# Designing a Vertical Handover Algorithm for Security-Constrained Applications
## 3 Design of the Proposed Algorithm  
In Section 2, many recent VHO research works have been considered [4; 8; 17; 18; 23; 25; 34; 36; 39; 43; 44; 45; 46; 47; 48; 49; 50; 51]. It was noticed that the security aspect of triggering VHO has not been adequately studied, particularly when an MU plans to utilize a payment application. Therefore, we present a comprehensive performance evaluation for a new secure VHO algorithm, taking into account the following critical issues: VHO security; VHO packet loss; VHO delay; and VHO throughput. We consider two types of RAT, namely Wi-Fi (access point: AP) and UMTS (base station: BS), as shown in Table 2 and Figure 2. There are two types of thresholds, namely the distance threshold and speed threshold. However, our system is not compatible with high-speed trains and is only confined within 4G, 5G, and Wi-Fi technology. 1. Distance threshold: Th\({}_{\text{BS}}\) is 1 km for BS and Th\({}_{\text{AP}}\) is 100 m for AP. 2. Speed threshold: Th\({}_{\text{pd}}\) is 1-3 m/s for pedestrians and Th\({}_{\text{vh}}\) is 10 m/s for the vehicle. _BS to AP_  
* If the MU reaches Th\({}_{\text{BS}}\) and/or Th\({}_{\text{pd}}\) and switches to a payment application, then VHO is triggered to an available AP to keep the sensitive session ongoing. It should be therefore considered MU's responsibility. * If the MU reaches Th\({}_{\text{BS}}\) and/or Th\({}_{\text{pd}}\) and does not switch to a payment application, then VHO is triggered to an available AP to keep the non-sensitive session ongoing. It should be considered by the algorithm dynamically, without MU intervention. * If the MU does not reach Th\({}_{\text{BS}}\),Th\({}_{\text{pd}}\) and switches to a payment application, then triggering VHO is not required. * If the MU does not reach the Th\({}_{\text{BS}}\),Th\({}_{\text{pd}}\) and does not switch to a payment application, then triggering VHO is not required. _AP to BS_  
* If the MU reaches Th\({}_{\text{AP}}\) and/or Th\({}_{\text{vh}}\) and switches to a payment application, then VHO is triggered to an available BS to secure and keep the sensitive session ongoing. It should be considered by the algorithm dynamically, without MU intervention. * If the MU reaches Th\({}_{\text{AP}}\) and/or Th\({}_{\text{vh}}\) and does not switch to a payment application, then VHO is triggered to an available BS to keep the non-sensitive session ongoing. It should be considered by the algorithm dynamically, without MU intervention. * If the MU does not reach Th\({}_{\text{AP}}\), Th\({}_{\text{vh}}\) and does not switch to a payment application, then VHO is triggered to an available BS to secure the ongoing sensitive session. It should be considered by the algorithm dynamically, without MU intervention. * If the MU does not reach the Th\({}_{\text{AP}}\), Th\({}_{\text{vh}}\) and does not switch to a payment application, then triggering VHO is not required. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Reference** & **Failed** & **VHO** & **Frequent** & **VHO** & **VHO Packet** \\  & **Handovers** & **Delay** & **VHOs** & **Throughput** & **Loss** \\ \hline
[8] & n/a & \(\surd\) & n/a & \(\surd\) & \(\surd\) \\
[17] & n/a & n/a & n/a & \(\surd\) & n/a \\
[36] & n/a & n/a & n/a & n/a & \(\surd\) \\
[39] & n/a & \(\surd\) & n/a & \(\surd\) & \(\surd\) \\
[43] & n/a & \(\surd\) & \(\surd\) & \(\surd\) & n/a \\
[44] & n/