## 4 Framework and Principles for VHO Scheme
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Room size & 6 m \(\times\) 6 m \(\times\) 3 m \\ The number of VLC APs & 9 \\ Simulation time & 7200 s \\ Number of iterations & 2000 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulation parameters. Figure 8: The blocking probability with link recovery rate \(\beta\). Figure 9: Random Movement of a Single MT over 100 s.

When assessing the QoE for distinct scenarios of RTAs, careful consideration must be given to the configuration of SINR values. The calculation of the overall average \(QoE\) is determined through the combined utilization of Equations (6)-(8):

\[QoE\_all_{average}=Average([MOS_{Vilde},MOS_{VilP},MOS_{VilP}]), \tag{17}\]

We assume a uniform data rate for the VLC network across its coverage area, except in the CCI regions where the received VLC signal experiences a significantly low SINR and a high BER. Similarly, we assume a uniform data rate for the RF network across its coverage area [4]. ## 6 Simulation Results and Comparative Analysis

In our study, we compare our proposed scheme with three existing time-resident VHO schemes, namely, HA-VHO [3], dynamic D-VHO [4], and D-VHO. We analyze the variations in average data rate, handover signal cost, and integrated average QoE as the link recovery rate increases. These analyses are performed for different MT mobility rates and probabilities of RTA activity. ### Average VHO Signaling Cost Comparison

The execution of VHO involves a signaling cost, which reflects the overhead incurred during the handover process. A high signaling cost indicates a significant ping-pong effect caused by frequent back-and-forth handovers. The combined signaling cost is computed by multiplying the number of VHOs with the signaling cost associated with a single VHO. Figure 10c,d demonstrate that all of the analyzed VHO schemes exhibit a wait-for-VLC-link-recovery strategy prior to performing handover. Therefore, as the link recovery rate increases, the signaling costs for these schemes decrease. This trend suggests that the number of required handovers decreases, resulting in a reduced signaling overhead. When the maximum movement speed of the MT (Vmax) is set to 0.6 m/s and the RTA activity probability is set to 0.1 and 0.9, respectively, the average signaling cost of Ac-VHO is lower than that of HA-VHO. Similarly, the signaling cost of HA-VHO is lower than that of dynamic D-VHO and D-VHO schemes when the link recovery rate exceeds 0.4/s. Next, we set the maximum movement speed of the MT to 1.4 m/s and compare the signaling costs generated for real-time applications with occurrence probabilities (\(\rho\)) of 0.1 and 0.9. Figure 10d illustrates that when the recovery rate surpasses 0.3/s, the signaling \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline The coverage radius of a VLC AP & \(\sqrt{2}\) m \\ Maximum distance in the CCI region L & 0.83 \\ MT at the maximum speed of rapid movement Vmax & 0.6 m/s, 1.4 m/s, \\ MT movement duration t & 2–10 s \\ The MT movement pause tw & 0–10 s \\ The MT movement direction range & 0–2\(\pi\) radians \\ The blocking rate of the VLC LoS link & 0.4/s \\ Disruption recovery rate of the VLC link \(\beta\) & 0.2–2/s \\ Data rate of the VLC network & 1 Gbps \\ Data rate of the RF channel & 600 Mbps \\ VHO signaling costs & 418 J \\ Average handover delay & 0.5 s \\ Static dwell time & 1 s \\ RTA active probabilities \(\rho\) & 0.1, 0.9 \\ VoIP RTA active probabilities \(\sigma\) & 0.2 \\ Average SINR when connected to VLC & 33 dB \\ Average SINR when connected to RF & 25 dB \\ Average SINR when connected to VLC & 3 dB \\ Average SINR when VLC LoS link is blocked & –20 dB \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._cost of Ac-VHO is lower than the other three time-resident VHO schemes. Since Ac-VHO mainly makes VHO decisions for different types of RTA, it maintains an overall smooth and low signaling cost when faced with an RTA activity probability of only 0.1, as shown in Figure 10a,b.