## 5 Protocol Performance Evaluation
### Simulation Results Evaluation
\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 (\%)** \\
**the WSN field (m)** & **(\%)** & **(\%)** & **(\%)** \\ \hline
100 & \(+372.50\) & \(+11.14\) & \(-9.88\) \\
200 & \(+320.41\) & \(+23.46\) & \(-18.77\) \\
300 & 0 & \(+35.91\) & \(-26.23\) \\ \hline \end{tabular}
\end{table} 
Table 3: 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 ranges from 0.1 to 0.5 J. * The mean energy consumption is particularly decreased in all simulation scenarios examined, no matter what the position of the base station is. More precisely, the average reduction of the energy consumption is linearly increased with the increase of the distance between the base station and the WSN field. Hence, in the case where the base station is located far away from the WSN field the superiority of SHPER protocol over TEEN protocol becomes extraordinary. This result is really important since in real life applications it is both more common and desirable to have the base station located far away from the sensors. However, simulation results show that, even when the base station is located at its shortest distance from the network field, the reduction of the average energy consumption is still notable. The comparison of Table 2 and Table 3 leads to the creation of Table 4. This table arithmetically demonstrates the percentage enhancement offered by using SHPER which concerns the metrics of the first node depletion time, the last node depletion time and the average consumption, in the case that nodes have different initial energy opposed to the case that all nodes have the same initial energy. Many WSN hierarchical routing protocols are based on the assumption of an equal energy reserve for all nodes. However, in view of the fact that non uniform energy distribution is the normal case in real life applications, this basic assumption is apparently impractical. Table 4 makes it clear that the enhancement concerning all energy performance metrics which is provided by the SHPER protocol becomes even greater in the case of non uniform node energy distribution. Thus, the more unbalanced the energy distribution in a WSN is the most beneficial the use of SHPER becomes. Actually, this is a great advantage of SHPER since its algorithm is more realistic and effective. This enhances the belief that SHPER is indeed capable of being implemented in real test-bed environment in future work. Therefore, SHPER achieves both remarkable power conservation and increased scalability through energy efficient multihop routing. Thus, it succeeds the main target that the majority of routing protocols proposed for WSNs aim at, which is the reduction of power consumption. Actually, there are some schemes proposed that intent to address both energy efficiency and either security [29] or quality of service [30]. In the initial development of the SHPER protocol, no other network performance metric apart from energy efficiency has been taken into consideration. However, this is possible to be achieved. [PERSON] _et al_. have proposed a hybrid scheme for power and perceived QoS aware routing of multimedia content over Wireless Multimedia Sensor Networks [31]. This scheme comprises the advantages of both energy efficient routing and video packet scheduling resulting to increased efficiency in terms of power consumption along with received video distortion. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Increase of first** & **Increase of last** & **Decrease of mean** \\
**node depletion** & **node depletion** & **energy** \\
**time (\%)** & **time (\%)** & **consumption (\%)** \\ \hline
152.13 & 11.00 & 9.37 \\ \hline \hline \end{tabular}
\end{table}