## 4 Framework and Principles for VHO Scheme
When the maximum velocity of the MT is set to Vmax = 0.6 m/s and the probability of occurrence \(\varrho\) is 0.1 or 0.9 for RTAs, as illustrated in Figure 12a,c, both Ac-VHO and HA-VHO exhibit a higher average comprehensive QoE (QoE_all) compared to D-VHO and dynamic D-VHO. The QoE_all value of Ac-VHO reaches a high level, close to 4.0, when the MT movement is slow, and the RTA is active with high probability. However, when the MT's velocity is increased to 1.4 m/s, as shown in Figure 12b,d, HA-VHO experiences a significantly lower average QoE_all, while Ac-VHO continues to maintain a higher average QoE_all. These simulation results can be attributed to the following factors:

* The proposed scheme incorporates specific delay tolerance intervals and VHO dwell times for each of the three main RTA categories (video, VoIP, and web). This enables the scheme to make optimal switching decisions when the MT encounters different types of active RTA. * Ac-VHO dynamically sets the dwell time based on the average interval at which the RTA becomes active, accounting for the impact of RTA activity on QoE. This ensures that the scheme adapts to changes in the RTA's active status and optimizes the QoE accordingly. * The proposed scheme classifies RTAs into distinct types and sets RTA delay psychological tolerance intervals based on user groups with varying psychological tolerance levels. This personalized approach allows for handover decisions that align with the actual needs of each user, thereby enhancing the QoE when facing different types of RTA activity. ## 7 Conclusions

In this study, we present a novel multi-RTA type-based classification VHO scheme specifically tailored for indoor VLC heterogeneous networks. The scheme intelligently determines handover decisions based on the encountered RTA types, considering the movement of a single MT. To evaluate its effectiveness, we develop models for the MT movement, VLC link blocking, and active state of the different RTA types. The proposed scheme prioritizes efficient and high-capacity VLC links to maintain higher data rates during low recovery rates of VLC link outages. By incorporating MT movement and link state in the dwell time settings, the scheme ensures efficient handover decisions even with changing motion patterns, ensuring stable communication quality. Moreover, the scheme accounts for user-specific psychological tolerance times for RTA delays, setting the handover dwell time accordingly for each RTA type, aligning with the MT's actual needs. Performance evaluation against three other VHO schemes demonstrates that our proposed scheme, called Ac-VHO, significantly reduces unnecessary handovers and signaling costs, resulting in a higher combined QoE value. Figure 12: Average comprehensive QoE values of the various VHO schemes against VLC link recovery rate when obstructed for: (**a**) Vmax = 0.6 m/s and \(\rho\) = 0.1; (**b**) Vmax = 1.4 m/s and \(\rho\) = 0.1; (**c**) Vmax = 0.6 m/s and \(\rho\) = 0.9; (**d**) Vmax = 1.4 m/s and \(\rho\) = 0.9. Considering factors such as user mobility, link state, RTA activity variability, and multi-user environments, it is crucial to determine appropriate handover timing and intelligently predict these variables. Additionally, channel utilization and fairness are essential considerations. In our future work, we aim to incorporate machine learning algorithms to design predictive and adaptive handover algorithms. Furthermore, we will enhance the MAC layer access protocol to improve multi-user access fairness. Conceptualization, B.C. ; methodology, B.C. ; software, B.C. ; validation, B.C. and R.C. ; formal analysis, B.C. ; investigation, B.C. and R.C. ; resources, B.C. and R.C. ; data curation, S.Z. and P.Z. ; writing--original draft preparation, B.C. ; writing--review and editing, B.C. and S.Z. ; visualization, B.C. and Y.L. ; supervision, S.Z. and C.L. ; project administration, B.C. and S.Z. ; funding acquisition, Q.Z., R.C., D.C. and S.Z. All authors have read and agreed to the published version of the manuscript.