausted but due to the more energy efficient routing in SHPER the power conservation becomes even more evident. A more analytical description of the effects of the use of the two protocols in comparison may be derived by focusing on the first node depletion time, the last node depletion time and the average energy consumption. Table 2 summarizes arithmetically the simulation results which are illustrated in Figure 7, Figure 8 and Figure 9, concerning these three metrics in the case of uniform energy distribution. Figure 15: Percentage of average decrease of energy consumption in SHPER opposed to TEEN over the distance of the base station from the WSN field (\(Er_{i}(0)\!\in\! [0.1,\!0.5]\) J). In a similar way, Table 3 summarizes arithmetically the percentage enhancement caused by the use of SHPER instead of TEEN concerning the metrics of the first node depletion time, the last node depletion time and the average consumption in the case of non uniform energy distribution. The examination of the data in Table 2 and Table 3 leads to the inference that the use of SHPER routing protocol instead of TEEN has the following consequences:  
1. The average time that the first node depletes is greatly increased when the base station is located relatively close to the WSN field. The extension of this time becomes gradually smaller as the distance between the base station and the WSN field increases. For long distances, there is not any extension of the first node depletion time, i.e., due to the remote location of the base station the first node which transmits to the base station becomes instantly exhausted. However, even in this case, the use of SHPER offers the accomplishment of more rational routing within the network thus leading to the retardation of the energy depletion. 2. The average time that the last node depletes is exceptionally prolonged when the base station is located far away from the WSN field. The extension of this time becomes gradually smaller as the distance between the base station and the WSN field decreases. Actually, this is an absolutely normal after-effect of the corresponding great increase of the time the first node depletes in shorter distances. However, even in the case that the base station is located at its shortest distance from the network field, simulation results show that the extension of the overall network lifetime is still remarkable. \begin{table}
\begin{tabular}{c c c c} \hline
**Distance between the base station and the depletion time** & **First node depletion time** & **Last node depletion time** & **Mean energy consumption (\%)** \\
**WSN field (m)** & **(\%)** & **(\%)** & **(\%)** \\ \hline
100 & \(+148.09\) & \(+9.90\) & \(-8.89\) \\
200 & \(+126.73\) & \(+20.53\) & \(-16.69\) \\
300 & 0 & \(+33.09\) & \(-24.60\) \\ \hline \end{tabular}
\end{table} 
Table 2: Percentage of change in WSN performance by the use of SHPER opposed to TEEN over the distance of the base station from the sensor field when the initial node energy is set to 0.5 J.