## 4 Framework and Principles for VHO Scheme
\begin{array}{ll}\min(\phi,t_{block})&if\;servicetype =\{\textit{`Video^{\prime}}\}\\ average(\phi,M_{CCI}(t))&if\;servicetype=\{\textit{`VoIP^{\prime}}\}\\ \max(\max(\varphi),M_{CCI}(t))&if\;servicetype=\{\textit{`Web^{\prime}}\}\\ \end{array} \right., \tag{16}\]  
In summary, we prioritize optimizing the user's psychological tolerance time to enhance the overall QoE in the presence of delays caused by various types of RTA. Following the pre-set residency durations, the MT performs the specified link residency. If the designated VHO dwell time elapses without the VLC link being restored, the MT promptly switches to the RF link while continuously monitoring the VLC link. Conversely, if the VLC link becomes accessible, the MT establishes the connection and proceeds with the VHO evaluation. The specific time-dwelling decisions for Ac-VHO are determined as Algorithm 1:```
Input:MT_coordinate_CCI_area;Blocking_state; Service_type; Output:T_dwell;  MT_coordinate is calculated from user random movement model;  Blocking_state is decided by the VLC link blocking model;  Service_type is decided by RTA active model of Equations (5) and (6); Initialize:  T_dwell(0) = 0;  Blocking_state(0) = 0;  Donate the set of timesteps as i for each i do if Blocking_state(t) = 0 ifMT_coordinate(t) is in CCI_area ifService_type(t) = 0 then  Set T_dwell(t) as Equation (12); else Service_type(t) is 'Video' or 'Web' or 'VolIP' then  Set T_dwell(t) as Equation (16);  end if end if else ifService_type(t) = 0 then  Set T_dwell(t) as Equation (11); else Service_type(t) is 'Video' or 'Web' or 'VolIP' then  Set T_dwell(t) as Equation (15);  end if end if endfor
```

**Algorithm 1**Time-dwelling handover decision of Ac_VHO

## 5 Basic Simulation Parameter Settings

This experimental simulation is based on Matlab. We use the network structure described in Section 3.1. The room dimensions are 6 \(\times\) 6 \(\times\) 3 m, and the VLC APs are strategically positioned in an overlapping square configuration to ensure optimal lighting and communication coverage. Specifically, nine VLC APs are deployed at the following coordinates: (1, 1, 3), (3, 1, 3), (5, 1, 3), (1, 3, 3), (3, 3, 3), (5, 3, 3), (1, 5, 3), (3, 5, 3), and (5, 5, 3). Additionally, there is an RF AP located at (3, 3, 3), providing signal coverage throughout the entire indoor space. The blocking probability model for the VLC link is characterized by a Poisson distribution with a parameter value of 0.4. As described in Section 3.3, the RTAs exhibit their respective activity patterns during the simulation. The multi-mode terminal in the simulation records the duration of each preceding outage period to calculate the average outage time and link recovery rate. Figure 8 illustrates the relationship between the blocking probability and the link recovery rate \(\beta\). As depicted in the graph, higher link recovery rates result in shorter average blocking times, leading to lower probabilities of blocking. When an MT enters the indoor environment, it undergoes random movement for a duration of T, as proposed in Section 3.2. To obtain accurate real-time position information on the MT, like a VLC indoor positioning system, we collect and record the motion position data. Based on the RWP-improved random movement model presented in Section 3.2, Figure 9 shows the random movement of the MT in a 6 \(\times\) 6 \(\times\) 3 m room over 100 s. The grey circular area represents the coverage area of the VLC APs. It is worth noting that in certain instances, the user may traverse into the overlapping CCI area, resulting in the degradation of VLC link quality. For VHO execution, we consider the handover delay that occurs when performing VHO, which is considered a normal random variable with a mean of 0.5 s and a variance of 0.1 s [3]. Moreover, each VHO incurs a certain handover cost. The specific parameters are shown in Table 3: Simulation parameters.