# Vertical Handover Algorithm for WBANs in Ubiquitous Healthcare with Quality of Service Guarantees
## 5 Evaluation and Discussion of the Results
### Simulation Results
#### 5.2.4 Energy Consumption Efficiency  
To evaluate the effectiveness of our proposed approach in term of the energy aspect, we first calculate and analyze the additional energy consumption of a handover execution in the total energy consumption of each application. We then compare the energy consumption efficiency of three handover approaches. The total energy consumption of wireless networks \(E_{Wifi,UIMTS,LTE}\) (mJ) can be computed as follows:  
\[E_{Wifi,UIMTS,LTE}(\text{mJ})=\sum\Bigl{(}E_{pro}+E_{transfer}+E_{tail}+E_{ idle}\Bigr{)}_{Wifi,UIMTS,LTE}+E_{handover} \tag{13}\]  
Furthermore, the additional energy consumption of a handover execution \(E_{handover}\) can be calculated as follows:  
\[E_{handover}=E_{turn-on}+E_{associating}+E_{promotion\ state}+E_{turn-of} \tag{14}\]  
where \(E_{turn-on}\), \(E_{associating}\), \(E_{promotionstate}\) and \(E_{turn-off}\) and are the energy consumptions of the states: turn-on the new network interface, discovering, associating to the new network, promotion state to establish a new connection and turn-off the current network interface, respectively [35]. Moreover, the promotion energy consumption (\(E_{pro}\)), tail energy consumption (\(E_{tail}\)) and idle energy consumption (\(E_{alle}\)) are measured as shown in Table 7[35]. Usually, the transfer energy occupies a large part of the total energy consumption. It depends mainly on the transmission time \(t\) (seconds) and the up/downlink throughput (Mbps). The transfer energy \(E_{transfer}\) for WiFi, UMTS and LTE is computed as follows [36]:  
\[\left\{ \begin{array}{l}E_{Transfer,WiFi}(\text{mJ})=\{283\times throughput \ (\text{Mbps})+132\}\times t\\ E_{Transfer,UIMTS}(\text{mJ})=\{869\times throughput\ (\text{Mbps})+818\}\times t\\ E_{Transfer,LTE}(\text{mJ})=\{438\times throughput\ (\text{Mbps})+1288\}\times t \end{array} \right. \tag{15}\]  
From Equations (13)-(15), we can easily calculate the total energy consumption for each application. The energy consumption efficiency is calculated as follows:  
\[E(\%)=\frac{E_{\text{max}}-\sum(E_{Wifi,UIMTS,LTE}+E_{handover})}{E_{\text{ max}}}\times 100 \tag{16}\]  
where \(E_{\text{max}}\) is the maximum energy consumption. For example, in the scenario simulation in Section 5.2.2, we assume that the handover to the LTE is executed immediately after the default connection to the WiFi network. Therefore, the total energy consumption of the LTE is the maximum consumption in this case. We assume that the simulation scenario is similar to Section 5.2.2 (mobile WBANs have an initial connection to AP and move in the area with 0.5 m/s speed; however, the running application is always \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \multicolumn{2}{c}{**WiFi**} & \multicolumn{2}{c}{**UMTS**} & \multicolumn{2}{c}{**LTE**} \\ \cline{2-7}  & **Power (mJ/s)** & **Duration (s)** & **Power (mJ/s)** & **Duration (s)** & **Power (mJ/s)** & **Duration (s)** \\ \hline WiFi turn on & 24 & - & 24 & - & 24 & - \\ WiFi turn off & 29 & - & 29 & - & 29 & - \\ Associating & 120 & 2 & 250 & 1 & 250 & 1 \\ Promotion & 124.4 & 0.08 & 659.4 & 0.058 & 1210.7 & 0.026 \\ Tail & 119.3 & 0.24 & 601.3 & 0.824 & 1060 & 0.1 \\ Idle on & 77.2 & 0.0076 & 374.2 & 0.055 & 594.3 & 0.0432 \\ Idle off & 0 & - & 0 & - & 0 & - \\ Idle cycle & - & 0.308 & - & 5.112 & - & 1.2802 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Network ranking order with respect to the ranking values. a normal traffic type during the simulation time). The average upload throughput is required for the setup, which is equal to 400 Kbps. As analyzed above, the two facts that mainly effect the total energy consumption of each application are the selected network to transmit data and the number of handovers. Figure 6a proves that the energy consumption of the WiFi, UMTS, and LTE networks are significantly different.